Objective
To assess the effectiveness of inner thigh “Taping” compared with “Traction” using a weighted bag when an intracervical Foley catheter is used for cervical ripening.
Study Design
We performed a randomized controlled trial at a tertiary hospital on women with a singleton pregnancy in cephalic presentation admitted for labor induction with a Bishop score ≤6. A 30 mL intracervical Foley catheter was placed for ripening. Women were randomly allocated to inner thigh Taping or to Traction with a 500 mL weighted bag of fluid. The primary outcome was time to delivery. Secondary outcomes were time to expulsion of the catheter, maternal discomfort (visual analog scale), mode of delivery, and maternal morbidities.
Results
We randomized 197 women. After exclusions (4 ineligible, 2 withdrawn by provider), we analyzed 191 (96 Taping, 95 Traction) women in their assigned groups. Groups were similar regarding maternal race, age, parity, gestational age, and induction indication. Time to delivery was not significantly different (mean ± standard deviation: 19.8 ± 8.5 vs 18.8 ± 8.0 hours; P = .39). Time to catheter expulsion was shorter in the Traction Group (median, 2.6; range, 0.2–10.8 vs median, 1.5; range, 0.1–6.3 hours; P < .001). Change in Bishop and pain scores, cesarean delivery rates, clinical amnionitis, and other maternal morbidities were similar between groups. Subset analyses of those with vaginal delivery and among nulliparas, and multiparas revealed similar results.
Conclusion
Traction on the intracervical Foley catheter during cervical ripening shortens the time to spontaneous catheter expulsion without affecting the time to delivery.
Over 20 years, the number of labor inductions has steadily increased from 9.5% of all deliveries in 1990 to nearly 1 in 4 deliveries in 2009. Regardless of parity, a patient’s initial cervical examination influences the chances for a successful vaginal delivery. Therefore, before beginning an induction, the Bishop score (cervical dilation, effacement, station, consistency, and position) is generally assessed. In patients with an unripe cervix, defined as a Bishop score of less than or equal to 6, the American College of Obstetricians and Gynecologists has stated that both mechanical and prostaglandin ripening are acceptable and safe.
Although the safety, efficacy, and risks of Foley catheter ripening have been compared with those of other methods for cervical ripening, few studies have compared different protocols for Foley placement. One study showed that the concurrent use of oxytocin and Foley catheter did not significantly shorten the time to delivery. Levy et al showed that a larger, 80 mL balloon resulted in a greater postripening dilation and a higher number of deliveries in 24 hours. However, there is heterogeneity among the studies in what, if any, traction is applied to the Foley catheter after it is placed into the cervix and the balloon inflated. Some have simply taped the catheter to the patient’s leg with no tension, others have placed the catheter under “gentle traction.” The practice at our institution has been to attach the Foley catheter to traction with a bag with 500 mL of fluid placed over the end of the bed in a fashion similar to Kashanian et al. However, it remains unclear if this practice provides added benefit to intracervical Foley catheter placement alone.
Therefore, we performed a randomized controlled trial to compare placing the intracervical Foley catheter under “Traction” (500 mL weight in the catheter bag draped over the end of the bed) with simple “Taping” of the catheter to the inner thigh of the patient. We hypothesized that the use of a weighted bag would result in a shorter labor course.
Materials and Methods
We performed a single-site randomized controlled trial in an urban tertiary care hospital between Dec. 2009 and July 2012. The institutional review board for Case Western Reserve University at MetroHealth Medical Center approved this study, and all participating women provided written informed consent. Group allocation was assigned by random number generator (Available at: http://www.randomizer.org . Accessed Nov. 29, 2009). Allocation was masked using sealed opaque envelopes that were opened after eligibility was confirmed and informed consent obtained. Each patient was assigned to the treatment in the next sequentially numbered envelope.
Eligibility criteria included: admission for an induction of labor, a fetus in cephalic presentation, and an unripe cervix defined as a Bishop score ≤6. Exclusion criteria were any medical conditions precluding vaginal delivery, age less than 18 years, inability to read and consent in the English language, clinically significant cervical or intrauterine infection, vaginal bleeding, intrauterine fetal demise, low lying placenta, prior cervical surgery, or a latex allergy and >1 previous cesarean delivery.
Once admitted, all women had a transcervical Foley catheter inserted. Patients were placed in the dorsal lithotomy position in stirrups in the delivery bed. A sterile vaginal speculum was used to visualize the cervix, and the cervix and vaginal apex were prepped with betadine solution. Using sterile uterine forceps, a 14 French, 30-mL Foley was introduced under direct visualization and passed through the cervix until the balloon was presumed to be above the internal os. The Foley balloon was then filled with 30 mL of normal saline and the end was placed under tension. For the “weighted bag” arm, a Foley bag was attached to the catheter, a 500 mL saline bag was taped to the leg, and the bag was placed to gravity over the end of the bed. The bed was raised so that the bag did not touch the floor. For the leg “Taping” arm, tension was placed on the Foley catheter, which was then taped to the patient’s inner thigh. The tension was assessed and retaped as needed every 30 minutes by the nursing staff. Patients and providers were not blinded to the type of tension used.
