WHITE SULPHUR SPRINGS, W.VA. — Women who experience a fourth-degree tear during delivery are significantly more likely to have persistent anal sphincter defects leading to fecal urgency or incontinence than are women with a third-degree tear, Catherine M. Nichols, M.D., said at the annual meeting of the South Atlantic Association of Obstetricians and Gynecologists.
Third-degree tears are much more likely to heal without persistent sphincter defects, which are associated with up to an 18-fold increase in the development of new postpartum bowel symptoms, said Dr. Nichols of Virginia Commonwealth University in Richmond.
Her prospective cohort study included 56 primiparous women, of whom 39 experienced a third-degree tear and 17 a fourth-degree tear at delivery. There were no significant demographic differences between the groups. The mean age of the study participants was 25 years.
Infant birth weight (median about 3,400 g) was similar in the two groups. Women who had a fourth-degree tear had a longer second stage of labor than did those with a third-degree tear (133 minutes vs. 78 minutes). Forceps deliveries occurred in 21% of the third-degree group and 47% of the fourth-degree group. Shoulder dystocia was more common in the fourth-degree group (24% vs. 13%, as was persistent occiput posterior position (24% vs. 13%) and midline episiotomy (76% vs. 49%).
After delivery, all of the women completed the Manchester Modified Bowel Function questionnaire to assess predelivery bowel function. At 6 weeks post partum, all women were examined at a dedicated perineal clinic, where they completed another questionnaire to assess new bowel symptoms and received a pelvic exam and an endoanal ultrasound exam to determine the state of both internal and external anal sphincters.
Of the 56 participants, 21 (38%) reported new bowel symptoms, which were incontinency to liquid stool or gas (14 women) and fecal urgency (19 women). Among those reporting new symptoms, 59% had a fourth-degree tear and 28% had a third-degree tear.
Disruption of both sphincters was more common among fourth-degree-tear patients. (See box.) Conversely, most women with third-degree tears had both sphincters intact.
Intact internal sphincters were found in significantly more women with third-degree tears than in those with fourth degree tears. Intact external sphincters were found in 67% of women with third-degree tears and in 41% of those with fourth-degree tears, but this difference was not statistically significant.
There was a very strong correlation between sphincter disruption and development of new symptoms. Women with an isolated defect of the external sphincter were 15.7 times more likely than those with no defects to report symptoms, and women with combined defects were 18.7 times more likely to report new symptoms.
KEVIN FOLEY, RESEARCH/SARAH GALLANT, DESIGN
Arrows indicate an area of disruption in the external anal sphincter (circular hyperechoic region). The internal anal sphincter (adjacent circular hypoechoic region) is intact. Courtesy Dr. Catherine M. Nichols