MKSAP: 30-year-old woman with diarrhea

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 30-year-old woman is evaluated for a 2-month history of diarrhea with three to five loose stools per day. She has mild abdominal cramps, bloating, intermittent nausea, and mild anorexia that has resulted in the loss of 2.3 kg (5.0 lb). She has had no fever or blood in the stool. She works in a day care center and has not traveled recently or had exposure to antibiotics. She is otherwise healthy and takes no medications.

On physical examination, temperature is 37.0 °C (98.6 °F), blood pressure is 112/74 mm Hg, and pulse rate is 70/min. The abdomen is soft with normal bowel sounds and mild distention but no tenderness.

Which of the following is the most appropriate management?

A. Colonoscopy
B. Stool cultures
C. Stool testing for ova and parasites
D. No further testing

MKSAP Answer and Critique

The correct answer is C. Stool testing for ova and parasites.

The most appropriate management is stool testing for ova and parasites. Infectious causes of chronic diarrhea are uncommon in immunocompetent adults in developed countries, except for infection with Giardia lamblia. Giardiasis should be considered in patients with exposure to young children or potentially contaminated water such as lakes and streams. Infection is asymptomatic in more than 50% of patients, and the protozoa clear spontaneously. In the remaining patients, symptoms typically occur 1 to 2 weeks after infection and include watery, foul-smelling diarrhea; bloating; flatulence; and belching. Significant weight loss is common because of anorexia and malabsorption, but fever is distinctly unusual. Gastrointestinal symptoms can persist for several weeks to months in the absence of treatment. Patients with hypogammaglobulinemia are at increased risk of developing severe or chronic infection. Given this patient’s profession as a day care worker, she is at risk for exposure to a number of infectious causes of diarrhea. The duration of her diarrhea, as well as the associated bloating and weight loss, are more consistent with giardiasis than a bacterial infection. Therefore, an assessment of this patient’s stools for ova and parasites would be more appropriate than stool cultures.

A colonoscopy is not indicated at this time because this patient is otherwise healthy and does not have gastrointestinal bleeding or signs suggesting inflammatory bowel disease, such as blood in the stool.

Given the chronic nature of this patient’s symptoms and her associated weight loss, avoiding further testing would not be appropriate. Her symptoms warrant evaluation with stool testing.

Key Point

  • Giardiasis should be considered in patients with chronic diarrhea and exposure to young children or potentially contaminated water such as lakes and streams.

This content is excerpted from MKSAP 17 with permission from the American College of Physicians (ACP). Use is restricted in the same manner as that defined in the MKSAP 16 Digital license agreement. This material should never be used as a substitute for clinical judgment and does not represent an official position of ACP. All content is licensed to on an “AS IS” basis without any warranty of any nature. The publisher, ACP, shall not be liable for any damage or loss of any kind arising out of or resulting from use of content, regardless of whether such liability is based in tort, contract or otherwise.

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