{"id":161406,"date":"2026-07-22T12:40:59","date_gmt":"2026-07-22T12:40:59","guid":{"rendered":"https:\/\/pabau.com\/?p=161406"},"modified":"2026-08-18T12:42:51","modified_gmt":"2026-08-18T12:42:51","slug":"icd-10-code-d66","status":"publish","type":"post","link":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/","title":{"rendered":"ICD-10 Code D66: Hereditary factor VIII deficiency (Hemophilia A)"},"content":{"rendered":"\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"MedicalWebPage\",\"headline\":\"ICD-10 Code D66: Hereditary factor VIII deficiency (Hemophilia A)\",\"description\":\"ICD-10 Code D66 (Hereditary factor VIII deficiency) is a billable 2026 ICD-10-CM code for Hemophilia A. Covers applicable-to inclusions, excludes notes, related codes, CPT pairings, and coding guidance.\",\"url\":\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-d66\/\",\"audience\":{\"@type\":\"MedicalAudience\",\"audienceType\":\"Clinician\"},\"reviewedBy\":{\"@type\":\"Person\",\"name\":\"Dr Vanja Kitanova\",\"jobTitle\":\"Medical Reviewer\",\"affiliation\":{\"@type\":\"Organization\",\"name\":\"Pabau\"},\"knowsAbout\":[\"Medical Coding\",\"Clinical Documentation\",\"Healthcare Billing\",\"Clinical Safety\"],\"sameAs\":\"https:\/\/pabau.com\/blog\/author\/vanja\/\"},\"datePublished\":\"2026-07-07\",\"dateModified\":\"2026-07-07\"}<\/script>\n\n\n        <div id=\"key_takeaways\">\n            <div class=\"header\">\n                                    <img decoding=\"async\" src=\"https:\/\/pabau.com\/wp-content\/uploads\/2025\/12\/Key-Takeaways-Icon.svg\" alt=\"Key Takeaways\" height=\"42\" width=\"42\">\n                                <h3>Key Takeaways<\/h3>\n            <\/div>\n            <div class=\"list\">\n                                                            <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#3D3D46\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p>ICD-10 Code D66 is a billable ICD-10-CM code for hereditary factor VIII deficiency, effective October 1, 2025 (FY2026)<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#3D3D46\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p>D66 covers Hemophilia A, classical hemophilia, Hemophilia NOS, and deficiency factor VIII with functional defect<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#3D3D46\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p>Excludes1 restriction: never code D66 alongside D68.0 (factor VIII deficiency with vascular defect \/ von Willebrand disease)<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#3D3D46\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p>Pabau&rsquo;s claims management software supports accurate ICD-10 code entry and reduces claim denials tied to coding errors<\/p>\n                        <\/div>\n                                                <\/div>\n        <\/div>\n    \n\n\n<p class=\"wp-block-paragraph\">ICD-10 Code D66 is a billable ICD-10-CM code for hereditary factor VIII deficiency, more commonly known as Hemophilia A. It covers classical hemophilia, Hemophilia NOS, and deficiency factor VIII with a functional defect. Its one Excludes1 restriction, against D68.0, is what trips up most claims.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This reference covers the 2026 billable status, applicable-to inclusions, Excludes1 and Excludes2 notes, the D65-D69 hierarchy, related codes, CPT pairings, the ICD-9 crosswalk, and documentation guidance.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\">\n<div class=\"wp-block-embed__wrapper\">\n<iframe title=\"ICD-10 Revisions: Stay Updated or Fall Behind\" width=\"800\" height=\"450\" src=\"https:\/\/www.youtube.com\/embed\/bqAyb-BCA0w?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div>\n<\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">ICD-10 Code D66: Definition, billable status, and 2026 edition details<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">ICD-10 Code D66 is a billable and specific ICD-10-CM code for hereditary factor VIII deficiency. It is valid for reimbursement purposes and can be used as a principal or secondary diagnosis on a claim. The 2026 edition of D66 became effective on October 1, 2025, under the CMS <a href=\"https:\/\/www.cms.gov\/medicare\/coding-billing\/icd-10-codes\" target=\"_blank\" rel=\"nofollow noopener\">ICD-10-CM update cycle<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Primary care and general practice software need to recognize D66 accurately too, since these visits often trigger the initial hematology referral.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Because D66 is a terminal (leaf-level) code, no further specificity is required. Coders do not need to select a sub-code beneath D66.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">That said, the absence of a sub-code structure does not mean documentation requirements are lighter. Payers routinely audit severity characterization and clinical context against what the physician has documented in the chart. Using claims management software that validates ICD-10 entries at the point of submission helps catch these mismatches before a denial is issued.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/cdn.pabau.com\/cdn\/attachments\/pulse\/content-engine\/diagnostic_codes\/icd-10-code-d66\/automate-claims-through-healthcode.webp\" alt=\"Automate claims and billing with Pabau\"\/><figcaption class=\"wp-element-caption\"><em>Automate claims and billing with Pabau<\/em><\/figcaption><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n\n\n<table style=\"width:100%;border-collapse:separate;border-spacing:0;border-radius:12px;overflow:hidden;font-size:15px;line-height:1.5;margin:1.5em 0 2em;box-shadow:0 2px 12px rgba(0,0,0,0.08)\">\n<thead>\n<tr>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Field<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Detail<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Code<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D66<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Official description<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Hereditary factor VIII deficiency<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Code type<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Billable \/ Specific (terminal code)<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Chapter