M10VTE, pulmonary embolism and amniotic-fluid embolism

Clinical overview

Pregnancy and the puerperium increase venous thromboembolism risk through hypercoagulability, venous stasis and vascular injury. Critical illness adds immobility, infection, surgery, central lines and inflammation. Prevention must be active, but haemorrhage, neuraxial procedures and delivery create competing risks that require daily reassessment.

Pulmonary embolism (PE) ranges from small haemodynamically stable emboli to acute right-heart failure and cardiac arrest. Diagnosis is difficult because dyspnoea, tachycardia and leg swelling can occur in normal pregnancy, yet normal pregnancy does not explain hypoxaemia, syncope, haemoptysis, pleuritic pain, unilateral objective swelling or shock. Imaging should answer the question promptly; radiation anxiety must not leave a life-threatening PE unconfirmed or untreated.

Amniotic-fluid embolism (AFE) is a different catastrophe: sudden cardiorespiratory compromise and coagulopathy during labour or shortly after birth, diagnosed clinically after excluding more treatable mimics. There is no confirmatory bedside test or proven specific drug regimen. Management is immediate organ support, delivery when it assists maternal resuscitation and aggressive haemostatic treatment.

Core knowledge

Prevention in critical illness

Assess VTE and bleeding risk at admission, after delivery, after surgery, with any clinical change and before transfer/discharge. Risk factors include previous VTE/thrombophilia, obesity, immobility, sepsis, severe pre-eclampsia, haemorrhage/transfusion, caesarean birth, cardiac disease, smoking, age and central venous access.

Use early mobilisation and mechanical prophylaxis when pharmacological prophylaxis is contraindicated. LMWH is the usual pharmacological agent during pregnancy/postpartum when renal function and bleeding risk permit. Dose category, weight adjustment, renal impairment, platelet count, timing around neuraxial procedures and duration follow the current local/RCOG/national protocol. Do not publish a single neuraxial interval detached from prophylactic versus therapeutic dose, drug, renal function and the anaesthetic guideline.

Restart prophylaxis after haemorrhage or procedure only when haemostasis is secure and the procedural team agrees. A prior contraindication must be revisited; “held” should have a review time.

Suspected DVT

Symptoms warrant objective testing. Compression ultrasonography is first-line for suspected proximal lower-limb DVT. If the initial study is negative but suspicion remains, repeat imaging or evaluate iliac/pelvic veins according to symptoms and specialist advice; pregnancy has proportionally more proximal/left-sided disease than general populations. Do not use a negative limited calf/proximal study to dismiss severe whole-leg or pelvic symptoms without reviewing its scope.

Suspected PE

Begin with haemodynamic assessment, ECG, chest radiograph and a search for DVT where appropriate. A positive proximal DVT in a patient with PE symptoms may establish VTE and avoid chest imaging, but absence does not exclude PE.

V/Q scanning and CTPA are both used in pregnancy. Choice depends on chest radiograph, local availability/expertise, alternative diagnoses, maternal breast/lung and fetal exposure considerations, contrast issues and urgency. Explain that the radiation doses from appropriate diagnostic studies are small relative to the risk of missed PE. Optimise technique and proceed.