Clinical Inquiries

Does amniotomy shorten spontaneous labor or improve outcomes?

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EVIDENCE-BASED ANSWER:

No. Amniotomy neither shortens spontaneous labor nor improves any of the following outcomes: length of first stage of labor, cesarean section rate, maternal satisfaction with childbirth, or Apgar score <7 at 5 minutes (strength of recommendation [SOR]: A, large meta-analyses of randomized controlled trials [RCTs] and a single RCT with conflicting results).

Amniotomy does result in about a 55% reduction of pitocin use in multiparous women, a small (5 minutes) decrease in the duration of second-stage labor in primiparous women, and about a 50% overall reduction in dysfunctional labor—ie, no progress in cervical dilation in 2 hours or ineffective uterine contractions (SOR: A, large meta-analyses of RCTs and a single RCT with conflicting results).

Amniotomy doesn’t improve other maternal outcomes—instrumented vaginal birth; pain relief; postpartum hemorrhage; serious morbidity or death; umbilical cord prolapse; cesarean section for fetal distress, prolonged labor, antepartum hemorrhage—nor fetal outcomes—serious neonatal morbidity or perinatal death; neonatal admission to intensive care; abnormal fetal heart rate tracing in first-stage labor; meconium aspiration; or fetal acidosis (SOR: A, large meta-analyses of RCTs and a single RCT with conflicting results).


 

References

EVIDENCE SUMMARY

A meta-analysis of 15 RCTs (5583 women) compared intentional artificial rupture of the amniotic membranes during labor (amniotomy) with intention to preserve the membranes (no amniotomy). The study found no differences in any of the measured primary outcomes: length of first stage of labor, cesarean section, maternal satisfaction with childbirth, or Apgar score <7 at 5 minutes.1

Investigators included 9 trials with both nulliparous and multiparous women and 6 trials with only nulliparous women. Thirteen trials compared amniotomy with intention to preserve the membranes, and 2 trials performed amniotomy in the control group if the membranes were intact at full cervical dilation.

Amniotomy doesn’t affect first-stage labor or cesarean risk

Five trials (1127 women) reported no difference in length of the first stage of labor between the amniotomy and no amniotomy groups (mean difference [MD]= −20 minutes; 95% confidence interval [CI], −96 to 55). Subgroups of primiparous and multiparous women showed no difference (MD= −58 minutes; 95% CI, −153 to 37 and MD= +23 minutes; 95% CI, −51 to 97, respectively).

Nine trials (5021 women) reported no significant difference in cesarean section risk overall or when compared by parity, multiparous vs primiparous (risk ratio [RR]= 1.27; 95% CI, 0.99-1.63). One trial (84 women) found no difference in maternal satisfaction scores with childbirth experience. Six trials (3598 women) that reported risk of low Apgar score (<4 at 1 minute or <7 at 5 minutes) found no difference overall (RR=0.53; 95% CI, 0.28-1.00), or when compared by parity (multiparous vs primiparous).

Amniotomy doesn’t shorten spontaneous labor nor improve length of first-stage labor, cesarean section rate, or maternal satisfaction with childbirth.

Investigators reported that the included trials varied in quality and described the following limitations: inconsistent or unspecified timing of amniotomy during labor, proportion of women in the control group undergoing amniotomy, and ≥30% of women not getting the allocated treatment in all but one of the trials.

Secondary outcomes: Amniotomy reduces oxytocin use

Eight trials (4264 women) evaluated oxytocin augmentation and found that amniotomy decreased its use in multiparous (RR=0.43; 95% CI, 0.30-0.60), but not primiparous, women.

Eight trials (1927 women) reported length of second stage of labor as a secondary outcome, with no difference overall (MD= −1.33 minutes; 95% CI, −2.92 to 0.26). Amniotomy produced a statistical but not clinically significant shortening in subanalysis of primiparous women (MD= −5.43 minutes; 95% CI, −9.98 to −0.89) but not multiparous women.

Continue to: Three trials...

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