category<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D65-D69: Coagulation defects, purpura, and other hemorrhagic conditions<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Block<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D50-D89: Diseases of the blood and blood-forming organs<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Effective date (FY2026)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">October 1, 2025<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Valid fiscal year<\/td>\n<td style=\"padding:12px 16px;color:#374151\">2026 (October 1, 2025 through September 30, 2026)<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">ICD-9-CM predecessor<\/td>\n<td style=\"padding:12px 16px;color:#374151\">286.0 (approximate match; verify via CMS GEM crosswalk files)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<h2 class=\"wp-block-heading\">Applicable to: Synonyms and inclusions for ICD-10 Code D66<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The Applicable To note in the ICD-10-CM tabular list tells coders which clinical terms map to D66. Any of the following diagnoses, when documented by the treating physician, supports coding to D66 as verified by the <a href=\"https:\/\/www.aapc.com\/codes\/icd-10-codes-range\/\" target=\"_blank\" rel=\"nofollow noopener\">AAPC ICD-10-CM code reference<\/a>.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><strong>Classical hemophilia<\/strong> (also called Hemophilia A; the most commonly used clinical term)<\/li><li><strong>Hemophilia A<\/strong> (congenital; the preferred modern terminology in hematology)<\/li><li><strong>Hemophilia NOS<\/strong> (not otherwise specified; use when the physician documents hemophilia without specifying type)<\/li><li><strong>Deficiency factor VIII (with functional defect)<\/strong> (specifically when the FVIII protein is present but non-functional rather than absent)<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u00ab\u00a0Hemophilia NOS\u00a0\u00bb is only appropriate when the physician&rsquo;s documentation does not specify type A or type B. If the record clearly identifies Hemophilia B, <a href=\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-d67\/\">D67<\/a> is the correct code instead.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Defaulting to D66 when type is unspecified, but the clinical context points strongly to factor IX involvement, is an error that auditors flag during post-payment review.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Excludes1 and Excludes2 notes for D66<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The Excludes1 restriction on D66 is where most coding errors originate. Excludes1 means the two conditions cannot coexist in the same patient at the same time, so the excluded code can never be reported with D66 on the same claim.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Excludes1: D68.0<\/strong> (factor VIII deficiency with vascular defect) is the code for von Willebrand disease when it also involves factor VIII. If the physician documents a factor VIII deficiency caused by a vascular or platelet adhesion problem, the hallmark of von Willebrand disease, the correct code is D68.0, not D66.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Coding both D66 and D68.0 on the same claim is a CMS-level edit violation that triggers automatic denial. Maintaining HIPAA-compliant coding workflows requires that coders verify the physician&rsquo;s documented mechanism before assigning D66.<\/p>\n\n\n\n<table style=\"width:100%;border-collapse:separate;border-spacing:0;border-radius:12px;overflow:hidden;font-size:15px;line-height:1.5;margin:1.5em 0 2em;box-shadow:0 2px 12px rgba(0,0,0,0.08)\">\n<thead>\n<tr>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Scenario<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Correct code<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Reason<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Physician documents Hemophilia A, no vascular component<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D66<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Straightforward Applicable To match<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Physician documents factor VIII deficiency with vascular defect (von Willebrand disease)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D68.0 only<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Excludes1 &#8211; D66 and D68.0 cannot appear on the same claim<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Physician documents Hemophilia NOS, type unspecified<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D66<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Hemophilia NOS is an Applicable To inclusion for D66<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Physician documents Hemophilia B (factor IX deficiency)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D67<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D66 is for factor VIII only; D67 covers factor IX deficiency<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<p class=\"wp-block-paragraph\">There are no Excludes2 notes on D66. Excludes2 would signal conditions that are related but separately reportable; that situation does not apply here.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Blood and immune diagnoses rest on lab results, and <a href=\"https:\/\/pabau.com\/features\/medical-lab-software\/\">medical lab software<\/a> moves orders and results without re-entry.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Clinical overview: Hereditary factor VIII deficiency (Hemophilia A)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Hereditary factor VIII deficiency is a congenital bleeding disorder caused by deficient or dysfunctional clotting factor VIII. The condition is X-linked recessive, which means it primarily affects males while females are typically carriers. Clinical severity depends on residual factor VIII activity levels in plasma.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Documenting severity in the chart is critical, even though ICD-10 Code D66 does not have sub-codes for mild, moderate, or severe disease. Payers use the severity characterization in the physician&rsquo;s note to validate medical necessity for high-cost factor replacement therapies.