Background:Non-cirrhotic portal hypertension (NCPH) accounts for ~50% of portal hypertension in India.Proximal splenorenal shunt (PSRS) is a one-time procedure that changes the natural course of the disease beneficially.Shunt thrombosis is an important complication of PSRS(5.6-47%).The aim of this study was to assess the hitherto unexplored association of pathological characteristics of splenic vein(SV) with shunt thrombosis in patients with Extrahepatic portal vein obstruction (EHPVO) and Non-cirrhotic portal fibrosis (NCPF) undergoing PSRS.

Methodology:A prospective observational study was conducted on 96 patients with NCPH(EHPVO:39 and NCPF:57)who underwent PSRS in the Department of Surgical Gastroenterology, JIPMER,Puducherry(2011-2016).All patients underwent preoperative Doppler-study of porto-splenomesenteric system,upper GI endoscopy and CT portovenogram. Histopathological(HPE) features of SV(presence of medial hypertrophy, wall thickening, intimal fibrosis, adventitial attenuation,venous thrombosis,vein wall calcification) were studied in all patients undergoing shunt surgery. SV and shunt diameter, extent of fall in portal pressure (mechanical properties) were assessed.

Results:Study group comprised of 96 patients (80% female) with NCPH, aged 12-55years. At 5 years follow-up, shunt thrombosis was noted in 20% patients.On HPE of veins, SV in all patients was found to be abnormal. Medial hypertrophy and wall thickening of SV were present in all.Intimal fibrosis was noted in 50% with shunt thrombosis and in 25% of patients without shunt thrombosis. On multivariate analysis, which considered only pathological characteristics, intimal fibrosis in SV wall was found to be significantly associated with shunt thrombosis(p=0.023).In a separate multivariate analysis in which the mechanical and pathological characteristics were considered together, none were found to be significantly related to shunt thrombosis(only intimal fibrosis p=0.06).

Conclusions:SV is pathological in all patients with or without shunt thrombosis,probably related to presence of hyperdynamic circulation.Pathological SV, when detected intra-operatively, should not obviate performance of shunt. However, when the pathological changes are considered as separate entities in the group, diseased intima (intimal fibrosis) emerges as a possible factor associated with shunt thrombosis. Hence, presence of intimal fibrosis on HPE should prompt a more rigorous follow-up for shunt thrombosis.