Infectious Aortitis Presenting as Constipation: A Diagnostic Pitfall

Aortitis is an uncommon but important differential diagnosis to consider in patients presenting with vague abdominal or back pain, often posing a diagnostic challenge due to its nonspecific symptoms and clinical features. We present the case of a 59-year-old male with a two-week history of back pain radiating to the lower abdomen, initially presumed to be constipation by his primary care physician, who was later diagnosed with Streptococcus pneumoniae-associated infectious aortitis. At the first assessment by his general practitioner, his symptoms were mild, and he was treated with laxatives; however, he subsequently presented to the ED with severe pain requiring opioid analgesia. On examination, he was afebrile, with severe abdominal tenderness and an empty rectum on digital rectal examination. His abdomen was rigid throughout. Laboratory investigations demonstrated elevated inflammatory markers, and imaging revealed features of aortitis, prompting urgent vascular surgical intervention with the insertion of a bovine graft. This procedure was performed after one week of inpatient observation and repeat imaging, which showed progression of the initial findings, including an enlarging aneurysm and a pocket of pus. The patient remained hospitalized for approximately two weeks after surgery, including seven days in the intensive therapy unit. He later developed a para-aortic collection, which was monitored without further surgical intervention, and was discharged with two to four weeks of IV antibiotics. This case highlights how vascular pathology can mimic benign gastrointestinal conditions in the early stages, underscoring the importance of prompt imaging and multidisciplinary collaboration among family medicine, general surgery, and vascular surgery teams to ensure timely diagnosis and management.