What are the next steps for a young adult or child with a history of abdominal pain or jaundice and a choledochal cyst visible on Magnetic Resonance Cholangiopancreatography (MRCP) but not found during intraoperative exploration?

Management of "Disappearing" Choledochal Cyst

Immediate Intraoperative Response

When a choledochal cyst visualized on preoperative MRCP is not found during surgical exploration, perform intraoperative cholangiography immediately to confirm biliary anatomy and exclude the presence of a cyst that may have decompressed or was misidentified. 1

Key Intraoperative Steps

• Perform intraoperative cholangiography (IOC) when biliary pathology is suspected but not visually identified during exploration. This is strongly recommended to map the biliary anatomy and identify any subtle abnormalities that may not be grossly apparent. 1

• Consider laparoscopic ultrasound (LUS) as an alternative or complementary technique to IOC for real-time assessment of the biliary tree during surgery, particularly if IOC is technically challenging or unavailable. 1

• Thoroughly explore the hepatoduodenal ligament and retroduodenal space to ensure a type I or type IV cyst has not collapsed or decompressed spontaneously, as choledochal cysts can rupture or decompress prior to or during surgical manipulation. 2, 3

Postoperative Diagnostic Algorithm

If Intraoperative Findings Remain Negative

• Obtain repeat MRCP within 2-4 weeks postoperatively to reassess the biliary anatomy once inflammation and surgical manipulation have resolved. MRCP has 93% sensitivity for detecting biliary abnormalities and provides superior visualization of intrahepatic ducts compared to other modalities. 1, 4

• Add IV gadolinium contrast to the repeat MRCP to improve detection of subtle biliary abnormalities, peribiliary enhancement, or unsuspected malignancy that may mimic a choledochal cyst. 5

• Consider endoscopic ultrasound (EUS) with or without ERCP if repeat MRCP remains equivocal. EUS has 95% sensitivity for biliary pathology and can provide tissue diagnosis if malignancy is suspected. 1

Differential Considerations for "Disappearing" Cyst

• Spontaneous decompression or rupture of the cyst may occur, particularly in type I or type IVA cysts, which can present with acute peritonitis or gradual resolution of symptoms. 2, 3

• Misinterpretation of MRCP findings should be considered, as dilated common bile duct from choledocholithiasis, biliary stricture, or transient obstruction can mimic a choledochal cyst on imaging. 1, 4

• Type III choledochal cyst (choledochocele) may be intermittently visible depending on the degree of distension and may not be apparent during surgical exploration of the extrahepatic biliary tree. 6

Critical Clinical Pitfalls

• Do not abandon the operation without definitive biliary imaging. Failure to perform IOC when biliary pathology is suspected can result in missed diagnoses and necessitate reoperation. 1

• Recognize that adult presentations differ significantly from pediatric cases. Adults rarely present with the classic triad (only 6% of cases) and more commonly have acute biliary symptoms or pancreatitis, which may confound the clinical picture. 3, 7

• Be aware of malignancy risk. Approximately 10% of adult choledochal cysts harbor cholangiocarcinoma, and a "disappearing" cyst may represent malignant transformation with altered anatomy. 7

Follow-Up Strategy

• Schedule close clinical follow-up at 4-6 weeks with repeat liver function tests and abdominal ultrasound to monitor for recurrent symptoms or biliary obstruction. 1

• Obtain repeat MRCP if symptoms persist or recur, as intermittent obstruction from a choledochocele or partially decompressed cyst may not be apparent on initial postoperative imaging. 6

• Maintain a low threshold for ERCP with tissue sampling if there is persistent biliary dilation, stricture, or concern for malignancy on follow-up imaging, given the 9.7% malignancy rate in adult choledochal cysts. 7