Vol 84, No 3 (2013)

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Evaluation of the efficacy and safety of Foley catheter pre-induction of labor

Marek Grabiec, Małgorzata Walentowicz-Sadłecka, Jacek Fórmaniak, Radosław Janicki, Anita Kazdepka-Ziemińska, Iwona Jagielska
DOI: 10.17772/gp/1560
Ginekol Pol 2013;84(3).


Introduction: Labor induction is being increasingly used (15-30% of pregnancies). The most common indications include late pregnancy, preeclampsia, intrauterine fetal growth retardation (IUGR), hypertension. Preinduction by speeding up the ripening of the cervix increases the chances of successful induction. There are mechanical and pharmacological methods of pre-induction: the Foley catheter, hygroscopic dilators, prostaglandin gel, misoprostol. There are various schemes of labor pre-induction and the differences relate primarily to duration of catheter time, amniotomy or the start of the oxytocin. Numerous studies on pre-induction and induction of labor aimed to compare the efficacy of these different methods. The effectiveness of the Foley catheter is usually assessed by comparing cervical maturity (Bishop score) and ripening of the cervix, evaluated in centimeters, before and after removing the catheter, time to labor since pre-induction and the number of births. In order to select the appropriate method, its safety for the mother and the fetus/newborn needs to be assessed. According to most authors, the use of a Foley catheter does not cause over-stimulation of the uterus, does not increase the risk of rupture or intrauterine infection, and does not adversely affect the fetus and newborn. Aim of the study: To assess the efficacy and safety of labor pre-induction using a Foley catheter. Material and methods: The study included 109 women hospitalized between 03.01.2011 and 11.30.2011, who underwent labor pre-induction with a Foley catheter. The inclusion criteria were: one fetal pregnancy, longitudinal cephalic fetal position, completed 36 weeks of pregnancy, fetal bladder preserved, Bishop score < 5 points. The exclusion criteria were: placenta previa, uterine infection, unexplained bleeding, abnormal fetal heart rate, and other reasons preventing vaginal delivery, such as fetal weight above 4500g. Vaginal swabs for the presence of Streptococcus agalactiae (GBS) were obtained from each patient. In case of a positive result perinatal antibiotic prophylaxis was administered before insertion of the catheter. The study group was divided into two subgroups according to parity: primiparous and multiparous. Indications for induction, method of pregnancy termination, the pregnancy and its complications were evaluated. The condition of the newborns was evaluated using the Apgar score, cord blood pH and infant birth weight. We analyzed cervical ripeness (Bishop score) before the insertion and after the removal of the catheter and serum C-reactive protein (CRP) before and 20 hours after insertion. CRP was not studied in pregnant women diagnosed with GBS colonization. The results were compared between the subgroups. An increase in the Bishop score to > 5 and delivery within 12 hours since the planned removal of the catheter, regardless of the method of pregnancy and the use of oxytocin, was considered as successful induction of labor. Results: Catheter pre-induction was performed in 109 pregnant women, what amounted to 7.87% all of deliveries in our department during the analyzed period. Mean patient age was 29.3 ± 5.35 years, mean duration of pregnancy 40 weeks of gestation (± 1 week 5 days), and primiparas constituted 66.06% of all cases. The most common indication for labor induction was post-term pregnancy (55.05%), hypertension and preeclampsia (16.51%). The following complications were observed in the study group after insertion of the catheter: 8 (7.34%) cases of premature rupture of the membranes (PROM), but none of them occurred in the process of inserting the catheter, 11 (10.09%) women had the catheter removed (patient’s request) due to pain and the feeling of discomfort before the scheduled time, 2 (1.84%) cases of bleeding (in the first case the cesarean section was performed and the baby was born in a good overall condition, in the second case the bleeding subsided spontaneously). There was a statistically significant increase in the Bishop score for the entire study group and in the two subgroups. Mean increase in the Bishop score was 2.68 ± 1.39 points for the entire cohort (p <0.005). The rate of successful pre-induction resulting in a delivery was 69.4%, with vaginal births accounting for 66.67% of all cases. Also, 30.66% of the pregnant women did not require the use of oxytocin. The most common indication for cesarean section was threatening intrauterine fetal asphyxia. Higher efficiency of pre-induction was found in the multiparous group. The observed increase in CRP (p <0.005) was within the normal range for pregnant women (<12 mg/l). None of the patients showed any clinical signs of infection. Mean birth weight of the infants was 3392 ± 644.72 g, mean Apgar score was 9.5 ± 0.80 and mean cord blood pH was 7.3 ± 0.08. Conclusions: The Foley catheter is an effective method of inducing cervical maturation. The Foley catheter is safe method of labor induction for the mother, fetus and newborn.

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