An audit of CTPA and V/Q scan for investigation of pulmonary embolism in pregnancy

Background: Pulmonary embolism (PE) can be fatal yet difficult to diagnose in pregnancy. Computed tomography pulmonary angiogram (CTPA) or ventilation/perfusion (V/Q) scans are often conducted, potentially leading to low positive scan rates. Methods: Retrospective data analysis was conducted for pregnant women and non-pregnant age-matched control who underwent CTPA and/or V/Q scan for investigation of PE. The main outcomes were the positive and non-diagnostic imaging rates. Results: In total, 440 women underwent V/Q or CTPA scans, 86 of whom were pregnant (19.5%). The positive scan rate was 3.5% and 8.8% in the pregnant and non-pregnant groups, respectively (p= 0.1). The non-diagnostic scan rate was similar between pregnant and non-pregnant groups (13.9% vs 9.9%, p= 0.3). Within the pregnant group, there were more non-diagnostic CTPAs than V/Q scans (p = 0.005). Conclusion: Our study confirms a low positive imaging rate and a relatively high non-diagnostic CTPA rate in pregnancy. Newer strategies are needed to reduce the number of negative imaging studies conducted.