Appendiceal perforation is the most serious complication of acute appendicitis. Following gangrenous changes, the appendiceal wall develops a full-thickness defect and luminal contents leak into the peritoneal cavity. Recognized on CT by wall defect, extraluminal air, periappendiceal fluid/phlegmon, and findings of diffuse peritoneal contamination. Requires emergent surgical intervention.
Age Range
5-80
Peak Age
30
Gender
Equal
Prevalence
Uncommon
Appendiceal perforation represents the final stage of obstructive appendicitis. Following luminal obstruction, increasing intraluminal pressure first impairs venous drainage, then arterial blood flow. The ischemic mucosa becomes susceptible to bacterial translocation, and transmural inflammation + necrosis (gangrene) develops. When a full-thickness defect forms in the necrotic wall segment, intraluminal contents (fecal material, bacteria, appendicolith) leak into the peritoneal cavity. Perforation typically occurs at the antimesenteric border of the appendix (the area with least blood flow) or distal to the appendicolith obstruction point. Free perforation leads to diffuse peritonitis, while localized perforation leads to abscess or phlegmon formation.
On CT, focal enhancement defect of the appendiceal wall combined with periappendiceal extraluminal air and phlegmon/collection represents the diagnostic triad of perforated appendicitis. This combination of findings provides over 95% specificity. Even if wall defect alone is not detected, presence of extraluminal appendicolith or air strongly supports perforation.
Focal enhancement defect or loss of wall continuity of the appendix is a direct sign of perforation. The defect is usually located at the antimesenteric border or tip of the appendix. Wall enhancement may be completely absent in the gangrenous segment.
Report Sentence
A focal enhancement defect of the appendiceal wall is identified, consistent with perforation.
Extraluminal free air (pneumoperitoneum) is seen in the periappendiceal area or peritoneal cavity. Air focus is usually small and localized, detected adjacent to the appendiceal wall defect. Diffuse pneumoperitoneum suggests a larger perforation.
Report Sentence
Extraluminal free air focus in the periappendiceal area is identified, supporting appendiceal perforation.
Diffuse free fluid is seen in the peritoneal cavity. Fluid accumulates in dependent areas such as pelvic floor, paracolic gutters, and Morrison's pouch. Fluid density may be higher than simple transudate (>20 HU) because inflammatory exudate contains protein and cellular debris.
Report Sentence
Diffuse free fluid in the peritoneal cavity is noted, consistent with diffuse peritonitis as a complication of perforated appendicitis.
Diffuse peritoneal enhancement and thickening indicate peritoneal irritation and inflammation. Parietal and visceral peritoneal layers may show smooth or nodular enhancement. Omental caking may be seen in advanced cases.
Report Sentence
Diffuse peritoneal enhancement and thickening is noted, consistent with peritonitis.
Unorganized inflammatory infiltration (phlegmon) is seen surrounding the perforation site. Phlegmon is more advanced than fat stranding, obliterating normal anatomical planes and creating a mass-like appearance of heterogeneous soft tissue density.
Report Sentence
Phlegmonous change is noted surrounding the appendix, consistent with perforated appendicitis.
Focal loss of appendiceal wall layers on ultrasound indicates perforation. The normal layered structure (target sign) is lost, accompanied by periappendiceal heterogeneous echogenicity and free fluid.
Report Sentence
Focal loss of appendiceal wall layers is noted, consistent with perforation.
Criteria
Perforation site not localized, diffuse four-quadrant free fluid and free air, diffuse peritoneal enhancement
Distinct Features
Most severe form. Requires emergent laparotomy. High risk of septic shock. Mortality 5-10% due to diffuse peritoneal contamination.
Criteria
Perforation site walled off by omentum/adjacent loops, localized phlegmon/collection, no diffuse free fluid
Distinct Features
Better prognosis. IV antibiotics + percutaneous drainage (if collection present) may be applied. Interval appendectomy planned at 6-8 weeks.
Distinguishing Feature
In abscess, organized rim-enhancing collection is predominant and free air is usually absent; in perforation, free air, wall defect, and unorganized phlegmon are more prominent
Distinguishing Feature
In uncomplicated acute appendicitis, wall is intact, no extraluminal air, and minimal free fluid; perforation shows wall defect, free air, and diffuse fluid
Distinguishing Feature
In adenocarcinoma perforation, irregular solid mass component, asymmetric wall thickening, and regional lymphadenopathy accompany; simple perforation lacks mass lesion
Urgency
emergentManagement
surgicalBiopsy
Not NeededFollow-up
3-monthAppendiceal perforation is a surgical emergency. Free perforation requires emergent laparotomy. In localized perforation, emergent surgery or IV antibiotics + interval appendectomy may be applied based on patient condition. Close follow-up for postoperative complications (wound infection, intraabdominal abscess, ileus) is required. Delayed perforation increases mortality (1-5% vs <0.1% in uncomplicated appendicitis). In patients >40 years with appendicitis complicated by perforation, underlying appendiceal neoplasm frequency is 5-10%, and follow-up imaging and colonoscopy are recommended.
Perforated appendicitis is a serious condition requiring emergency surgery. Perforation rate increases proportionally with diagnostic delay, rising significantly after 36 hours from symptom onset. Treatment is emergent appendectomy (laparoscopic or open) and broad-spectrum antibiotic therapy. Peritoneal lavage may be needed in the presence of generalized peritonitis. Children and elderly have higher perforation rates.