Transjugular Intrahepatic Portosystemic Shunt Malfunction

Doppler can be used to determine the status of a transjugular intrahepatic portosystemic shunt (TIPS). A normal TIPS study is shown above. The following are bad prognostic signs:

• Absent flow in shunt.
• Hepatopetal flow in the intrahepatic portal veins. Flow in the left and right portal veins should become hepatofugal after TIPS placement, that is out of the liver and toward the shunt. Hepatopetal flow in either the right or the left portal vein has an 85% positive predictive value for shunt stenosis, but hepatofugal flow has only a 60% negative predictive value. A change in flow direction from hepatofugal to hepatopetal, on the other hand, is a strong indication of shunt malfunction with approximately 90% positive predictive value, but is not very sensitive.
• Low mean main portal vein velocity (<30 cm/s) has 80% sensitivity and 75% specificity for detection of shunt stenosis.
• Peak shunt velocity that is too low (<90 cm/s) or too high (>190 cm/s). The velocity is usually slower near the portal venous end and fastest in the middle segment of the shunt. Flow is usually turbulent.
  
  
• >50 cm/s change in shunt velocity compared with the immediate postprocedural study. This has a reported 90% sensitivity and 75% specificity for detection of shunt stenosis. A decrease of greater than 40 cm/sec or an increase of greater than 60 cm/sec had 75% sensitivity and 85% specificity in another report. 50 seems like a nice round number, so let's stick with that.
• Decrease (>20%) in main portal vein velocity compared compared with the immediate postprocedural study has 80% sensitivity and 75% specificity for detection of shunt stenosis.

Note: Sensitivity, specificity, and positive and negative predictive values rounded to the nearest 5 to ease memorization and better reflect the actual precision of numbers in medicine.

References

• Kanterman RY, Darcy MD, Middleton WD, Sterling KM, Teefey SA, Pilgram TK. Doppler sonography findings associated with transjugular intrahepatic portosystemic shunt malfunction. AJR Am J Roentgenol. 1997 Feb;168(2):467-72.
• Pozniak MA and Henesler KP. T.I.P.S. Imaging. GE Ultrasound.