A Boy With Frequent Diarrhea: Differentiating IBS From IBD

Lindsey G. Albenberg, DO; Wenjing Zong, MD


March 18, 2019

Editorial Collaboration

Medscape &

Case Presentation: Adolescent Male With Diarrhea

A 10-year-old boy presents for evaluation of diarrhea. He was well until 3 weeks ago, when he started to pass loose stools three to four times per day. In the 5 days before presentation, he developed suprapubic pain with defecation. The patient was seen in the emergency department, where laboratory results were normal.

What's Going On?

Irritable bowel syndrome (IBS). A common chronic condition that can include symptoms such as abdominal pain, bloating, diarrhea, or constipation, IBS can be difficult to diagnose. Patients with IBS will often have negative stool infectious studies and fecal calprotectin, normal laboratory evaluation, and appropriate growth. But ongoing gastrointestinal (GI) symptoms should raise the index of suspicion, and the patient may benefit from an evaluation with a GI specialist.

Inflammatory bowel disease (IBD). In contrast, IBD is a chronic inflammatory condition that can involve just the colon (ulcerative colitis) or any part of the GI tract (Crohn disease). IBD can also be difficult to diagnose. Patients with IBD can have a normal laboratory evaluation. If the patient has had abdominal pain or diarrhea for an extended period, and the stool test results rule out infection as the cause, a referral to a GI specialist is warranted. A referral is also appropriate if other indications of IBD are present, such as bloody stool, extraintestinal signs or symptoms, or growth failure. In children, growth failure in the setting of GI symptoms should raise suspicion for IBD.

Key Points in the History

Answers to these questions help determine the severity of the problem and may help narrow the differential diagnosis.

If the child is suffering from diarrhea, ask the following questions:

  • How long has the patient had diarrhea? Is the diarrhea constant, or does it come and go?

  • Is there anything unusual or alarming about the stool?

Bloody stool, nocturnal bowel movements, and tenesmus may be indicators of IBD. Bowel movement urgency, as well as diarrhea for 5 days or longer or intermittent diarrhea for 3 weeks or longer, may be an indicator of either IBS or IBD.

If the child is suffering from abdominal pain, ask the following questions:

  • How long has the pain been present? Has the pain been constant, or does it come and go?

  • How does the child describe or indicate the pain?

  • Does it occur during the day or at night?

  • Does it interfere with the child's sleep or daily activities?

  • Does it occur after meals or after eating certain types of food?

  • Is the pain related to, worsened by, or relieved by having a bowel movement?

Abdominal pain for 5 days or longer, or intermittent pain for 3 weeks or longer, may be an indicator of IBS or IBD and may require further investigation.