All patients received an infusion of oxytocin which was initiated at 2 milliunits/minute and increased 1-2 milliunits/minute every 20 minutes to a maximum of 6 milliunits/minute while the Foley was in place, as this was the practice at our institution. After expulsion of the Foley, the resident or attending physician performed a cervical examination to document the time and the cervical examination, and the oxytocin was titrated to achieve acceptable contraction rates without tachysystole with a maximum of 36 milliunits/minute. Amniotomy was performed when feasible. The patient’s labor and delivery was managed according to routine obstetric and institutional protocols. All patients had continuous fetal heart rate and uterine activity monitoring.
The primary outcome was the time from the start of induction, defined as the placement of the Foley catheter, to the time of delivery of the neonate. The secondary outcomes included the Foley catheter expulsion time (time from placement of the catheter until the catheter passed fully through the cervix), the change in cervical examination after Foley catheter expulsion, and the patient’s pain score with the Foley in place. The pain assessment was done using a visual analog pain scale performed by clinical nursing staff throughout the patient’s labor course. For this study the highest pain score obtained with the catheter in situ was used for analysis. Uterine infection was defined as clinical chorioamnionitis or endomyometritis in the patient’s medical record based on the presence of at least 2 of the following: elevated maternal temperature during or after delivery (>38.0°C), leukocytosis (white blood cells >16K), uterine tenderness, no evident extrauterine source of infection, and treatment with parenteral antibiotics. Postpartum hemorrhage was defined as estimated blood loss of over 500 mL at vaginal delivery or 1000 mL at cesarean delivery.
Statistical considerations
Sample size was calculated based on our primary outcome for the entire cohort. Based on our institutional data and the published literature we used 24 hours as an average length of induction. To find a 20% difference with a 40% standard deviation, power of 90%, and alpha of .05, we estimated we needed 86 patients in each arm. We aimed to recruit 194 patients to account for potential dropouts and missing data. Given the clear differences in the literature between nulliparous and multiparous patients in induction outcome, we specified a priori that we would conduct subgroup analyses dividing the subjects into these 2 groups.
Statistical analysis was performed by SPSS 20.0 (SPSS, Inc, Chicago, IL). We used χ 2 test or Fisher exact test (for categorical variables), and Student t test or the Mann-Whitney U test (for continuous variables), where appropriate. Categorical variables were also analyzed for relative risk (RR), with 95% confidence interval (CI). Statistical significance was set at P < .05. Data were analyzed in an intent-to-treat manner.
Results
We randomly assigned a total of 197 women to the Traction and Taping arms. Six patients were excluded from analysis: 4 had been consented but were minors and thus determined by the institutional review board to be ineligible for analysis, and 2 were withdrawn by their providers who cancelled their inductions. There were 9 minor protocol deviations (2 patients received misoprostol, 6 patients could not have a Foley catheter placed because of patient habitus or discomfort, and 1 had a Foley placed intracervically requiring replacement), but these were included in the intent to treat analysis. At the conclusion of the study there were a total of 191 patients for analysis (96 Taping, 95 Traction, Figure 1 ).
Demographic and baseline information are provided in Table 1 . Study groups were similar regarding maternal age, parity, and race. Maternal comorbidities, including chronic and pregnancy-associated hypertensive diseases, preexisting and gestational diabetes mellitus, and pre-pregnancy and third trimester obesity were common in our population, and they were similar between groups. Our study patients were, on average, induced in their 38 th week of pregnancy and with similar induction indications and Bishop scores.
