Contrast-enhanced CT findings of gallbladder volvulus

An 84-year old female presented to the emergency department with upper abdominal pain radiating to the back that started suddenly but progressively worsened over the last six hours. She complained of nausea and vomiting and drowsiness. Her past medical history included breast cancer with liver and bone metastases diagnosed 5 years previously.

Computed tomography imaging acquired in the portal venous phase demonstrated a markedly distended gallbladder with a thickened wall. The gallbladder neck had a swirled appearance (Figure 1). There was small volume of peri-hepatic fluid that was assumed to be reactive (Figure 2). The degree of gallbladder distension ruled out gallbladder perforation. The common bile duct was measured as 15 mm in maximal diameter but this was unchanged when compared to previous serial imaging over the last 5 years. There was no evidence of intrahepatic biliary dilatation. The liver appearance was stable with areas of capsular retraction at the site of treated liver metastases. Allowing for simple renal cysts, the rest of the study was unremarkable (Figure 3 and 4).

Gallbladder volvulus is a rare condition that occurs following mechanical rotation of the gallbladder on its mesentery along the axis of the cystic duct and cystic artery [1,2]. Congenital variation in the peritoneal attachment of the gallbladder and elongation of the gallbladder mesentery in the elderly from loss of visceral fat and liver atrophy are predisposing factors to torsion [3]. Intense peristalsis of the stomach and colon have been suggested as precipitating factors leading to torsion in the clockwise or anti-clockwise direction respectively [4].

Clinical presentation of gallbladder volvulus varies from intermittent right upper quadrant pain resembling biliary colic in incomplete torsion (<180^o) to acute abdomen with vascular compromise leading to gallbladder ischaemia [5]. Abdominal pain of short duration with early onset of vomiting in gallbladder volvulus often gets initially misdiagnosed as acute cholecystitis. Important differentiating factors are patient characteristics including thin predominantly female elderly patients with chronic lung disease or spine deformity, and signs including palpable abdominal mass and lack of fever or leucocytosis [6]. Gallbladder calculi are found in less than 50% of cases [2,5].

Imaging is playing increasingly important role in pre-operative diagnosis of gallbladder volvulus which was traditionally diagnosed during surgery [1,2,4,7,8]. Ultrasound findings include a large thick-walled floating gallbladder outside its normal anatomical fossa [2, 9]. Multiple studies report markedly enlarged gallbladder with pericholecystic fluid and loss of wall enhancement on computed tomography, sometimes with a rare but specific sign where the twisted pedicle is seen as a ‘twirl’ [9,10,11]. Although not routinely performed in the acute setting, magnetic resonance imaging demonstrates haemorrhage and necrosis as high signal intensity within the gallbladder wall on T1 weighted sequence [7]. Correct radiological interpretation prevents unnecessary intervention such as percutaneous drainage of a distended gallbladder presumed to be due to acute cholecystitis [8]. Gallbladder volvulus is a surgical emergency that has good prognosis with urgent, preferably laparoscopic, derotation and cholecystectomy [3,10]. A delay in diagnosis and thus appropriate management can result in gallbladder rupture and biliary peritonitis, which significantly increases the mortality rate [5,7].

Our case illustrates the importance of considering gallbladder volvulus as a differential diagnosis in a cachexic elderly female patient presenting with acute abdominal pain resembling acute cholecystitis [5,10]. Following prompt radiological diagnosis on CT imaging, the patient underwent emergency open cholecystectomy with removal of a completely infarcted gallbladder (Figure 5) and had uneventful post-operative recovery.

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