# Improving Clinical Prediction of Pulmonary Embolism in Pregnancy and Postpartum by Modifying Wells Score with a Population Specific Risk Factor: A retrospective study

## TL;DR

This study improves the prediction of pulmonary embolism in pregnant and postpartum women by adjusting the Wells score to account for sickle cell disease.

## Contribution

Modifying the Wells score with a population-specific risk factor (sickle cell disease) improves diagnostic accuracy for pulmonary embolism in pregnant and postpartum women.

## Key findings

- The Wells score had a 95.2% negative predictive value for low-risk patients.
- Incorporating sickle cell disease increased the sensitivity and specificity of the modified score.
- Women with sickle cell disease had a significantly higher incidence of pulmonary embolism.

## Abstract

Pulmonary embolism (PE) is a significant cause of maternal mortality, necessitating accurate clinical prediction tools to optimise diagnosis and reduce unnecessary imaging. This study aimed to examine the Wells score's (WS) predictive value for PE, the effect of incorporating sickle cell disease (SCD) on its predictive accuracy and to estimate prevalence of PE in pregnanct and postpartum women.

This retrospective study included pregnant and postpartum women who underwent computed tomography-pulmonary angiography (CTPA) for suspected PE at two tertiary hospitals (Sultan Qaboos University Hospital and Royal Hospital in Muscat, Oman) from 2013 to 2019. The relationship between WS and CTPA was evaluated before and after adding 3 points for SCD.

A total of 193 pregnant and postpartum women with a mean age of 31.45 ± 5.60 years underwent CTPA for suspected PE. PE incidence was 0.31 in 1,000 deliveries and 28 women (14.5%) had PE confirmed in CTPA. WS stratified probability of PE as low in 44 (22.8%) patients, moderate in 142 (73.6%) patients and high in 7 (3.6%) patients. In the women with a low score, 2 (4.5%) had PE, giving 95.2% negative predictive value (NPV) of low WS. High WS had a sensitivity of 33.3% and a specificity of 87.0%. Women with SCD had a higher incidence of PE compared to those without (36.7% versus 10.4%, odds ratio = 4.9, 95% confidence interval: 2.0–12.1; P < 0.001). When modifying WS with additional SCD points, NPV for the low score patients was 94.4%, while for the high score group sensitivity and specificity were 72.3% and 85.7%, respectively.

The study confirms that low WS effectively excludes PE, reducing the need of imaging in pregnancy and postpartum. Incorporating SCD enhances sensitivity and specificity of a high score aiding to prioritise women for diagnostic imaging or empirical anticoagulation.