REVIEW CME LEARNING OBJECTIVE: Readers will differentiate the types of chronic constipation and apply traditional CREDIT and newer treatments to best advantage UMAR HAYAT, MD MOHANNAD DUGUM, MD SAMITA GARG, MD Department of Internal Medicine, Division of Gastroenterology, Hepatology, and Department of Gastroenterology and Hepatol- Medicine Institute, Cleveland Clinic Nutrition, Department of Medicine, University of ogy, Digestive Disease Institute, Cleveland Clinic; Pittsburgh, PA Assistant Professor, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH Chronic constipation: Update on management ABSTRACT hronic constipation has a variety of pos- C sible causes and mechanisms. Although Managing chronic constipation involves identifying and traditional conservative treatments are still treating secondary causes, instituting lifestyle changes, valid and first-line, if these fail, clinicians can prescribing pharmacologic and nonpharmacologic thera- choose from a growing list of new treatments, pies, and, occasionally, referring for surgery. Several new tailored to the cause in the individual patient. drugs have been approved, and others are in the pipeline. This article discusses how defecation works (or doesn’t), the types of chronic constipation, KEY POINTS the available diagnostic tools, and traditional Although newer drugs are available, lifestyle modifica- and newer treatments, including some still in tions and laxatives continue to be the treatments of development. choice for chronic constipation, as they have high re- ■ THE EPIDEMIOLOGY OF CONSTIPATION sponse rates and few adverse effects and are relatively affordable. Chronic constipation is one of the most com- mon gastrointestinal disorders, affecting about 15% of all adults and 30% of those over the Chronic constipation requires different management age of 60.1 It can be a primary disorder or sec- approaches depending on whether colonic transit time ondary to other factors. is normal or prolonged and whether outlet function is Constipation is more prevalent in wom- abnormal. en and in institutionalized elderly people.2 It is associated with lower socioeconomic Surgical treatments for constipation are reserved for pa- status, depression, less self-reported physical tients whose symptoms persist despite maximal medical activity, certain medications, and stressful therapy. life events.3 Given its high prevalence and its impact on quality of life, it is also asso- ciated with significant utilization of health- care resources.4 Constipation defined by Rome IV criteria Physicians and patients may disagree about what constitutes constipation. Physicians primarily regard it as infrequent bowel movements, while patients tend to have a broader definition. Ac- cording to the Rome IV criteria,5 chronic consti- pation is defined by the presence of the follow- ing for at least 3 months (with symptom onset at least 6 months prior to diagnosis): (1) Two or more of the following for more doi:10.3949/ccjm.84a.15141 than 25% of defecations: CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 84 • NUMBER 5 MAY 2017 397 Downloaded from www.ccjm.org on September 30, 2021. For personal use only. All other uses require permission. CHRONIC CONSTIPATION • Straining Normal-transit constipation is the most • Lumpy or hard stools common type of constipation. The term is • Sensation of incomplete evacuation sometimes used interchangeably with consti- • Sensation of anorectal obstruction or pation-predominant irritable bowel syndrome, blockage but the latter is a distinct entity characterized • Manual maneuvers to facilitate evacuation by abdominal pain relieved by defecation as • Fewer than 3 spontaneous bowel move- the primary symptom, as well as having occa- ments per week. sional loose stools. These 2 conditions can be (2) Loose stools are rarely present without hard to tell apart, especially if the patient can- the use of laxatives. not describe the symptoms precisely. (3) The patient does not meet the criteria Slow-transit constipation for diagnosis of irritable bowel syndrome. Slow-transit constipation—also called de- layed-transit constipation, colonoparesis, co- ■ DEFECATION IS COMPLEX lonic inertia, and pseudo-obstruction—is de- Defecation begins when the rectum fills with fined as prolonged stool transit in the colon, stool, causing relaxation of the internal anal ie, for more than 5 days.9 It can be the result sphincter and the urge to defecate. The external of colonic smooth muscle dysfunction, com- anal sphincter, which is under voluntary con- promised colonic neural pathways, or both, trol, can then either contract to delay defeca- leading to slow colon peristalsis. tion or relax to allow the stool to be expelled.6 Factors that can affect colonic motility