A Focus On: Diagnosing Pulmonary Embolism in Pregnancy

X-ray of Pulmonary embolism. From: Chapter 4 Respiratory. Piers Page and Greg Skinner. In: Emergencies in Clinical Medicine, Edited by Piers Page and Greg Skinner. Publisher: Oxford University Press. DOI: 10.1093/med/9780199202522.001.0001 © Oxford University Press 2008

Pulmonary embolism (PE) during pregnancy is, at the same time both rare (complicating only a very small percentage of all pregnancies) and a significant health problem, being the second most common cause of maternal death in the developed world after haemorrhage. The risk of PE in a pregnant woman is 5 times the risk in a non pregnant woman of the same age, and of deep venous thrombosis higher than that. It is generally accepted that the risks of untreated PE outweigh the risks of treatment but also that the risks of anticoagulation mean it shouldn’t be given to women who don’t need it.

Clinicians looking after pregnant women are therefore encouraged to have a high index of suspicion for the condition. Unfortunately even as PE is a difficult thing to diagnose clinically in non pregnant populations it is even more so during pregnancy. Many of the commonest symptoms of venous thromboembolic (VTE) disease such as shortness of breath, leg swelling and chest discomfort are fairly common features of pregnancy itself. As a result less than 10% of pregnant patients undergoing investigation turn out to have VTE.

Clinical scoring tests such as the Wells score specifically excluded pregnant women, and there are no fully validated clinical assessment criteria in this group. The recent rapid development of CTPA has led to myriad studies and publications into the best way to assess possible PE but most of these also excluded women who were pregnant. Studies looking specifically at PE in pregnancy are relatively rare.

In an attempt to bring some clarity to this difficult topic the American Thoracic Society and Society of Thoracic Radiology recently reviewed what evidence there is and published a set of concise and useful guidelines, which are recommended to clinicians and radiologists dealing with pregnant patients.

MJ Darby, Consultant Radiologist, Leeds Teaching Hospital Trust, Leeds, UK

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