All statistical analyses were performed using SPSS software
All statistical analyses were performed using SPSS software (version 15; SPSS Inc., Chicago, IL, USA). Continuous data are expressed as mean (standard deviation) and were analyzed with two independent-samples tests. Chi-square and Fisher\'s exact tests were used for categorical data. The significance boundary (p) was given as 0.05.
Results A total of 148 patients who satisfied the trial criteria were recruited into the study; of these, 44 patients declined to participate, and thus 104 patients [patients with oligohydramnios (n=40) and control patients (n=64)] completed the study (Fig. 1). The demographic variables of the patients in Groups A and B are presented in Table 1; age, parity, and Bishop scores were insignificant between the groups (p>0.05 for all). Gestational age was significantly different between the groups (p=0.001). Table 2 summarizes the obstetric and neonatal outcomes. The mean time intervals from induction to delivery were 21.76±4.49 hours and 20.86±4.04 hours for the oligohydramnios and control groups, respectively (p>0.05). CS rate was significantly different between the groups, 40.0% and 15.6% for the oligohydramnios and the control groups, respectively (p=0.005). Hyperstimulation occurred in four of 40 patients in the oligohydramnios group and in one of 64 patients in the control group, without reaching statistically significant difference. Of the patients in Groups A and B, 7.5% (3/40) and 3.1% (2/64), respectively, needed admission to neonatal intensive care unit within 24 hours after delivery (p>0.05). There was no statistically significant difference in the 5th-minute Apgar score and postpartum hemorrhage between the groups (p>0.05). There were no uterine ruptures, infectious complications, or other major maternal complications.
Discussion Our study regarding the efficacy and safety of dinoprostone for cervical ripening and labor induction in term pregnancies with a Bishop score≤5 between patients with isolated oligohydramnios and normal amniotic fluid revealed that notch signaling pathway dinoprostone did not decrease the mean time interval from induction to delivery. In addition to these results, the rate of CS in patients with oligohydramnios was higher than in those with normal amniotic fluid. Induction of labor is a widely used procedure for various maternal and fetal indications, one of which is oligohydramnios. In many cases, the cervix may not be ripened enough, especially in primigravidas. Therefore, there is a need to prepare the cervix for a likely vaginal birth. Various techniques have been used for this purpose, with vaginal dinoprostone administration being one of the most commonly used methods of all. In this prospective study, dinoprostone administered by the standard once-daily regimen demonstrated a significantly higher rate of labor success within 24 hours in the oligohydramnios and control groups (72% vs. 78%), and the rate of oxytocin use was similar in both groups. Venturini et al and Stefos et al studied dinoprostone gel action vaginally and concluded that it was noneffective in lessening the duration of labor. The primary outcomes of our study also supported the previous results. Classically, oligohydramnios has been related to increased neonatal mortality and morbidity in high-risk pregnancy status. However, some investigators have found an association between an active induction of labor in term low-risk pregnancy with isolated oligohydramnios and an increased rate of cesarean section without causing any detrimental neonatal outcomes, when compared with normal AFI. A meta-analysis done by Chauchan et alindicated that there was no association between olygohydramnios and neonatal acidosis, even though acidosis resulted in AFI<5 with an increased risk of CS due to fetal distress and lower Apgar score. However, this analysis involved high-risk and preterm pregnancies. Some retrospective studies of term pregnancies with isolated oligohydramnios reported no differences in Apgar score, requirement of neonatal intensive care unit, fetal acidosis, or perinatal death from normal AFI pregnancies with induction of labor. Similarly, we also found an increased rate of cesarean section in patients with oligohydramnios without an increase in adverse perinatal outcomes. By contrast, in a retrospective study by Danon et al, patients with uncomplicated oligohydramnios at term underwent induction of labor with prostaglandin E2; the investigators concluded that the induction of labor for oligohydramnios was an overtreatment, and proposed close surveillance to lower the rate of CS.