What is the cause of left lower quadrant abdominal tenderness in a 54-year-old male with a history of hypertension and Irritable Bowel Syndrome (IBS), diarrhea-predominant, who presents with abdominal discomfort and flatulence after eating a normal diet, without hematochezia, mucus in stool, nausea, vomiting, or fever, and has a recent normal colonoscopy except for a polyp, and takes dicyclomine (Bentyl) for IBS?

Differential Diagnosis for 54-year-old Male with Left Lower Quadrant Abdominal Tenderness

• Single most likely diagnosis:
  • Irritable Bowel Syndrome (IBS) exacerbation: The patient has a history of diarrhea-predominant IBS, and his symptoms of left lower quadrant abdominal tenderness, flatulence, and a "gurgling/annoying sensation" are consistent with an exacerbation of his IBS, especially given the recent bowel movement and resolution of some symptoms.
• Other Likely diagnoses:
  • Diverticulitis: Although the patient's last colonoscopy was normal except for a polyp, diverticulitis can occur without a history of diverticulosis on colonoscopy. The left lower quadrant tenderness and recent onset of discomfort are consistent with this diagnosis.
  • Gastroenteritis: The patient's symptoms of abdominal tenderness, flatulence, and recent bowel movement could be consistent with a viral or bacterial gastroenteritis, especially given his recent food intake at a barbecue restaurant.
  • Constipation: The patient reports a small bowel movement yesterday, and his symptoms could be consistent with constipation, especially given his history of IBS.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Appendicitis: Although the patient's symptoms are not classic for appendicitis (e.g., no nausea, vomiting, or fever), it is a diagnosis that must be considered, especially given the abdominal tenderness.
  • Intestinal obstruction: The patient's symptoms of abdominal tenderness, flatulence, and recent bowel movement could be consistent with an intestinal obstruction, which would require prompt surgical intervention.
  • Inflammatory bowel disease (IBD) flare: The patient's symptoms could be consistent with a flare of IBD, such as Crohn's disease or ulcerative colitis, which would require prompt medical attention.
• Rare diagnoses:
  • Intussusception: A rare condition in which a portion of the intestine telescopes into another portion, causing abdominal pain and tenderness.
  • Volvulus: A rare condition in which a portion of the intestine twists around its mesentery, causing abdominal pain and tenderness.
  • Ischemic colitis: A rare condition in which the blood supply to the colon is compromised, causing abdominal pain and tenderness.