Applications of duplex ultrasonography in the liver transplant patient

Duplex Ultrasonographic Evaluation of Liver Transplants

Two hundred and twenty-two duplex ultrasonographic examinations were performed on 36 liver transplants in 30 patients over a period of 5 years and 9 months. Positive sonographic findings were correlated with 13 angiographic examinations. Arterial complications included 4 thromboses, 5 stenoses, and one mycotic aneurysm. A false-negative result was obtained in 2 cases of stenosis and a false-positive result in one case of thrombosis. One portal vein thrombosis, 2 stenoses, and 2 cases of portal hypertension were diagnosed correctly. Sensitivity was 87%, specificity 95%, and accuracy 93%. Duplex Doppler was least effective in the diagnosis of hepatic artery stenosis. Five cases showed biliary complications of ischemic origin. Angiography is indicated when duplex Doppler is positive or doubtful, but also when the clinical condition is unclear.

The value of Doppler ultrasound in cirrhosis and portal hypertension

BACKGROUND

Cirrhosis and portal hypertension affect the flow profile of the liver vasculature. In these conditions Doppler ultrasound can provide important information on the hemodynamics of the portal venous system, the hepatic artery and the hepatic veins.

METHODS

The value of Doppler ultrasound in the assessment of the patient with cirrhosis and portal hypertension was determined by reviewing the literature.

RESULTS

Portal venous blood flow becomes reversed with advanced portal hypertension. Reversed flow is also demonstrated in patients with veno-occlusive disease and portosystemic shunts. Despite general agreement that portal flow velocity is decreased in cirrhotic patients, the absolute values of portal flow velocity in both healthy subjects and cirrhotic patients vary considerably. Errors in Doppler measurements, observer variability and collateral pathways contribute to these variations. Furthermore, portal blood flow is influenced by numerous factors such as changes in the body position, phase of respiration, timing of meals, exercise and cardiac output. Finally, portal flow may be unaltered due to a combination of high inflow from the splanchnic organs and increased resistance within the liver. High resistive index of the hepatic artery is seen in patients with end-stage liver disease, particularly in children with severe cirrhosis secondary to biliary atresia. However, hepatic artery flow remains normal in most patients. Abnormal hepatic vein flow profiles are seen in patients with cirrhosis, but dampening or flattening of the flow profile has a multifactorial origin (Budd-Chiari, metastases, ascites) and can be observed in healthy subjects.

CONCLUSIONS

Although many factors may affect the accuracy of volume flow and velocity measurements and the flow profile of the liver vasculature may change in different situations, Doppler ultrasound is useful in the assessment of the patient with cirrhosis and portal hypertension.

Impact of colour Doppler sonography on detection of thrombosis of the hepatic artery and the portal vein after liver transplantation

Sixty patients who received 75 consecutive liver grafts and had routine Doppler sonography monitoring in the early postoperative period (three times a day) were reviewed for vascular complications. Thrombosis of the hepatic artery was detected in seven patients (3, 4, 20, 24, 48, 70 and 84 h after liver transplantation) and was then confirmed by emergency laparotomy in six cases. In one patient, thrombosis was verified by angiography before laparotomy. In two patients thrombectomy was successful, in five patients retransplantation had to be performed. Portal vein occlusion was detected in three patients (24, 26 and 90 h after transplantation) and all were successfully treated by thrombectomy and partial arterialization of the portal vein. Colour Doppler sonography was associated with no false-positive or -negative results. The specificity was 100% for the diagnosis of hepatic artery and portal vein thrombosis. In our opinion colour Doppler sonography will be able to replace time-consuming angiography in vascular diagnostics in the early postoperative phase after liver transplantation. Furthermore, there is evidence that frequent use of this non-invasive technique permits early detection of clinically unsuspected vascular complications and subsequent immediate relaparotomy, which is linked to a reduction in the rate of retransplantation.

Ultrasound and cholangiography for the diagnosis of biliary complications after orthotopic liver transplantation: a comparative study

The ability of ultrasound to detect biliary obstruction, bile leakage and generalized ductal changes after orthotopic liver transplantation (OLT) was compared to cholangiography. Cholangiography was considered to be the gold standard. Adequate opacification of the biliary tree was achieved in 139 cholangiograms. Biliary obstruction, intermediate or large bile leakage, and generalized ductal changes were diagnosed with cholangiography in 15% (21/139), 14% (20/139), and 16% (22/139), respectively. Normal ultrasound findings could not exclude biliary stricture, generalized ductal changes, or bile leakage, and fluid collections were not correlated with bile leakage. Abnormal ultrasound findings were highly predictive of the cholangiographic diagnosis of biliary obstruction or generalized ductal changes (specificity of 98% and 100%, respectively). An irregular appearance of the bile ducts and increased periductal echogenicity proved to be characteristic features for generalized ductal changes.

Postoperative Hepatic Transplants

The role of duplex ultrasound in the hepatic transplant patient after surgery is to assess vascular compromise, limited biliary complications, and fluid collections. Debate surrounds sonography's strengths and limitations in detecting the most serious and common complication, hepatic artery thrombosis, which is key in this discussion. Sonographers should be familiar with the limitations and the exciting, new technology developing in hepatic transplant imaging to ensure quality patient care.

Duplex Doppler endosonography in the diagnosis of splenic vein, portal vein, and portosystemic shunt thrombosis

BACKGROUND/AIMS

Endoscopic ultrasonography is a promising procedure for imaging mesenteric vascular structures.

METHODS

Duplex and color Doppler endosonography were used to prospectively evaluate 20 asymptomatic paid volunteers. Subsequently, 11 patients with nondiagnostic transabdominal ultrasound and suspected thrombosis of the splenic and/or portal veins or a portosystemic shunt were evaluated with duplex endosonography. The final diagnosis was based on CT, angiography, and/or surgery or autopsy findings in 9 of 11 patients.

RESULTS

In normal volunteers, mesenteric vessel flow velocities and diameters were similar to previously described values. In 10 of the 11 patients with failed transabdominal ultrasound, duplex endosonography was able to provide the correct diagnosis (accuracy of ultrasound 0% versus EUS 91%, p < .001). Mean portal vein diameter was greater in the patient group than in the normal volunteers (18.5 mm versus 10.7 mm, p < .001) and all of the normal volunteers had a portal vein diameter less than 13 mm. No complications were experienced.

CONCLUSION

Duplex endosonography allows visualization of the intra-abdominal vasculature and can be considered when transabdominal ultrasound is nondiagnostic in patients with suspected thrombosis of their splenic vein, portal vein, or portosystemic shunt. EUS is able to identify indirect findings of portal hypertension including portal vein enlargement and venous collaterals.