Radiology Resident Case of the Week
The clinical manifestations are essentially indistinguishable from those of non gaseous cholecystitis: Beginning as an attack of biliary colic which rapidly progresses. The pain generalizes in the right upper abdomen. The pain may radiate to the inter scapular area, right scapula, or shoulder. Peritoneal signs of inflammation such as increased pain with jarring or on deep respiration may be apparent. The patient is anorectic and often nauseated. Vomiting is relatively common and may produce symptoms and signs of vascular and extracellular volume depletion. Jaundice is unusual early in the course but may occur when edematous inflammatory changes involve the bile ducts and surrounding lymph nodes. A low-grade fever is typical, occasionally accompanied by chills or rigors. The right upper quadrant of the abdomen is almost invariably tender to palpation. An enlarged, tense gallbladder is palpable in one-quarter to one-half of patients. Palpation of the right upper quadrant does not reliably produce increased pain and inspiratory arrest (Murphy's sign). This is thought to be due to diabetic neuropathy. A light blow delivered to the right subcostal area may elicit a marked increase in pain. Localized rebound tenderness in the right upper quadrant is common, as are abdominal distention and hypoactive bowel sounds from paralytic ileus, but generalized peritoneal signs and abdominal rigidity are usually lacking, until perforation supervenes.
Gangrene of the gallbladder results from ischemia of the wall and patchy or complete tissue necrosis. Gangrene usually predisposes to perforation of the gallbladder, but perforation also may occur before gangrene presents. Localized perforations are usually contained by the omentum or by adhesions produced by recurrent inflammation of the gallbladder. Bacterial superinfection of the walled-off gallbladder contents results in abscess formation. Perforation increases the mortality rate to approximately 30 percent. Such patients may experience a sudden transient relief of RUQ pain as the distended gallbladder decompresses; this is followed by signs of generalized peritonitis.
The mortality rate is much higher (15-20%) than usual acute cholecystitis, as the evolving inflammatory and infectious decline is rapid and leads to perforation and subsequent unpleasant events if not promptly recognized and addressed. Prompt surgical intervention coupled with appropriate antibiotics is mandatory.
Etiology/Pathophysiology
Emphysematous cholecystitis is thought to be a result of small vessel ischemic disease. Acute cholecystitis followed by ischemia secondary to cystic artery occlusion or gangrene of the gallbladder wall and infection by gas-producing organisms. Bacteria most frequently cultured in this setting include anaerobes such as Clostridium species, and aerobes such as E. coli.
Pathology:
Acute cholecystitis leads to inflammatory edema which results first in occlusion of the venous/lymphatic return from the gallbladder and more edema, resulting eventually in occlusion or stenosis of the arterial supply of the gallbladder. Gas production begins in the gallbladder wall as ischemia leads to colonization then infection with gas forming organisms. Early, gas production is confined to the wall, then progresses to the lumen with distention of the gallbladder walls. Coagulative necrosis of the mucosa with venous congestion.
Miscellaneous
Imaging
Plain film: The diagnosis is usually made on plain abdominal film by the finding of gas within the gallbladder lumen, dissecting within the gallbladder wall to form a gaseous ring, or in the pericholecystic tissues.
Ultrasound: High level echoes are seen, outlining the gallbladder wall. Hyperechoic ring down artifiact seen in wall, protruding into the lumen.
CT: Gas within the lumen and wall, also occasionally seen in the intrahepatic biliary ducts.
DDX
Enteric fistula, Incompetent sphincter of Oddi, Periduodenal abscess, Periappendiceal abscess in malpositioned appendix, Gallbladder lipomatosis
Key references
Goodman, P; Halpert, R.D. (1993). Gastrointestinal Radiology: The Requisites.
Juhl, J.H. (1981). Essentials of Roentgen Interpretation.
Berk, R.N.; Ferrucci, J.T.; Leopold, G.R. (1982). Radiology of the Gallbladder and Bile Ducts: Diagnosis and Intervention.
Isselbacher, K.J.; et al. (1994). Harrison's Principles of Internal Medicine.
ACR Code
762.284
Keywords:
emphysematous, cholecystitis, gangrene