Skip to textbook content
Doctor’s PassportTextbook
QuestionsFlashcardsBriefsDashboardAccount
TopicsAll topics

Loading topic navigation…

Textbook navigation
TopicsAll topics

Loading topic navigation…
Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Venous thromboembolism risk and anticoagulation

Obstetrics and gynaecology · UK scope · Sources checked 7 Sept 2026 · Clinical review pending

RapidFull
!
Suspected pulmonary embolism needs immediate assessment

Sudden breathlessness, pleuritic chest pain, haemoptysis, syncope or collapse during pregnancy or postpartum may represent pulmonary embolism.

Action: Arrange emergency hospital assessment, support airway and circulation, obtain objective testing and start therapeutic LMWH while investigation proceeds unless strongly contraindicated; haemodynamic instability requires immediate senior multidisciplinary consideration of reperfusion and critical care.

Synopsis

Repeatedly assess pregnancy-associated thrombosis risk, investigate suspected venous thromboembolism without delay, and prescribe anticoagulation with safe delivery and neuraxial timing.

  • Document VTE risk at booking, during admission or new illness, and after birth; risk changes throughout pregnancy and the puerperium.
  • RCOG generally considers four current risk factors for antenatal LMWH, three for LMWH from 28 weeks and two for at least ten days postpartum, with separate pathways for prior VTE and thrombophilia.
  • Most previous VTE histories warrant antenatal LMWH; the single major-surgery-provoked event without other risks is an important specialist-assessed exception.
  • Compression duplex ultrasound investigates suspected DVT; if negative but suspicion remains high, RCOG specifies repeat scans on days three and seven.
  • Investigate suspected PE with appropriate chest imaging; a normal oxygen saturation, normal ECG or prophylactic heparin does not rule it out.
  • Use weight-adjusted LMWH for confirmed VTE and continue through pregnancy for at least six weeks postpartum and at least three months in total.
  • For standard prophylactic LMWH allow at least twelve hours before neuraxial procedures; for therapeutic LMWH allow at least twenty-four hours, with anaesthetic review of modifiers.
  • If labour or vaginal bleeding starts, omit further LMWH and contact maternity services for reassessment and a supervised plan.

Key red flags

Chest pain with acute breathlessness, syncope, hypoxia or haemoptysis requires urgent assessment for pulmonary embolism even if the patient is already receiving prophylaxis.

Unilateral whole-leg swelling, groin or buttock pain, or marked new asymmetry warrants urgent imaging for proximal or pelvic thrombosis.

Major bleeding, new neurological symptoms after neuraxial procedures or suspected heparin-induced thrombocytopenia requires immediate review of anticoagulation.

Investigation priorities

01
Compression duplex ultrasoundFirst step

Demonstrate lower-limb venous thrombosis objectively when symptoms suggest DVT.

Management branches

PreventionTranslate risk assessment into a usable plan

Antenatal booking, hospital admission, new risk factors or birth changes thrombosis risk.

  1. Complete the appropriate maternity assessment and identify prior VTE or thrombophilia that requires a separate specialist pathway.
  2. Prescribe the correct prophylactic dose and duration when indicated, checking weight, renal function, bleeding and neuraxial considerations.
  3. Teach injection technique, safe sharps handling and when to withhold a dose, and confirm the patient can obtain the full prescribed course.

Key medicines

Enoxaparin standard prophylaxisRCOG suggested subcutaneous daily doses by weight are 20 mg below 50 kg, 40 mg at 50–90 kg, 60 mg at 91–130 kg, 80 mg at 131–170 kg and 0.6 mg/kg above 170 kg; prescribe the indicated antenatal or postpartum duration.These are prophylactic doses, not acute-VTE treatment or mechanical-valve therapy; adjust for renal impairment and bleeding risk and check higher-dose scheduling with the maternity protocol.
Enoxaparin therapeutic treatmentA commonly used pregnancy treatment regimen is 1 mg/kg subcutaneously every twelve hours using booking or early-pregnancy weight; continue through pregnancy and at least six weeks postpartum, with at least three months total treatment.RCOG permits locally specified once- or twice-daily regimens because evidence does not establish one universal schedule; renal impairment, extreme weight, recurrence and peripartum timing require specialist adjustment.
Open full textbook →Answer 2 questions
Sources and review status4 sources · checked 7 Sept 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 7 Sept 2026; clinical approval remains outstanding.

  • RCOG Green-top 37a: VTE prevention in pregnancy and puerperium
  • RCOG Green-top 37b: Acute thromboembolic disease in pregnancy
  • RCOG: Diagnosis and treatment of venous thrombosis in pregnancy
  • NHS: Deep vein thrombosis

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom