Treatment of Constipation
Treatment of chronic constipation is best managed by first determining the underlying cause. While there may be several contributing factors, the 3 broad subgroups include: normal transit constipation, slow transit constipation, and pelvic floor dysfunction. Treatment will vary depending upon the subgroup assigned. For example, initial treatment of milder chronic constipation with normal transit generally involves a recommendation to increase fiber intake, but there is evidence that only a minority of patients with slow-transit constipation or defecation disorders benefit from fiber therapy.
Normal Transit Constipation
Fiber – In addition to increasing their fiber intake, patients with normal-transit constipation are often advised to increase their water consumption and physical activity. However, there are several caveats to be noted with this approach. Although many Americans consume only a fraction of the recommended 20–35 gm of fiber daily, some patients are already taking adequate quantities of fiber. Many others tolerate fiber supplementation poorly, especially if fiber intake is dramatically increased over a short time period. Side effects can include bloating, gassiness, and cramping, any of which may be perceived by the patient as worse than the constipation itself.
Adding fiber gradually and slowly over one to two weeks may reduce or eliminate the discomfort. Individuals may tolerate dietary and various commercial fiber supplements differently, so substitution of one fiber source for another may prove helpful. At least one small study has suggested that addition of a regular exercise program alone had little benefit in the treatment of chronic idiopathic (of unknown cause) constipation.
Laxatives – Should simple conservative measures fail, the addition of a laxative is the next step in treating chronic constipation.
Patients should start with an osmotic laxative, which works by drawing water into the colon. Examples of this class include polyethylene glycol or PEG (e.g., MiraLax), magnesium hydroxide (e.g., Milk of Magnesia), magnesium citrate (e.g., Citroma, Citro-Mag), sorbitol, and lactulose (e.g., Acilac, Enulose). Osmotic laxatives must be used with care in patients with a reduction in kidney function (renal insufficiency) and cardiac disorders.
Stimulant laxatives are the second choice in constipation therapy. This class of drugs includes senna (e.g., Senokot, Ex-Lax), cascara sagrada, and bisacodyl (e.g., Dulcolax, Correctol). Although chronic use of these drugs has been thought to cause damage to the intestine’s nervous system, it is now believed this concern has been overstated.
Other medications – Lubiprostone (Amitiza) is a prescription drug used to relieve stomach pain, bloating, and straining and produce softer and more frequent bowel movements in men and women who have chronic idiopathic (functional) constipation. It is also prescribed to treat irritable bowel syndrome with constipation in women who are at least 18 years of age. Lubiprostone helps promote secretions through chloride channels in the bowel. It works by increasing the amount of fluid that flows into the bowel and allowing the stool to pass more easily.
Prucaloprideis a highly selective serotonin 5-HT4 receptor agonist. It is available for the treatment of women with chronic constipation in Canada and a number of countries in Europe, but not in the United States.
Linaclotide (a GC-C receptor agonist) is a newer medication being studied to treat chronic constipation and IBS with constipation. The U.S. Federal Drug Administration (FDA) is currently reviewing the New Drug Application (NDA) for linaclotide with a decision expected in September 2012.
Slow Transit Constipation
Medications – Initial treatment of slow transit constipation is based on escalating doses of laxatives. Unfortunately, many patients are on multiple agents with poor results at the time they consult a physician. Under the guidance of their doctor, some patients will benefit from simplification and standardization of their laxative regimen; for example, by discontinuing all but a single agent, such as polyethylene glycol, taken daily in an adequate dose to achieve the desired effect. Alternatively, a trial of lubiprostone (as outlined above) may be considered.
Surgery – A small number of selected patients with well documented slow-transit constipation that is resistant to medical treatment, and without evidence of functional outlet obstruction may be candidates for colon resection – surgical removal of the colon with connection of the small intestine to the remaining rectum. This procedure, called total abdominal colectomy with ileorectal anastomosis, can be performed using either standard open surgery or laparoscopic surgery, which is performed with special instruments using several small incisions. The operation reliably increases the frequency of bowel movements; patient satisfaction ranges from 39–100%.
