A 68-year-old woman with a history of diverticulosis presents with acute left lower quadrant pain, fever, and peritoneal signs. CT abdomen shows free air adjacent to the sigmoid colon with localized collection. Regarding imaging features that differentiate perforation sites and severity, all of the following statements are accurate EXCEPT:

Explanation

## Portal Venous Gas — Misconception **Warning:** Portal venous gas (pneumatosis hepatis) is NOT a reliable early indicator of perforation. It is actually a LATE finding that indicates: - Advanced bowel necrosis - Severe sepsis - Poor prognosis (mortality 50–75%) - Often indicates the need for surgery, but is NOT an early sign Portal venous gas can occur in conditions other than perforation (e.g., incompetent ileocecal valve, bowel obstruction with mucosal injury, gastric insufflation). Its presence indicates severe pathology but is neither specific nor early. ## Accurate Imaging Findings in Perforation | Feature | Clinical Significance | |---------|----------------------| | **Contained perforation** | Localized abscess; better prognosis; may be managed conservatively with antibiotics + drainage | | **Generalized peritonitis** | Diffuse free air; requires urgent surgical intervention | | **Cecal perforation** | Larger diameter (Laplace law) + thin wall → higher risk of rupture and diffuse peritonitis | | **Sigmoid perforation** | Smaller diameter, thicker wall → more likely to be contained; diverticular perforation often localized | | **Ileocecal perforation** | Air confined to right paracolic gutter/iliac fossa due to peritoneal attachments | | **Portal venous gas** | LATE finding; indicates severe necrosis, not early perforation; poor prognostic sign | **High-Yield:** Contained vs. diffuse perforation is the KEY prognostic and management distinction: - **Contained** → percutaneous drainage + antibiotics (non-operative management possible) - **Diffuse** → emergency surgery **Clinical Pearl:** In diverticular perforation, the omentum and peritoneal attachments often wall off the perforation, creating a localized abscess—this is why diverticular perforation may be managed conservatively if caught early. ## Why Option 2 Is Wrong Portal venous gas is a LATE, poor-prognostic sign indicating advanced bowel necrosis and sepsis—not an early, reliable indicator of perforation. Its presence mandates urgent intervention, but it is neither sensitive nor specific for perforation and is not present in all cases.