Natural history of pancreatitis-induced splenic vein thrombosis: a systematic review and meta-analysis of its incidence and rate of gastrointestinal bleeding

Background: Pancreatitis-induced splenic vein thrombosis (PISVT) is an acquired anatomic abnormality that impacts decision making in pancreatic surgery. Despite this influence, its incidence and the rate of associated gastrointestinal (GI) bleeding are imprecisely known. Methods: The MEDLINE, EMBASE, Cochrane Central Register of Clinical Trials and Cochrane Database of Systematic Reviews databases were searched from their inception to June 2010 for abstracts documenting PISVT in acute (AP) or chronic pancreatitis (CP). Two reviewers independently graded abstracts for inclusion in this review. Heterogeneity in combining data was assumed prior to pooling. Random-effects meta-analyses were performed to estimate percentages and 95% confidence intervals. Results: After review of 241 abstracts, 47 studies and 52 case reports were graded as relevant. These represent a cohort of 805 patients with PISVT reported in the literature. A meta-analysis of studies meeting inclusion criteria shows mean incidences of PISVT of 14.1% in all patients, 22.6% in patients with AP and 12.4% in patients with CP. The incidence of associated splenomegaly was only 51.9% in these patients. Varices were identified in 53.0% of patients and were gastric in 77.3% of cases. The overall rate of GI bleeding was 12.3%. Conclusions: Although reported incidences of PISVT vary widely across studies, an overall incidence of 14.1% is reported. Splenomegaly is an unreliable sign of PISVT. Although the true natural history of PISVT remains unknown, the collective reported rate of associated GI bleeding is 12.3%.