A Comparative Study of Extra-Amniotic Infusion of Corticosteroids versus Normal Saline for Induction of Labour.
corticosteroid, foley catheter, induction of labor, ripe cervix
K Pushpalatha. A Comparative Study of Extra-Amniotic Infusion of Corticosteroids versus Normal Saline for Induction of Labour.. The Internet Journal of Third World Medicine. 2008 Volume 8 Number 1.
Ripening of the cervix is normally a physiologic process that precedes uterine contractions and includes a highly complex biochemical process. The purpose of cervical ripening and induction of labor is to achieve vaginal delivery and to avoid operative delivery by cesarean section (1,2).The rate of women undergoing labor induction is increasing, primarily because of patient-physician preferences. The widespread availability of preinduction cervical ripening agents has contributed to this rising trend. Approximately half of all women undergoing an induction of labor will have an unfavorable cervix that will require some ripening agent. Pharmacologic and mechanical dilator techniques have been proven to ripen the unfavorable cervix (3).Numerous techniques have been attempted to ripen the unfavorable cervix and enhance the changes necessary for labor in the lower uterine segment (4,5), including intravenous infusion of oxytocin (6),which is associated with a prolonged induction period, high failure rate and considerable patient discomfort (7,8,2), intravaginal or intracervical administration of prostaglandin (9-15), which could cause uterine tetany (16,17), and intracervical Foley balloon catheter insertion (12-14), which ripens the cervix mechanically, usually without causing contractions (18-20). The role of corticosteroids in the process of labor is not entirely understood. Nevertheless, several reports have suggested that intramuscular or intraamniotic injection of corticosteroids results in higher rates of induction of labor and vaginal deliveries in lambs and humans (21-23). Some assumptions regarding their possible role in parturition have been proposed as being effective in a paracrine or autocrine fashion because receptors for glucocorticoids have been identified in the amniotic membranes (24). So, local corticosteroids may be involved in the course of labor induction. The aim of this study was to examine the hypothesis that corticosteroids, when administered extra-amniotically, can enhance the labor process and reduce the induction-to-delivery interval
Material and Methods
In this randomized controlled trial we compared extra-amniotic injection of corticosteroids with injected saline solution for cervical ripening and induction of labor. This double-blind, randomized controlled study was conducted on 50 women with singleton gestations and a gestational age of 36 to 42 weeks, who were referred to the J. J. M. Medical College Davanagere, Karnataka India for induction of labor with a Bishopscore of less than or equal to 4 from October 1998 through October 2000.The indications for labor induction during the study period included postdate pregnancy, suspected fetal distress, hypertensive disorders, intrauterine growth restriction , full term pregnancy with unknown dates. Exclusion criteria were known uterine anomaly, invasive cervical carcinoma, cephalopelvic disproportion (because of malpresentation or abnormal pelvic bone structures), known placenta previa or low-lying placenta, vasa previa, reported or documented episode of midtrimester or third trimester bleeding, active genital herpes infection, maternal fever, intrauterine fetal death, previous classical uterine incision, and three or more uterine contractions in 10 minutes. Eligible patients were informed of the purpose of the study and were requested to sign an informed consent that was approved by the local ethics committee. After giving their consent, patients were assigned to one of two arms according to a computer-generated random list. The type of therapy given in each group was blinded to both patients and physician. Patients who required cervical ripening and induction were randomized to one of 2 groups:
1) In study group, a 26F catheter with a 30 ml balloon was inserted under direct vision through the cervix of patients, using sterile technique. The balloon was inflated with 30 ml of sterile water, and 20 mg of dexamethasone mixed with sterile saline solution up to a volume of 20 ml was injected through the catheter into the extra-amniotic space, followed by infusion of 1 ml/min of sterile saline solution into the extra-amniotic space by means of an infusion pump. The balloon was then taped to the patient's inner thigh.
2) In control group, women received the same treatment except that 20 mg of corticosteroids was replaced by 20 ml of pure saline solution. The patients were monitored for fetal heart rate every 20 minutes during the first hour and then every hour for the next 5 hours. Gentle traction of the catheter was performed every hour to watch for expulsion of the balloon. If the balloon was not expelled within 6 hours, it was deflated and extracted. Thereafter intravenous oxytocin was administered in an initial dose of 2.5 mIU/min, with subsequent increase of 2.5 mIU/min every 20 minutes until three contractions in 10 minutes were achieved (as long as the fetal heart rate was satisfactory). After a further 2 hours the patients were reexamined for Bishop score. Only when the patient entered the active phase of labor, which was defined as three or more contractions in 10 minutes and cervical dilatation ≥4 cm, the protocol was continued. If the patient did not demonstrate these minimal conditions, oxytocin was stopped and failure of induction was announced. Amniotomy was permitted only in the active phase. The patients were followed up for the common complications of balloon application: nausea and vomiting, uterine hypertonus, and febrile morbidity. Since cord blood gas test is not routinely performed in our medical center, neonatal outcome assessment included Apgar score. Mean values of maternal age, gestational age, and time intervals were compared between the study and control groups with use of the two-sample
Fifty subjects (study group 25, control group 25) were enrolled in the study. Table1 shows the clinical characteristics in the two groups.
There were no statistical differences in maternal age, gestational age or parity between the two groups. Indications for induction of labor are depicted in table 2.
There was no significant difference between two groups in any of indications. Table 3 demonstrates the interval between induction to pain, induction to active phase and induction to delivery in the two groups. Nineteen (76 %) patients in the study group and 21 (84 %) in the control group entered the active phase of labor. The mean interval from induction of labor to the active phase was significantly shorter in the study group (5.0±1.8 hours) compared with the control group (6.69±1.52 hours,
All of the women who entered the active phase of labor were delivered vaginally (19 patients in the study group and 21 in the control group).
There was no significant difference in the rate of cesarean delivery between the two groups. No maternal or fetal complication was seen in study or control group and there was no significant difference between two groups with respect to maternal or fetal complications. Nevertheless, the sample size was not sufficient to rule out a significant difference in the rate of complications with appropriate power.
One of the common practices of modern obstetrical care is to induce labor and delivery when fetal and/or maternal complications arise (3,25).Various methods and agents of cervical ripening and labor induction have been described in the obstetrics literature (2).Regardless of the ripening agent used, each has been shown to significantly improve the pre induction cervical score, shorten the induction to vaginal delivery time, and reduce the need for oxytocin (3).In a review of 11 reported studies, it has been suggested that ripening efficacy by catheter balloon is similar to, or better than, other methods (25); however our study demonstrated a possible role of corticosteroids, acting locally in the fetal membranes, in shortening the time interval from induction of labor to delivery in pregnancies requiring induction, which was in agreement with previous study by Barkai