Hyaluronidase for cervical ripening and induction of labour.

backgroundDilatation and effacement of the cervix are not only a result of uterine contractions, but are also dependent upon ripening processes within the cervix. The cervix is a fibrous organ composed principally of hyaluronic acid, collagen and proteoglycan. Hyaluronic acid increases markedly after the onset of labour. An increase in the level of hyaluronic acid is associated with an increase in tissue water content. Cervical ripening during labour is characterised by changes of the cervix and an increased water content. Cervical injection of hyaluronidase was postulated to increase cervical ripening. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

objectivesTo determine the effects of hyaluronidase for third trimester cervical ripening or induction of labour in comparison with other methods of induction of labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (January 2006) and bibliographies of relevant papers. SELECTION CRITERIA: Clinical trials of hyaluronidase for third trimester cervical ripening or labour induction. DATA COLLECTION AND ANALYSIS: A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. We assessed trial quality. We contacted study authors for additional information. We collected adverse effects information from the trials. MAIN

resultsOne trial, with 168 women participating, was included in the review. When compared with placebo for cervical ripening intracervical injections of hyaluronidase resulted in women receiving significantly fewer caesarean sections (18% versus 49%, relative risk (RR) 0.37, 95% confidence interval (CI) 0.22 to 0.61), less need for oxytocin augmentation (10% versus 47%, RR 0.20, 95% CI 0.10 to 0.41), and increased cervical favourability after 24 hours (60% versus 98%, RR 0.62, 95% CI 0.52 to 0.74). No side-effects for mother or baby were reported in this trial. AUTHORS'

conclusionsIntracervical injections of hyaluronidase for cervical ripening appear beneficial. However, this is not common practice. In addition it is an invasive procedure that women may find unacceptable in the presence of less invasive methods.