Criteria for failed labor induction: Prospective evaluation of a standardized protocol

Objective: To assess the safety and efficacy of a protocol that mandated at least 12 hours of oxytocin administration after membrane rupture before ce sarean delivery far failed labor induction in the latent phase. Methods: Gravidas at or beyond 36 weeks' gestation undergoing indicated ind uction with cervical dilatation up to 2 cm were studied prospectively. Prio r cesarean was aln exclusion criterion. If the fetal heart rate pattern was reassuring, cesarean was not permitted before the active phase of labor (4 -cm dilatation and at least 90% effacement or 5-cm dilatation regardless of effacement) unless the membranes had been ruptured and oxytocin administer ed for at least 12 hours. Results: Five hundred nine women were treated according to protocol; 360 (7 1%) were nulliparas and 149 (29%) were parous. Twenty-five percent of nulli paras and 9% of parous women were delivered by cesarean. After 6 hours of r uptured membranes and oxytocin, 14% of nulliparas were still in the latent phase; 39% of whom delivered vaginally, compared with 7% still in the laten t phase after 9 hours (vaginal delivery rate 28%), and 4% after 12 hours (v aginal delivery rate 13%). In contrast, after 6 hours of ruptured membranes and oxytocin, only five (3%) parous women were still in the latent phase. Among those, none remained in the latent phase for 12 hours and all were de livered vaginally. No women had serious complications. Severe neonatal morb idities were infrequent and not related to duration of the latent phase. Conclusion: By requiring a minimum of 12 hours of oxytocin after membrane r upture before failed labor induction could be diagnosed, many nulliparas wh o remained in the latent phase at 6 and 9 hours had safe vaginal deliveries , and failed labor induction was eliminated as an indication for cesarean i n parous women. (Obstet Gynecol 2000;916: 671-7. (C) 2000 by The American C ollege of Obstetricians and Gynecologists).