Fecal Incontinence
- Article Author:
- Rushikesh Shah
- Article Editor:
- Juan Villanueva Herrero
- Updated:
- 9/19/2020 9:01:47 AM
- For CME on this topic:
- Fecal Incontinence CME
- PubMed Link:
- Fecal Incontinence
Introduction
Fecal incontinence (FI) is the involuntary passage of fecal matter through anus or inability to control the discharge of bowel contents. Its severity can range from an involuntary passage of flatus to complete evacuation of fecal matter. Depending on the severity of the disease, it has a significant impact on a patient’s quality of life [1].
Patients with fecal incontinence have an unintentional loss of liquid or solid stool. In true anal incontinence, there is loss of control of the anal sphincter which leads to the untimely release of feces. On the other hand, fecal incontinence can also result from enlarged skin tags, poor hygiene, hemorrhoids, rectal prolapse and fistula in ano. Other common causes include the use of laxatives, inflammatory bowel disease, and parasitic infections.
Etiology
Causes include:
- Central nervous system (CNS)
- Autonomic nervous system (ANS)
- Inflammatory bowel disease (IBD)
- Irritable bowel syndrome (IBS)
- Diabetes mellitus (DM)
- Multiple sclerosis (MS)
- Cerebrovascular accident (CVA)
- Anal surgery
- Spinal cord trauma
- Vaginal delivery
Epidemiology
The prevalence of FI is difficult to estimate because often, this condition is underreported due to social stigma. The overall reported prevalence of FI ranges from 2% to 21% with a median of 7.7%. There is significant variation depending on age. The prevalence of FI is reported as 7% in women younger than 30 years which rises to 22% in their seventh decades. In geriatric patients, prevalence is reported as high as 25% to 35% of nursing home residents and 10% to 25% of hospitalized patients. In fact, FI is the second leading cause of nursing home placement in the geriatric population. [2][3]
Overall, it appears that rates of fecal incontinence are on the rise. Following cesarean section, fecal incontinence is very common. Other factors linked to fecal incontinence include advanced age, vaginal delivery, and depression.
Finally, the cost of managing fecal incontinence is enormous. The public spends hundreds of millions of dollars on adult diapers to control fecal and urinary incontinence.
Pathophysiology
It is vital to understand the physiology of continence to understand the pathophysiology of incontinence. The anatomical structures which help to maintain control of bowel function are the following:
- Rectum as a stool reservoir and can hold up to 300 ml volume without any increase in pressure. Beyond this limit, an urge to defecate occurs. The rectum is connected with the anus which is a 3 cm to 4 cm hollow muscular tube which at rest lies at a 90-degree angle from the rectum. During defecation, this angle becomes obtuse, about 110 to 130 degrees allowing for the passage of stool.
- Internal anal sphincter which is innervated by an enteric nervous system is responsible for 80% to 85% of anal canal resting tone. The anorectal inhibitory reflex allows for the internal sphincter to relax allowing anal sensory receptors to sense rectal contents. This helps to differentiate solid or liquid stool from gas.
- External anal sphincter, innervated by pudendal nerve, contracts and maintains continence during a sudden increase in intraabdominal pressure such as during coughing or lifting.
- Puborectalis muscle forms a sling around the anorectal junction and maintains the anorectal angle which maintains the anatomical barrier against the discharge of stool.
To maintain fecal continence, there is a complex interplay of several organ systems and nerves. As the fecal mass presents to the rectum, this causes distension. The sensation of rectal distension is transmitted by the parasympathetic nerves (S2-S4), which induces relaxation of the rectoanal inhibitor reflex and contraction of the rectoanal contractile reflex. The rectal lining has a rich supply of nerve endings that can sample if the mass is liquid or solid. It is believed that abnormal sampling and lowered anorectal sensation most likely contribute to fecal incontinence in many individuals. Any pathology that interferes with these processes like trauma, stroke, vaginal delivery or paralysis can result in fecal incontinence.
History and Physical
History
Fecal incontinence can be differentiated as the following three different subtypes:
- Passive incontinence: Passive discharge of fecal material without any awareness; indicates neurological disease, impaired anorectal reflexes or sphincter dysfunction
- Urge Incontinence: Inability to retain stool despite active attempts with preserved sensation; indicates sphincter dysfunction or inability of the rectum to hold stool
- Fecal seepage: Undesired leakage of stool often after a bowel movement with normal continence.
