Effect of early amniotomy on dystocia risk and cesarean delivery in nulliparous women: a randomized clinical trial.

PURPOSE: Artificial rupture of amniotic membranes (amniotomy) which induces or accelerates labor is the most common obstetrical procedure. There is controversy about the effect of early amniotomy on dystocia and cesarean delivery. The study aim was to determine the effect of early amniotomy on the risk of dystocia and cesarean delivery in nulliparous women.

METHODS

This randomized controlled clinical trial was conducted on 300 nulliparous women. They were randomly assigned into the experimental (early amniotomy; artificial amniotomy at cervical dilation ≤ 4 cm) and control (routine management) groups (each 150 women). Length of labor, dystocia, cesarean delivery, placental abruption, and umbilical cord prolapse were compared between the groups.

RESULTS

Early amniotomy shortened labor duration significantly in experimental group (7.5 ± 0.7 h) compared to control group (9.9 ± 1.0 h) (P < 0.001). Dystocia (6.7 vs. 25.3 %, P < 0.0001), cesarean delivery (11.3 vs. 39.3 %, P < 0.001), and placental abruption (4.7 vs. 13.3 %, P = 0.009) were significantly lower in experimental group compared to the control group. Multiple logistic regression showed that early amniotomy decreased the odds of dystocia 80.6 % (95 % CI 58.6-90.1 %) and the odds of cesarean section 81.7 % (95 % CI 66.2-90.1 %).

CONCLUSION

Early amniotomy was associated with lower rate of dystocia and cesarean delivery as well as shorter duration of labor.