Splenic Arteriovenous Fistula: An Unusual Cause of Portal Hypertension Primarily Diagnosed by Color Duplex Sonography

Splenic arteriovenous fistulas (AVFs) are rare lesions. Herein, we report a 40-year-old man with portal hypertension secondary to splenic AVF, which was primarily diagnosed by color Duplex sonography. Sonography revealed a non-pulsatile, cyst-like mass at the splenic hilum with an unusual comma-shaped extension. In color duplex sonography, complete color fill-in of the lesion with the characteristic reversed red and blue color flow (Yin-Yang pattern) was observed. Duplex Doppler interrogation of the AVF revealed high velocity low-impedance arterial flow and moderately pulsatile venous flow within the lateral and medial part of the lesion, respectively. The comma-like extension demonstrated a low-resistance arterial waveform with very high peak systolic velocity. Based on these findings, a diagnosis of splenic AVF was made which was confirmed at surgery. Special emphasis was made on sonographic findings enabling the correct diagnosis.