Sonographic assessment of the distal end of the thoracic duct in healthy volunteers and in patients with portal hypertension.

Objective: Our study assessed the feasibility of detecting and measuring by sonography the diameter of the thoracic duct in healthy subjects and in patients with cirrhosis and portal hypertension. We also evaluated the relationship of thoracic duct size with age and with clinical, endoscopic, and sonographic signs of portal hypertension.

Subjects And Methods: The left supraclavicular area of 24 patients with cirrhosis and 23 healthy subjects was examined with high-frequency probes using transverse and oblique scans to visualize the distal end of the thoracic duct. All patients with cirrhosis, diagnosed by liver biopsy or clinical and biochemical data, had endoscopic or sonographic signs of portal hypertension. The severity of the liver disease was determined by Child-Pugh's criteria; the diameter of portal vessels and the size of esophageal varices were also considered.

Results: The thoracic duct was visualized in 19 of 24 patients with cirrhosis and in 18 of 23 control subjects (percent of visualization was 79% and 78%, respectively). The diameter of the duct was larger in patients with cirrhosis than in healthy subjects (3.1 +/- 1.2 mm versus 1.9 +/- 0.5 mm; p < .0001), but no relationship was found among clinical, endoscopic, and sonographic signs of portal hypertension. A direct relationship between age and the size of the thoracic duct was found only among healthy subjects.

Conclusion: This is the first report of the sonographic visualization of the distal end of the thoracic duct. Its diameter is small in healthy young subjects, whereas in patients with cirrhosis its increased diameter seems to be associated only with the presence of portal hypertension and not with its severity.