Utility of Doppler ultrasonography for predicting improvement of platelet count after transjugular intrahepatic portosystemic shunt

OBJECTIVE Portal pressure gradient (PPG) after transjugular intrahepatic portosystemic shunt (TIPS) <12 mmHg has been reported as the only factor predictive of increase in platelet count. As flow velocities measured on Doppler ultrasound are related to pressure gradient based on the Bernoulli equation, we used this parameter to predict increased platelet count after TIPS placement. METHODS A total of 161 consecutive patients who underwent TIPS placement entered this retrospective study. The platelet count was measured before, one week after and one month after TIPS placement. Clinically significant thrombocytopenia was defined as platelet count ≤100 000. Pre- and post-TIPS PPGs were measured. The velocity of blood flow in the proximal, mid and distal TIPS stent was measured using Doppler ultrasound, and the difference in the highest and lowest measured velocity was entitled flow velocity gradient (FVG), which was considered normal when ≤100 cm/s. RESULTS In 121 patients with pre-TIPS thrombocytopenia, the mean platelet count one week and one month after TIPS placement increased 25.7 x 103 and 35.0 x 103 in 90 patients with PPG≤12 mmHg (P=0.028 and P=0.015), while there was no significant change in platelet count in patients with a PPG >12 mmHg (P=0.098 and P=0.075). Platelets increased significantly when FVG≤ 100 cm/s (n=95) vs FVG >100 cm/s (n=26) one week (37.0x103 vs 11.0x103; P =  0.005 vs 0.07) and one month after TIPS placement (17.0x103 vs 5.2x103; P =  0.01 vs 0.21). CONCLUSION FVG >100 cm/s is not associated with increase in post-TIPS platelet count. On the other hand, findings suggestive of proper TIPS function (FVG ≤100 cm/s and PPG≤ 12 mmHg) predict a significant increase in post-TIPS platelet count.