Avoid codeine-based preparations because they may cause constipation and lead to excessive straining and disruption of the repair.
Recommend a stool softener
It is vital that constipation be avoided as the patient heals; passage of constipated stool or fecal impaction can disrupt the repair. We prescribe a stool softener (lactulose, 15 mL twice daily) for 10 to 14 days and have encountered no problem with bowel evacuation.18
We recommend that the patient telephone a healthcare provider 24 to 48 hours after hospital discharge to confirm that bowel evacuation has occurred. If it hasn’t, we add mineral oil, magnesium hydroxide, or another oral bowel stimulant to the stool softener and bulking agent.
Mahoney and colleagues conducted a randomized trial (n=105) of constipating versus laxative regimens and found the latter to be associated with earlier and less painful first bowel motion and earlier hospital discharge.19 Nineteen percent of women following the constipating regimen had troublesome constipation (two required hospitalization for fecal impaction), compared with 5% of women receiving a laxative. There were no significant differences in continence scores, anal manometry, and endoanal US findings.
Give the patient adequate information
Before the patient is discharged from the hospital, we give her a booklet that describes the implications of OASIS and explains when and where to seek help if symptoms of infection or incontinence develop. All women also complete a validated bowel-health and quality-of-life questionnaire regarding conditions prior to the delivery. We also recommend pelvic floor and anal sphincter exercises as soon as her discomfort resolves.
Perform a comprehensive follow-up exam
All women who sustain OASIS should be assessed by a senior obstetrician 6 to 8 weeks after delivery. In our practice, these women are seen in a dedicated perineal clinic.20 The clinic provides a supportive environment and increases the patient’s confidence in the team.21
At the clinic, each woman completes the same symptom questionnaire that she was given before hospital discharge. She then undergoes a genital examination in which the physician checks the degree of scarring, residual granulation tissue, and tenderness; ensures that the patient understands the circumstances surrounding the delivery and injury; and addresses any concerns. All women then undergo anal manometry and endoanal US (FIGURE 8). Each patient is encouraged to continue pelvic floor exercises. If she has minimal sphincter contractility, she may need electrical stimulation.
If a dedicated perineal clinic is unavailable, the patient should be given clear instructions, preferably in writing, before leaving the hospital. During the 6 weeks immediately after delivery, she should be instructed to look for signs of infection or wound dehiscence and to telephone the physician to report any increase in pain or swelling, rectal bleeding, or purulent discharge. Any incontinence of stool or flatus also should be reported.
FIGURE 8 Defect visible on US
Endoanal sonogram showing a defect in the external anal sphincter between 11 o’clock and 1 o’clock (between the yellow arrows) (S, subepithelium; E, external anal sphincter). SOURCE: Sultan AH, Thakar R2 (used with permission).
7. Is vaginal delivery advisable after OASIS?
No randomized trials have determined the most appropriate mode of delivery after a third- or fourth-degree tear. We base our counseling of the patient on a completed symptom questionnaire and findings from manometry and endoanal US (FIGURE 8). If vaginal delivery is contemplated, these tests should be performed during the current pregnancy unless they were abnormal at an earlier date. FIGURE 9 is a simple flow diagram from our unit that illustrates management of subsequent delivery after OASIS.
When determining the mode of delivery, thorough counseling and clear documentation of that counseling are extremely important.
FIGURE 9 How do you determine the mode of delivery after OASIS?
Vaginal delivery is possible unless anal sphincter function is impaired
One study found that when a large sonographic defect (more than one quadrant) is present, or the squeeze-pressure increment (above resting pressure) is less than 20 mm Hg, the risk of impaired continence after a subsequent delivery increases dramatically.22
Based on these findings, we conducted a prospective study that found no deterioration of sphincter function or increase in symptoms after vaginal delivery unless the patient had significant compromise of anal sphincter function before the pregnancy.23 Therefore, we encourage asymptomatic women who have minimal compromise of anal sphincter function to undergo vaginal delivery.
Routine episiotomy is not protective
There is no evidence that routine episiotomy prevents recurrent OASIS. If episiotomy is deemed to be necessary—e.g., for a thick inelastic or scarred perineum—mediolateral episiotomy is preferred.
High likelihood of success in some women