# Aortic Arch Mural Thrombus Concurrent with Deep Surgical-Site Infection after Colorectal Cancer Surgery in an Enhanced Recovery after Surgery Program: A Case Report

## TL;DR

A patient developed a dangerous blood clot in the aorta alongside a deep infection after colorectal cancer surgery, highlighting risks in early post-discharge recovery.

## Contribution

This case highlights the rare but serious complication of aortic mural thrombus in the context of ERAS protocols and deep surgical-site infection.

## Key findings

- Aortic mural thrombus developed alongside Streptococcus anginosus-positive deep surgical-site infection without bacteremia or aortitis.
- The patient experienced acute carotid occlusion and died from septic shock and coagulation issues.
- The case suggests a vulnerable period for complications between postoperative days 7–10 in ERAS pathways.

## Abstract

Aortic mural thrombus (AMT) in a non-atherosclerotic aorta is rare but potentially catastrophic and may be difficult to distinguish from septic aortic pathology when it occurs alongside a deep postoperative infection. Enhanced recovery after surgery (ERAS) shortens hospital stay and shifts the recognition of serious complications to the early post-discharge period. We report the case of a patient who underwent colorectal cancer surgery within an ERAS protocol who developed a large AMT on POD 10, coincident with Streptococcus anginosus-positive deep surgical-site infection (SSI) but without bacteremia or aortitis on imaging.

A 76-year-old male with stage IVc cecal adenocarcinoma and diabetes underwent robotic-assisted ileocecal resection via the ERAS pathway. Prophylactic cefmetazole was discontinued within 24 h, and the patient was discharged on POD 5 with down-trending but elevated C-reactive protein levels. On POD 10, the patient presented with fever, leukocytosis, and decreased mobility. Contrast-enhanced CT revealed a ~38-mm AMT without mural thickening, abnormal enhancement, periaortic fat stranding, aneurysmal dilatation, or complex atherosclerotic plaque, in addition to deep port-site infection and intra-abdominal abscesses. Blood cultures (two sets) remained negative, whereas abscess and wound cultures yielded S. anginosus with polymicrobial co-pathogens. The patient underwent surgical washout and drainage, broad-spectrum antibiotics (piperacillin-tazobactam, followed by ceftriaxone and metronidazole), and systemic anticoagulation with unfractionated heparin. Transesophageal echocardiography showed a mural arch mass corresponding to the CT lesion, but no definite valvular vegetation or new significant regurgitation. On POD 16, the patient developed acute left common–internal carotid occlusion with a large middle cerebral artery infarction and died on POD 20 of septic shock and disseminated intravascular coagulation.

In this patient who underwent ERAS colorectal cancer surgery, AMT developed around POD 10 in parallel with SAG-positive deep SSI, but without aortitis or bacteremia, favoring a bland mural thrombus driven by malignancy- and sepsis-related hypercoagulability while retaining nonbacterial thrombotic endocarditis/infective endocarditis in the differential diagnosis. The case highlights PODs 7–10 as a vulnerable window in ERAS pathways and supports a focused safety bundle that includes CRP-guided discharge thresholds, selective low-dose imaging, and POD 7 ± 1 follow-up to improve early post-discharge surveillance.