NSW obstetric anal sphincter injuries rise

Researchers analysed singleton births in NSW hospitals from 2001 to 2009, alongside population-based data collection.

They found the rate of anal sphincter injuries rose from 4.1% in 2001 to 5.3% in 2009 for primiparas, and from 0.9% to 1.2% for multiparas.

Although there are factors in the NSW population that increase the risk of an injury – such as a rise in women born in Asia – these were possibly offset by changes in other risk factors (e.g. the increase in infants born <41 weeks’ gestation for multiparas). 

“This rise is largely unexplained and may be attributable to changes in the clinical diagnosis and medical recording of OASIS [obstetric anal sphincter injuries] or to other factors that are currently not recorded in these data sets,” the authors wrote. 

ANZJOG 2013; 53:9-16