Colonic muscles propel stool toward the such as opioid use and hypothyroidism should rectum in repetitive localized contractions that be carefully considered in these patients. Opi- help mix and promote absorption of the content, oids are notorious for causing constipation by and larger coordinated (high-amplitude propa- decreasing bowel tone and contractility and gating) contractions that, in healthy individu- thereby increasing colonic transit time. They als, move the stool forward from the proximal also tighten up the anal sphincters, resulting 10 Chronic to the distal colon multiple times daily. These in decreased rectal evacuation. contractions usually occur in the morning and constipation Outlet dysfunction are accentuated by gastric distention from food Outlet dysfunction, also called pelvic floor is linked to and the resulting gastrocolic reflex. dysfunction or defecatory disorder, is associ- lower Serotonin (5-HT) is released by entero- ated with incomplete rectal evacuation. It chromaffin cells in response to distention of can be a consequence of weak rectal expulsion socioeconomic the gut wall. It mediates peristaltic move- forces (slow colonic transit, rectal hyposensi- status, ments of the gastrointestinal tract by binding tivity), functional resistance to rectal evacu- to receptors (especially 5-HT4), stimulating depression, ation (high anal resting pressure, anismus, release of neurotransmitters such as acetyl- incomplete relaxation of the anal sphincter, lack of physical choline, causing smooth-muscle contraction dyssynergic defecation), or structural outlet activity, certain behind the luminal contents and propelling obstruction (excessive perineal descent, rec- them forward. toceles, rectal intussusception). About 50% of medications, patients with outlet dysfunction have concur- and stressful ■ PRIMARY CONSTIPATION DISORDERS rent slow-transit constipation. life events The American Gastroenterological Associa- Dyssynergic defecation is the most com- tion7 classifies constipation into 3 groups on mon outlet dysfunction disorder, accounting the basis of colonic transit time and anorectal for about half of the cases referred to tertiary function: centers. It is defined as a paradoxical eleva- tion in anal sphincter tone or less than 20% Normal-transit constipation relaxation of the resting anal sphincter pres- Stool normally takes 20 to 72 hours to pass sure with weak abdominal and pelvic propul- through the colon, with transit time affected sive forces.11 Anorectal biofeedback is a thera- by diet, drugs, level of physical activity, and peutic option for dyssynergic defecation, as we emotional status.8 discuss later in this article. 398 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 84 • NUMBER 5 MAY 2017 Downloaded from www.ccjm.org on September 30, 2021. For personal use only. All other uses require permission. HAYAT AND COLLEAGUES ■ SECONDARY CONSTIPATION TABLE 1 Constipation can be secondary to several con- ditions and factors (Table 1), including: Causes of secondary constipation • Neurologic disorders that affect gastroin- Neurologic and motility disorders testinal motility (eg, Hirschsprung disease, Amyloidosis Parkinson disease, multiple sclerosis, spi- Diabetes nal cord injury, stroke, spinal or ganglionic Hirschsprung disease tumor, hypothyroidism, amyloidosis, dia- Hypothyroidism betes mellitus, hypercalcemia) Multiple sclerosis Parkinson disease • Drugs used to treat neurologic disorders Spinal cord injury • Mechanical obstruction Spinal or ganglionic tumors • Diet (eg, low fiber, decreased fluid intake). Stroke ■ EVALUATION OF CONSTIPATION Diseases in which treatment can cause constipation Bipolar disorder It is crucial for physicians to efficiently use the Chronic pain available diagnostic tools for constipation to Depression tailor the treatment to the patient. Parkinson disease Evaluation of chronic constipation be- Schizophrenia gins with a thorough history and physical ex- Medications amination to rule out secondary constipation Anticholinergics (Figure 1). Red flags such as unintentional Anticonvulsants weight loss, blood in the stool, rectal pain, Antidepressants fever, and iron-deficiency anemia should Antipsychotics prompt referral for colonoscopy to evaluate Antispasmodics for malignancy, colitis, or other potential co- Calcium channel blockers Opioids lonic abnormalities.12 A detailed perineal and rectal examina- Other causes Red flags: tion can help diagnose defecatory disorders Chagas disease unintentional and should include evaluation of the resting Conversion disorder anal tone and the sphincter during simulated Decreased fluid intake weight loss, Hypercalcemia evacuation. Hyperparathyroidism blood in Laboratory tests of thyroid function, elec- Low-fiber