Constipation

Published on 15/05/2015 by admin

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Last modified 15/05/2015

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Chapter 32

Constipation

Jan M. Shoenberger

Perspective

The term constipation refers to a symptom or complex of symptoms and not a specific diagnosis. Patients and health care providers often define constipation differently. Most health care providers define constipation based on stool frequency. Patients often use the term constipation to describe a broad set of complaints, including straining, hard or infrequent stools, pain during a bowel movement, a feeling of incomplete evacuation, or abdominal bloating. Constipation may be acute (new for the patient) or chronic. Chronic constipation is defined as the presence of symptoms for at least 3 months. In clinical practice, attempting to identify the cause of the symptoms will often result in the best chance of effective treatment and will help determine disposition. A definitive diagnosis often is not possible in the emergency department (ED), and appropriate follow-up evaluation should be arranged in those cases. When constipation becomes severe with constant pain, some clinicians use the term obstipation. Obstipation represents the progression of the symptom of constipation toward bowel obstruction.

In the ED, the complaint of constipation should be of concern when it represents a significant change from a patient’s own normal pattern that is creating discomfort for the patient. This change may manifest as a decrease in frequency of defecation, sudden and persistent change in the character or amount of stools (especially decrease in stool caliber), blood in the stool, or problems expelling the stool.¹

The prevalence of constipation varies worldwide. In North America the prevalence is approximately 16%.² In adults, constipation is more common in women, the elderly, those with high body mass index, and those with low socioeconomic status.² A consistent trend of increasing prevalence of constipation is observed with age, with significant increases after the age of 70 years. The high prevalence among elderly patients is multifactorial and related to a diet low in fiber, sedentary habits, multiple medications, and various disease processes that impair neurologic and motor control.

Pathophysiology

Normally the gastrointestinal tract is presented with 9 to 10 L/day of secretions and ingested fluids. The small intestine usually absorbs all of this except for approximately 500 mL. The colon mixes the ileal effluent, ferments and salvages the unabsorbed carbohydrate residues, and desiccates the contents to form stool. The process of stool transport and evacuation is complex and is regulated by neurotransmitters, intrinsic colonic reflexes, and a multitude of learned and reflex mechanisms that are not fully understood. Constipation may result from structural, metabolic, mechanical, neurologic, or behavioral disorders that affect the colon or anorectum either directly or indirectly.3–5

Diagnostic Approach

Differential Considerations

The causes of constipation are numerous. Causes of constipation can be divided into primary (no apparent external cause) and secondary causes (summarized in Box 32-1). These two groupings have some overlap. In the ED, patients most commonly have acute constipation resulting from side effects of medications or avoidance of defecation secondary to presence of painful perianal lesions such as fissures, hemorrhoids, or perirectal abscesses.

BOX 32-1

Causes of Constipation

Congenital

Hirschsprung’s disease

Imperforate anus

Anorectal atresia

Aganglionosis

Primary Causes (e.g., Functional Disorders)

Idiopathic slow transit

Irritable bowel syndrome

Secondary Causes

Neurologic