Fourth-degree tears more likely to result in bowel symptoms

OB/GYN News, Feb 15, 2005 by Michele G. Sullivan

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 women was 25 years.

Infant birth weight (median about 3,400 grams) 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 women, 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 a total of 67% of women who had third-degree tears and in 41% of those with fourth-degree tears. This difference, however, was not statistically significant.

There was a very strong correlation between sphincter disruption and the 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, Dr. Nichols said at the meeting.

Condition of Sphincters by Tear Status

                               3rd Degree  4th Degree

Intact Internal Sphincter      91%         47%
Intact External Sphincter      67%         41%
Both Sphincters Intact         65%         35%
Disruption of Both Sphincters  8%          46%

Source: Dr. Nichols

Note: Table made from bar graph.

BY MICHELE G. SULLIVAN

Mid-Atlantic Bureau