Background: Splenic rupture or infarction can occur secondary to acute infectious mononucleosis. Patients with abdominal pain and known or suspected infectious mononucleosis mandate evaluation for these complications, which can have significant morbidity or mortality.

Methods: An 18-year old man presented to the emergency department (ED) with a 2-day history of left upper quadrant abdominal pain. He had been diagnosed with mononucleosis 4 days before his ED presentation. Physical examination was notable for focal left upper quadrant tenderness. The treating physician's principal diagnostic considerations were splenic rupture or infarction secondary to mononucleosis. Point-of-care ultrasound was performed by the emergency physician, demonstrating multiple hypoechoic areas in the splenic parenchyma with absent Doppler flow, consistent with multiple splenic infarcts. The patient was admitted for observation, managed conservatively, and had an uneventful course.

Conclusions: Emergency ultrasound of the spleen can allow rapid diagnosis of splenic infarction and exclusion of splenic rupture in a patient at risk for splenic pathology.