Gallbladder and cystic duct agenesis: Magnetic Resonance Imaging and MR cholangiopancreatography findings

Clinical History

A 46-year-old man presented to us with right upper quadrant abdominal pain, sudden in onset and colicky in nature; physical examination showed a soft right hypochondrium and a positive Murphy’s sign.
Routine haematology and biochemical tests were normal.

Imaging Findings

Abdominal ultrasound did not visualize very well the gallbladder: it showed hyperechoic shadows in the gallbladder fossa, suspected for a sclero-atrophic gallbladder. It also showed dilated intra- and extra-hepatic bile ducts and a stone inside a dilated common bile duct (CBD). The patient was investigated with Magnetic Resonance Imaging (MRI) and MR cholangiopancreatography (MRCP) after fasting for 7 hours, using a protocol consisted of an axial T1-weighted 2D FLASH, axial T2-weighted TSE sequences and MR cholangiography sequences. Magnetic resonance did not show both the gallbladder and the cystic duct, failed to demonstrate a gallbladder in its ectopic positions but confirmed the other ultrasound findings.
The patient underwent a choledocholithotomy.

Discussion

Gallbladder agenesis (GA) is rare, often discovered incidentally, usually asymptomatic, with a mean age of 46 years at the time of the diagnosis: the prevalence range is 0.007–0.13%.
GA is due to failure of the developmental process that begins in the 4th week of intrauterine life; it can be accompanied by lack of the cystic duct or associated with hypoplastic cystic duct. It usually occurs alone in 70–82% of cases or together with cardiovascular and gastrointestinal abnormalities [1, 2].
Symptoms are present in about 23% of cases: right upper quadrant abdominal pain, nausea, fatty food intolerance, dyspepsia and jaundice; GA is associated with a dilatation of the common duct or gallstones in 25-50% of cases.
GA represents a difficulty: if the diagnosis is made during surgical exploration, the biliary tree can be exposed to possible complications such as iatrogenic injury [1-3].
Widespread availability of imaging techniques provide an excellent alternative to open exploration and intra-operative cholangiography.
Ultrasonography (US) is the initial investigation for patient with right upper quadrant abdominal pain even if it depends on the examiner’s experience and on patient conditions; GA also cannot be reliably differentiated from the shrunken gallbladder of chronic cholecystitis [1, 2].
Endoscopic retrograde cholangiopancreatography (ERCP) is a further technique, but it is associated with significant mortality and morbidity and the non-visualization of the gallbladder is commonly interpreted as an occlusion of the cystic duct [1, 4].
MRCP is a non invasive imaging method that does not require contrast administration; it is not compromised by biliary stasis and can provide accurate anatomical details about the biliary tree, also excluding ectopic gallbladder. It allowed to make the correct preoperatively diagnosis with a noninvasive examination, avoiding unnecessary surgical procedures and minimizing the risk of complications. It may not replace ultrasound as the gold standard of acute gallbladder imaging, representing a complementary technique to inconclusive sonographic studies [1, 3-11].
No guidelines are available on how to manage this condition. Some authors suggest radiologic investigation (MRCP, CT, ECRP) when US findings are doubtful. Many patients became asymptomatic after exploratory surgery. If symptoms continue postoperatively, it is possible a treatment with oral smooth muscle relaxants and, if this fails, sphincterotomy.
If the diagnosis is made preoperatively, there are two possible clinical situations: patients with choledocholithiasis who should undergo choledocholithotomy, or completely asymptomatic patients for whom no definitive procedure is required [3, 4, 6].

Differential Diagnosis List

Final Diagnosis

Gallbladder and cystic duct agenesis

URL:	https://eurorad.org/case/11234
DOI:	10.1594/EURORAD/CASE.11234
ISSN:	1563-4086