Background & aims: Recent non-malignant non-cirrhotic portal venous system thrombosis (PVT) is a rare condition. Among risk factors for PVT, cytomegalovirus (CMV) disease is usually listed based on a small number of reported cases. The aim of this study was to determine the characteristics and outcomes of PVT associated with CMV disease.

Methods: We conducted a French multicenter retrospective study comparing patients with recent PVT and CMV disease (“CMV positive”; n = 23) to patients with recent PVT for whom CMV testing was negative (“CMV negative”; n = 53) or unavailable (“CMV unknown”; n = 297).

Results: Compared to patients from the “CMV negative” and “CMV unknown” groups, patients from the “CMV positive” group were younger, more frequently had fever, and had higher heart rate, lymphocyte count and serum ALT levels (p ≤0.01 for all). The prevalence of immunosuppression did not differ between the 3 groups (4%, 4% and 6%, respectively). Extension of PVT was similar between the 3 groups. Thirteen out of 23 “CMV positive” patients had another risk factor for thrombosis. Besides CMV disease, the number of risk factors for thrombosis was similar between the 3 groups. Heterozygosity for the prothrombin G20210A gene variant was more frequent in “CMV positive” patients (22%) than in the “CMV negative” (4%, p = 0.01) and “CMV unknown” (8%, p = 0.03) groups. Recanalization rate was not influenced by CMV status.

Conclusions: In patients with recent PVT, features of mononucleosis syndrome should raise suspicion of CMV disease. CMV disease does not influence thrombosis extension nor recanalization. More than half of “CMV positive” patients have another risk factor for thrombosis, with a particular link to the prothrombin G20210A gene variant.

Lay summary: Patients with cytomegalovirus (CMV)-associated portal venous system thrombosis have similar thrombosis extension and evolution as patients without CMV disease. However, patients with CMV-associated portal venous system thrombosis more frequently have the prothrombin G20210A gene variant, suggesting that these entities act synergistically to promote thrombosis.