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A chart that simply states \u00ab\u00a0hemophilia A\u00a0\u00bb without a severity indicator can trigger a medical necessity denial, even when D66 is correctly coded. Structured patient records that prompt for severity documentation at the point of care reduce this risk.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/cdn.pabau.com\/cdn\/attachments\/pulse\/content-engine\/diagnostic_codes\/icd-10-code-d66\/comprehensive-patient-records.webp\" alt=\"Comprehensive patient records\"\/><figcaption class=\"wp-element-caption\"><em>Comprehensive patient records<\/em><\/figcaption><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n\n\n<p class=\"wp-block-paragraph\">Common signs include spontaneous bleeding into joints (hemarthrosis), soft-tissue bleeding, and prolonged bleeding after trauma or surgery. Diagnosis typically rests on factor VIII activity assays, APTT measurement, and genetic testing in family-history cases.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Recurrent hemarthrosis can cause lasting joint damage. Treatment agents commonly used alongside a D66 diagnosis include:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><strong>Factor VIII concentrates<\/strong>: recombinant products including Advate, Helixate, and Kogenate<\/li><li><strong>Emicizumab (Hemlibra)<\/strong>: a subcutaneous bispecific antibody that bridges factors IXa and X, used for prophylaxis including in patients with inhibitors<\/li><li><strong>Desmopressin (DDAVP)<\/strong>: for mild Hemophilia A where residual factor VIII levels are sufficient to respond<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Digital intake forms that capture family history of bleeding disorders and prior factor replacement therapy improve the quality of the initial clinical record, which in turn supports stronger coding specificity on every subsequent encounter.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/cdn.pabau.com\/cdn\/attachments\/pulse\/content-engine\/diagnostic_codes\/icd-10-code-d66\/customizable-consent-and-intake-forms.webp\" alt=\"Customizable consent and intake forms\"\/><figcaption class=\"wp-element-caption\"><em>Customizable consent and intake forms<\/em><\/figcaption><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n\n\n<h2 class=\"wp-block-heading\">ICD-10 Code D66 within the coagulation defects code hierarchy<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Understanding where D66 sits in the ICD-10-CM tabular structure helps coders navigate adjacent categories correctly. The full hierarchy for D66 is shown below. This mirrors the structure in the official <a href=\"https:\/\/icd10cmtool.cdc.gov\/\" target=\"_blank\" rel=\"nofollow noopener\">CDC\/NCHS ICD-10-CM web tool<\/a>, which is the primary reference for US code lookups.<\/p>\n\n\n\n<table style=\"width:100%;border-collapse:separate;border-spacing:0;border-radius:12px;overflow:hidden;font-size:15px;line-height:1.5;margin:1.5em 0 2em;box-shadow:0 2px 12px rgba(0,0,0,0.08)\">\n<thead>\n<tr>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Level<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Code \/ Range<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Description<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Chapter<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D50-D89<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Block<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D65-D69<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Coagulation defects, purpura, and other hemorrhagic conditions<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">Category<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D66<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Hereditary factor VIII deficiency (terminal, billable)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<p class=\"wp-block-paragraph\">The D65-D69 block covers a cluster of related hemorrhagic and coagulation disorders. Coders working in hematology or hemophilia treatment centers (HTCs) encounter most of these codes regularly.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D66 relates closely to adjacent codes such as D67 (factor IX deficiency) and D68 (other coagulation defects). Disseminated intravascular coagulation is coded separately under D65. The same specificity and exclusion-note principles that govern D66 apply across the entire D65-D69 range.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Related ICD-10 codes for coagulation defects<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">D66 is rarely the only code a hematology coder needs to know. The table below covers the codes most frequently encountered alongside or instead of D66, with guidance on when to use each.<\/p>\n\n\n\n<table style=\"width:100%;border-collapse:separate;border-spacing:0;border-radius:12px;overflow:hidden;font-size:15px;line-height:1.5;margin:1.5em 0 2em;box-shadow:0 2px 12px rgba(0,0,0,0.08)\">\n<thead>\n<tr>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Code<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Description<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">When to use instead of D66<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">D66<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Hereditary factor VIII deficiency (Hemophilia A)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Primary code when physician documents Hemophilia A, classical hemophilia, or Hemophilia NOS without vascular component<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">D67<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Hereditary factor IX deficiency (Hemophilia B, Christmas disease)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">When physician documents Hemophilia B or factor IX deficiency; never substitute D66 for D67<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">D68.0<\/td>\n<td style=\"padding:12px 16px;color:#374151\">von Willebrand disease (factor VIII deficiency with vascular defect)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">When factor VIII deficiency is due to vascular\/platelet adhesion (von Willebrand); Excludes1 from D66<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">D68<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Other coagulation defects<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Parent category; sub-codes (D68.0-D68.9) cover acquired or other hereditary