What is the recommended diagnostic algorithm for choledochal cysts in patients (especially females, children, or young adults) presenting with unexplained jaundice, right‑upper‑quadrant pain, a palpable abdominal mass, or recurrent cholangitis?

Diagnostic Algorithm for Choledochal Cysts

Initial Imaging Modality

Abdominal ultrasound should be obtained as the first-line imaging modality for patients presenting with unexplained jaundice, right upper quadrant pain, palpable abdominal mass, or recurrent cholangitis when choledochal cyst is suspected. 1, 2, 3

• Ultrasound is sensitive for preliminary diagnosis and can detect cystic dilatation of bile ducts in all patients with choledochal cysts 2
• This modality is widely available, involves no radiation exposure, and allows evaluation of gallbladder morphology 4
• Ultrasound reliably demonstrates biliary dilatation and identifies obstructive causes 5

Definitive Diagnostic Imaging

Magnetic resonance cholangiopancreatography (MRCP) must be obtained to accurately define cyst anatomy, classify the cyst type according to Todani classification, and plan surgical intervention. 1, 2, 6

• MRCP accurately defines cyst anatomy and the site of biliary origin in all cases with extrahepatic cysts 2
• This imaging provides exact visualization, localization, and classification of biliary pathology essential for treatment planning 5
• MRCP is the primary diagnostic modality for choledochal cysts and should be obtained even when ultrasound findings are suggestive 1

Supplementary Diagnostic Procedures

Endoscopic retrograde cholangiopancreatography (ERCP) should be reserved for cases where MRCP is equivocal, when therapeutic intervention is planned, or when smaller cysts require better definition. 2

• ERCP clearly demonstrates the cyst and can be combined with therapeutic sphincterotomy for type III cysts (choledochocele) 1, 2
• Percutaneous transhepatic cholangiography (PTC) may define smaller cysts that are not well visualized on other modalities 2
• Cytological examination of bile juice obtained during PTC can detect malignancy, which is a critical consideration given the risk of cholangiocarcinoma 2

Clinical Presentation Patterns

The classic triad of abdominal pain, jaundice, and palpable mass is uncommon in adults, occurring in only a minority of cases. 3

• Abdominal pain and jaundice are the predominant symptoms in adult presentations 3
• Approximately 80% of choledochal cysts are diagnosed within the first decade of life, making adult presentation less typical 1
• Past history of cholangitis and pancreatitis may be present in some patients 3
• Physical examination may reveal jaundice, hepatomegaly, and splenomegaly in approximately half of symptomatic patients 5

Laboratory Evaluation

Obtain alkaline phosphatase, bilirubin (total and direct), aminotransferases, and inflammatory markers (white blood cell count, C-reactive protein) to assess biliary stasis and inflammation. 5

• Elevated alkaline phosphatase is the most common biochemical abnormality 5
• Bilirubin elevation greater than 2× upper limit of normal indicates biliary stasis 5
• Leukocytosis reflects systemic inflammatory response in acute presentations 5

Special Considerations and Pitfalls

Do not rely solely on ultrasound for surgical planning, as intraoperative findings may differ significantly from preoperative imaging despite adequate MRCP evaluation. 6

• Surgeons must be prepared for intraoperative biliary tree exploration and modification of the treatment plan 6
• Anomalous biliary tree anatomy may require double bilioenteric anastomosis rather than standard hepaticojejunostomy 6

Consider primary sclerosing cholangitis in the differential diagnosis when interpreting cholangiographic findings, as it can mimic type I choledochal cyst. 7

• Primary sclerosing cholangitis may present with bile duct irregularities, diffuse narrowing, and localized ectatic areas that resemble choledochal cyst 7
• Percutaneous needle liver biopsy can confirm the diagnosis when sclerosing cholangitis is suspected 7

Pediatric and Pregnant Populations

In children with suspected choledochal cysts, follow the same imaging pathway as adults, beginning with ultrasound followed by MRCP for definitive characterization. 8

• Although choledochal cysts are more common in children, the diagnostic approach mirrors that of adults 8
• For pregnant patients, both ultrasound and MRI are appropriate initial imaging options without clear preference for one over the other 8, 9