Anal incontinence occurs when a woman is not able to control her bowel movements, resulting in accidental passing of air.
Fecal Incontinence occurs when the condition progresses and the weak bowel control results in the accidental passage of stool.
This problem has been shown to affect an estimated 7% of women over their life time. Anal incontinence is more common with vaginal delivery than cesarean section because of the potential for damage to the anus and/or rectum during vaginal delivery. However it can still be associated with deliveries by cesarean section.
Risk Factors for Anal Incontinence
Risk factors include pregnancy, prolonged labor, vaginal delivery, the use of forceps or vacuum during to assist vaginal delivery, episiotomy (or even accidental tearing of the tissues during vaginal delivery), aging, neurological conditions, and chronic constipation.
Some findings associated with anal or fecal incontinence are:
- Abnormal stool consistency – Bowel movements with normal formed consistency are easiest to control. Diarrhea or loose bowel movements are more likely to cause anal incontinence because of both looser consistency and increased urgency. Severe constipation can also sometimes lead to anal incontinence.
- Anal sphincter injury – The circular muscles of the anus that allow us to control bowel movements are called the “anal sphincter muscles”. These muscles can be damaged or torn during vaginal delivery. It is estimated that as many as 40% of women experience muscle injuries in this area during childbirth, more commonly when episiotomy or forceps delivery is performed. Injury to the muscles can cause decreased strength resulting in problems postponing passage of bowel movements. In some cases, the muscle damage can be repaired with surgery.
- Nerve injury – Injury to the anal sphincter nerves can cause decreased sensation and muscle strength, both of which can contribute to anal incontinence. Nerve damage can be caused by injury during vaginal delivery, chronic constipation, or by illnesses that affect the nerves such as diabetes, spinal cord injury, etc. The nerve damage that occurs during vaginal delivery can often improve with healing of the nerves over the next 1 to 2 years after childbirth.
- Prolapse – Rectocoeles and other forms of prolapse can sometimes cause anal incontinence by causing stool to be incompletely emptied during bowel movements.
- Fistula – Abnormal connections between tissues are known as “fistulas”. These can occasionally develop between the rectum and vagina, following vaginal delivery or vaginal surgery. They can also occur spontaneously as a result of inflammatory conditions of the colon or other bowel conditions.
A specialist such as a urogynecologist, colorectal surgeon, or gastroenterologist should generally evaluate anal incontinence. The evaluation should always begin with discussion of the symptoms and physical examination. Occasionally the treatments are simple as Kegel exercises or pelvic floor rehabilitation.
Other tests that are sometimes necessary include:
- Ultrasound – to evaluate the anal sphincter muscles
- MRI or defecography – to evaluate the surrounding tissues for possible anatomic problems such as pelvic organ prolapse
- Nerve testing and/or anal manometry – to evaluate possible injury to the nerves which can cause decreased strength and sensation
- Colonoscopy or sigmoidoscopy – to evaluate for other possible causes such as fistula, colitis, Crohn’s disease, etc.