clotting factor deficiencies not classified under D66 or D67<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">D65<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Disseminated intravascular coagulation (DIC)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Acquired, not hereditary; completely separate disease process from D66<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n        <div id=\"book_a_demo\">\n            <div class=\"left-side\">\n                <div class=\"logo\">\n                    <img decoding=\"async\"\n                        src=\"https:\/\/pabau.com\/wp-content\/uploads\/2026\/01\/Logo.svg\"\n                        alt=\"Logo\"\n                        loading=\"lazy\"\n                    \/>\n                <\/div>\n\n                <h3 class=\"heading\">\n                    Reduce coding errors before claims go out                <\/h3>\n\n                <p class=\"description\">\n                    Pabau&rsquo;s automated billing workflows flag ICD-10 mismatches and missing documentation before submission, so your team spends less time on rework and more time on patient care.                <\/p>\n\n                <div class=\"button-group\">\n                    <a href=\"\/book-demo\/\" class=\"btn btn-scale-effect btn-cta-color btn-md\">\n                        <span class=\"btn-text\">Book a demo<\/span>\n                        <div class=\"btn-icon btn-icon-right\" aria-hidden=\"true\">\n                            <svg\n                                width=\"14\"\n                                height=\"12\"\n                                viewBox=\"0 0 14 12\"\n                                fill=\"none\"\n                                xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\n                            >\n                                <path\n                                    d=\"M0.75 4.77295C0.335786 4.77295 0 5.10874 0 5.52295C0 5.93716 0.335786 6.27295 0.75 6.27295V5.52295V4.77295ZM13.2803 6.05328C13.5732 5.76039 13.5732 5.28551 13.2803 4.99262L8.50736 0.219648C8.21447 -0.073245 7.73959 -0.073245 7.4467 0.219648C7.15381 0.512542 7.15381 0.987415 7.4467 1.28031L11.6893 5.52295L7.4467 9.76559C7.15381 10.0585 7.15381 10.5334 7.4467 10.8263C7.73959 11.1191 8.21447 11.1191 8.50736 10.8263L13.2803 6.05328ZM0.75 5.52295V6.27295L12.75 6.27295V5.52295V4.77295L0.75 4.77295V5.52295Z\"\n                                    fill=\"currentColor\"\n                                ><\/path>\n                            <\/svg>\n                        <\/div>\n                    <\/a>\n                <\/div>\n            <\/div>\n\n            <div class=\"right-side\">\n                <img decoding=\"async\"\n                    src=\"https:\/\/pabau.com\/wp-content\/uploads\/2026\/01\/Home-Page-Concept-4.webp\"\n                    alt=\"Pabau claims management dashboard\"\n                    loading=\"lazy\"\n                \/>\n            <\/div>\n        <\/div>\n        \n\n\n<h2 class=\"wp-block-heading\">CPT codes commonly billed with ICD-10 Code D66<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">CPT codes are procedure-level; D66 is a diagnosis-level code. The table below lists CPT codes frequently paired with D66 on hematology claims. These pairings are reference information only. Actual billing must reflect the documented service and comply with payer-specific coverage policies. Hematology EMR workflows that surface common CPT-to-diagnosis pairings at scheduling reduce the manual lookup burden for coding staff.<\/p>\n\n\n\n<table style=\"width:100%;border-collapse:separate;border-spacing:0;border-radius:12px;overflow:hidden;font-size:15px;line-height:1.5;margin:1.5em 0 2em;box-shadow:0 2px 12px rgba(0,0,0,0.08)\">\n<thead>\n<tr>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">CPT code<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Description<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Common context with D66<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">85240<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Clotting factor VIII (AHF), one stage<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Factor VIII activity assay used to confirm diagnosis and establish severity<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">85730<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Thromboplastin time, partial (APTT)<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Screening lab used in the diagnostic workup for hemophilia<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">96365<\/td>\n<td style=\"padding:12px 16px;color:#374151\">IV infusion for therapy\/prophylaxis\/diagnosis, initial<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Factor VIII concentrate infusion administration<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">96366<\/td>\n<td style=\"padding:12px 16px;color:#374151\">IV infusion for therapy\/prophylaxis\/diagnosis, each additional hour<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Add-on to 96365 for extended infusion sessions<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">99214<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Office or other outpatient visit, moderate medical decision making<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Hematology E&amp;M for established hemophilia A management visits<\/td>\n<\/tr>\n<tr style=\"border-bottom:1px solid #E8ECF0;background:#F9FAFB\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">96372<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Therapeutic, prophylactic, or diagnostic injection, subcutaneous or intramuscular<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Used when emicizumab (Hemlibra) is administered subcutaneously in-office<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n        <div id=\"pro_tip\">\n            <div class=\"img\">\n                <svg width=\"42\" height=\"42\" viewBox=\"0 0 42 42\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                    <path fill-rule=\"evenodd\" clip-rule=\"evenodd\"\n                        d=\"M12.6383 19.5238C12.6632 21.2071 12.8734 22.9926 12.0685 24.5523C11.0341 26.8917 8.45076 28.169 7.56292 30.5918C6.63082 33.1061 7.19505 36.185 9.31371 37.9786C10.929 39.5678 13.4183 39.9873 15.6061 39.5463C17.4592 39.073 19.1049 37.8388 19.9706 36.1608C20.781 34.7141 20.7866 