Insertion of a double balloon catheter for induction of labour in pregnant women without previous caesarean section

5.1 Uterine tachysystole was significantly lower in the double balloon catheter (DBC) group than the prostaglandin gel group (5% [3/67] versus 17% [10/59] respectively, p=0.04), as was non‑reassuring fetal heart rate (2% [1/67] versus 15% [9/59] respectively; p=0.01) in a randomised controlled trial (RCT) of 126 women with oligohydramnios and unfavourable cervices.

5.2 'Fetal malpresentation after catheter removal' was reported in 2 women in the DBC group (1 had a fetus with face presentation and 1 had a fetus with a transverse lie) in an RCT of 302 pregnant women (293 in the final analysis) comparing DBC (n=148) against single balloon catheter (SBC; n=145). One woman had a vaginal delivery after an external cephalic version was performed and 1 had a caesarean section.

5.3 Cord prolapse was reported in 1 woman in the DBC group in the RCT of 302 pregnant women comparing DBC (n=148) against SBC (n=145). She had an emergency caesarean delivery.

5.4 Cord blood pH was lower in the prostaglandin gel group than the DBC and SBC groups (median arterial pH: prostaglandin gel group 7.25, DBC group 7.26, SBC group 7.26; a single p value of 0.05 was cited) in an RCT of 330 nulliparous pregnant women.

5.5 There was no statistically significant difference in the incidence of postpartum haemorrhage (that is, more than 1000 ml blood loss) between the DBC, SBC and prostaglandin gel groups (DBC 5% [5/107], SBC 5% [5/110], prostaglandin gel group 11% [12/113]; a single p value of 0.143 was cited) in the RCT of 330 nulliparous pregnant women.

5.6 Birth canal injury was reported in 1 woman and 5 women respectively in the DBC and prostaglandin gel groups (p=0.10) in the RCT of 126 pregnant women.

5.7 Intrapartum fever was reported in 8 and 2 women respectively in the DBC and SBC groups (p=0.10) in the RCT of 302 pregnant women comparing DBC (n=148) against SBC (n=145).

5.8 Postpartum endometritis after caesarean section occurred in 1 woman in the DBC plus oral misoprostol group (n=59) and in no women in the oral misoprostol alone group (n=63) in an RCT of 122 pregnant women with unfavourable cervices at term.

5.9 Infection of the newborn occurred in 4 cases in the DBC plus oral misoprostol group (n=162) and in 1 case in the oral misoprostol alone group (n=151) in an RCT of 326 pregnant women with unfavourable cervices at term (p values not reported).

5.10 Statistically significant differences in women's reported pain during cervical ripening (assessed on a visual analogue scale 0 to 10, higher scores representing maximum pain) between the DBC, SBC and prostaglandin gel groups were described in the RCT of 330 nulliparous pregnant women; a pain score of more than 4 was reported in 55% of women in the DBC group, 36% in the SBC group, and 63% in the prostaglandin gel group (single p value <0.001 was cited). Pain perception during the insertion procedure was similar in the DBC plus extra‑amniotic saline infusion (EASI) and the SBC plus EASI groups (assessed on a visual analogue scale of 1–10, higher scores representing worst pain; mean scores were 3.1 and 3.7 respectively; p=0.19) in a nested study (n=186) within a quasi‑RCT of 188 patients comparing DBC plus EASI (n=60) against SBC plus EASI (n=126). Maternal discomfort due to the device was reported in 5 patients in the DBC group (n=107) in the RCT of 330 women; 2 women were unable to void, 2 women had decreased balloon volume and, in 1 woman, the device was removed.

5.11 In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed the following anecdotal adverse event: prolonged interval from 'commencement of induction to delivery'. They considered that the following were theoretical adverse events: rupture of membranes, scar rupture (if used in a woman with previous caesarean section), infection, procedural pain and pain after insertion, bleeding and placental abruption.