RESUMO
BACKGROUND: Acute mesenteric ischemia poses a diagnostic challenge due to nonspecific clinical clues and lack of awareness owing to its rarity. Ischemia due to mesenteric venous thrombosis has a good prognosis compared to arterial cause and can be managed conservatively with early diagnosis. The portomesenteric venous system is an unusual site of thrombosis in patients with protein S deficiency, and its thrombosis is an uncommon cause of acute mesenteric ischemia. CASE PRESENTATION: We present a case of a 27-year-old Mongolian man who presented with acute abdominal pain increasing in severity, and refractory to repeated attempts at treatment with a misdiagnosis of acute peptic ulcer disease. Contrast-enhanced computed tomography of his abdomen detected complete occlusion of the superior mesenteric vein, an extension of acute thrombus into the portal vein, and ischemic mid-jejunal loops. Early diagnosis and immediate anticoagulation with continuous intravenous infusion of unfractionated heparin prevented subsequent consequences. On further workup, our patient was diagnosed with isolated protein S deficiency. We started lifelong thromboprophylaxis with warfarin to prevent recurrence and our patient was asymptomatic on the latest follow-up 5 months after discharge. CONCLUSION: Despite accurate detection of acute mesenteric ischemia by contrast-enhanced computed tomography, high index of suspicion is indispensable for its early diagnosis. Early diagnosis and immediate anticoagulation will prevent subsequent complications and need for surgical intervention. Young patients without known risk factors presenting with venous thrombosis in atypical sites should be investigated for prothrombotic diseases.