Fecal Impaction

Etiology

Fecal impaction commonly occurs among the elderly who are hospitalized patients or under institutional care. It is associated with generalized diseases, such as scleroderma and chronic renal failure, and conditions which cause an alteration in the normal anatomy such as congenital abnormalities in the anorectal region or previous surgical procedure of the intestine. In older adults who regularly consume nonsteroidal anti-inflammatory drugs, a higher occurrence of fecal impaction has been reported. Among hospitalized patients, administration in the elderly of medications with an opioid can result in fecal impaction, especially in those who have a history of chronic constipation and are bedridden.[3][4]

Epidemiology

Fecal impaction commonly occurs among elderly individuals, rarely presenting as an acute emergency to a hospital. Severe constipation is a significant problem that affects almost 70% of elderly people who are under care in nursing homes. Among those affected, about 7% will have the condition detected during a digital rectal examination. Fecal impaction is more common among older women who are in institutional care and have associated neuropsychiatric disorders. It is a cause for increased morbidity among the elderly, and if allowed to progress, this can lead to complications causing mortality in the older age group.[5][6][7]

Pathophysiology

The continuous contact between the hard feces and the colonic mucosa can cause an increase in mucus secretion. Fecal impaction also causes an increase in intraluminal pressure in the colon which causes a decrease in perfusion of the colonic mucosa and wall. The resulting localized inflammation can give rise to colitis, ulcerations, and possible perforation. When stercoral perforation occurs, the most frequent site is the sigmoid colon. Stercoral perforation that occurs in the rectosigmoid region is attributed to feces being hardest in the rectosigmoid. Also, the diameter of sigmoid is the narrowest in the colon. These factors lead to an increased intraluminal pressure and result in hypoperfusion of the antimesenteric wall casing perforation. The impacted fecal mass may cause compression of adjacent structures such as urinary bladder, causing urinary retention. [8][9]

History and Physical

 Patients with fecal impaction often give a history of inability to evacuate stools spontaneously and complain of total constipation. In most instances, an associated history of progressive abdominal distension with increasing abdominal discomfort or pain is present. Physical examination findings often reveal a distended abdomen. In thinly built or emaciated individuals, hard fecal mass masses may be palpable along the colon. Occasionally, patients may also present with a spurious or overflow diarrhea. The diagnosis of fecal impaction is primarily based on clinical signs. A  detailed history of bowel habits and a full physical examination which includes a digital rectal exam is mandatory.

Evaluation

A digital rectal examination is mandatory as the first diagnostic evaluation to confirm the diagnosis of fecal impaction. When a rectal exam does not reveal fecal impaction or hard fecal masses in the rectum, the possibility of fecal impaction more proximal in the bowel or other causes, such as strictures or volvulus of the colon, should be considered. The most useful and commonly used radiological imaging for evaluation is a CT abdomen with oral or rectal contrast. A plain x-ray of the abdomen can, at times, reveal fecal overloading of the colon with colonic distention of the in the segment proximal to the region of fecal impaction. Rarely, a contrast enema or sigmoidoscopy are indicated in a patient who has no history suggestive of the colonic disease.

Treatment / Management

The treatment options are a digital evacuation of the impacted fecal mass or the rectal administration of stool softening agents, usually enemas or suppositories.[10][1][11](B3)

Manual Disimpaction

In many cases of fecal impaction, manual disimpaction is required. This is a helpful procedure if one can palpate hard stool in the rectal area. The procedure is best done using ample lubrication and gently removing the impacted stool with the index finger. Sometimes, the procedure can be aided with the use of an anoscope and suction. Most patients find immediate relief once fecal disimpaction is performed.

Proximal and Distal Fecal Impaction

If the abdominal x-ray reveals that the fecal impaction is located distally, then the use of enemas and suppositories can be helpful. The enema is best delivered with a Foley catheter past the hardened stool. The best method is to use ample water and combine it with docusate or sorbitol. It is important to administer small amounts of enema so as not to create discomfort in the patient. Once the enema is administered, one can help the process of evacuation by gently massaging the lower abdomen. This process may have to be repeated several times until only clear liquid passes. It’s also important to pay attention to the patient’s complaints. During disimpaction, discomfort is normal, but the pain isn’t. If a patient complains of pain, it’s best to stop the enema and reevaluate.

For proximal fecal impaction, the ideal laxative is polyethylene glycol. One may have to administer from 1 to 3 liters of polyethylene glycol over a period of hours before a response is seen. If abdominal cramps and nausea occur, then no more polyethylene glycol should be ingested. Another laxative that can help with proximal impaction is magnesium citrate.

Polyethylene glycol can be given orally if conditions like volvulus or structural bowel obstruction due to any cause are ruled out. Administration of an appropriate laxative or fiber supplement with increased intake of water after the evacuation of the impacted fecal mass is administered to prevent recurrence. Early surgical evaluation and intervention are necessary if there are associated signs of peritonitis. Stercoral perforation is associated with a high mortality in the elderly if not recognized and treated early.

Barium Impaction

Sometimes impaction occurs after a barium study. Barium is not water soluble and can become a hard solid mass once the water is absorbed. Barium impaction is more likely to occur in patients who already have a functional or anatomical abnormality of the lower gastrointestinal tract. Barium impaction is also very common in people who have undergone some type of intestinal bypass procedure.

To prevent barium impaction, all patients should be encouraged to consume extra fluids. In some cases use of an osmotic laxative like sorbitol or milk of magnesia may be helpful. Barium impaction is usually seen on plain abdominal x-rays. Sometimes there may be perforation of the colon, which can also be visualized on the plain x-ray. If a perforation is noted, immediate surgery is required. If there is no perforation, barium removal is done similar to fecal impaction.

Lower Gastrointestinal and Rectal Surgery

In many people who have undergone repair of anal fistulas and removal of hemorrhoids, fecal impaction is quite rare but constipation is very common. The reason for fecal impaction is multifactorial and related to use of opiates, sphincter spasm, edema around the anal tissues, and a fear of going to the bathroom. In most mild cases, administration of an enema is sufficient; but in severe cases, one may need to perform manual disimpaction in the operating room. The patient will usually need some type of anesthesia to relax the anal sphincter complex before the fecal impaction can be removed.

These patients are encouraged to change their lifestyle, drink ample water, exercise, and eat a high fiber diet to prevent constipation.

Differential Diagnosis

• Constipation
• Inspissated stool syndrome

Prognosis

Fecal impaction is a significant but preventable problem in the elderly population within hospitals and other institutions. The best way to treat it is to prevent it from developing in the first place. The cause of constipation should be identified early and managed appropriately. The patient should be educated about lifestyle measures and dietary habits to prevent fecal impaction. Unfortunately, recurrent fecal impaction is very common in elderly and institutionalized patients. Often these patients present to the emergency department because the presenting symptoms can mimic other sinister intestinal pathology.

Complications

• Stercoral Perforation (due to the fecal impaction itself or administration of enema)
• Rectal discomfort
• Fecal incontinence
• Urinary incontinence