Forceps associated with severe perineal tears. (Risk Increased 12-Fold).

SAN FRANCISCO -- The risk for a third-or fourth-degree perineal tear increased 12-fold in women who underwent forceps-assisted deliveries in a retrospective study of 267 vaginal births.

In a separate study of 148 nulliparous women who sustained fourth-degree lacerations during delivery; those who had at least two subsequent vaginal deliveries were at increased risk of developing fecal incontinence.

Both studies were presented at the annual meeting of the American Urogynecologic Society.

In the first study investigators reviewed medical records for 2,095 vaginal deliveries in a 2-year period finding 91 cases of third or fourth-degree lacerations for an incidence of 4%. Outcomes in these women were then compared with those of 176 control women who had first- or second degree lacerations or no perineal injuries.

Forceps-assisted delivery, nulliparity, and larger infant weight each were associated with greater risk for third or fourth-degree tears, said Dr. Lisa Christianson of the University of Virginia. Charlottesville.

Having an episiotomy was associated with a threefold increased risk of third or fourth-degree laceration, but the confidence interval ranged from no increased risk to a sixfold increased risk. Because the study was retrospective. any associations found cannot he construed as causal.

There were too few vacuum assisted de liveries and mediolateral episiotomies "both of which are increasing at our institution to detect any association between these procedures and severe lacerations.