Bleeding while anticoagulated

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Bleeding while anticoagulated is a clinical syndrome, not an INR or anti-Xa result. Major bleeding includes fatal bleeding, bleeding in a critical organ or compartment, haemodynamic compromise, uncontrolled loss, a substantial haemoglobin fall or transfusion need. A small intracranial or airway bleed may be more urgent than a larger controlled soft-tissue bleed. Begin ABCDE care, obtain large-bore access, activate the major-haemorrhage protocol when physiology warrants, stop anticoagulants and avoid unnecessary antiplatelet or NSAID exposure. Seek early neurosurgical, endoscopic, interventional radiology, vascular, trauma, obstetric or surgical control according to anatomy.

Exposure reconstruction directs reversal. For warfarin obtain INR but do not delay PCC in life-threatening bleeding. For DOACs record the exact last dose, Cockcroft–Gault renal function and interacting P-glycoprotein or CYP3A4 drugs. PT and APTT cannot exclude apixaban or rivaroxaban; use drug-calibrated anti-Xa if it returns fast enough to change action. Thrombin time is sensitive to dabigatran. For heparin identify infusion units received or the most recent LMWH dose and time. Also test FBC, fibrinogen, renal and liver function and group samples to find thrombocytopenia, consumption or organ failure.

Use the narrowest effective reversal. Warfarin bleeding needs four-factor PCC plus IV phytomenadione because PCC is rapid and vitamin K sustains the effect. Dabigatran has specific neutralisation with idarucizumab. Andexanet reverses apixaban and rivaroxaban within the licensed severe-bleeding indication, but UK commissioning and site criteria apply and thrombosis risk is important. When andexanet is unavailable or unsuitable, a local protocol may use four-factor PCC off label. Protamine neutralises UFH and partly LMWH. Do not use vitamin K for DOACs, protamine for warfarin or idarucizumab for factor Xa inhibitors.

Blood components follow deficit and haemorrhage, not anticoagulant name. Maintain red-cell oxygen delivery within the major-haemorrhage protocol; replace fibrinogen for documented or strongly suspected critical deficiency; use platelets for thrombocytopenia or defined procedural and antiplatelet situations. Prevent hypothermia and monitor ionised calcium during massive transfusion. Tranexamic acid 1 g IV over 10 minutes followed by 1 g over 8 hours is recommended early, within 3 hours, for qualifying major trauma unless contraindicated. HALT-IT showed no mortality benefit and more venous events or seizures with routine high-dose treatment in gastrointestinal bleeding.

Minor or clinically relevant non-major bleeding usually needs pressure, topical or procedural care, dose omission and correction of renal or interaction causes, not prothrombotic reversal. Epistaxis, haematuria, abnormal uterine bleeding and iron-deficiency anaemia still warrant diagnostic pathways. Do not permanently reduce an evidence-based dose to conceal an untreated lesion. If recurrent bleeding makes full anticoagulation unsafe, revisit the agent, indication, gastroprotection, antiplatelet need, blood-pressure control and whether a procedural alternative exists.

Restart prevents a second disaster. Confirm haemostasis, stable haemoglobin, source treatment, renal recovery and the correct future dose. A recent proximal VTE, mechanical mitral valve, high-risk APS or high embolic AF raises the cost of delay; an unsecured intracranial source raises the cost of early treatment. Use joint specialty review for intracranial bleeding and mechanical valves. Mechanical prophylaxis and later prophylactic-intensity anticoagulation may bridge the interval in selected patients, but neither should be automatic. State the drug, dose, date, responsible team and conditions that would delay restart.

Key points

Classify the clinical bleed first: critical site, haemodynamic compromise, uncontrolled loss or substantial transfusion need makes it major regardless of the laboratory result.
Stop anticoagulant and unnecessary antiplatelets, resuscitate, correct temperature and calcium, and obtain source control; reversal alone cannot close a vessel or treat a lesion.
Record exact drug, indication, dose, last dose time, renal trajectory, weight and interacting medicines before exposure information is lost during transfer.
Warfarin major bleeding: four-factor PCC using the stocked product schedule plus 5–10 mg slow IV phytomenadione.
Dabigatran major bleeding: idarucizumab 5 g IV as two consecutive 2.5 g doses; assess rebound especially in overdose or renal failure.
Apixaban or rivaroxaban life-threatening or uncontrolled bleeding: consider andexanet within its licence and current NICE/local access, or specialist off-label PCC when specific reversal is inappropriate.
UFH bleeding: stop infusion and give slow IV protamine from recent exposure; LMWH is only partially reversed and fondaparinux has no specific antidote.
Do not transfuse platelets for a normal count merely because aspirin or a DOAC was taken; target thrombocytopenia, a procedural threshold or a specialist antiplatelet strategy.
Routine tranexamic acid is not supported for gastrointestinal bleeding; use it promptly for qualifying trauma under the major-trauma regimen and for other indications according to their evidence.
Make the restart decision daily once haemostasis is secure, with site, source, indication, time since thrombosis, renal function and patient priorities documented.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Excess anticoagulant exposure

