[Anal sphincter injury during operative vaginal delivery using spatulas. What are the risk factors?]

To assess risk factors for anal sphincter injury during operative vaginal delivery using spatulas.

A monocentric retrospective study of all assisted vaginal deliveries using Thierry and Teissier's spatulas between January 1st, 2008 and December 31st, 2009 in a teaching level III maternity. We studied risk factors such as primiparity, gestational age, maternal age, previous perineal laceration, level and type of presentation, type of expulsion, unsuccessful extraction and successive use of tools, episiotomy, type of anaesthesia and birth weight.

There were 346 perineal tears (60.5%); among them, 175 (31%) were type 1, 131 (23%) type 2, 35 (6.1%) type 3 and five (0.9%) type 4. There were 235 episiotomy (41.1%). There was no statistically significant difference between all the supposed risk factors and the severe perineal tears.

There are no relationship between third and fourth degree perineal lesions during spatula's delivery and supposed risk factors of anal sphincter injury. Only statistical tendances between first vaginal delivery and anal sphincter injury and between occipitosacral delivery and anal sphincter injury were found. We need further randomized studies comparing assisted births using spatulas, forceps and vacuum extractors to better assess perineal tears risk factors.