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Diagnosis of Constipation

Consulting a Doctor for Evaluation

The most important step by the physician in the evaluation of constipation in an individual is to obtain a complete patient history. When talking to a doctor it is helpful to be prepared to describe:

  • the nature of the symptoms,
  • when symptoms started and how long they have persisted,
  • past medical procedures, and
  • any medications being taken.

The doctor will gather information from the patient about the nature of his or her condition: is the complaint of infrequency of stool, hard stools, painful evacuation, or difficult evacuation? For example, infrequent call to stool (not feeling the need to have a bowel movement) may suggest slow-transit constipation, while the perceived need to defecate but with an inability to evacuate is more suggestive of a functional outlet obstruction.

The onset of the constipation is an important consideration. Most patients describe a longstanding problem. A more sudden onset should alert the clinician to the possibility of a serious underlying cause.

Other symptoms of concern include rectal bleeding, a decrease in bowel movement diameter, a constant sense of the need to defecate, unexplained weight loss, nausea, and vomiting. The presence of such symptoms, or a significant family history of colorectal cancer, mandates complete colonic evaluation, preferably by colonoscopy.

Colonoscopy is a fiber optic (endoscopic) procedure in which a thin, flexible, lighted viewing tube (a colonoscope) is threaded up through the rectum for the purpose of inspecting the entire colon and rectum and, if there is an abnormality, taking a tissue sample of it (biopsy) for examination under a microscope, or removing it.

Age of onset is another important factor: severe constipation presenting in childhood raises the question of a congenital disorder such as meningocele (a birth defect in which the tissue that lines the spinal cord protrudes through an opening in the spinal column), Hirschsprung’s disease (absence of colonic ganglion [nerve] cells), or the presence of a painful anal fissure (a split or tear in the skin at the anal opening) that can lead to voluntary avoidance of defecation.

Functional fecal retention – the holding back of stool because of fear of a painful bowel movement – in children can lead to encopresis (fecal soiling). Encopresis may present as diarrhea or incontinence due to seepage of liquid stool around a fecal impaction (a build-up of hard stool packed so tightly in the colon or rectum that normal pushing action is not enough to expel the stool).

Social or environmental factors, such as lack of available toilet facilities, may contribute to constipation both in children and adults and should be considered as a possible cause.

The physician should obtain a complete past medical history. Numerous underlying diagnoses can cause or contribute to constipation, and these should be noted or excluded as appropriate. Medications being taken should be carefully reviewed for possible causative or contributory drugs.

Medications Associated with Constipation

Note: Many medications list constipation as a side effect and not all are listed here. Be sure to tell your doctor about any drugs or supplements being taken, both prescription and over-the-counter.



Prescription Drugs




Anticholinergic agents

Librax, belladonna

Tricyclic antidepressants

Amitriptyline, nortriptyline

Calcium channel blockers

Verapamil hydrochloride

Antiparkinsonian drugs

Amantadine hydrochloride


Ephedrine, terbutaline







Nonprescription Drugs


Antacids, especially aluminum-containing

Maalox, Mylanta

Iron supplements


Antidiarrheal agents

Loperamide, attapulgite

Nonsteroidal anti-inflammatory agents

Ibuprofen, naproxen

A complete physical examination should be performed to identify possible conditions that contribute to the constipation. Attention is focused on examination of the perineum (the area between the anus and the genitals), anus, and rectum.

The physician will look for signs that suggest the presence of rectal prolapse, a condition in which the rectum turns inside out and protrudes between the buttocks. This condition may be perceived by the patient as incomplete evacuation.

In women, a rectocele can be identified as a bulge in the back of the vaginal wall while the patient strains, or as a noticeable defect between the rectum and vagina on digital examination (exam in which the doctor inserts his or her finger).

Digital rectal examination can be useful to disclose abnormalities that may be present such as hemorrhoids, anal fissures, pelvic descent, and paradoxical puborectalis contraction when bearing down.

Standard Tests

Several standard tests can be of use in the diagnosis of the constipated patient. In the case of sudden onset, an abdominal series of x-rays may disclose the presence of a bowel obstruction or fecal impaction.

Should “alarm” symptoms be present (e.g., weight loss, blood reported in stool), or if the patient is 50 years of age or older, a full colonic evaluation is mandatory to examine for organic disease. This evaluation is generally best performed by colonoscopy, but barium enema (a test in which the large intestine is coated with x-ray contrast [barium] to visualize abnormalities) can be done to screen for abnormalities if colonoscopy is not readily available, although a follow-up colonoscopy may become necessary if an abnormality is found.

For some patients, blood tests should be done to exclude abnormalities that can cause constipation, such as high calcium levels, low potassium or magnesium levels, or low thyroid hormone levels.


Causes of Constipation Testing in Constipation


Last modified on September 12, 2014 at 01:44:34 PM