Essential history to assess underlying etiology in FI include:
- Nature of incontinence (gas, stool consistency), history of urgency
- Onset, duration, timing
- Effect of FI on quality of life
- H/O constipation
- Medication which can cause constipation or diarrhea
- Medical history (IBD, DM, thyroid problems, spinal problem, neurological diseases, urinary incontinence)
- Obstetric history in females (use of forceps, perineal tears, number of deliveries).
There are Tools for evaluating fecal incontinence based on surveys.
Physical Examination
A detailed neurological exam should be performed to evaluate for neurological disease. A detailed rectal exam is a key in the evaluation of FI; it can be best divided into following steps, but the accuracy of rectal exam and evaluation of various structures depend to a large extent on examiner’s experience:
- Inspection: Examine for hemorrhoids, the presence of the fecal matter, scars, skin excoriation. Also, assess for prolapse and excess perineal descent (more than 3 cm).
- Anal wink reflex: Can be done by gently stroking perianal skin by cotton bud which will cause brisk contraction of the external anal sphincter. The absence of this reflex indicates a loss of spinal arc and possibly underlying neurological disease.
- During the digital rectal exam, a resting rectal tone should be assessed to evaluate the internal anal sphincter. After this, patients should be asked to bear down during which the function of puborectalis (to straighten the anorectal angle), as well as pelvic floor muscles, can be assessed. The final step is to ask the patient to squeeze during which increased pressure due to the contraction of the external anal sphincter is felt.
- The clinician can also insert a finger in the rectum and ask the patient to tighten the anal sphincter; this will give some idea about the muscle tone.
Evaluation
Diagnostic testing is guided by whether incontinence is related to stool consistency [4][5].
If diarrhea is suspected as a primary reason for incontinence:
- Stool studies for infection, osmolality, fat content and pancreatic insufficiency
- Evaluation of diabetes and thyroid disorder
- Evaluate for bacterial overgrowth and lactose/fructose intolerance
- Colonoscopy to evaluate mucosal disease (IBD/Colitis), mass, ulcer, and stricture.
If incontinence is without any diarrhea then more specific testing should be pursued. The most valuable tests for the evaluation of FI are anorectal manometry and endoscopic ultrasound. Defecography is usually reserved for refractory symptoms or before operative planning intervention.
- Endoscopic Ultrasound (EUS) to assess the internal and external anal sphincters. The test is performed with the patient in the lithotomy or left lateral position. The test allows the clinician to measure the thickness of the muscle
- Magnetic Resonance Imaging (MRI)
- Anal manometry is used to assess the resting and squeeze rectal pressure. In addition, the technique can be used to assess rectal capacity and compliance.
- Measuring pudendal nerve latency is also done to assess the integrity of the pelvic floor neuromuscular integrity
- Electromyography (EMG) can help assess the electrical activity initiated by the muscle at rest, during voluntary contraction and after a Valsalva maneuver.
- Defecography is done to assess the evacuation of the rectum under fluoroscopy. In most cases, contrast is inserted into the rectum and images are obtained during defecation.
Treatment / Management
- Supportive measures to improve patient’s generalized well-being and nutritional status
- Hygiene maintenance: avoid perianal skin soiling with regular cleaning, zinc oxide application, incontinence pads.
- Avoid food which can provoke diarrhea (high lactose/ fructose diet)
- Patients with mild cognitive impairment might benefit from regular defecation program.
Medical Management
Directed at improving stool consistency and reducing stool frequency
- Bulking agents (methylcellulose) to improve stool consistency
- Loperamide (Imodium) 4 mg three times a day to reduce stool frequency, improve urgency, increase colonic transit time and increases anal sphincter resting tone
- Diphenoxylate (Lomotil) also results in clinical improvement, but objective tests do not improve
- Treatment of other underlying disorders if suspected such as bile salt malabsorption, IBS, and IBD
- In postmenopausal women, estrogen replacement therapy might be beneficial
- In cases of combined urinary and fecal incontinence, amitriptyline might be helpful.
If the above therapy fails, further investigation should be done with anorectal manometry with imaging (EUS/MRI).
