Portal vein thrombosis has a varied etiology and occurs secondary to intra-abdominal sepsis, surgical intervention [such as post splenectomy or portosystemic shunt], liver dysfunction as in cirrhosis, malignancy or secondary to pancreatitis. Recently certain prothrombotic conditions [inherited and acquired, most common being myeloproliferative disorder] have also been recognized as a risk factor for the development of portal vein thrombosis. Hence, a hypercoaguable cause must be ruled out in all of these patients with portal thrombosis. In about half of the cases no known cause can be identified. Depending on the extent of the thrombus, patients with portal vein thrombus may be asymptomatic, or present with abdominal pain or variceal bleed. It can cause or exacerbate portal hypertension and a chronic thrombus can lead to cavernous transformation of the portal vein [development of multiple collateral channels].
In patients who have undergone liver transplantation, clinically unsuspected vascular complications of the hepatic artery [most common is arterial thrombosis] and portal vein may be detected and screening sonograms are performed accordingly in the post-operative period. These complications may occur as early as within the first two weeks following transplantation or may occur long term. Early detection of these lesions before the onset of clinical or biochemical dysfunction obviously has prognostic implications, since if undetected, these might lead to graft failure.
Ultrasound with color Doppler studies can accurately and non-invasively diagnose these conditions and is routinely employed to screen these patients for any vascular complications. The hepatic artery, portal vein, inferior vena cava and the hepatic veins are thoroughly evaluated. Most studies report good specificity and sensitivity with Doppler studies. Thus in patients with normal duplex sonograms, invasive angiographies can be avoided. Portal vein thrombus usually presents with echogenic material filling the main portal vein or one of its branches partially or completely. The absence of demonstrable flow in the portal vein with ultrasound may not always be abnormal, since very sluggish flow may not be detected. In such cases, further imaging studies such as CT or MRI may be required before treating the patient.
Oral anticoagulation, transcatheter thrombolysis, surgical thrombectomy and cavo-portal hemi-transposition are some of the treatment options available to treat portal vein thrombosis.