On physical examination, the patient appears
healthy without any distress. Her body mass index
is 26 kg/m2, and vital signs are normal. General
examination is normal. Abdomen is flat, and bowel
sounds are normal. Mild tenderness is noted in
both lower quadrants. Rectal examination reveals
normal anal skin folds. Digital examination reveals
a normal resting tone with pellet-like stool that is
heme-negative. When asked to attempt defecation, she shows poor perineal descent and paradoxical contraction of the anal sphincter.
Laboratory testing reveals normal levels of thyro-
tropin and thyroxine, no anemia on complete blood
count, and normal levels of calcium, glucose, and
• What are the possible causes for this pa-
tient’s altered bowel habits?
• What is the approach to physical examina-
tion in patients with constipation?
CAUSES OF CONSTIPATION
Constipation is a common digestive disorder,
affecting up to 20% of the world’s population. 1
Primary or idiopathic constipation consists of 3
common overlapping subtypes: slow-transit consti-
pation, dyssynergic defecation, and constipation-
predominant irritable bowel syndrome. Slow-transit
constipation involves the slow movement of stool
through the colon. This is usually seen on a colonic
transit study or with wireless motility capsule study.
Dyssynergia in general is caused by functional out-
let obstruction with or without normal colonic transit.
Patients with dyssynergia often complain of incom-
plete evacuation, excessive straining, bloating, and
blockage.2 Often patients with dyssynergia resort
to manual disimpaction/vaginal splinting and/or
abdominal pressure to facilitate bowel movements.
Secondary constipation may result from metabolic
disorders (eg, hypercalcemia and hypokalemia,
disorders associated with renal failure, hypothyroid-
ism, and diabetes) as well as medications, including
narcotics, anticholinergics, and antidepressants.
Physical examination in patients with constipation should include a detailed rectal examination.
The perianal skin should be inspected closely for
fissures, fistulae, and skin excoriation. The anocutaneous reflex should be checked along with resting and squeeze anal tone. A study by Rao et al3
showed that rectal examination could identify 76%
of patients with dyssynergia. The sensitivity and
positive predictive value for diagnosing dyssynergia with digital rectal examination was 81% and
99%, respectively, making it a good screening test
for dyssynergia. 3
• When is colonoscopy indicated in the work-
up of constipation?
• What imaging studies may be useful?
Colonoscopic evaluation is only indicated in patients with alarming features such as rectal bleeding, weight loss, unexplained abdominal pain, palpable mass in the abdomen or rectum, persistent
and unexplained anal/rectal pain, or anemia, as
well as in patients over age 50 years. 4
Colonic Transit Study
Two imaging studies can be useful in the evalu-
ation of a patient with constipation: colonic transit