32.9904 20.5293 31.3985C20.1006 29.3092 18.3775 27.8705 16.9807 26.362C14.8814 24.1005 14.6684 20.6854 15.595 17.8915C16.4331 15.4768 19.0026 14.2344 20.0425 11.9461C20.7202 10.6769 20.7506 9.20327 20.6068 7.81304C20.1864 5.40098 18.3139 3.23631 15.8716 2.56674C13.9742 2.03969 11.8224 2.30052 10.1739 3.37614C8.70522 4.34688 7.5878 5.86618 7.28356 7.58178C6.76081 9.82981 7.53525 12.2822 9.20307 13.9118C10.7658 15.4741 12.4806 17.2273 12.6383 19.5238Z\"\n                        fill=\"#2BADD4\" \/>\n                    <path fill-rule=\"evenodd\" clip-rule=\"evenodd\"\n                        d=\"M22.7048 19.8387C22.6822 22.3279 24.4507 24.6234 26.7493 25.4682C28.0531 25.961 29.4725 25.9183 30.7989 25.5487C32.0575 24.9955 33.301 24.2237 34.0069 23.0092C34.8384 21.5811 35.2982 19.8286 34.7832 18.2094C34.3611 16.2507 32.8739 14.6541 31.0275 13.9426C28.6736 12.9595 25.8073 13.7942 24.1719 15.7001C23.2022 16.8366 22.6143 18.3326 22.7048 19.8387Z\"\n                        fill=\"#2BADD4\" \/>\n                <\/svg>\n            <\/div>\n            <div class=\"text\">\n                <h3>Pro Tip<\/h3>\n                <p>Always confirm factor VIII inhibitor status in the documentation before coding administration of emicizumab (Hemlibra). Payers often require evidence of inhibitor presence or prior prophylaxis failure to approve emicizumab claims paired with D66. A missing inhibitor status note is one of the most frequent prior-authorization denial reasons for this drug class.<\/p>\n            <\/div>\n        <\/div>\n    \n\n\n<h2 class=\"wp-block-heading\">ICD-9-CM to ICD-10-CM crosswalk for D66<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Legacy systems and older payer contracts occasionally require ICD-9-CM equivalents for audit or historical claims reconciliation. The ICD-9-CM predecessor for D66 is 286.0, titled \u00ab\u00a0Congenital factor VIII disorder.\u00a0\u00bb This is an approximate match rather than an exact one-to-one equivalence, since the ICD-9 code covers the same clinical entity but with slightly broader scope.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For authoritative migration guidance, verify against the official CMS General Equivalence Mapping (GEM) crosswalk files rather than relying on commercial tools alone. When migrating codes through EHR integration, GEM files are the correct reference for mapping historical ICD-9 claims data to ICD-10.<\/p>\n\n\n\n<table style=\"width:100%;border-collapse:separate;border-spacing:0;border-radius:12px;overflow:hidden;font-size:15px;line-height:1.5;margin:1.5em 0 2em;box-shadow:0 2px 12px rgba(0,0,0,0.08)\">\n<thead>\n<tr>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">ICD-9-CM code<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Description<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">ICD-10-CM equivalent<\/th>\n<th style=\"background:#121D36;color:#fff;padding:14px 16px;text-align:left;font-weight:600;font-size:14px;letter-spacing:0.3px;border-bottom:2px solid #2BADD4\">Match type<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr style=\"border-bottom:1px solid #E8ECF0\">\n<td style=\"padding:12px 16px;font-weight:600;color:#121D36\">286.0<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Congenital factor VIII disorder<\/td>\n<td style=\"padding:12px 16px;color:#374151\">D66<\/td>\n<td style=\"padding:12px 16px;color:#374151\">Approximate (verify via CMS GEM files)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<h2 class=\"wp-block-heading\">Coding tips and common documentation errors for ICD-10 Code D66<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Most D66 denials trace back to one of four documentation issues. Each one is preventable with the right workflow. Using practice management software with built-in coding prompts can surface these issues before a claim leaves the practice.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><strong>Missing severity characterization.<\/strong> ICD-10 Code D66 does not distinguish mild, moderate, or severe Hemophilia A. But the physician&rsquo;s note must still document severity because payers use that language to evaluate medical necessity for factor replacement dosing regimens. Code D66 plus document severity, even though the code itself does not reflect it.<\/li><li><strong>Coding D66 when von Willebrand disease is present.<\/strong> If the record indicates a vascular defect component, D68.0 is the correct code and D66 must not appear on the same claim. Query the physician if the documentation is ambiguous between Hemophilia A and von Willebrand disease.<\/li><li><strong>Using D66 for Hemophilia B.<\/strong> D67 is the correct code for factor IX deficiency. Defaulting to D66 for any \u00ab\u00a0hemophilia\u00a0\u00bb diagnosis without confirming the factor type is a common error among coders new to hematology.<\/li><li><strong>Combining codes incorrectly for complications.<\/strong> Hemarthrosis, intracranial bleeding, and other hemorrhagic complications have their own ICD-10 codes. D66 is the underlying disease code, and a complication code from the relevant body-system chapter may be added as a secondary diagnosis when the complication is the reason for the encounter. When that encounter is a hospital admission, sequence the complication as principal and D66 as secondary, alongside an admission code such as 99221.<\/li><\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Accurate documentation of D66 also matters beyond the claim itself. Structured automated billing workflows that flag incomplete fields at the point of chart completion help practices catch missing documentation in real time, rather than discovering it during a payer audit.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/cdn.pabau.com\/cdn\/attachments\/pulse\/content-engine\/diagnostic_codes\/icd-10-code-d66\/appointment-scheduling-in-pabau.webp\" alt=\"Appointment scheduling in Pabau\"\/><figcaption class=\"wp-element-caption\"><em>Appointment scheduling in Pabau<\/em><\/figcaption><\/figure>\n\n\n\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n\n\n<h2 class=\"wp-block-heading\">Related ICD-10 codes<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-d329-meningioma-unspecified\/\">ICD-10 code D32.9 \u2014 Benign Neoplasm of Meninges, Unspecified<\/a><\/li>\n\n\n<li><a href=\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-d693\/\">Immune thrombocytopenic purpura ICD-10 code<\/a><\/li>\n\n\n<li><a href=\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-d735\/\">ICD-10 code D73.5 \u2014 Infarction of spleen<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Conclusion<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Hemophilia A billing hinges on two things: getting D66 right and keeping D68.0 off the same claim. Most denials in this space are documentation-driven, not code-selection errors. The code is straightforward. The challenge is ensuring physician notes carry the severity characterization and mechanism specificity that payers require to approve high-cost factor replacement therapy.