Diagnostic ultrasound ( PDFDrive )

172 PART II Abdominal and Pelvic Sonography
A
B
FIG. 6.9 Common Bile Duct Obstruction Caused by Extrinsic Factors. (A) Pancreatic adenocarcinoma. Short transition zone with shouldering,
large duct caliber, along with an obstructive mass are typical indings in malignant obstruction. (B) Pancreatitis. Elongated tapering of the duct
suggests a benign cause. Note mild sympathetic gallbladder wall thickening caused by adjacent inlammation.
Causes of Biliary Obstruction
BENIGN MISCELLANEOUS
Choledocholithiasis a
Hemobilia a
Congenital biliary diseases
Caroli disease a
Choledochal cysts
Cholangitis
Infectious
Acute pyogenic cholangitis a
Biliary parasites a
Recurrent pyogenic cholangitis a
HIV cholangiopathy
Sclerosing cholangitis
NEOPLASMS
Cholangiocarcinoma
Gallbladder carcinoma
Locally invasive tumors (esp. pancreatic adenocarcinoma)
Ampullary tumors
Metastases
EXTRINSIC COMPRESSION
Mirizzi syndrome a
Pancreatitis
Adenopathy
a Denotes causes of painful jaundice.
initiation of the imaging investigation (Fig. 6.9). hese scans
should be performed with knowledge of the patient’s clinical
condition, especially whether the patient has painless jaundice
or has painful jaundice, as seen with acute obstruction or infection
afecting the biliary tree.
Acute biliary obstruction in the absence of infection may
present with RUQ pain and a predominant transaminitis suggesting
acute hepatitis rather than cholestasis. 18,19 Early on, the
bile ducts may only be minimally dilated, with imaging indings
of a nonspeciic hepatitis manifest by edema in the portal triads
(echogenic periportal thickening) and luid accumulation in the
gallbladder wall. herefore in patients with unexplained acute
hepatitis, the distal biliary tree should always be examined carefully
for choledocholithiasis even if the bile ducts do not appear
signiicantly dilated.
he ultrasound examination should focus on answering the
following three questions:
1. Are the bile ducts or gallbladder dilated?
2. If dilated, to what level?
3. What is the cause of the obstruction?
Choledocholithiasis
Choledocholithiasis is classiied into primary and secondary
forms. Primary choledocholithiasis denotes de novo formation
of stones, oten made of calcium bilirubinate (pigment stones)
within the ducts. he etiologic factors are oten related to diseases
causing strictures or dilation of the bile ducts, leading to stasis,
as follows:
• Sclerosing cholangitis
• Caroli disease
• Parasitic infections of the liver (e.g., Clonorchis, Fasciola,
Ascaris) 20
• Chronic hemolytic diseases, such as sickle cell disease
• Prior biliary surgery, such as biliary-enteric anastomoses