| Characteristic | Taping (n = 96) | Traction (n = 95) | P value |
|---|---|---|---|
| Maternal age, y | 25.5 (5.9) | 25.7 (6.9) | .78 |
| Gestational age, wks | 38.2 (2.4) | 38.6 (4.4) | .32 |
| Nulliparity a | 66 (68.8) | 68 (71.6) | .37 |
| State insurance a | 80 (83.4) | 75 (79) | .36 |
| Race/Ethnicity a | .89 | ||
| Caucasian | 28 (29.2) | 31 (32.6) | — |
| African American | 50 (52.1) | 50 (52.6) | — |
| Hispanic | 8 (8.3) | 7 (7.4) | — |
| Other | 9 (9.3) | 6 (6.30) | — |
| Hypertension a | 44 (45.8) | 45 (46.3) | .59 |
| Diabetes a | 13 (13.5) | 14 (13.7) | .94 |
| Prepregnancy BMI, kg/m 2 | 30.6 (8.9) | 30.3 (8.9) | .84 |
| Delivery BMI, kg/m 2 | 35.9 (8.1) | 35.0 (8.7) | .42 |
| Admission Bishop Score | 3 [0–8] | 4 [0–7] | .27 |
| Primary indication for induction a | .92 | ||
| Postdates (≥41 wks 0 d) | 15 (15.8) | 14 (14.7) | — |
| Oligohydramnios | 12 (12.6) | 14 (14.7) | — |
| Gestational hypertension | 38 (40) | 35 (36.8) | — |
| Diabetes | 7 (7.4) | 8 (8.4) | — |
| Suspected fetal growth restriction | 7 (7.4) | 10 (10.5) | — |
| Other | 14 (14.7) | 11 (11.6) | — |
We found no statistically significant difference in time from Foley insertion to delivery between study groups ( Table 2 ), our primary outcome. Patients in the Taping group delivered, on average, in 18.8 ± 8.0 hours while the Traction group delivered in 19.8 ± 8.5 hours on average ( P = .39; Figure 2 ). The time to catheter expulsion was significantly longer in the Taping group (median, 2.6; range, 0.2–10.8 vs median, 1.5; range, 0.1–6.3 hours; P < .001). However, the change in cervical dilation was not different between the groups. The total amount of oxytocin used was similar. The number of deliveries within 24 hours was similar in the 2 groups (RR, 1.20; 95% CI, 0.89–1.61).We found no differences between the groups in the time to vaginal delivery overall (17.3 ± 6.9 vs 17.9 ± 7.4 hours, P = .66), or in the rate of vaginal birth for those delivering before (70.8 vs 70.3%, P = .95) or after 24 hours (41.7 vs 38.7%, P = .82), or in the overall frequency of cesarean delivery (36.5 vs 40.0%, P = .62). For both groups the likelihood of cesarean delivery was significantly higher if the induction lasted over 24 hours (Taping RR, 2.0; 95% CI, 1.22–3.28; for Traction RR, 2.07; 95% CI, 1.29–3.30; Table 2 ).
| Variable | Taping (n = 96) | Traction (n = 95) | P value | RR | 95% CI |
|---|---|---|---|---|---|
| Time to expulsion, h | 2.6 [0.2–10.8] | 1.5 [0.1–6.3] | < .001 | — | — |
| Dilation after expulsion, cm | 3 [1–4.5] | 3 [1–4.5] | .20 | — | — |
| Time to delivery, h | 18.8 (8.0) | 19.8 (8.5) | .39 | — | — |
| Time to vaginal delivery, h | 17.3 (6.9) | 17.9 (7.4) | .66 | — | — |
| Delivery within 24 h a | 72 (75.0) | 64 (67.3) | .24 | 1.20 | 0.89–1.61 |
| Vaginal delivery within 24 h a | 51 (70.8) | 45 (70.3) | .95 | 1.02 | 0.71–1.44 |
| Vaginal delivery after 24 h a | 10 (41.7) | 12 (38.7) | .82 | 1.07 | 0.58–1.96 |
| Cesarean delivery a | 35 (36.5) | 38 (40.0) | .62 | 0.93 | 0.70–1.24 |
| Total units of oxytocin | 316 (10.2) | 327 (10.6) | .80 | — | — |
There were no differences between groups in analgesia use or pain scores ( Table 3 ). Approximately 90% of both groups received epidural anesthesia ( P = .62), and median pain rating was 5 (scale of 0-10) in both groups while the Foley catheter was in place ( P = .70). There were no significant differences in clinically relevant complications during induction or labor and delivery, including clinical chorioamnionitis and postpartum hemorrhage ( Table 3 ).
| Outcome | Taping (n = 96) | Traction (n = 95) | P value |
|---|---|---|---|
| Maternal | |||
| Epidural a | 87 (90.6) | 88 (92.6) | .62 |
| Pain score while in cervix (1-10) | 5 [0–10] | 5 [0–10] | .7 |
| Estimated blood loss, mL | 490 (317) | 507 (352) | .73 |
| Postpartum hemorrhage a | 7 (7.3) | 5 (5.3) | .56 |
| Cervical laceration a | 0 | 1 (1.1) | .35 |
| Chorioamnionitis a | 6 (6.2) | 7 (7.4) | .76 |
| Endomyometritis a | 2 (2.1) | 3 (3.2) | .64 |
| Length of stay, d | 3.8 (1.3) | 3.8 (1.5) | .81 |
| Neonatal | |||
| Birthweight, g | 2969 (646) | 3020 (738) | .60 |
| >4000 g a | 3 (3.1) | 4 (4.2) | .69 |
| <2500 g a | 21 (21.9) | 22 (23.1) | .83 |
| NICU admission a | 16 (16.7) | 10 (10.5) | .22 |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