Despite these results, there are a number of important issues that must be considered before deciding upon total abdominal colectomy.
- While the operation does increase bowel movement frequency, it does not reliably decrease such symptoms as abdominal pain, bloating, or distension.
- The frequency of bowel movements after surgery is not entirely predictable. A few patients may have persisting constipation. Others develop unacceptable diarrhea.
- In addition to excessive stool frequency, a minority of patients are unable to control the high volume of liquid stool that is presented to the rectum after surgery, and thus are faced with fecal incontinence. Patients with risk factors for incontinence (such as history of impaired continence, obstetrical injury, or anal surgery such as fistulotomy or sphincterotomy) require careful evaluation before colectomy can be considered.
- While excessive bowel movement frequency and incontinence may each improve during the first postoperative year, it's important to understand that the operation is irreversible, and functional failure could lead to creation of a permanent ileostomy, a surgically created opening of the abdominal wall to the small intestine, allowing the fecal waste to empty into a bag.
- Colectomy for constipation appears to be associated with a relatively high incidence of intestinal blockage, either from adhesions or due to poor motility in the remaining small intestine.
Another procedure, the Malone antegrade continent enema (ACE), involves the creation of a small opening (stoma) in the appendix, upper colon, or small intestine by an open or laparoscopic technique. This stoma is flushed on a regular schedule to empty the large bowel. The technique has seen most use in children with either incontinence or severe constipation. However, a limited experience has now been reported in constipated adults, with success rates of approximately 50% being reported. A more recent approach has been to create a continent conduit from the lower (sigmoid) colon, which is used to provide access for colonic irrigation. While successful results have been reported, experience to date with this technique is highly limited. Finally, in rare cases of severe refractory constipation, creation of an ileostomy may prove to be the best option.
Pelvic Floor Dysfunction (Outlet Obstruction)
Biofeedback – Biofeedback therapy is the first step for patients with functional outlet obstruction, mainly for pelvic floor dyssynergia (anismus). The main goal of the therapy is to break the pattern of inappropriate (paradoxical) sphincter contraction by teaching patients to relax their pelvic floor muscles during straining efforts.
This pelvic floor retraining may be accompanied by training to improve the efficiency of the abdominal pushing effort, as well as sensory training to improve perception of stool in the rectum. Approximately two-thirds of constipated patients treated with biofeedback are reported to have successful results, but larger controlled clinical trials are needed.
Botox – There have been anecdotal reports of botulin toxin (Botox) injection to alleviate non-relaxation or paradoxical contraction of the puborectalis muscle with straining. While some cases appear to have been successfully treated, no formal endorsement of this therapy can be offered until additional data become available.
Surgery – Surgical options for outlet obstruction constipation are limited. Rectocele repair can be helpful in patients with large rectoceles who must support the back of the vagina with their fingers in order to effect defecation (“splinting”). Complete preoperative evaluation (preferably including defecography to demonstrate improved rectal emptying with vaginal support) and careful patient selection are critical to ensure optimal outcomes.
Combined Slow-Transit Constipation and Functional Outlet Obstruction
Patients with combined slow-transit constipation and pelvic floor dyssynergia should first undergo biofeedback. With constipation that persists after successful pelvic floor retraining, subtotal colectomy can be considered if medical treatment options including laxatives and other drugs fail to relieve symptoms. Good results can be achieved with this treatment, but some patients continue to suffer from poor rectal emptying after treatment.
The term constipation includes a complex of symptoms related to slow, impaired, difficult, or painful defecation. Because constipation is a symptom and not a disease, patients should be evaluated for possible underlying causes. “Alarm” symptoms in particular should trigger a complete colonic evaluation to exclude serious underlying cause.
Most cases of functional constipation can be treated based on symptoms, with or without the addition of laxatives. Patients with constipation resistant to initial treatment should undergo specialized evaluation to determine the presence of impaired colonic transit or outlet obstruction. Treatment of these conditions may require medication, biofeedback, or surgery. However, most constipated patients can be successfully treated when a complete evaluation is performed and a rational treatment plan pursued in partnership between the individual patient and his or her physician.