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Pabau&rsquo;s claims management software helps hematology and specialty practices catch ICD-10 mismatches, incomplete severity documentation, and Excludes1 violations before submission. If your billing workflow depends on manual code review, it is worth seeing how automated validation changes the picture. <a href=\"https:\/\/pabau.com\/book-demo\/\">Book a demo<\/a> to see it in action.<\/p>\n\n\n        <div id=\"expert_picks\">\n            <div class=\"header\">\n                                    <img decoding=\"async\" src=\"https:\/\/pabau.com\/wp-content\/uploads\/2025\/11\/Expert-Picks.svg\" alt=\"Continue your research\" height=\"42\" width=\"42\">\n                                <h3>Continue your research<\/h3>\n            <\/div>\n            <div class=\"content\">\n                                                            <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#54B2D3\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p><strong>Need another recently added diagnostic reference?<\/strong> <a href=\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-m353\/\">M35.3<\/a> covers polymyalgia rheumatica billing, another autoimmune-adjacent code hematology and rheumatology coders cross paths with.<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#54B2D3\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p><strong>Looking for an anesthesia billing example?<\/strong> <a href=\"https:\/\/pabau.com\/procedure-codes\/cpt-code-00942\/\">00942<\/a> shows how anesthesia CPT codes are structured and paired with a primary procedure.<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#54B2D3\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p><strong>Coding durable medical equipment claims?<\/strong> <a href=\"https:\/\/pabau.com\/procedure-codes\/hcpcs-code-e0482\/\">E0482<\/a> walks through a HCPCS billing scenario for a cough-stimulating device.<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#54B2D3\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p><strong>Need a lab-finding diagnosis code?<\/strong> <a href=\"https:\/\/pabau.com\/diagnostic-codes\/icd-10-code-r81\/\">R81<\/a> covers glycosuria, a common incidental finding coders encounter during routine workups.<\/p>\n                        <\/div>\n                                                                                <div class=\"item\">\n                            <div>\n                                <svg width=\"20\" height=\"27\" viewBox=\"0 0 20 27\" fill=\"none\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\">\n                                    <path\n                                        d=\"M18.6223 14.3857C19.1246 13.8975 19.1246 13.1045 18.6223 12.6162L12.1938 6.36621C11.6915 5.87793 10.8759 5.87793 10.3737 6.36621C9.87143 6.85449 9.87143 7.64746 10.3737 8.13574L14.6125 12.2529H2.28571C1.57455 12.2529 1 12.8115 1 13.5029C1 14.1943 1.57455 14.7529 2.28571 14.7529H14.6085L10.3777 18.8701C9.87545 19.3584 9.87545 20.1514 10.3777 20.6396C10.8799 21.1279 11.6955 21.1279 12.1978 20.6396L18.6263 14.3896L18.6223 14.3857Z\"\n                                        fill=\"#54B2D3\" \/>\n                                <\/svg>\n                            <\/div>\n                            <p><strong>Want a billing cheat sheet for another specialty?<\/strong> Pabau&rsquo;s <a href=\"https:\/\/pabau.com\/templates\/chiropractic-billing-cheat-sheet\/\">chiropractic billing cheat sheet<\/a> template shows how one specialty organizes its CPT and ICD-10 references for faster claims.<\/p>\n                        <\/div>\n                                                <\/div>\n        <\/div>\n    \n\n\n<h2 class=\"wp-block-heading\">Frequently Asked Questions<\/h2>\n\n\n\n<div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1784718647082\"><h3 class=\"schema-faq-question\">What is ICD-10 Code D66?<\/h3> <p class=\"schema-faq-answer\">ICD-10 Code D66 is a billable ICD-10-CM diagnosis code for hereditary factor VIII deficiency, most commonly known as Hemophilia A. It is valid for reimbursement on claims submitted under the 2026 ICD-10-CM edition (effective October 1, 2025) and applies to classical hemophilia, Hemophilia NOS, and deficiency factor VIII with functional defect.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1784718647083\"><h3 class=\"schema-faq-question\">What is the ICD-10 code for Hemophilia A?<\/h3> <p class=\"schema-faq-answer\">The ICD-10 code for Hemophilia A is D66 (Hereditary factor VIII deficiency). Both \u00ab\u00a0Hemophilia A\u00a0\u00bb and \u00ab\u00a0classical hemophilia\u00a0\u00bb are listed under the Applicable To inclusions for D66 in the official ICD-10-CM tabular list.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1784718647084\"><h3 class=\"schema-faq-question\">What is the difference between D66 and D67?<\/h3> <p class=\"schema-faq-answer\">D66 is for hereditary factor VIII deficiency (Hemophilia A), while D67 covers hereditary factor IX deficiency (Hemophilia B, also called Christmas disease). The two codes must never be used interchangeably. If the physician&rsquo;s documentation does not specify which factor is deficient, D66 may be used only when Hemophilia NOS is documented and there is no clinical indication of Hemophilia B.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1784718647085\"><h3 class=\"schema-faq-question\">What are the Excludes1 restrictions for D66?<\/h3> <p class=\"schema-faq-answer\">D66 has one Excludes1 restriction: D68.0 (factor VIII deficiency with vascular defect). D68.0 covers von Willebrand disease when factor VIII involvement is present. Because Excludes1 means the two conditions cannot coexist in the same patient at the same time, D66 and D68.0 must never appear together on a single claim.