Options for women with pregnancies complicated by previable PPROM include expectant management or termination of pregnancy, either via dilation and evacuation or induction termination. Much research has focused on neonatal outcomes, but there is little data to provide guidance for counseling women about maternal risk after previable PPROM. Women who deliver near the limits of viability are nearly six times more likely to have a composite poor maternal outcome than those who deliver at term. There is no data to inform clinicians and patients regarding the extent to which a termination of a previable PPROM pregnancy mitigates this risk. The few studies that have addressed maternal morbidity after previable PPROM have either been underpowered or focused primarily on women who choose expectant management. In order to provide data to guide counseling about maternal risk after previable PPROM, we will conduct a retrospective cohort study of women who presented with PPROM between 14 0/7 and 23 6/7 weeks gestational age.
Based on prior literature, our composite morbidity outcome will include chorioamnionitis, unplanned surgical procedure after delivery of the fetus (either dilation and curettage for retained placenta in the case of induction termination or laparoscopy/laparotomy in the case of dilation and evacuation), injury to cervix or uterus requiring repair, unplanned hysterectomy, unplanned hysterotomy, uterine rupture, hemorrhage, blood transfusion, maternal ICU admission, acute renal insufficiency, venous thromboembolism, pulmonary embolism, ED visit within six weeks of delivery/termination, and maternal death.
Based on a previous retrospective study of previable PPROM, we will assume a combined maternal morbidity of 0.4 in the expectantly managed group. Based on a retrospective cohort study of pregnancy terminations for fetal indications we will assume a maternal morbidity of 0.2 in the group that selects termination. We thus hypothesize that the composite maternal morbidity in the termination group will be half of the composite maternal morbidity in the expectant management group. To test our hypothesis we will review medical records from of women who presented with PPROM between 14 0/7 and 23 6/7 weeks gestational age at the county safety-net hospital (Denver Health Medical Center) and at the University of Colorado Hospital, a large academic referral center. We will exclude women who present with chorioamnionitis, who deliver within 24 hours of membrane rupture, and whose fetuses have known major anomalies. We will search the EMR for dating criteria, concomitant medical conditions, and maternal outcomes.
Based on a preliminary review of three years worth of data with ICD-10 codes for PPROM at University of Colorado, there are 60 cases of previable PPROM, 46 of which did not meet our exclusion criteria. Of these, 1/3 chose pregnancy termination and 2/3 elected expectant management. Assuming 2/3 of the cohort will choose expectant management, we calculate that we will need a sample size of 208 women to detect (with 80% power and an alpha=0.05) a 20 percentage-point difference in the risk of composite maternal morbidity in the termination group vs. the expectant management group.
Our findings will give women with PPROM in the second trimester data about how their choices impact risks to themselves, not just the fetus. The results of this study will inform counseling by generalists, maternal-fetal medicine specialists and family planning specialists, all of whom may be called upon to counsel and manage these patients.