Diagnosis: Acute Diverticulitis
The most likely diagnosis is acute diverticulitis, which is the leading cause of left lower quadrant pain in elderly adults and is characterized by mesenteric stranding on CT imaging. 1, 2
Primary Diagnostic Reasoning
Mesenteric stranding on CT is the key finding that points directly to acute diverticulitis, as this represents inflammatory changes in the pericolonic fat that are pathognomonic for this condition 1, 3
The American College of Radiology identifies acute sigmoid or descending colonic diverticulitis as the most common cause of left lower quadrant pain in adults, with approximately 70% of elderly patients having underlying diverticulosis 2
The patient's age and location of pain (left lower quadrant) fit the classic demographic and anatomic distribution for diverticulitis 1, 2
Supporting Clinical Features
Normal CBC and metabolic panel do not exclude diverticulitis, as uncomplicated diverticulitis frequently presents without leukocytosis or metabolic derangements 3
Normal CEA level helps exclude malignancy as a primary concern, though it does not definitively rule out perforated adenocarcinoma 2
The left inguinal hernia is an incidental finding and unlikely to be the primary cause of the mesenteric stranding or left lower quadrant pain, as inguinal hernias typically present with groin masses or pain radiating to the groin rather than isolated left lower quadrant abdominal pain 4
Critical Differential to Exclude
Perforated adenocarcinoma can perfectly mimic diverticulitis both clinically and radiographically, making this the most important alternative diagnosis to consider 2
The key distinguishing feature is pericolonic lymphadenopathy >1 cm in short axis, which strongly suggests malignancy over diverticulitis 3, 2
Review the CT report specifically for lymph node size, extraluminal air, abscess formation, and bowel wall thickening pattern 3, 2
Immediate Management Considerations
Assess for surgical abdomen: Check for fever with inability to pass gas/stool, severe tenderness with guarding, vomiting, bloody stools, or signs of shock—any of these mandate immediate surgical consultation 3, 5
Most diverticulitis is uncomplicated and can be managed with outpatient antibiotics for 7 days maximum, though conservative management without antibiotics is acceptable in immunocompetent patients 3, 2
Colonoscopy after diverticulitis is not routinely indicated unless the patient has not had age-appropriate screening (which this patient has, with two normal colonoscopies 10 years apart) or if there are abnormal pericolonic lymph nodes on CT 3, 2
Common Pitfalls to Avoid
Do not assume the inguinal hernia is causing the symptoms—mesenteric stranding indicates intra-abdominal inflammatory pathology, not hernia-related complications 3, 2
Do not miss colon cancer, which can present identically to diverticulitis; lymphadenopathy >1 cm is the key differentiator requiring colonoscopy with biopsy 3, 2
Clinical diagnosis alone has a 34-68% misdiagnosis rate, making CT imaging essential for confirmation 2