What is the probable cause of intermittent left periumbilical pain in a patient with normal abdominal ultrasound and blood investigations, and no associated fever, vomiting, or urinary/bowel problems?

Probable Cause: Functional Abdominal Pain or Early/Mild Diverticular Disease

In a 38-year-old male with intermittent left periumbilical pain and completely normal ultrasound and blood work, the most probable cause is functional abdominal pain disorder, though early diverticular disease or other structural pathology cannot be definitively excluded without CT imaging. 1, 2

Why Further Imaging is Critical

• Ultrasound has significant limitations for evaluating left-sided abdominal pain - it is operator-dependent, limited by bowel gas and obesity, and cannot adequately visualize the colon, mesentery, or retroperitoneum where pathology may exist 1
• CT abdomen and pelvis with IV contrast is the gold standard for evaluating left periumbilical/lower quadrant pain, with 98-100% diagnostic accuracy and the ability to detect alternative diagnoses in up to 49% of cases 1, 2
• Clinical examination and basic labs alone are unreliable - misdiagnosis rates range from 34-68% when imaging is not performed 2

Recommended Diagnostic Approach

Order CT abdomen and pelvis with IV contrast as the next step, rated 8/9 (usually appropriate) by the American College of Radiology for nonlocalized abdominal pain 1, 2

What CT Will Identify or Exclude:

• Early or atypical diverticulitis - though rare at age 38, CT has 98-100% sensitivity and can detect subtle pericolonic fat stranding or bowel wall thickening missed on ultrasound 2, 3
• Small bowel pathology including early Crohn's disease, epiploic appendagitis, or mesenteric adenitis 2
• Colonic pathology such as colitis, early inflammatory bowel disease, or rarely malignancy (though less likely at this age) 2
• Vascular causes including mesenteric ischemia (consider if pain is postprandial with weight loss) 4
• Hernias or other structural abnormalities not visible on ultrasound 2

If CT is Normal: Consider Functional Disorder

• Functional bowel disorders become the most likely diagnosis when structural pathology has been excluded by CT 3
• Irritable bowel syndrome (IBS) should be considered if pain is related to bowel movements or dietary triggers 3
• Functional dyspepsia if pain is postprandial with early satiety or upper abdominal burning 4

Critical Pitfalls to Avoid

• Do not assume normal ultrasound and labs exclude significant pathology - ultrasound sensitivity for left-sided abdominal pathology is poor compared to CT 1
• Do not dismiss intermittent pain as benign without imaging - CT alters diagnosis in nearly half of cases with nonlocalized abdominal pain 4
• Watch for red flag symptoms that mandate urgent evaluation: fever, inability to pass gas/stool, severe tenderness with guarding, vomiting, bloody stools, or progressively worsening pain 2

Alternative Consideration if CT Cannot Be Obtained

• MRI abdomen and pelvis without and with IV contrast can provide similar diagnostic information with 86-94% sensitivity and 88-92% specificity for inflammatory conditions, though it has longer scan times and higher cost 1, 3

Management Based on CT Results

• If CT shows uncomplicated diverticulitis: Conservative management without antibiotics for immunocompetent patients 2
• If CT is completely normal: Reassurance, dietary modification, and consider gastroenterology referral for functional bowel disorder management 3
• If CT shows alternative diagnosis: Treat accordingly based on specific findings 2