Case
A 58-year-old woman presents with over 25 years of constipation she defines as the urge to expel a bowel movement but the inability to evacuate satisfactorily. She strains excessively at hard stools and occasionally uses her finger to assist rectal emptying. Following a negative colonoscopy, she was instructed to use fiber supplements and various laxative preparations, but she has experienced minimal improvement. Her history is notable for two previous “difficult” vaginal deliveries. She has urinary dysfunction and has had surgery for urogynecologic prolapse. She wishes to consider colon resection for her refractory symptoms.
Therapeutics
Treatment of functional constipation depends on the underlying physiologic etiology, being mindful of other factors influencing the presentation (e.g., medications and psychological factors). For patients who do not respond to fiber supplementation, osmotic laxatives can be titrated to clinical response. Stimulant laxatives and prokinetic agents are best reserved for patients with more refractory constipation. Throughout any treatment program, one should remain vigilant of pelvic floor dysfunction, as pelvic floor rehabilitation is the treatment of choice. Surgery is rarely indicated for constipation, and exclusion of pelvic floor dysfunction is essential. Fecal impaction should be cleared prior to beginning maintenance regimens.
Fiber and Fluids
Increasing fiber intake to 15-25 g/day may be accomplished with dietary changes, supplements, or both. Although increasing water intake on its own has not been shown to improve constipation, maintaining adequate fluid intake is sensible during fiber supplementation. A softer, bulkier stool that is easier to pass is the ultimate goal. Increasing the dose of fiber slowly over several weeks to months can lessen common side-effects (bloating, gas, and distension) and enhance compliance. Synthetic supplements may be better tolerated than other fiber preparations.
Laxatives
Osmotic laxatives work by retaining or drawing water into the gut lumen and are the agents of choice for patients not responding to fiber supplementation. There is no clearly superior osmotic agent; the choice should be based on relevant medical history (cardiac or renal status), cost, and tolerance of the various preparations. The dose should be titrated based on the clinical response. For chronic or more severe constipation, regular dosing is indicated. Although stimulant laxatives, which promote intestinal motility, do not appear to lead to tolerance or bowel injury, these drugs are better reserved for those with a failed response to osmotic agents, and may be required for the management of opioid-induced constipation.
Stool Softeners, Suppositories, and Enemas
Stool softeners are of limited overall efficacy. Suppositories, which usually work within minutes, help initiate and/or facilitate rectal evacuation. They may be used in conjunction with meals to capture the gastrocolic reflex. In general, enemas may be used judiciously on an as-needed basis, particularly for obstructed defecation with fecal impaction. Routine use is typically discouraged. Suppositories and enemas may be included as part of a standardized bowel program, particularly for the institutionalized with a history of impaction.
Prokinetics and Other Agents
Although prokinetic agents, such as tegaserod and pru-calopride, appear efficacious for constipation, they are of limited availability. Metoclopramide and erythromycin are of doubtful benefit in constipation. Lubiprostone, a bicyclic fatty acid that activates chloride channels on the apical membrane of the intestinal epithelial cells, helps in constipation by moving water into the gut lumen. In light of the cost, this medication is best reserved for a lack of efficacy with less expensive alternatives.
Pelvic Floor Rehabilitation (Biofeedback)
Pelvic floor rehabilitation is the treatment of choice for pelvic floor dysfunction. Therapy concentrates on sensory and muscular retraining of the rectum and pelvic floor, with the goals of normalization of sensation, muscular relaxation and/ or strengthening, and improved defecatory dynamics with resolution of any paradoxical pelvic floor contractions. Different therapeutic protocols exist, and the best approach is unclear. Uncontrolled studies suggest that biofeedback is effective in over 70% of patients , and these findings have been confirmed in several randomized, controlled trials.
The presence of descending perineum syndrome may limit results. Biofeedback has been shown to be superior to laxatives in patients with a functional defecation disorder, and the effect was durable. The key is identifying the problem and available therapeutic resources. A patient’s physical and mental abilities must be assessed. Although no physiologic, anatomic, or demographic variables clearly impact treatment outcome, many feel that psychopathology may play a role, Concomitant slow colon transit frequently requires simultaneous treatment.
Surgery
Although rarely indicated, subtotal colectomy with ileo-rectal anastomosis is the treatment of choice for medically-refractory slow transit constipation, but only if pelvic floor dysfunction is excluded. Patients with predominant bloating and pain respond poorly. Surgical indications for pelvic floor abnormalities are ill-defined. Surgery should be considered only if functional significance can be determined. Division of the puborectalis is not recommended. Anatomic abnormalities (e.g., rectoceles) are common, but they are frequently the result of pelvic floor dysfunction. Treatment of the underlying pelvic floor dysfunction first is a reasonable treatment approach, with surgery reserved for those not responding to more conservative therapy.
Additional Comments
Adjunctive therapy may be necessary for psychopathology associated with functional constipation, and maintaining adequate caloric intake is essential. Evidence does not support the popular notion that toxins from constipation harm the body or that irrigation is needed. There is no obvious significance of an elongated colon (dolichocolon), and surgical shortening does not lead to reliable clinical improvement. Likewise, physical activity and water intake are controversial subjects, with unclear associations with colon transit and constipation. Although mineral oil, col-chicine, and misoprostol may improve constipation, these agents have potential side effects and complications that outweigh any benefits. Emerging therapies, such as sacral nerve stimulation, botulinum toxin injection for pelvic floor dysfunction, alteration of the bacterial milieu, and several novel medications may play more of a role in the future of constipation management.
Case continued
The patient used a daily osmotic laxative to provide stools that were soft and easy to pass. She completed a pelvic floor rehabilitation program, learning to relax her musculature and eliminate paradoxical contractions during defecation. Relieved that she avoided colectomy, she is now off of osmotic laxatives with no residual constipation.
Jennifer is a clinical pharmacologist. She helps doctors of all medical specialties choose medications. Jennifer consults about drug dosage, interactions, and side effects.