Overdose, duplicated administration, renal or hepatic deterioration and strong metabolic interactions can raise drug effect beyond that intended for the indication.

Anatomical bleeding lesion

Ulcer, tumour, vascular malformation, trauma, surgery or obstetric pathology often provides the source; anticoagulation amplifies but does not explain away the lesion.

Combined haemostatic impairment

Thrombocytopenia, antiplatelets, uraemia, liver disease, DIC, inherited bleeding disease or massive transfusion can coexist and require mechanism-specific correction.

Correct-dose spontaneous bleeding

Intracranial and gastrointestinal haemorrhage can occur despite an appropriate dose and normal organ function, particularly with age, frailty and previous bleeding.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Impaired clot propagation
Inhibition or depletion of thrombin and factor Xa limits fibrin generation, so a small damaged vessel may continue bleeding despite primary platelet adhesion.
2
Critical-compartment pressure
Blood in the skull, spinal canal, pericardium, airway or fascial compartment causes organ failure through compression before total volume loss becomes large.
3
Shock and coagulopathy
Ongoing loss causes hypoperfusion, acidosis, hypothermia, calcium depletion and dilution, which further impair haemostasis and create a self-reinforcing haemorrhage cycle.
4
Reversal-related thrombosis
Restoring coagulation removes pharmacological protection and some concentrates add procoagulant substrate, exposing the original embolic disease and an acute inflammatory thrombotic state.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Critical anatomyRed flag

Neurology, airway compromise, cord symptoms, tamponade, retroperitoneal pain or a tense compartment requires emergency action before large-volume loss is visible.

Haemodynamic loss

Tachycardia, hypotension, syncope, cool peripheries, confusion, oliguria and rising lactate indicate inadequate circulating volume or oxygen delivery.

Residual anticoagulant

Recent dose, acute kidney injury, overdose, low weight and strong metabolic inhibition increase active exposure and reversal relevance.

Additional haemostatic defect

Fever, shock, falling platelets, low fibrinogen, liver failure or uraemia suggests a combined mechanism beyond prescribed anticoagulation.

High thrombotic cost

Recent thrombosis, active cancer, mechanical mitral valve, severe APS and previous embolism make unnecessary interruption dangerous after haemostasis.

Red flags requiring action

New focal neurology, severe headache, reduced consciousness or significant head trauma demands immediate CT and anticoagulant reversal assessment even without shock.
Hypotension, tachycardia, syncope, rising lactate, oliguria or continued haemoglobin fall indicates physiologically major bleeding and should activate a major-haemorrhage response.
Airway bleeding, spinal cord symptoms, tense limb swelling, severe abdominal or back pain or pericardial compromise can be fatal from pressure at a small blood volume.
Recent VTE, mechanical mitral valve, triple-positive APS or very high-risk AF creates substantial restart urgency once haemostasis is achieved; reversal is not a permanent treatment decision.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line: FBC, group, renal and liver profileFirst stepFirst line
Why
Assess loss, reserve, clearance and transfusion readiness.
Interpretation and limitations
Repeat haemoglobin because acute loss may initially be hidden; platelets, creatinine and hepatic dysfunction alter component, reversal and restart decisions.
02
PT, APTT, fibrinogen and INR
Why
Identify warfarin intensity and broader coagulation failure.
Interpretation and limitations
INR guides vitamin-K-antagonist PCC dosing. Normal PT/APTT does not exclude factor Xa inhibitor; low fibrinogen or global derangement suggests consumption, liver disease or massive-haemorrhage coagulopathy.
03
Confirmatory drug-specific assayConfirmatory
Why
Quantify residual DOAC or heparin when the result can change urgent action.
Interpretation and limitations
Use calibrated anti-Xa for the named Xa inhibitor, diluted thrombin time or ecarin testing for dabigatran and heparin anti-Xa when appropriate; confirm assay calibration before interpretation.
04
Reference-standard anatomical test
Why
Locate the source and define definitive haemostasis.
Interpretation and limitations
CT, CT angiography, endoscopy, ultrasound or operative exploration depends on site and stability; negative initial imaging does not end assessment if physiology or serial haemoglobin worsens.
05
Cause-directed haemostasis testing
Why
Find DIC, platelet dysfunction, factor deficiency or haemolysis when bleeding exceeds expected drug effect.
Interpretation and limitations
Use serial platelets, fibrinogen, D-dimer, film, haemolysis tests and specialist factor studies; viscoelastic testing can guide a major-haemorrhage protocol but is not a DOAC concentration.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Non-haemorrhagic collapse

