Background: Abdominal aortic mural thrombus is uncommon in the absence of aneurysm or atherosclerosis.
Case Report: We report the case of a 46-year-old man who presented to our institution with perforated appendicitis for which he initially declined surgery. Four days after admission he ultimately consented to appendectomy and abdominal washout. Follow-up imaging to evaluate for intra-abdominal abscess revealed mural thrombus of the infra-renal abdominal aorta extending into the left iliac artery. This thrombus was not present on the admission CT scan. The patient had no clinical signs of limb ischemia. Conservative treatment with therapeutic anticoagulation resulted in resolution of the thrombus.
Conclusions: While portal, mesenteric, and major retroperitoneal venous thrombosis are well associated with major intra-abdominal infection and inflammatory bowel disease, aorto-iliac arterial thrombus formation in the absence of associated aneurysm, atherosclerosis or embolic source is exceedingly rare. We are unaware of other reports of in-situ aorto-iliac arterial thrombus formation secondary to perforated appendicitis.

Keywords: appendicitis, aorto-iliac thrombus, Thrombosis, appendicitis, Abdominal Abscess