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1784718647086\"><h3 class=\"schema-faq-question\">Is classical hemophilia coded with D66?<\/h3> <p class=\"schema-faq-answer\">Yes. Classical hemophilia is one of the Applicable To inclusions explicitly listed under D66 in the ICD-10-CM tabular list. When a physician documents \u00ab\u00a0classical hemophilia,\u00a0\u00bb D66 is the correct code.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1784718647087\"><h3 class=\"schema-faq-question\">What rare bleeding disorders fall under codes near D66?<\/h3> <p class=\"schema-faq-answer\">The D65-D69 block covers a range of rare bleeding disorders including disseminated intravascular coagulation (D65), Hemophilia B (D67), von Willebrand disease (D68.0), and other hereditary or acquired coagulation defects (D68.1-D68.9). Purpura and related conditions fall under D69. D66 is specific to hereditary factor VIII deficiency and should not be used as a default for unspecified bleeding disorders in this block.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1784718647088\"><h3 class=\"schema-faq-question\">What does Hemophilia NOS mean for ICD-10 Code D66?<\/h3> <p class=\"schema-faq-answer\">Hemophilia NOS (not otherwise specified) is an Applicable To inclusion for D66, used when the physician documents hemophilia without identifying the type as A or B. Coders should query the physician to specify the factor type whenever possible, since an NOS designation may prompt payer scrutiny. However, when the factor type is genuinely unspecified and there is no clinical indication of Hemophilia B, D66 is the appropriate assignment.<\/p> <\/div> <\/div>\n\n","protected":false},"excerpt":{"rendered":"<p>ICD-10 Code D66 is a billable ICD-10-CM code for hereditary factor VIII deficiency, more commonly known as Hemophilia A. It covers classical hemophilia, Hemophilia NOS, and deficiency factor VIII with a functional defect. Its one Excludes1 restriction, against D68.0, is what trips up most claims. This reference covers the 2026 billable status, applicable-to inclusions, Excludes1 [&hellip;]<\/p>\n","protected":false},"author":77,"featured_media":161405,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_yoast_wpseo_linkdex":"91","_yoast_wpseo_content_score":"30","_yoast_wpseo_is_cornerstone":"","_yoast_wpseo_keywordsynonyms":"[\"\",\"\",\"\",\"\"]","_yoast_wpseo_focuskw_text_input":"","_seo_original_html":"","footnotes":""},"categories":[1549,1550],"tags":[4270,4272,4271,1305],"class_list":["post-161406","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-diagnostic-codes","category-icd-10-cm","tag-d66","tag-factor-viii-deficiency","tag-hemophilia-a","tag-icd-10-codes"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v28.2 (Yoast SEO v28.2) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>ICD-10 Code D66: Hereditary factor VIII deficiency (Hemophilia A)<\/title>\n<meta name=\"description\" content=\"ICD-10 code D66 covers hereditary factor VIII deficiency (Hemophilia A), a billable code. See CPT pairings and how it differs from D68.0.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"ICD-10 Code D66: Hereditary factor VIII deficiency (Hemophilia A)\" \/>\n<meta property=\"og:description\" content=\"ICD-10 code D66 covers hereditary factor VIII deficiency (Hemophilia A), a billable code. See CPT pairings and how it differs from D68.0.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/\" \/>\n<meta property=\"og:site_name\" content=\"Pabau\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/Pabau\/\" \/>\n<meta property=\"article:published_time\" content=\"2026-07-22T12:40:59+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-08-18T12:42:51+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/pabau.com\/wp-content\/uploads\/2026\/07\/icd-10-code-d66.webp\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"630\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/webp\" \/>\n<meta name=\"author\" content=\"Katy Piper\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@pabaucrm\" \/>\n<meta name=\"twitter:site\" content=\"@pabaucrm\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"Katy Piper\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"12 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/\"},\"author\":{\"name\":\"Katy Piper\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/#\\\/schema\\\/person\\\/5de22f4ff3ec59b1925ef02dce956d7d\"},\"headline\":\"ICD-10 Code D66: Hereditary factor VIII deficiency (Hemophilia A)\",\"datePublished\":\"2026-07-22T12:40:59+00:00\",\"dateModified\":\"2026-08-18T12:42:51+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/\"},\"wordCount\":2413,\"publisher\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/#organization\"},\"image\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/pabau.com\\\/wp-content\\\/uploads\\\/2026\\\/07\\\/icd-10-code-d66.webp\",\"keywords\":[\"D66\",\"factor VIII deficiency\",\"hemophilia A\",\"ICD-10 codes\"],\"articleSection\":[\"Diagnostic Codes\",\"ICD-10-CM\"],\"inLanguage\":\"fr-FR\"},{\"@type\":[\"WebPage\",\"FAQPage\"],\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/\",\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/\",\"name\":\"ICD-10 Code D66: Hereditary factor VIII deficiency (Hemophilia A)\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/pabau.com\\\/wp-content\\\/uploads\\\/2026\\\/07\\\/icd-10-code-d66.webp\",\"datePublished\":\"2026-07-22T12:40:59+00:00\",\"dateModified\":\"2026-08-18T12:42:51+00:00\",\"description\":\"ICD-10 code D66 covers hereditary factor VIII deficiency (Hemophilia A), a billable code. 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It combines scheduling, electronic health records, clinical forms, payments, marketing automation, reporting, and patient engagement tools into one secure cloud system to help practices streamline operations and grow their business.