July 5, 2006

Leader: Linda Douglas, MD

Title: Membrane sweeping at initiation of induction of labor improves outcomes.

Clinical Question (PICO format): Does sweeping membranes at the initiation of labor induction vs. no membrane sweeping improve clinical outcomes of mode of delivery (spontaneous vaginal vs. operative/C-section), induction to delivery time interval, use of or duration of oxytocin in labor, or women’s satisfaction? Data were also collected on discomfort with the intervention. Secondary outcomes included: meconium staining, 5 min Apgar score, NICU admission, and indications for NICU admission.

Reference:

Tan PC, Jacob R, Omar SZ. Membrane sweeping at initiation of formal induction of labor. Obstet Gynecol 2006;107:569-77.

Study Design: Randomized controlled trial (single-blinded)

Population: Malaysian population of nulliparous and multiparous women, inpatient delivery setting. N = 274 women originally randomized.

Randomization: Quazirandomized by “shuffling” concealed allocation assignments within blocks of twenty. Table 1 appeared to show adequate randomization as there were no significant differences between the groups of women at baseline.

Allocation: Concealed from women and from the investigators analyzing data; the physicians who did the membrane stripping were sometimes making the decisions in labor, but the method of induction, the rate of oxytocin increase and other intrapartum variables were standardized by hospital protocol.

Followup: Adequate. All patients were accounted for. Only ten randomized patients did not complete the trial.

Intention to treat? Yes

Funding:

Unknown/not stated

Bottom Line:

Statistically significant results: Membrane sweeping at the initiation of labor induction resulted in higher spontaneous vaginal delivery rate (69% vs 56%, P = .04, NNT = 8), shorter induction to delivery interval (14 hours vs 19 hours, P = .003), shorter use of oxytocin infusion (2.6 vs 4.3 hours), fewer patients requiring oxytocin, ARR = 13%, NNT = 8) and improved patient satisfaction as measured by a visual analog scale.

Patient discomfort immediately after the intervention was greater in the intervention group. Subgroup analysis by nulliparity or multiparity showed similar trends favoring the intervention group, these were not statistically significant, likely due to the small numbers of patients in the study. (LOE 1b)

JC Group discussion points: The authors stated that their original power analysis resulted in a planned 270 women PER ARM of the study; their final group was only 274 women randomized, total. The reason for this difference was not explained. Although the primary outcomes were statistically significant, some were barely so; the authors could have strengthened their conclusions with a larger group of patients, as originally planned. (Since the hospital had 5000 deliveries per year, this would have been feasible).

A slightly higher percentage of women had Bishop scores of 5 or higher, though not enough to affect the protocol-driven method of induction (prostaglandin pessary or amniotomy/oxytocin) The initial cervical exam was done AFTER membrane stripping, so may have affected the cervical dilation measurement.

The study did not show any significant differences in neonatal outcomes or indications for NICU admission, but was not powered to do so. Cord Ph and Apgar results were essentially identical.

Should this change our practice? Most of the JC attendees had not been doing membrane stripping at the time of labor induction, and felt that they would now consider doing so.

For more information about membrane sweeping and labor induction see the Cochrane review:

Boulvain, M. Stan, C. Irion, O. Membrane sweeping for induction of labour. [Systematic Review] Cochrane Pregnancy and Childbirth Group Cochrane Database of Systematic Reviews. 2, 2006.