E1825. Imaging Characteristics of Types of Gallbladder Perforation Using the Neimeier Classification
  1. Bing Wang; Medical College of Georgia at Augusta University
  2. Steven Yi; Medical College of Georgia at Augusta University
  3. Jayanth Keshavamurthy; Medical College of Georgia at Augusta University
  4. Supriya Gupta; AMITA Health St. Mary's Hospital
  5. Frank Miller; Northwestern University Feinberg School of Medicine
  6. Courtney Moreno; Emory University School of Medicine
  7. Pardeep Mittal; Medical College of Georgia at Augusta University
Gallbladder perforation is a rare but life-threatening complication of acute cholecystitis with mural ischemia and necrosis. The Neimeier classification proposed in 1934 remains the gold standard in grading gallbladder perforation. Accurate and timely diagnosis of gallbladder perforation is critical but often difficult and delayed due to overlapping symptoms with other causes of acute abdomen. The purpose of this exhibit is to review multimodality imaging characteristics of the different types of gallbladder perforation using a case-based approach.

Educational Goals / Teaching Points
The goals of this exhibit include reviewing the epidemiology, risk factors, pathophysiology, and natural history of gallbladder perforation; reviewing the original and variations of the Neimeier classification; identifying multimodality imaging findings of the different types of gallbladder perforation and differential diagnoses; and discussing the management implications and potential complications of the different types of gallbladder perforation.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The most common site of gallstone perforation is the fundus due to limited blood supply in this region. According to the original Neimeier classification, there are three main clinical subtypes. Type 1 is acute with free perforation into the peritoneal cavity and characterized by gallbladder wall thickening, focal wall defect, surrounding inflammatory changes, and pericholecystic fluid collection on imaging. Type 2 is subacute with pericholecystic abscess. Imaging findings include well-defined abscess formation in the pericholecystic region along with signs of gallbladder inflammation. Type 3 is chronic with cholecystoenteric fistula, demonstrated by the presence of intraluminal gas, communication between gallbladder lumen and duodenum, and surrounding inflammatory changes. A fourth type suggested by Andersen et al. in 1987 describes chronic perforation with cholecystobiliary fistula formation. Important differential diagnoses to consider include emphysematous cholecystitis, gallstone ileus, Bouveret syndrome, and Mirizzi syndrome. Treatment for gallbladder perforation include urgent cholecystectomy for Type 1 perforation, percutaneous drainage of gallbladder and pericholecystic abscess with subsequent cholecystectomy for Type 2 perforation, and cholecystectomy with possible enterotomy for Type 3 perforation.

Neimeier classification remains gold standard in classifying gallbladder perforation. Prompt diagnosis of gallbladder perforation require familiarity with characteristic multimodality imaging appearances of different types of gallbladder in order to ensure timely clinical referral and management.