Pregnancy-related cardiovascular physiologic changes increase the likelihood of pulmonary edema, with the risk of fluid extravasating into the pulmonary interstitium being potentially at a maximum during the early postpartum period. Data on the impact of labor and peripartum hemodynamic strain on lung ultrasound (LUS) are limited, and the prevalence of subclinical pulmonary interstitial syndrome in peripartum women is poorly described. The primary aim of this exploratory study was to estimate the prevalence of pulmonary interstitial syndrome in healthy term parturients undergoing vaginal (VD), elective (eCD), and unplanned intrapartum cesarean deliveries (uCD). Secondary aims were to estimate the prevalence of positive lung regions (≥3 B-lines on LUS per region) and to assess the associations between positive lung regions and possible contributing factors.
In this prospective observational cohort study, healthy women at term undergoing VD, eCD, or uCD were enrolled. Following international consensus recommendations, a LUS examination was performed within 4 hours after delivery applying an 8-region technique. Pulmonary interstitial syndrome was defined by the presence of 2 or more positive lung regions per hemithorax. Ultrasound studies were reviewed by 2 blinded reviewers and assessed for interobserver reliability.
Seventy-five women were assessed (n = 25 per group). No pulmonary interstitial syndrome was found in the VD and eCD groups (each 0 of 25; 0%, 95% confidence interval [CI], 0-13.7). Pulmonary interstitial syndrome was found in 2 of 25 (8%, 95% CI, 1-26) women undergoing an uCD (P = .490 for VD versus uCD and P = .490 for eCD versus uCD). In 1 woman, this correlated clinically with the development of pulmonary edema. One or more positive lung regions were present in 5 of 25 (20%), 6 of 25 (24%), and 11 of 25 (44%) parturients following VD, eCD, and uCD, respectively (P = .136). Positive lung regions were predominantly found in lateral lung regions. The number of positive lung regions showed a weak correlation with patient age (r = 0.25, 95% CI, 0.05-0.47; P = .033). No significant association was found between LUS pattern and parity, duration of labor, labor augmentation, labor induction, estimated total intravenous fluid intake, or net intravenous fluid intake.
Although many focal areas of increased extravascular lung water (20%–44% prevalence) can be identified on LUS, the overall prevalence of pulmonary interstitial syndrome was 2.7% (2 of 75; 95% CI, 0.3-9.3) among healthy term parturients soon after delivery. Focal areas of positive lung water regions were weakly correlated with maternal age.