Differential Diagnosis for Postprandial Bloating, Abdominal Pain, and Urgent Defecation

• Single Most Likely Diagnosis
  • Irritable Bowel Syndrome (IBS): This condition is characterized by recurrent abdominal pain associated with a change in bowel habits, such as diarrhea or constipation, and bloating. The symptoms described are classic for IBS, especially given the postprandial onset.
• Other Likely Diagnoses
  • Lactose Intolerance: This condition leads to bloating, gas, and diarrhea after consuming lactose-containing products due to the inability to digest lactose properly.
  • Fructose Malabsorption: Similar to lactose intolerance, this condition causes symptoms after consuming fructose due to poor absorption in the small intestine.
  • Small Intestine Bacterial Overgrowth (SIBO): An overgrowth of bacteria in the small intestine can lead to bloating, abdominal pain, and changes in bowel habits after eating.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause abdominal pain, urgent defecation, and bloating, although they typically also include blood in the stool and weight loss.
• Do Not Miss Diagnoses
  • Acute Mesenteric Ischemia: Although less common, this condition is a medical emergency that can present with severe abdominal pain out of proportion to physical examination findings, and it requires immediate intervention.
  • Intestinal Obstruction: This can cause severe abdominal pain, bloating, and changes in bowel habits, and it is a surgical emergency.
  • Appendicitis: While the classic presentation includes right lower quadrant pain, some cases can present with more diffuse or atypical symptoms, including bloating and changes in bowel habits.
• Rare Diagnoses
  • Celiac Disease: An autoimmune reaction to gluten that can cause abdominal pain, bloating, and changes in bowel habits, although it often includes other systemic symptoms like fatigue and weight loss.
  • Carbohydrate Malabsorption (e.g., sorbitol, sucrose): Similar to lactose and fructose malabsorption but less common.
  • Giardiasis: A parasitic infection that can cause bloating, abdominal pain, and diarrhea, especially in travelers or those exposed to contaminated water.
  • Colorectal Cancer: Although rare in younger populations, it can present with changes in bowel habits, abdominal pain, and bloating, especially if there is a family history or other risk factors.