Pulmonary embolism (PE) is the commonest cause of maternal death in UK. It is a frequently occurring diagnostic challenge. The false negative and false positive rates for the diagnosis of PE are spectacularly high. Undiagnosed PE has a mortality rate as high as 30%, which falls to 2-8% if the condition is diagnosed and treated appropriately. [Rodger M, Wells PS. Diagnosis of pulmonary embolism. Thromb Res 2001;103:v225-38; Guidelines on Diagnosis and Management of Acute Pulmonary Embolism. Task Force on Pulmonary Embolism, European Society of Cardiology. Eur Heart J 2000;21(16):1301-36]. Physiologic changes of pregnancy further complicate the diagnosis of PE. Although the danger of maternal and foetal death secondary to maternal PE and unnecessary anticoagulation far outweighs the risk of radiation involved in scanning, doctors still hesitate to request appropriate investigation because of concern regarding radiation exposure to the foetus and the absence of any clear, updated guideline. Worried parents need to be counselled appropriately before tests to alleviate anxiety and misunderstanding.