Biofeedback Therapy
Indicated for patients with impaired external sphincter tone and loss of sensation to rectal distention if detected during manometry. Biofeedback therapy is based on the concept of cognitive retraining of the pelvic floor and abdominal musculature to overcome the above defects. Studies report a wide range of success rates ranging from 38 % to 100%. This wide variation is due to small-scale studies with methodological limitations with a different definition of outcomes.
Surgery
In patients with refractory symptoms that do not respond to the above measures.
Surgical approaches can be divided into four categories:
- For patients with the simple structural abnormality of sphincters, such as due to obstetric trauma, overlapping sphincter repair might be sufficient. The success rate is 70% to 80%.
- For patients with the anatomically intact but weak sphincter, a post-anal approach for augmentation of anorectal angle is performed. The success rate is 20% to 58%.
- For patients with severe structural damage to the anal sphincter, the construction of neosphincter is performed using either autologous skeletal muscle (gracilis or gluteus) or artificial bowel sphincter. The success rate is 38% to 90%.
- Rectal augmentation (side to side ileorectal pouch or ileo-rectoplasty) is considered in patients with the reservoir or rectal sensorimotor dysfunction.
Recently injection of silicone has been shown to augment the function of the internal anal sphincter. Others have shown promise with carbon-coated microbeads. Sacral nerve stimulation is a minimally invasive approach for fecal incontinence. The stimulator may benefit patients with minor anal sphincter deficits due to a neurological issue. The two step procedure involves initially placing temporary external electrodes into the sacral foramen. The stimulation decreases symptoms of fecal incontinence by enhancing the squeeze and resting anal pressures and colonic motility. Patients who respond, then undergo permanent placement of an embedded neurostimulator. While good outcomes have been reported in several studies, the surgery can be associated with hematoma, seroma, and infection. In addition, lead migration and paresthesias are not uncommon. To counter these problems. sacral transcutaneous electrical nerve stimulation is now being evaluated.
Another relatively new method to manage fecal incontinence is the use of an injectable anal bulking agent. The hyaluronic acid derivative is injected into the anal mucosa and if the treatment can be repeated. Early results show that some patients may have a reduction in episodes of fecal incontinence.
In 2015, the vaginal bowel control device was approved for fecal incontinence. The vaginal insert has an inflatable balloon which exerts pressure through the vaginal wall onto the rectal area, and thus reducing fecal incontinence. The device does need regular cleaning and can be inflated and deflated as needed.
Differential Diagnosis
- Vaginal/anal foreign body
- Rectovaginal fistula
- Fistula in ano
- Anorectal abscess
- Rectal prolapse
Prognosis
The prognosis for most patients with fecal incontinence is guarded. Short term outcomes after sphincteroplasty vary from 30-60%. Satisfactory results are seen in less than 50% of patients in the long term. The quality of life is poor and mental anguish is common.
Complications
Fecal incontinence is a complex issue that is not easy to manage. The vast number of methods used to manage the condition is an indication that no method works reliably. Patients with fecal incontinence have enormous mental anguish, depression, and anxiety. The overall quality of life is poor. Complications are mainly related to surgery which includes the following:
- Separation of skin and subcutaneous tissue
- Devascularization of vessels leading to necrosis
- Infection
- Bleeding, hematoma
- Fecal and anal pain
- Continued fecal incontinence
Enhancing Healthcare Team Outcomes
Fecal incontinence has multiple causes and is best managed by an interprofessional team that includes a pediatric surgeon, colorectal surgeon, dietitian, internist, a pediatrician, colorectal nurse, and a mental health worker. The treatment depends on the cause; the majority of non-congenital causes can be managed with conservative treatment and a change in diet but most congenital disorders require corrective surgery.
Because of severe depression and anguish, a mental health nurse should be consulted. The dietitian should educate the patient on a high fiber diet. The pharmacist should educate the patient on drugs that will slow down colonic motility and avoidance of laxatives. The nurse should also educate the patient on kegel exercises to strengthen the pelvic floor muscles. Long term follow-up is necessary as only a few patients obtain a cure from fecal incontinence. Close communication between the team members is essential in order to improve outcomes.
The outcomes do depend on the cause, but in a significant number of people, recurrence is common and the quality of life is poor [9][10].