\",\"foundingDate\":\"2011-10-20\",\"numberOfEmployees\":{\"@type\":\"QuantitativeValue\",\"minValue\":\"201\",\"maxValue\":\"500\"}},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/#\\\/schema\\\/person\\\/5de22f4ff3ec59b1925ef02dce956d7d\",\"name\":\"Katy Piper\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\\\/\\\/pabau.com\\\/wp-content\\\/uploads\\\/2026\\\/03\\\/cropped-Snip20260306_177-96x96.png\",\"url\":\"https:\\\/\\\/pabau.com\\\/wp-content\\\/uploads\\\/2026\\\/03\\\/cropped-Snip20260306_177-96x96.png\",\"contentUrl\":\"https:\\\/\\\/pabau.com\\\/wp-content\\\/uploads\\\/2026\\\/03\\\/cropped-Snip20260306_177-96x96.png\",\"caption\":\"Katy Piper\"},\"description\":\"Katy Piper is a content writer covering aesthetics, dermatology, and clinic operations, with a knack for making clinical detail feel approachable. Outside of work, she's usually chasing her border collie around muddy fields or hunting down the best flat white in town.\",\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/blog\\\/author\\\/katy-piper\\\/\"},{\"@type\":\"Question\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647082\",\"position\":1,\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647082\",\"name\":\"What is ICD-10 Code D66?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ICD-10 Code D66 is a billable ICD-10-CM diagnosis code for hereditary factor VIII deficiency, most commonly known as Hemophilia A. It is valid for reimbursement on claims submitted under the 2026 ICD-10-CM edition (effective October 1, 2025) and applies to classical hemophilia, Hemophilia NOS, and deficiency factor VIII with functional defect.\",\"inLanguage\":\"fr-FR\"},\"inLanguage\":\"fr-FR\"},{\"@type\":\"Question\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647083\",\"position\":2,\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647083\",\"name\":\"What is the ICD-10 code for Hemophilia A?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The ICD-10 code for Hemophilia A is D66 (Hereditary factor VIII deficiency). Both \\\"Hemophilia A\\\" and \\\"classical hemophilia\\\" are listed under the Applicable To inclusions for D66 in the official ICD-10-CM tabular list.\",\"inLanguage\":\"fr-FR\"},\"inLanguage\":\"fr-FR\"},{\"@type\":\"Question\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647084\",\"position\":3,\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647084\",\"name\":\"What is the difference between D66 and D67?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"D66 is for hereditary factor VIII deficiency (Hemophilia A), while D67 covers hereditary factor IX deficiency (Hemophilia B, also called Christmas disease). The two codes must never be used interchangeably. If the physician's documentation does not specify which factor is deficient, D66 may be used only when Hemophilia NOS is documented and there is no clinical indication of Hemophilia B.\",\"inLanguage\":\"fr-FR\"},\"inLanguage\":\"fr-FR\"},{\"@type\":\"Question\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647085\",\"position\":4,\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647085\",\"name\":\"What are the Excludes1 restrictions for D66?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"D66 has one Excludes1 restriction: D68.0 (factor VIII deficiency with vascular defect). D68.0 covers von Willebrand disease when factor VIII involvement is present. Because Excludes1 means the two conditions cannot coexist in the same patient at the same time, D66 and D68.0 must never appear together on a single claim.\",\"inLanguage\":\"fr-FR\"},\"inLanguage\":\"fr-FR\"},{\"@type\":\"Question\",\"@id\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647086\",\"position\":5,\"url\":\"https:\\\/\\\/pabau.com\\\/fr\\\/diagnostic-codes\\\/icd-10-code-d66\\\/#faq-question-1784718647086\",\"name\":\"Is classical hemophilia coded with D66?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. Classical hemophilia is one of the Applicable To inclusions explicitly listed under D66 in the ICD-10-CM tabular list. 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It is valid for reimbursement on claims submitted under the 2026 ICD-10-CM edition (effective October 1, 2025) and applies to classical hemophilia, Hemophilia NOS, and deficiency factor VIII with functional defect.","inLanguage":"fr-FR"},"inLanguage":"fr-FR"},{"@type":"Question","@id":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647083","position":2,"url":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647083","name":"What is the ICD-10 code for Hemophilia A?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"The ICD-10 code for Hemophilia A is D66 (Hereditary factor VIII deficiency). 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If the physician's documentation does not specify which factor is deficient, D66 may be used only when Hemophilia NOS is documented and there is no clinical indication of Hemophilia B.","inLanguage":"fr-FR"},"inLanguage":"fr-FR"},{"@type":"Question","@id":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647085","position":4,"url":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647085","name":"What are the Excludes1 restrictions for D66?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"D66 has one Excludes1 restriction: D68.0 (factor VIII deficiency with vascular defect). D68.0 covers von Willebrand disease when factor VIII involvement is present. Because Excludes1 means the two conditions cannot coexist in the same patient at the same time, D66 and D68.0 must never appear together on a single claim.","inLanguage":"fr-FR"},"inLanguage":"fr-FR"},{"@type":"Question","@id":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647086","position":5,"url":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647086","name":"Is classical hemophilia coded with D66?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Yes. Classical hemophilia is one of the Applicable To inclusions explicitly listed under D66 in the ICD-10-CM tabular list. When a physician documents \"classical hemophilia,\" D66 is the correct code.","inLanguage":"fr-FR"},"inLanguage":"fr-FR"},{"@type":"Question","@id":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647087","position":6,"url":"https:\/\/pabau.com\/fr\/diagnostic-codes\/icd-10-code-d66\/#faq-question-1784718647087","name":"What rare bleeding disorders fall under codes near D66?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"The D65-D69 block covers a range of rare bleeding disorders including disseminated intravascular coagulation (D65), Hemophilia B (D67), von Willebrand disease (D68.0), and other hereditary or acquired coagulation defects (D68.1-D68.9). Purpura and related conditions fall under D69. 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