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Published on: March 29, 2018
Third-trimester resolution of low placentation and risk of postpartum hemorrhage
Alexa Cohen1, Teresa Qi1, Christine Miguel1
1Montefiore Medical Center/Albert Einstein College of Medicine, Division of Fetal Medicine and Ultrasound, Department of Obstetrics and Gynecology and Women's Health.
Objective:
Low placentation is associated with increased risk of postpartum hemorrhage (PPH). There is a paucity of data on the association between second trimester low placentation that later resolves, and PPH. Our objective was to investigate the association of resolved low placentation and other prenatal ultrasound markers, and PPH with delivery.
Study Design:
This was a retrospective matched case-control (1:1) study of full term, singleton pregnancies complicated by PPH who delivered vaginally at our academic center between 2018-2022. All patients received a transvaginal ultrasound in the second and third trimester. PPH was defined as quantitative blood loss (QBL) >1L within 24 hours of delivery. Primary exposure variable was second-trimester low placentation (defined as previa or low-lying placenta within 10mm from internal os) that resolved before labor. Additional exposure variables included uterine leiomyoma, first-trimester subchorionic hematoma, second-trimester cervical length< 25mm, and third-trimester polyhydramnios or large for gestational age (LGA) fetus. Chi-square test and unpaired student t-test were used to compare categorical and continuous variables, respectively. Multivariable logistic regression analysis was performed to adjust for confounders.
Results:
We compared 400 gravidas with PPH to 400 without. Gravidas were matched by age, parity, gestational age and mode of vaginal delivery. PPH occurred more often in cases with resolved previa versus controls (12 % vs 4.6 %, p < 0.01). On multivariate analysis, those with resolved previa were 2.58 times more likely to have PPH, compared to controls (aOR 2.58, 95% CI 1.49 - 4.81, p < 0.001). PPH rates were also increased in those with leiomyoma (aOR 3.50, 95% CI 1.59 - 7.72, p = 0.002). Rates of subchorionic hematoma, short cervical length, polyhydramnios and LGA fetus were similar between groups.
Conclusion:
Low placentation on second-trimester ultrasound is associated with an increased risk of PPH, even when it appears to resolve in the third trimester. Routine assessment of placentation in the second trimester should be considered to improve prediction and management of PPH.
