SAQ 407 – Obstetrics and Gynaecology – suspected pulmonary embolism
Model Answer
Obstetrics and Gynaecology – suspected pulmonary embolism.
a. Differential diagnoses
- Pulmonary embolism.
- Spontaneous pneumothorax.
- Trauma including domestic violence.
- Costochondritis or musculoskeletal chest pain.
- Pneumonia.
- Pleurisy.
b. Imaging in pregnancy
| Test | Benefit | Risks |
|---|---|---|
| V/Q scan | Lower breast and thyroid radiation than CTPA. | Sensitivity and interpretation may vary; fetal radiation may be higher than CTPA; availability may be limited; bladder radiation reduction may require catheterisation. |
| CTPA | More available, quick, sensitive with good negative predictive value, and may show alternative diagnoses. | Higher maternal breast/thyroid radiation, especially relevant in younger pregnant patients; greater chance of a non-diagnostic study in pregnancy. |
c. Investigation approach
- Balance a high-sensitivity diagnosis against maternal and fetal radiation risk.
- If there are clinical DVT signs, perform compression ultrasound first; anticoagulate if positive.
- If chest imaging is required, either CTPA or perfusion-only V/Q can be reasonable depending on local expertise, CXR findings, and shared decision-making.
- Do not rely on CXR or echocardiography alone to exclude PE.
- Wells, PERC, and D-dimer rule-out strategies are not reliable as sole exclusion tools in this setting.
- Discuss the risks, benefits, and uncertainty with the patient.
d. Rash on LMWH
- Concern is heparin-induced thrombocytopaenia.
- Investigate with FBC/platelet count and coagulation studies, with formal HIT testing if clinically suspected.
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