# Bleeding and Clotting in Surgery

> Bleeding and clotting for BDS General Surgery — haemostasis phases, PT INR versus aPTT, platelet and coagulation disorders, blood components, local measures.

- Canonical URL: https://prepelephant.com/topics/bds/general-surgery/bleeding-clotting-surgical-bds
- Exam / course: BDS · Subject: General Surgery
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Bleeding and Clotting in Surgery", PrepElephant, https://prepelephant.com/topics/bds/general-surgery/bleeding-clotting-surgical-bds

## Direct answer

A patient who oozes from venepuncture sites and old scars hours after surgery has a clotting problem, not a surgical one — immediate bleeding is a vessel problem, delayed ooze is a haemostatic system problem. Haemostasis runs in three linked acts: primary haemostasis (platelet adhesion via von Willebrand factor, aggregation, the platelet plug), secondary haemostasis (the coagulation cascade ending in thrombin converting fibrinogen to fibrin), and fibrinolysis that later removes the clot. The laboratory map is symmetrical and examinable: bleeding time and platelet count test platelets; prothrombin time with INR tests the extrinsic and common pathways (factors VII, X, V, II, I); activated partial thromboplastin time tests the intrinsic and common pathways (XII through VIII, then the common ladder). Surgical management layers local measures — pressure, packing, ligature, diathermy — over component replacement matched to whichever arm of the system has failed.

## What you must remember

- **Three acts of haemostasis:** platelet plug (primary), coagulation cascade to fibrin (secondary), fibrinolysis for clot removal (plasmin on fibrin) — surgical bleeding localises the failing act by timing.
- **Test-to-pathway pairs:** bleeding time 2-7 minutes and platelet count 150,000-450,000 per microlitre reflect platelets; PT 11-14 seconds (INR near 1) reflects the extrinsic pathway; aPTT 25-35 seconds reflects intrinsic; clotting time 5-10 minutes is a crude whole-blood screen — the commonly quoted viva numbers.
- **Classical disorder patterns:** haemophilia A (factor VIII deficiency — prolonged aPTT, normal PT, deep muscle and joint bleeds, X-linked), von Willebrand disease (mucocutaneous bleeding, both platelet-type and aPTT abnormalities), thrombocytopenia (petechiae, gum bleeding), DIC (prolonged PT and aPTT, low platelets, raised D-dimer, seen in sepsis and retained dead fetus).
- **Liver disease and vitamin K:** the liver makes all clotting factors except von Willebrand factor; vitamin K-dependent factors are II, VII, IX and X — obstructive jaundice and malabsorption bleed from vitamin K deficiency, correctable by intravenous vitamin K.
- **Component therapy:** fresh frozen plasma replaces clotting factors (bleeding with prolonged PT/aPTT), platelet concentrates for thrombocytopenia with bleeding, cryoprecipitate for fibrinogen and factor VIII, packed cells for blood loss — and desmopressin for mild haemophilia and von Willebrand disease.
- **Local haemostatic arsenal:** pressure and elevation first, packing (roller gauze, haemostatic gauze), ligature and diathermy, bone wax for cancellous bone, vasoconstrictors such as adrenaline with local anaesthetic (1:100,000 in dental practice), topical agents like oxidised cellulose.
- **Emergency drugs that matter:** warfarin reversed with vitamin K and FFP (prothrombin complex concentrate where available), heparin reversed with protamine sulphate, antiplatelet drugs held where safe before elective surgery.

## Working through the exodontia candidate who keeps bleeding

A planned extraction in a young man is followed by persistent ooze from the socket despite 30 minutes of pressure. Work through it in order: is this local or systemic? Ask the bleeding-score questions the night before — previous dental extractions, tonsillectomy, circumcision, menstrual flooding, family history (X-linked inheritance points to haemophilia), anticoagulant or antiplatelet drugs, liver disease, alcohol. At the chairside, re-examine under anaesthesia: a torn vessel, a spurting artery, a foreign body or a fracture — most persistent post-extraction bleeding is local. If the socket is clean and oozing continues from mucosa and venepuncture sites, order platelet count, PT/INR and aPTT. The pattern reads itself: isolated prolonged aPTT in a boy with a family history is haemophilia A until factor assays say otherwise; prolonged PT with normal aPTT in a jaundiced patient is vitamin K deficiency; all three abnormal with petechiae in a septic patient is DIC. Treatment then follows the deficit — local measures with a haemostatic pack and sutures for everyone, tranexamic acid mouthwash for fibrinolysis-driven ooze, FFP or factor replacement for the coagulopathies, and platelets for counts below roughly 50,000 with active bleeding. The dental lesson: the screening history costs one minute; the missing factor costs a night in theatre.

## Where students slip

The recurring confusion is PT versus aPTT: PT is extrinsic (factor VII, tissue factor, a one-step pathway — hence it shortens correctly first in vitamin K deficiency because factor VII has the shortest half-life), aPTT is intrinsic (contact factors). A useful mnemonic-free anchor: PT monitors warfarin because warfarin degrades vitamin K-dependent factors; aPTT monitors heparin because heparin potentiates antithrombin against thrombin and factor Xa. The second slip is calling every gum bleeding a platelet problem — gingival bleeding occurs in platelet disorders, vitamin K deficiency, leukaemia and scurvy alike; the test panel, not the site, separates them.

## Frequently asked questions

### Which test monitors the extrinsic pathway of coagulation?

Prothrombin time, expressed as the INR; it is prolonged in factor VII deficiency and vitamin K deficiency and is used to monitor warfarin therapy.

### How do the laboratory findings of haemophilia A and DIC differ?

Haemophilia A shows an isolated prolonged aPTT with normal PT and platelets; DIC prolongs both PT and aPTT with thrombocytopenia and raised fibrin degradation products.

### What first-line local measures control post-extraction bleeding?

Direct pressure with a moist gauze pack, removal of debris, a resorbable haemostatic dressing in the socket and suturing; the vasoconstrictor in local anaesthetic and tranexamic acid mouthwash help persisting ooze.

### Why does vitamin K deficiency prolong PT before aPTT?

Factor VII, the extrinsic factor with the shortest plasma half-life, falls earliest when vitamin K-dependent synthesis fails, so PT rises first.

### What blood component corrects thrombocytopenic bleeding?

Platelet concentrate, given for active bleeding with counts generally below 50,000 per microlitre, or prophylactically below 10,000.