Portal vein thrombosis as a clinical dilemma in Echis carinatus envenomation: a case report and review of the literature

Snakebite envenoming is a major neglected tropical disease, particularly in rural regions of tropical and subtropical countries. Echis carinatus (saw-scaled viper; SSV), prevalent in the desert regions of Iran, is a medically significant species of the Viperidae family whose venom disrupts hemostasis through potent procoagulant activity. While venom-induced consumption coagulopathy (VICC) is well recognized as a hemorrhagic complication, thrombotic sequelae are rare and poorly documented. We report the case of a 15-year-old male who presented to the emergency department shortly after a SSV bite to the ankle. Initial manifestations included local swelling, mild bleeding, and dizziness. He was promptly treated with intravenous polyvalent antivenom, tetanus toxoid vaccination, and supportive therapy. Baseline investigations revealed coagulopathy, which normalized with treatment; however, serial follow-up demonstrated progressive cytopenias. At approximately three months post-envenomation, the patient developed abdominal pain. Imaging revealed aneurysmal dilatation of the portal vein, intrahepatic portal vein thrombosis (PVT), vascular collaterals, and splenomegaly. Endoscopic evaluation confirmed secondary esophageal varices consistent with portal hypertension. The patient underwent multiple sessions of endoscopic band ligation and was managed with apixaban, propranolol, and proton pump inhibition. Despite therapy, persistent splenomegaly and thrombocytopenia were observed. Review of available laboratory data suggests that the thrombotic process began within the first month following envenomation; however, due to delayed referral and limited access to specialized care, diagnosis and treatment were initiated after the thrombus had already produced irreversible sequelae. This case demonstrates a rare but serious thrombotic complication of SSV envenomation, mediated by a rebound hypercoagulable phase following VICC, progressing to PVT, portal hypertension, splenomegaly, and esophageal varices. While acute management of snakebite focuses on antivenom and supportive measures, this report highlights the importance of long-term surveillance to detect delayed vascular complications. Furthermore, it underscores how diagnostic and therapeutic delays can allow thrombotic processes to evolve into chronic, irreversible outcomes. Clinicians in endemic regions should maintain vigilance for both hemorrhagic and thrombotic manifestations of Echis carinatus envenoming.