AANP Family Nurse Practitioner (FNP) Certification ExamDiagnosisMedium
A 24-year-old female presents with recurrent episodes of abdominal pain, bloating, and alternating constipation and diarrhea for the past 8 months. She reports that her symptoms are often worse after eating and improve after a bowel movement. She has undergone a colonoscopy, which was normal. Her blood tests (CBC, ESR, CRP, celiac serology) are all unremarkable. What is the most likely diagnosis?
- AInflammatory Bowel Disease (IBD)
- BLactose Intolerance
- CCeliac Disease
- DIrritable Bowel Syndrome (IBS)
Show answer & explanationAnswer & explanation
Correct answer: D. Irritable Bowel Syndrome (IBS)
The patient's chronic abdominal pain, bloating, altered bowel habits (constipation and diarrhea), improvement with defecation, and normal diagnostic workup (colonoscopy, labs) are classic features of Irritable Bowel Syndrome (IBS) according to the Rome IV criteria.
Why the other options are wrong
- A. IBD (Crohn's or Ulcerative Colitis) would typically show inflammation on colonoscopy and/or elevated inflammatory markers (ESR, CRP), which are absent here.
- B. Lactose intolerance typically causes bloating, gas, and diarrhea after consuming dairy, but not usually alternating constipation, and is not associated with abdominal pain consistently relieved by bowel movements.
- C. Celiac disease would be ruled out by normal celiac serology and, if biopsied during colonoscopy, normal small bowel histology.
Irritable Bowel Syndrome (IBS)
A common functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits without any identifiable organic cause.
- Chronic abdominal pain related to defecation, with change in stool frequency or form.
- Symptoms present for at least 6 months, with active symptoms for the last 3 months.
- Diagnosis of exclusion after ruling out other organic causes (e.g., IBD, celiac).
Memory trick: IBS is 'Irritable' because it's 'Invisible' on tests, but 'Intensely' painful.