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Accidental Stool Leak is Common in Pregnant and Postpartum Women

  • 18 Jul 2022
  • 3 mins

Many women will find that their bodies are never the same after pregnancy and delivery. Pelvic floor and abdominal wall dysfunction are frequently seen in pregnancy due to physiological changes with pregnancy and delivery.

The pelvic floor, a group of muscles and ligaments that support the bladder, uterus, and bowel, can be weakened during pregnancy and childbirth. The weakening of the pelvic floor muscles can lead to many conditions. It includes urinary incontinence, bowel urgency, and anal incontinence. All these can happen as your womb and baby get bigger and weigh more throughout pregnancy. In addition, the growth puts pressure on your pelvic floor muscles, and as these muscles stretch, they can weaken and not work so well.


Leaking Stools

The condition is called fecal incontinence, and it refers to an involuntary loss of solid or liquid feces. There are two types of fecal incontinence - urge incontinence and passive incontinence.

Urge incontinence occurs when one has a stool leak despite maximum effort to retain them-the urge is overpowering, and she did not make it to the bathroom in time.

On the other hand, passive incontinence occurs when the patient's stools leak without warning. As a result, she doesn't even know that she must go to the bathroom.


Normal Physiology of Passing Motion

"Colonic mass movement combined with a series of wave-like muscle contractions will bring the stool to the rectum. What that does is it stimulates the rectal muscle which will trigger the mechanoreceptor on the rectum. It then sends a signal to our brain to you that it's time to pass motion," she explained.

At the same time, there is an involuntary relaxation of the internal anal sphincter. This is an important mechanism because it allows the anus to do anal sampling which will in turn tell our brain whether it'll be a liquid stool, solid stool, or just passing gas.

"In the toilet, the anal rectal angle will voluntarily straighten and pelvic floor will descent, facilitated by sitting down or squatting down and increasing abdominal pressure. Then relaxation of the external sphincter takes place, stool gets evacuated, and everything goes back to normal," Dr. Lim explained.

In summary, the colon moves to push the content towards the rectum and anus. Once it’s there, it triggers a series of mechanisms to sense, control and eventually expel the feces. This requires a complex interaction between our brain, nerve, abdominal and pelvic floor muscle.


Childbirth affects fecal continence

"Childbirth itself might lead to fecal incontinence through nerve and/or muscle injury," Dr. Lim explained.

The passage of the baby's head through the pelvis can stretch and compress the pudendal nerve, a major nerve in the pelvic region. Damage to the pudendal nerve can impair control of the anal sphincter muscles, which help to hold in or release feces.

During vaginal delivery, direct injury can also be inflicted on the anal sphincter muscles.

Obstetric anal sphincter injuries are more likely to occur during labor induction or a prolonged second stage of labor. Furthermore, if the baby is large or is delivered with an instrument like forceps, the risk factor is significantly heightened. Studies have shown that nearly one-quarter of women who had an instrumental delivery developed fecal incontinence of varying degree.

However, according to Dr. Lim, the true incidence and prevalence of fecal incontinence are underestimated because it is an area that patients are embarrassed and reluctant to talk about.

"We have a significant portion of patients in their reproductive age that does have some functional bowel symptoms, pre-pregnancy, during pregnancy, or post pregnancy," she added.


Treatment Options

It begins with a history and physical exam and a medical imaging-endoanal ultrasound or MRI to detect the extent of the patient's anal sphincter injuries. "I also do rectal manometry to assess pressure, sensation, and maximum volume they can hold."

"We encourage patients to go for physiotherapy where they are given dedicated exercise to strengthen their core muscle. I would also recommend that they do it with biofeedback so that the physiotherapist can advise the right muscles to stimulate based on the visual inputs," Dr. Lim advised.

Besides regular exercise, Dr. Lim also recommends making appropriate lifestyle changes. "A diet high in fiber plays an important role in aiding the patient's recovery. Also, if the patient is overweight, the physiotherapist will address certain weight control measures," she added.

When the patient does not respond to non-surgical treatments, she may have to undergo a surgery – anal sphincteroplasty as a last resort. This is the main surgical procedure for anal incontinence where the patient's anal sphincter injuries are muscle related. The muscles are surgically repaired-most trials involving anal sphincteroplasty report about 70 to 80 percent success rates in the short term.


Persistent Incontinence

According to Dr. Lim, there is no direct answer to why some have persistent neuropathy.

"We suspect that it is related to the extent of nerve injury and then or other underlying medical condition. But, overall, there's about one in 10 persistent incontinence, and it's not uncommon," Dr. Lim remarked.

Whatever the causes, fecal incontinence can be embarrassing and persistent. However, don't shy away from talking to your doctor about this common problem.

Contributed by

Dr. Frances Lim
General Surgeon
Colorectal Clinic Associates (CCA)
Farrer Park Hospital