Analysis of predictive variables of success of the mechanical cervical ripening with Foley catheter in patients with a prior cesarean section and a postterm pregnancy

Abstract

Objectives: Analysis of success variables of cervical ripening with the Foley catheter in patients with prior cesarean section (PCD), post-term pregnancy (PP), and a Bishop score £6. Evaluation of technique’s safety. Study design: Prospective cohort trial in which 120 patients were enrolled, from April 2014 to May 2018. PCD was codified in four groups: 1) failed Induction (FI); 2) non-progressive labor (NPL) or cephalopelvic disproportion (CPD); 3) abruptio placentae (AP), risk of fetal distress (RFD) or placenta previa; or 4) other causes. Inclusion criteria: singleton pregnancy; >40+6 weeks’ gestation; cephalic presentation; Bishop Score £6; PCD >18 months; signed consent of vaginal delivery (VD). Exclusion criteria: myomectomy with entry into the endometrial cavity; >1 PCDs or uterine rupture; other presentations; macrosomia; multiple pregnancy; placenta or vasa previa; premature rupture of membranes (PROM); inferior genital tract infection. Used material and protocol: Foley catheter insertion at 9 am, followed by 2 hours of fetal cardiotocograph register (CR). This was repeated 6 hours later. Catheter removal 12 hours after the insertion. Intravenous oxytocin was started at 8 am the following day. Statistical analysis: multivariable logistic regression to assess the similarity of populations. Assessment of the relation between VD and APL with the PCD indication and the CL through logistic regressions. The analysis were performed using R (3.5.1), clickR packages (0.3.64), and Boot Validation (0.1.6). Results: A total of 86/109 (78.9%) achieved APL. Whereas 52/86 (60.47%) finished by VD, 34/86 (39.53%) had a cesarean delivery (CD). No significant differences were found between populations. PCD indications for AP, RFD or placenta previa (OR = 7.85 IC95% [1.87, 39], p=0.007) have a higher likelihood of VD. The PCD indication for NPL or CPD; and AP, RFD and placenta previa, have a higher likelihood of achieving APL (OR 14,55 [IC 95% 2.01, 308.5], p=0.023; OR 15,81 [IC 95% 2.03, 359.78], p=0.024; respectively). As CL was higher, the likelihood of APL was lower (OR=0.92 IC95% [0.84, 0.99], p=0.034). No uterine rupture registered. Conclusions: Cervical ripening with the Foley catheter was satisfactory in 78.9% (86/109). PCD indications that are different from FI associate a higher likelihood of VD. CL has a decreasing effect on the likelihood of APL. The Foley catheter is a safe method for cervical ripening.