Women who have minimal compromise of anal sphincter function should be counseled that they have an 88% (in centers practicing midline episiotomy) to 95% (in centers practicing mediolateral episiotomy) chance of delivering without sustaining another OASIS.24,25 This should reassure them if they have misgivings about vaginal delivery.
Threshold for C-section is lower if additional risk factors are present
If traumatic delivery is anticipated, as in the presence of one or more additional risk factors (macrosomia, shoulder dystocia, prolonged labor, difficult instrumental delivery), cesarean section may be appropriate.
Consider emotional needs
Some women who have sustained OASIS may be scarred emotionally as well as physically and may find it difficult to cope with the thought of another vaginal delivery. These women deserve sympathy, psychological support, and consideration of their request for cesarean section.
When cesarean is a good idea
Women who have a minor degree of incontinence (e.g., fecal urgency or flatus incontinence) may be managed with dietary advice, constipating agents (loperamide or codeine phosphate), and physiotherapy or biofeedback. These women who have some degree of anal sphincter compromise but whose symptoms are controlled should be counseled that cesarean delivery is recommended (FIGURE 9).
Women who have sustained a previous third- or fourth-degree tear with subsequent severe incontinence should be offered secondary sphincter repair by a colorectal surgeon or urogynecologist with expertise in secondary sphincter repair. All subsequent deliveries by these women should be by cesarean section.
Some women with fecal incontinence may choose to complete their family before embarking on anal sphincter surgery. It remains unclear whether these women should be allowed a vaginal delivery, but it is likely that most damage has already occurred and that the risk of further injury is minimal and possibly insignificant. The benefit of cesarean delivery, if any, should be weighed against its risks for all subsequent pregnancies.
Women who have undergone a previous successful secondary sphincter repair for fecal incontinence should be delivered by cesarean delivery.9
Not all women fit neatly into one category
There are going to be women who do not entirely fit any of the categories described—such as those who have isolated internal sphincter defects or irritable bowel syndrome. Management of these women should be individualized, with the mode of delivery determined by mutual agreement after taking into account symptoms and clinical and other findings.
If there are no facilities for anal manometry and US, the physician should base management on symptoms and clinical evaluation. Asymptomatic women who do not have clinical evidence of sphincter compromise during anal tone assessment may be allowed to undergo vaginal delivery. All women who are symptomatic should be referred to a center with facilities for anorectal assessment to establish the ideal management and mode of delivery.
Pay attention to modifiable risk factors
In the case described at the beginning of this article, two risk factors could have been modified to minimize the patient’s risk of OASIS—namely, midline episiotomy and forceps delivery. In a quasirandomized study by Coats, involving 407 nulliparous women, which compared mediolateral and midline episiotomy (when episiotomy was necessary), tears into or through the anal sphincter occurred in 12% of women undergoing midline episiotomy and 2% of those undergoing mediolateral episiotomy.26
If operative vaginal delivery is required, vacuum extraction is preferred. In a meta-analysis of randomized studies, Thakar and Eason found that fewer women have anal sphincter trauma with vacuum delivery than with forceps.27 One anal sphincter tear is avoided for every 18 women delivered by vacuum extraction instead of forceps. A randomized trial conducted in the United Kingdom involving mediolateral episiotomy found severe vaginal laceration in 17% of forceps deliveries and 11% of vacuum deliveries.28 A randomized controlled trial in Canada involving midline episiotomy found third- or fourth-degree tears in 29% of forceps deliveries, versus 12% of vacuum deliveries.29
Coding for obstetric anal sphincter injury
Q. What is the proper code for reporting an anal sphincter injury incurred in pregnancy?
A. That depends—on when the tear occurred, whether the patient is currently pregnant, and whether there were additional lacerations of the perineum.
ICD-9-CM offers four codes in this setting. Choose one, as follows:
- If you note an anal tear at the time of, or after, delivery but there is no perineal laceration, report 664.6×. This code takes a fifth digit: “1,” for the patient who has just delivered, or “4,” if you are treating the tear after she has been discharged.
- If the tear is noted in addition to a third-degree perineal tear, report 664.2× instead; fifth-digit choices for this code are also “1” and “4.”
- If the patient had an anal tear before delivery, from a prior pregnancy, code 654.8× [congenital or acquired abnormality of the vulva].
- Last, if you are treating the patient for an old anal tear and she is not pregnant at the moment, report 569.43 and add any additional codes that have resulted from the tear, such as fecal incontinence (787.6).
—Melanie Witt, RN, CPC-OGS, MA