Diagnostic ultrasound ( PDFDrive )

CHAPTER 51 The Pediatric Liver and Spleen 1767
A
B
C
FIG. 51.36 Normal Anatomy After Segmental
Transplant. (A) Portal venous anastomosis after transplantation.
Note the mild caliber change of the preanastomotic
and postanastomotic segments, likely relecting
small size of the recipient patient and larger size of the
graft donor. Caliber change is in the wrong direction for
an anastomotic stricture. MPV, Main portal vein. (B)
Characteristic curved course of MPV. (C) Normal pulsed
Doppler tracing of hepatic artery (HA). Note the sharp
systolic upstroke and good forward low throughout
diastole.
IVC or right atrium. Both the hepatic veins and the IVC may
thrombose, starting at the anastomosis. he immediate postoperative
examination outlines the surgical anatomy in these children
and serves as a useful standard for comparison in assessing the
continued patency of the anastomosed vessels. Stumps of oversewn
grat IVC are also frequently encountered, lying between the
liver parenchyma and native IVC. hrombus in the remnant of
donor IVC seldom propagates but can be seen as intraluminal
echoes perioperatively. With time, these donor IVC remnants
become less visible, collapsing and blending into the medium-level
echoes of the retroperitoneum.
Grat rejection does not result in predictable low alterations
of the hepatic artery, unlike the increased intrarenal resistance
to low noted in acute renal allograt rejection. However,
changes in the normal phasicity of hepatic venous blood low
have been linked to grat rejection. Speciically, when normal
triphasic hepatic venous blood low becomes monophasic, biopsy
specimens show evidence of acute rejection (sensitivity 92%,
speciicity 48%) or other hepatic disease (cholangitis, ibrosis,
centrilobular congestion and necrosis, lymphoproliferative disease,
cholestasis, hepatitis). 95,97 Some liver transplant recipients never
demonstrate triphasic low, presumably because of poor elasticity
in the donor grat, and thus these criteria are not useful in this
subgroup.
Biliary air or pneumobilia is another common inding in
patients ater liver transplant (see Fig. 51.38H, Video 51.11).
Anecdotally, it is less frequent in the immediate postoperative
period (despite routine stenting of the duct) and is more likely
to be noted on routine follow-up scans several months later. he
source of air is retrograde passage from the gastrointestinal tract,
through the Roux loop and choledochoenterostomy and into
the bile ducts. Careful examination of the liver parenchyma on
routine follow-up sonography is important to exclude biliary
tree abnormalities, abscess, focal areas of ischemia, and complications
of percutaneous biopsy (e.g., bile lake, AV shunts, hemorrhage).
Biliary ductal dilation may be caused by stenosis of the
choledochoenterostomy, bile duct ischemia with secondary
stricture, stone disease, and compression of ducts by external