Sepsis, myocardial infarction, pulmonary embolism, anaphylaxis and arrhythmia can mimic bleeding shock and may coexist when anticoagulation is interrupted.

Haemolysis or marrow failure

Falling haemoglobin without an evident source may reflect haemolysis, dilution or impaired production; reticulocytes, film and haemolysis studies refine the mechanism.

Disseminated intravascular coagulation

Sepsis, malignancy, trauma or obstetric catastrophe can cause simultaneous consumption, bleeding and thrombosis with falling fibrinogen and platelets beyond drug effect.

Laboratory anticoagulant effect only

A prolonged PT or APTT without clinical bleeding may reflect treatment, lupus anticoagulant or factor deficiency and does not itself justify emergency reversal.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Major bleedStabilise, reverse and control sourceFirst stepBleeding is critical-site, haemodynamic, uncontrolled or requires major transfusion.

1Stop antithrombotics, activate ABCDE and major-haemorrhage care, obtain exposure and laboratory data and call the anatomical source-control team.
2Give drug-specific reversal or factor replacement using the warfarin, dabigatran, factor-Xa or heparin branch while correcting temperature, calcium and component deficits.
3Confirm clinical haemostasis and source treatment, watch for thrombosis and start a daily restart assessment.

02Non-major bleedTreat locally without over-reversalBleeding is controlled, outside a critical site and without haemodynamic or major haemoglobin consequence.

1Confirm severity, drug, dose, last ingestion, renal function, haemoglobin and contributing medicines.
2Use pressure, topical, dental, ENT, gynaecological or urological measures and omit or delay doses when appropriate.
3Investigate the lesion, correct drug accumulation or interaction and resume the correct regimen once haemostasis is secure.

03Post-haemostasisChoose a safe restart timeBleeding has stopped and the source is controlled or stabilised.

1Reassess bleed anatomy, rebleeding consequence, haemoglobin trend, procedure findings and renal or liver recovery.
2Reconstruct anticoagulation indication, time since thrombosis, embolic risk, valve type, cancer and available mechanical prophylaxis.
3Agree and document no restart, prophylactic transition or therapeutic restart with exact drug, dose, date and review owner.

04Recurrent bleedingModify causes, not blindly the doseBleeding recurs after treatment is restarted or persists despite apparently correct reversal.

1Re-image or re-endoscope as appropriate and reconsider an untreated lesion, consumption, thrombocytopenia, renal accumulation or wrong administration.
2Remove unnecessary antiplatelets or NSAIDs, optimise blood pressure and gastroprotection where indicated and correct the anticoagulant regimen.
3AlternativeUse multidisciplinary review to compare alternative agent, procedural stroke prevention, limited duration or cessation against the actual thrombosis risk.

Key medicines and prescribing safety5 treatments · regimens, roles and cautions

Rapid and sustained restoration of vitamin-K-dependent factor activity, scaled to clinical bleeding severity.

Warfarin reversal

For major bleeding give four-factor PCC using the stocked product's INR and weight table plus phytomenadione 5–10 mg by slow IV injection; for INR above 8 without bleeding use 1–5 mg oral phytomenadione and prompt recheck.

PCC is thrombotic and should not be routine for non-bleeding INR elevation. Use product maximums, give vitamin K with emergency PCC, reassess INR and haemostasis and avoid automatic redosing without senior review.

Specific neutralisation of free and thrombin-bound dabigatran.

Idarucizumab

Give 5 g intravenously as two consecutive 2.5 g/50 mL doses for dabigatran-associated life-threatening or uncontrolled bleeding or urgent surgery that cannot wait.

It does not reverse factor Xa inhibitors. Monitor recurrent bleeding and assay rebound in severe renal impairment or overdose, watch thrombosis and consider repeat 5 g only for SmPC-supported clinical recurrence.

Licensed adult apixaban or rivaroxaban reversal for life-threatening or uncontrolled bleeding when current UK access criteria are satisfied.

