EP910 - Intestinal necrosis from acute on chronic mesenteric ischemia from venous thrombosis

Purpose/Background: Acute mesenteric ischemia (AMI) is rare, accounting for 0.09-0.2% of hospital admissions in the US, and around 1% of patients who present with an acute abdomen. Of the causes of AMI, mesenteric venous thrombosis has been identified in only 5% of cases. With the mortality rate reaching as high as 60-80%, timely diagnosis, and urgent management are paramount.

Methods/Interventions: A 67-year-old woman presented with a 1-month history of intermittent severe abdominal pain and vomiting. At the ED, she was seen hypertensive, and in severe abdominal pain. Physical examination showed a soft, nontender abdomen with normoactive bowel sounds. Plain radiographs showed no sign of bowel obstruction nor pneumoperitoneum. Computed tomography (CT) scan, however, revealed an extensive filling defect—a thrombus--along the entire portal system and a long segment submucosal thickening along the ileum suggestive of venous ischemia. She was started on unfractionated heparin drip at 80u/kg bolus, with an initial maintenance dose of 18u/kg. This was adjusted with serial PTT measurements (target: 55-85s). Close serial monitoring of the abdomen was also done. The patient was advised emergent surgery when found to have developed peritoneal signs. Intraoperatively, a 20 cm non-viable segment of ileum--250 cm from the ligament of Treitz--required resection. A double-barrel ileostomy was created.

Results/Outcomes: Postoperatively, the diet was gradually progressed to avoid congestion from the increased splanchnic flow, allowing for recanalization of the portal venous system. In a multidisciplinary team meeting, it was agreed that the patient undergo lifetime anticoagulation and regular CT angiogram monitoring. She was discharged well.

Conclusion/Discussion: The diagnosis of AMI requires a high index of suspicion and urgent evaluation. Patients typically present with abdominal pain disproportional to the physical examination. Patients with an embolic etiology may present with sudden severe pain; those with thrombosis may have progressive pain; and those with a nonocclusive etiology may exhibit slow progression. CT angiography, given its high specificity and sensitivity, may be used for initial evaluation. The goal for all these patients is maximizing intestinal salvage with revascularization procedures (arterial etiology) and anticoagulation (venous etiology). Serial abdominal exams may assist in detecting progression of disease severity. To date, no one biomarker may accurately predict the presence, or extent, of nonviable bowel.

For cases of venous mesenteric ischemia, most are due to systemic pro-thrombotic states and local triggering factors, such as malignancy and inflammatory lesions. The main goal of treatment is recanalization, and prevention of infarction and recurrence of the thrombosis. Given its rarity, no guidelines on management regarding this condition have been published. Currently, the mainstay of treatment is the use of systemic anticoagulation, with a small subset requiring possible endovascular options (i.e., catheter directed thrombolysis).

Patients with peritoneal signs from bowel necrosis or perforation require surgery. The goal of surgery is the removal of all irreversibly ischemic bowel segments, while saving as much length as possible.

Superior mesenteric vein thrombosis
Abdominal CT scan showing the extent of the venous thrombosis, with the green arrows pointing towards the filling defect corresponding to the thrombus along the superior mesenteric vein

Small bowel congestion and ischemia
Intraoperative findings of generalized congestion with a non-viable ileal segment