Passive management of labour may predispose to anal sphincter injury

To compare anal sphincter damage in two groups of primigravid women in Sydney: one passively managed in public hospitals, the other more actively managed in adjacent private hospitals. Data from actively managed labours at the National Women's Hospital, Dublin, served as an independent control.

We carried out a comparative study of third and fourth degree anal sphincter tears in all primiparas delivering at term in the years 2010-2015 in six Sydney public teaching hospitals with data from patients delivered in six adjacent Sydney private hospitals. A second comparator was published data from the National Women's Hospital, Dublin, where active management is still performed under the direction of midwives. All data was publicly available from www.health.nsw.gov.au/hsnsw . The difference between the two groups: public hospitals were under MANDATORY (NSW DG's upper case emphasis) direction from the Director General of NSW Health (PD 2010-045 File no 09/638-3) for labour to proceed without any augmentation.

The study comprised 130,000 women. The mean third and fourth degree anal sphincter tear rate was 8.17% for the public hospitals and 1.52% for the private hospitals in the same period (p < 0.0003). Dublin's rate was 2.6%. There was no significant difference in the emergency Caesarean section rate 2010-2015 (13.7% private vs 12.7% public, 7.9% in National Women's Hospital Dublin) as well as an increase in epidurals, forceps/ventouse and lower Apgar scores.

Passive management of labour instituted in Sydney public hospitals by government directive seems to be associated with a higher rate of obstetric anal sphincter injuries than was observed with active management. In addition, there were more epidurals, forceps/ventouse, and lower Apgar scores. Our hypothesis of deflexion of the head causing deficient powers is logically appealing, but needs further proof.