Management of Foley Catheter Induction Among Nulliparous Women

A Retrospective Study

Heidi Kruit; Oskari Heikinheimo; Veli-Matti Ulander; Ansa Aitokallio-Tallberg; Irmeli Nupponen; Jorma Paavonen; Leena Rahkonen


BMC Pregnancy Childbirth. 2015;15(276) 

In This Article


We found that the need for oxytocin for induction and early epidural analgesia were associated with caesarean delivery in nulliparous women undergoing IOL by Foley catheter. Gestational diabetes was associated with maternal intrapartum infection, while early epidural analgesia was associated with neonatal infection. Surprisingly, Bishop score at the start of IOL, duration of the balloon remaining in the cervical canal, timing of amniotomy or timing of oxytocin induction had no association with caesarean section or infections. We acknowledge the limitations of our retrospective single-institution study; we may have been susceptible to selection bias, and our results may not be applicable to other settings.

The caesarean section rate in our study was 39.1 %. Frederiks et al. found a similar 42 % caesarean delivery rate in nulliparous women with a variety of induction methods.[8] In another recent study, the overall rate of successful IOL in combination with different methods and an unfavourable Bishop score (<6) at 41 weeks of gestation was 51.3 %.[7] We found a higher rate of successful labour induction resulting in vaginal delivery than these other recent studies. (The caesarean section rate among the 59 excluded women with sequential use of Foley catheter and intravaginal prostaglandin was even higher, 45.8 % (n = 27)).

The degree of cervical ripeness in this study was assessed using the Bishop score, which was originally derived from observations made on multiparous women.[12] We used Bishop score ≥ 6 as a marker for a ripened cervix, at which time amniotomy and oxytocin augmentation may be used. Perhaps a more modern concept for a favourable cervix in a nulliparous women would be Bishop score ≥ 8.[13]

In previous studies, low Bishop score (<5), increased maternal age, obesity and large birth weight have been associated with induction failure and operative delivery.[4,5,8,14–17] This trend was also seen in our study. However, in multivariate regression analysis, only the need for oxytocin to induce contractions and early epidural analgesia remained associated with caesarean delivery, as also seen in a previous study.[18] It has been suggested that since IOL, oxytocin use, low parity, prelabour rupture of membranes and obesity are all linked with increased caesarean delivery risk,[19] this may explain the increased caesarean rate related to early epidural.[20] However, the request for analgesia early in labour (cervical dilation of ≤ 3 cm) may be a marker for other risk factors for caesarean delivery.[21]

The most common indication for caesarean delivery was failure to progress (failed induction and labour arrest), as was also noted in previous studies.[3,5] Several studies suggest that a substantial proportion of women undergoing IOL and remaining in the latent phase for 12–18 hours with oxytocin administration and ruptured membranes will deliver vaginally if induction is continued.[22–24] Previous studies have shown that active labour does not occur until about 6 cm of cervical dilation in women undergoing IOL, and that a diagnosis of failed induction should be made with caution prior to that stage.[25,26] ACOG clinical guidelines recommend that arrest in the first stage of labour should be reserved for women ≥ 6 cm of cervical dilation with ruptured membranes who are failing to progress despite of 4 hours of adequate uterine activity or 6 hours of oxytocin administration without cervical change.[11] In our study, the definitions for failed induction and arrest of labour varied. This suggests that some women undergoing IOL in our clinic might have been diagnosed with failed induction or labour arrest too early.

Macones et al. demonstrated that early amniotomy at ≤ 4 cm of cervical dilation during IOL shortened the time to delivery in nulliparous women, but did not impact the caesarean delivery rate,[27] which was in line with our results. Oxytocin is more often used with Foley catheter IOL compared to pharmaceutical IOL or spontaneous labour.[3] Oxytocin use was high in our study, which may partly explain our high caesarean section rate. The timing of oxytocin administration for IOL was not associated with caesarean section or maternal or neonatal infections. To our knowledge, no other study has focused on this in the context of Foley catheter IOL.

In one previous study, Foley catheter IOL was associated with increased infectious morbidity.[28] In several other studies, as well as in a recent Cochrane review, Foley catheter IOL has not been linked to increased maternal or neonatal infection rates.[3,29,30] This is in agreement with our results. In our study, gestational diabetes was associated with maternal intrapartum infection. In a previous Danish study, type II or gestational diabetes showed a modestly increased risk of post-caesarean infection.[31] In our study, the rate of neonatal clinical sepsis was similar to that in previous studies,[3,29] but the rate of suspected neonatal infections was higher. We believe that potential bias related to Foley catheter induction and longer induction-to-delivery interval resulted in more neonates being admitted to the neonatal ward for observation or antibiotic administration. The duration of labour after ruptured membranes has previously been linked to neonatal infections.[9,10] In our study, early epidural analgesia was associated with caesarean delivery and neonatal infections. This can be explained by the prolongation of labour.