Table 1.
Description of studies
| Study | Type | Country and duration |
Catheters Compared | Single balloon, n |
Double balloon, n |
Exclusion criteria | Parity included |
Outcome measured | Results |
|---|---|---|---|---|---|---|---|---|---|
| Salim et al, 2011 | RCT | Israel (2008–2010) | Single-balloon (60 mL) vs. double-balloon (80 mL each side) | 145 | 148 | Contraindication to vaginal delivery, previous cesarean delivery, low-lying placenta, fetal malformations, IUFD, clinical amnionitis, women who were carriers of hepatitis B, C, or HIV, women with a latex allergy | Nulliparous Multiparous | Time duration from catheter insertion to delivery | No difference between groups or when analyzed nulliparous women only |
| Sayed Ahmed et al, 2016 | RCT | Egypt (2013–2014) | Single-balloon (50 mL) vs. double-balloon (80 mL each side) | 37 | 37 | Previous cesarean delivery, macrosomic babies, nonreassuring fetal conditions, ruptured membranes, placenta previa, malpresentation | Nulliparous | Cervical ripening and changes in bishop score | Double-balloon catheter results in greater ripening, but duration from balloon insertion to delivery was significantly shorter with single-balloon catheter |
| Hoppe et al, 2015 | RCT | United States (2010–2013) | Single-balloon (30 mL) vs. double-balloon (80 mL each side) | 48 | 50 | Contraindication to vaginal delivery, planned or received exogenous prostaglandin administration as an initial induction agent, unexplained vaginal bleeding, active HSV, more than one previous cesarean delivery, history of a classical cesarean delivery, previous attempt at induction of labor during current pregnancy, non-English speaking | Nulliparous Multiparous | Bishop score ≥ 6 at the time of catheter removal, mean change in Bishop score after removal | Double-balloon catheter more effective for preinduction ripening and achieving vaginal delivery |
| Pennell et al, 2009 | RCT | Australia (2001–2003) | Single-balloon (30 mL) vs. double-balloon (80 mL each side) vs. PGE2 gel | 110 | 107 | Age < 16 y, previous uterine surgery, low-lying placenta, any active or purulent infection of the lower vaginal tract, or an abnormal preinduction fetal heart rate tracing | Nulliparous | Cesarean delivery rate | No difference in the rate of cesarean delivery. The induction to delivery interval was longer in the double balloon group |
Abbreviations: HIV, human immunodeficiency virus; HSV, herpes simplex virus; IUFD, intrauterine fetal death; PGE2, prostaglandin E2; RCT, randomized controlled study.