Risk factors for third degree perineal ruptures during delivery

Abstract

Objective To determine risk factors for the occurrence of third degree perineal tears during vaginal delivery.Design A population-based observational study. Population All 284,783 vaginal deliveries in 1994 and 1995 recorded in the Dutch National Obstetric Database were included in the study. Methods Third degree perineal rupture was de®ned as any rupture involving the anal sphincter muscles. Logistic regression analysis was used to assess risk factors.Main outcome measures An overall rate of third degree perineal ruptures of 1.94% was found. High fetal birthweight, long duration of the second stage of delivery and primiparity were associated with an elevated risk of anal sphincter damage. Mediolateral episiotomy appeared to protect strongly against damage to the anal sphincter complex during delivery (OR: 0.21, 95% CI: 0.20±0.23). All types of assisted vaginal delivery were associated with third degree perineal ruptures, with forceps delivery (OR: 3.33, 95%-CI: 2.97±3.74) carrying the largest risk of all assisted vaginal deliveries. Use of forceps combined with other types of assisted vaginal delivery appeared to increase the risk even further. Conclusions Mediolateral episiotomy protects strongly against the occurrence of third degree perineal ruptures and may thus serve as a primary method of prevention of faecal incontinence. Forceps delivery is a stronger risk factor for third degree perineal tears than vacuum extraction. If the obstetric situation permits use of either instrument, the vacuum extractor should be the instrument of choice with respect to the prevention of faecal incontinence.

Decreased rate of obstetrical anal sphincter laceration is associated with change in obstetric practice

“…This association is likely due to increased mechanical stress during delivery of a large fetus. Other fetal factors that have been associated with anal sphincter laceration include the presence of shoulder dystocia at delivery and occiput posterior position [17]. In this study, shoulder dystocia was a risk factor for anal sphincter laceration with an adjusted odds ratio of 2.03.…”

“…The current rate of anal sphincter laceration of 7.9% is consistent with these reported rates. Other recently published rates have ranged from a low of 1.94% [17] to a high of 17% [10].…”

“…Most risk factors for anal sphincter laceration are not modifiable, these include primiparity [9,13,15], race [9,13,15], perineal anatomy [18], fetal position [17], and birth weight [9,[13][14][15]. Potentially modifiable risk factors for obstetrical anal sphincter injury, such as operative vaginal delivery and episiotomy, have been established [9][10][11][12][13][14][15].…”

The use of liquid petroleum jelly in the prevention of perineal lacerations during birth

“…A study (7) of the risk factors related to third degree laceration during birth found a significant increase (OR=1.12) when the expulsive period was longer than 15 minutes. The authors concluded that the stretching of perineal muscles for an extended period of time can lead to local ischemia, which can increase perineal ruptures.…”

“…Moreover, there is no agreement about which risk factors increase or decrease perineal trauma (5)(6)(7)(8) .…”