Snapshot A 20-year-old woman presents to the clinic complaining of intermittent abdominal pain. She reports that the pain has been present for as long as she can remember and would improve after she defecates or when she is relaxed. It is especially worse now as she is feeling stressed because of final exams. Her past medical history is significant for an extensive gastrointestinal workup (e.g., fecal leukocytes, stool culture, fecal RBCs, and colonoscopy) with no abnormalities. A physical examination demonstrates an anxious patient with unremarkable findings. Introduction Clinical definition idiopathic functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits patients often present as teens or in their 20’s Associated conditions 50% of patients have comorbid psychiatric disease (e.g., major depression) fibromyalgia chronic fatigue syndrome GERD and functional dyspepsia Epidemiology Demographics prevalence in North America estimated to be around 10-15% higher prevalence in women (14%) compared to men (9%) ETIOLOGY Pathogenesis pathophysiology is uncertain as it is likely a disorder resulting from interaction from several factors gastrointestinal tract motor abnormalities (e.g., abnormal transit time) are detectable in some patients hypersensitization of visceral afferent nerves in the gut alterations in particular immune cells and markers suggested genetic susceptibility psychosocial factors may influence the expression of symptoms Presentation Symptoms chronic abdominal pain with periodic exacerbations can be exacerbated with stress or meals may be relieved with defecation non-bloody diarrhea constipation Physical exam abdominal distension mild abdominal tenderness imaging Abdominal imaging (e.g., radiograph) done in patients with constipation assess for stool accumulation and determine severity Studies Diagnostic testing diagnostic approach diagnosis is based on clinical symptoms and the fulfillment of symptom-based diagnostic criteria with a limited workup to exclude organic disease Rome IV criteria for IBS recurrent abdominal discomfort occurring at least 1x/week for 3 months associated with at least 2 of the following related to defecation change in stool frequency change in stool form (appearance) studies laboratory testing done primarily to exclude alternative diagnosis CBC, CRP, and fecal calprotein serologic testing for celiac disease if diarrhea present colonoscopy indicated if patients have alarm features age of onset > 50 years rectal bleeding/melena weight loss abnormal CBC family history of inflammatory bowel disease (IBD) or colorectal cancer Differential Celiac disease distinguishing factors positive serologic tests for celiac disease Inflammatory bowel disease distinguishing factors lesions present on colonoscopy Treatment First-line lifestyle and dietary modification (e.g., avoidance of gas-producing foods) high fiber and low fat diet psychiatric support with continuity of care laxatives (e.g., polyethylene glycol) are indicated in patients with moderate to severe IBS with constipation antidiarrheal agents (e.g., loperamide) are indicated in patients with moderate to severe IBS with diarrhea antispasmodics (e.g., dicyclomine) are used on a as needed basis for IBS-related abdominal pain Second-line bile acid sequestrants in patients with moderate to severe IBS with diarrhea tricyclic antidepressants for patients with coexisting depression and persistent abdominal pain despite antispasmodic use Complications Dehydration Electrolyte imbalance Bowel impaction Hemorrhoids