Isolated Superior Mesenteric Artery Dissection Mimicking Impending Rupture of Abdominal Aortic Aneurysm

BACKGROUND Isolated superior mesenteric artery dissection (SMAD) is a rare vascular disease that is difficult to diagnose. We report a case of SMAD in a patient with an abdominal aortic aneurysm (AAA) that mimicked an impending rupture of the AAA. In addition, we describe several clinical biases that contributed to the delayed diagnosis. CASE REPORT A 66-year-old man presented with a 3-day history of abdominal pain, without a history of trauma, that worsened gradually and caused him to visit our hospital. The patient's medical history included an AAA under observation. The patient was well oriented and initially remained hemodynamically stable, and the abdomen was soft and non-tender on palpation. An emergency contrast-enhanced computed tomography (CT) scan confirmed a 44-mm AAA without any leakage, but with an isolated SMAD. His previous physician confirmed there was no change in the AAA size since 3 months prior to hospital admission. Thus, the symptoms were caused by the isolated SMAD. The patient showed improvement with pain-relieving and antihypertensive management, without anticoagulation therapy or revascularization, and was discharged on day 25 of admission without any complications. CONCLUSIONS The misdiagnosis in this case was attributable to several clinical biases, including search satisfaction, Sutton's slip, and anchoring bias. Physicians should guard against presumptive diagnoses based on patient symptoms or initial plausible findings and instead pursue a thorough workup to reach a definitive diagnosis.