13.2 Congenital Bleeding and Clotting Disorders

2. Bleeding and Clotting Disorders

Haemostasis is divided into primary haemostasis (platelet plug formation via platelet adhesion, activation, and aggregation) and secondary haemostasis (activation of the coagulation cascade yielding a stable cross-linked fibrin mesh).

Congenital Coagulopathies

Inherited bleeding disorders stem from quantitative or qualitative deficiencies in specific plasma clotting factors:

Clinical Severity Classification of Haemophilia

• Severe ($< 1%\text{ factor activity}$): Frequent spontaneous haemarthroses (joint bleeding), deep muscle haematomas, and severe prolonged haemorrhage following minor trauma or tooth extraction.
• Moderate ($1-5%\text{ factor activity}$): Spontaneous bleeding is rare; severe prolonged bleeding occurs after minor surgical procedures or dental extractions.
• Mild ($5-40%\text{ factor activity}$): Bleeding occurs only after major trauma or significant surgery. Often remains undiagnosed until adulthood following a dental extraction.

Clinical Management in Dental Surgery

• Haemophilia Centre Liaison: Any invasive dental procedure in a patient with an inherited coagulopathy requires mandatory formal consultation with their Comprehensive Care Haemophilia Centre before initiating treatment. The haematologist will formulate a haemostatic plan incorporating factor replacement or desmopressin.
• Desmopressin (DDAVP): Synthetic vasopressin analogue (administered IV, SC, or intranasally). It stimulates the exocytosis of stored endogenous Factor VIII and vWF from endothelial Weibel-Palade bodies. It is effective in mild Haemophilia A and Type 1 vWD, but has no effect in Haemophilia B (which lacks Factor IX) or severe Haemophilia A.
• Antifibrinolytic Therapy: Tranexamic acid is a synthetic lysine analogue that competitively blocks plasminogen activation, preventing fibrin clot dissolution. Prescribed as a 5% mouthwash (10 mL rinsed for 2 minutes QDS for 5–7 days) or oral tablets (15–25 mg/kg TDS).

[!CAUTION] The Inferior Alveolar Nerve Block (IANB) Trap in Haemophilia: Administering an inferior alveolar nerve block (IANB) to a patient with haemophilia or severe coagulopathy without prior factor replacement is strictly contraindicated. The pterygomandibular space contains an extensive plexus of veins and arteries within loose, unconfined connective tissue. Inadvertent vascular laceration causes deep, non-compressible intramuscular bleeding, resulting in an expanding dissecting haematoma that tracks into the parapharyngeal, sublingual, and retropharyngeal spaces. This produces acute upper airway displacement and fatal asphyxiation. Safe alternatives include buccal infiltrations using 4% articaine with adrenaline, intraligamentary, or intraosseous anaesthesia.

Thrombocytopenia

Thrombocytopenia is defined as a peripheral blood platelet count falling below the normal reference range ($150-400 \times 10^9\text{/L}$):

• Platelet Count $> 100 \times 10^9\text{/L}$: Normal surgical haemostasis; all dental procedures can proceed without modification.
• Platelet Count $50-100 \times 10^9\text{/L}$: Simple dental extractions (1 to 3 teeth), supragingival/subgingival scaling, and minor restorative care proceed safely with local haemostatic measures (suturing, oxidized cellulose, tranexamic acid). Avoid extensive surgical flaps or osseous surgery.
• Platelet Count $20-50 \times 10^9\text{/L}$: Non-surgical dental care only. Any necessary surgical extraction requires platelet transfusion performed immediately prior to treatment in a hospital environment in liaison with haematology.
• Platelet Count $< 20 \times 10^9\text{/L}$: High risk of spontaneous, life-threatening mucosal haemorrhage (manifesting intraorally as spontaneous gingival bleeding, petechiae, purpura, and large blood-filled bullae). Emergency hospital admission.

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Planning Dental Surgery in a Patient with a Bleeding Disorder

The examinable principle is that management is determined by the severity of the disorder and the invasiveness of the procedure, and that it is planned with the patient's haemophilia centre rather than improvised. Routine examination, radiographs, supragingival scaling and simple restorative work with good moisture control generally need no special measures. Procedures with a bleeding risk — extraction, subgingival instrumentation, biopsy, block local anaesthesia — need a prior discussion with the haematologist.

In haemophilia A and B, cover may be with factor replacement, and in mild haemophilia A with desmopressin, which releases stored factor VIII and von Willebrand factor from endothelium. In von Willebrand disease type 1, desmopressin is again often sufficient. Tranexamic acid, systemically or as a mouthwash, is a valuable adjunct because it inhibits plasminogen activation and counteracts the high fibrinolytic activity of saliva. Local measures matter as much as systemic cover: atraumatic technique, an oxidised cellulose or collagen pack, sutures and firm pressure.

Anaesthetic and Prescribing Cautions

Certain choices are hard rules. Inferior alveolar and other deep block injections are avoided in an uncovered patient with a significant coagulopathy because a haematoma in the pterygomandibular space can compromise the airway; infiltration, intraligamentary or intraosseous techniques are preferred where feasible. Aspirin and other non-steroidal anti-inflammatory drugs are avoided for analgesia because they impair platelet function; paracetamol is the analgesic of choice. Intramuscular injections are avoided. Finally, patients with inherited bleeding disorders historically treated with pooled blood products have an increased prevalence of blood-borne viral infection, which reinforces — but does not change — standard infection control precautions applied to every patient.