Through use of reflected sound waves, ultrasonography provides
accurate visualization of the abdominal aorta, liver, gall-bladder,
pancreas, bile ducts, kidneys, ureters, and bladder. The technique
requires the emission of high-frequency sound waves from a transducer
into the particular organ being studied. As the sound waves are
echoed back to the transducer, a picture is generated of the given
organ.
The kidney is ultrasonographically evaluated in order to diagnose and
locate renal cysts, to differentiate renal cysts from solid renal
tumors, to demonstrate renal and pelvic calculi, to document
hydronephrosis, and to guide a percutaneously inserted needle for
cyst aspiration or biopsy.
Another use of sonography is in the assessment of the abdominal
aorta or aneurysmal dialation. Sonographic evidence of an aortic
aneurysm greater than 5 cm or any size aneurysm that is documented
to be significantly enlarging is an indication for abdominal aorta
aneurysm resection. Ultrasound is also an ideal way to follow
aneurysms before and after surgery.
Ultrasound is used in detecting cystic structures of the liver
(e.g. benign cysts, hepatic abscesses, dilated hepatic ducts) and
solid intrahepatic tumors (primary and metastatic).
Serial testing of the liver is also done to determine the effect of
certain medications upon the function and structure of the organ.
The gallbladder and extrahepatic ducts can be visualized and are
examined for evidence of gallstones, polyps, or dilation secondary to
obstructive structures or tumors. The pancreas is examined for
evidence of tumor, pseudocysts, acute inflammation, chronic
inflammation, or pancreatic abscess. Ultrasound of the pancreas is
frequently performed serially to document and demonstrate resolution
of acute pancreatic inflammatory processes.
