Contribution of ultrasound pulmonary ratio in pre-viable premature ruptures of membranes

To evaluate the ultrasound measurement of the observed-to-expected (o/e) lung-to-head ratio (LHR) and the Quantitative Lung Index (QLI) for the prediction of pulmonary hypoplasia in the pre-viable preterm premature ruptures of membranes (PPROM) before 24 weeks gestational age (GA). Thirty-four patients with a PPROM before 24 weeks GA and who delivered a live birth between October 2008 and October 2015 at Croix-Rousse's hospital were included. The measurements of both the LHR (right, left and total) and the QLI (right, left) were retrospectively performed by ultrasounds during the latency period. The observed LHR was divided by the expected LHR, which was obtained from recent literature data. The primary outcome was the onset of a lethal pulmonary hypoplasia. Receiver operating characteristics (ROC) curves assessed the predictive value of these ultrasound measurements for pulmonary hypoplasia. The areas under the ROC curves (AUCs) for the right o/eLHR, the right QLI and the total o/e LHR measured by manually drawing the pulmonary area on the last ultrasound before the delivery, were respectively 0.87 [95% CI: 0.75-1], 0.83 [95% CI: 0.69-0.98] and 0.78 [95% CI: 0.51-1]. Only the total o/eLHR measurements remained associated with lethal pulmonary hypoplasia after adjusting for prematurity and persistent oligohydramnios. The right and total o/eLHR and the right QLI measurements might be helpful in predicting pulmonary hypoplasia in pre-viable PPROM.