Use of hyaluronidase for cervical ripening: a randomized trial

Abstract

Objective: To investigate the action of intracervical administration of hyaluronidase (HAase) as an inductor of cervical ripening on an outpatient basis.

Methods: A randomized double-blind trial was conducted with 168 pregnant women at term, Bishop score (BS)<5, normal fetal vitality and no uterine contractions. An evaluation was performed at the first visit, when either 20,000 UI of lyophilized HAase (5 ml) or placebo was administered via cervical injection. After 48 h, if the BS remained<5, a second dose was administered. The primary outcome was the BS after 48 h or 96 h. The outcome was considered positive when BS>/=5.

Results: The results indicate that the proportion of positive response for the HAase group (55%) after 48 h is significantly higher (p<0.0001) than the corresponding proportion for the placebo group (7%) with an absolute risk reduction (ARR) of 48%=55-7% (95%CI=40-56%). After 96 h, these proportions are 93% in the Haase group and 22% in the placebo group (p<0.0001, ARR=71%, 95%CI=61-81%). The average duration of labour for the nulliparae in the HAase group (6.5h) is significantly smaller (p<0.0001) than for those under placebo (12.0 h) with an absolute difference of 5.5h (95%CI=4.6-6.4h). For the multiparae, the results are 4.3h for the HAase patients versus 9.5h for the placebo patients (p<0.0001) with an absolute difference of 5.2h (95%CI=4.1-6.3h). The proportion of vaginal deliveries for women who received HAase was 82% versus 51% for the placebo group (p=0.0007, ARR=31%, 95%CI=19-44%). The proportion of vaginal deliveries for patients with prior cesareans in the HAase group (69%) was also significantly higher (p<0.0001) than that corresponding to the placebo group (13%) with ARR=56% (95%CI=26-86%). No uterine hyper stimulation occurred in the study.

Conclusion: We detected significant associations between intracervical injection of HAase and ripening of the cervix, as well as with shorter duration of labour and larger chance of vaginal delivery, suggesting that this is a simple, effective and safe method even for women with prior cesarean.