Safety Study of Membrane Sweeping in Pregnancy

The question of routine membrane sweeping and prelabor rupture of membranes has not been specifically addressed in a randomized control trial. A meta analysis of membrane sweeping found ten publications which analyzed this question as a secondary outcome, though none of these studies sought to analyze PROM in their objectives. This meta analysis found the relative risk of prelabor rupture of membranes to be 1.14 with membrane sweeping, however the confidence interval was 0.89 to 1.45 making the finding not significant. Despite this, we feel that a study to specifically address this issue is warranted. The largest study in the meta analysis (and the only one with a statistically significant difference on its own) did find a significant risk of PROM. The studies in the meta analysis vary greatly in their incidence of PROM, ranging from 2-39% in the membranes sweeping group and 2-26% in the control groups. This wide variation, the fact these studies were not primarily designed to compare PROM rates, and the reported 8-10% PROM in other texts and studies gives question to the ability of this meta analysis to detect a difference in PROM rates between the two groups. As the effect of membrane sweeping on PROM may influence clinicians attitudes toward this intervention, further specific research is warranted.

Our Objective are:

1. To determine the rate of prelabor rupture of membranes in uncomplicated term pregnancies undergoing routine membrane sweeping versus those without intervention. For the purpose of this study, PROM is defined as the confirmation of ruptured amniotic fluid with uterine contractions less than 10 minutes apart.
2. To determine the impact of membrane sweeping on successful labor induction for post datism and pregnancies going past 41 weeks
3. To determine the impact of membrane sweeping and PROM with clinical variables

Patients will be randomized by a computer generated randomizer to either receive membrane sweeping or vaginal exam without membrane sweeping. Patients will receive either membrane sweeping or vaginal exam without membrane sweeping at each weekly visit from 38 weeks gestation onwards. Patients in the no intervention group will receive no cervical evaluation unless clinically indicated. Patients in the membrane sweeping group will have a finger placed into the cervical os, the finger will be rotated in a 360 degree fashion which will separate the amniotic membranes from by a circular motion. Patients in this group whose cervix is not open enough to have the membranes swept will have it gently stretched and if the cervix is closed it will be gently massaged to stimulate the release of prostaglandins (1). Due to the nature of the intervention, it is not possible to blind the physician who is performing the vaginal exam to which group the patient is in. However, the admitting and delivering physicians will be blinded to the group allocations. This will minimize bias. Such blinding will be done by having a patient identifier code in the chart which the clinic physicians will use to access the randomizer online for determination of which exam to perform. Admitting and delivering physicians will not access this code. Between 38 and 42 weeks gestation, clinical data from each prenatal visit will be kept to include patient age, gestational age, parity, race, cervical exam, post-graduate year level of physician or if the provider is a midwife or attending staff, and whether or not membrane sweeping was performed. In Labor and Delivery data will then be collected on gestational age at delivery, indication for admission, inductions, reason for induction, estimated gestational age at delivery, PROM, cervical exam at admission, Bishop's score on admission, labor outcomes, route or delivery, pregnancy complications, neonatal complications, GBS status, and NICU admissions. PROM as an indication for admission will be confirmed by nitrazine testing, ferning test, and speculum examination. Two of the three tests must indicate PROM for the patient to be given the diagnoses of PROM. PROM will be defined as the above positive testing with contractions more than 10 minutes apart at the time of rupture of membranes. If the PROM occurred just prior to the examination, this assessment will be made on the tocometer. If the PROM occurred prior to the patient presenting to Labor and Delivery, this assessment will be based on the patient's subjective assessment of her contractions at the time of membrane rupture. Labor is defined as regular contractions leading to cervical change. The frequency of contractions required to cause cervical change varies from patient to patient, however for the purpose of this study the patient will be considered to have SROM (spontaneous rupture of membranes due to labor) if contractions are more frequent than every 10 minutes. Patients will be analyzed on an intent to treat basis.