Andexanet alfa

Use low dose 400 mg IV bolus then 4 mg/min for 120 minutes or high dose 800 mg bolus then 8 mg/min for 120 minutes according to apixaban or rivaroxaban dose and last-dose time.

Not licensed for edoxaban or LMWH and not established for routine urgent-surgery pretreatment. Thrombosis is common, heparin may become ineffective and exact SmPC selection plus current NICE/local policy is mandatory.

Rapid UFH neutralisation and incomplete LMWH reversal during major bleeding.

Protamine sulfate

Give slowly IV over about 10 minutes, maximum 50 mg per dose, calculated from actual recent UFH or LMWH exposure; about 1 mg neutralises 100 IU recent UFH, while LMWH reversal is partial.

Reduce for elapsed time and avoid excess, which is anticoagulant. Monitor severe hypotension, pulmonary vasoconstriction and anaphylactoid reaction; no specific effect exists for fondaparinux or DOACs.

Antifibrinolytic treatment that reduces death from bleeding in appropriately selected early trauma; anticoagulant exposure does not remove the trauma indication.

Tranexamic acid for major trauma

For an adult with or at risk of significant trauma haemorrhage, give 1 g IV over 10 minutes then 1 g IV over 8 hours as soon as possible and within 3 hours of injury under the major-trauma protocol.

Do not use routinely for gastrointestinal bleeding or simply to normalise a coagulation test. Adjust for renal impairment, avoid delayed trauma administration beyond the evidence window and review thrombotic, seizure and urinary-tract clot risk.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Death or permanent disability

Intracranial expansion, airway obstruction, exsanguination and delayed source control can cause death, stroke disability, cord injury or irreversible limb damage.

Recurrent thrombosis

Prolonged withdrawal after haemostasis can cause recurrent VTE, cardioembolic stroke, valve thrombosis or cancer-associated clot, particularly after recent events.

Transfusion and reversal harm

Volume overload, hypocalcaemia, transfusion reactions, alloimmunisation and arterial or venous thrombosis can follow intensive replacement or prohaemostatic concentrates.

Rebleeding

An untreated source, premature full-dose restart, residual renal accumulation or short-lived factor replacement without sustained correction can cause renewed haemorrhage.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

During active haemorrhage monitor observations, neurological state, urine output, serial haemoglobin, platelets, fibrinogen, coagulation, ionised calcium, temperature, acid-base status and transfusion requirement.
After reversal, assess clinical haemostasis rather than relying on one laboratory value; repeat INR after PCC and use an agent-appropriate test for suspected DOAC or heparin rebound.
Track arterial and venous thrombosis after PCC or andexanet and after anticoagulant withdrawal, including neurological, cardiac, limb and catheter symptoms.
Review the source outcome, renal and hepatic recovery, interacting medicines and antiplatelet necessity before selecting a restart dose.
Give the patient and every receiving team a written stop or restart plan with agent, dose, date, indication, warning symptoms and accountable clinician.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Anatomy outranks volume

A few millilitres in the posterior fossa or airway may be more dangerous than a larger controlled limb haematoma. Critical site defines urgency.

Early haemoglobin can mislead

Concentration may remain normal until redistribution or resuscitation occurs. Physiology, witnessed loss and serial measurements guide the major-haemorrhage response.

Reversal has a price

PCC and andexanet expose a patient with an existing clot tendency to additional thrombotic risk; reserve them for bleeding where the haemostatic benefit is substantial.

The lesion still matters

Anticoagulation often unmasks malignancy, ulceration or vascular disease. Labelling the medicine as the sole cause invites recurrence after restart.

Restart is not binary

Depending on anatomy and thrombotic risk, the sequence can include mechanical prophylaxis, prophylactic dosing and later therapeutic treatment, but each transition needs a reason and owner.

11Common pitfallsFrequent interpretation and management errors.

01
Do not wait for haemoglobin to fall before treating shock or critical-site bleeding; acute concentrations lag behind blood loss.
02
Do not reverse because a routine coagulation test is abnormal without assessing bleeding, exposure and indication.
03
Do not use FFP instead of four-factor PCC for warfarin major bleeding when PCC is available and appropriate.
04
Do not give routine high-dose tranexamic acid for gastrointestinal bleeding; seek endoscopic or interventional haemostasis.
05
Do not assume haematuria or postmenopausal bleeding is an acceptable anticoagulant side effect; investigate the urinary or genital tract.
06
Do not allow the anticoagulant to remain omitted indefinitely after discharge because no team accepted responsibility for restart review.