Abstract: Popliteal entrapment syndrome occurs when the popliteal artery is compressed due to the anomalous course of the popliteal artery and/or position of adjacent muscle. The popliteal artery normally enters the popliteal fossa by passing under the semimembranosus muscle, traveling obliquely through the fossa and exiting between the gastrocnemius heads. Variations in embryological development can result in an anomalous course of the popliteal artery and/or adjacent muscles in turn causing arterial compression. Popliteal entrapment syndrome is a rare entity with the incidence rate reported at 0.16%. As such, while there is a significant body of literature surrounding popliteal entrapment syndrome, given its rarity and differing definitions of the causative anatomical pathology, the quality of evidence is poor. This case highlights a unique pathognomonic finding of a wide separation of the popliteal artery and vein caused by an aberrant slip of the gastrocnemius muscle on ultrasound and MRI; a finding which should alert clinicians to the diagnosis of popliteal entrapment syndrome. Diagnosis of popliteal entrapment syndrome is typically made based on radiological and clinical findings. MRI allows for visualization of the anatomical variation underlying the entrapment. Recognition and correct diagnosis are particularly important for surgical planning, and preventing progression to thrombosis, embolization and/or aneurysmal degradation of the vessel.Abstract: Popliteal entrapment syndrome occurs when the popliteal artery is compressed due to the anomalous course of the popliteal artery and/or position of adjacent muscle. The popliteal artery normally enters the popliteal fossa by passing under the semimembranosus muscle, traveling obliquely through the fossa and exiting between the gastrocnemius heads. ...Show More