TUCSON, ARIZ. — The rate of anal sphincter laceration during vaginal delivery has sharply declined in recent years, paralleling modifications in obstetric practice, a University of Southern California study revealed.
Anal sphincter laceration occurred in 11.2% of vaginal deliveries at the colossal Los Angeles County/USC Medical Center in 1996, compared with 7.9% in 2004, with about a 6% reduction in risk every year after 1996, reported Dr. Steven Minaglia at the annual meeting of the Society of Gynecologic Surgeons.
During the time period studied, episiotomies declined from 9% to 8% of vaginal deliveries, vacuum deliveries from 5.1% to 2.9%, and forceps deliveries from 1.7% to 0%.
“Of note, the C-section rate went from 18.2% to 32.3%,” he said.
The retrospective study assessed characteristics in 1,703 patients who had an anal sphincter laceration and 14,964 who did not have such an injury, for a total of 16,667 singleton vaginal deliveries at greater than 20 weeks of gestation.
Younger age, lower parity, and higher birth weight all were associated with a higher likelihood of an anal sphincter laceration. Other important risk factors independently associated with a laceration included vacuum delivery (odds ratio 3.19), forceps delivery (OR 2.79), episiotomy (OR 1.36), shoulder dystocia (OR 2.03), and gestational age (OR 1.03, about a 4% increased risk for each week of gestation).
Dr. Minaglia, of the division of female pelvic medicine and reconstructive surgery, encouraged a further minimization of modifiable risk factors such as episiotomy and operative delivery to minimize long-term harm associated with sphincter laceration.