高野 英行, 相原 敏則, 角田 博子, 西川 正則

Hideyuki TAKANO, Toshinori AIHARA, Hiroko S TSUNODA, Masanori NISHIKAWA

埼玉県立小児医療センター放射線科

Department of Radiology, Saitama Children's Medical Center

キーワード : Hematuria, Nutcracker phenomenon, Left renal vein

The nutcracker phenomenon refers to left renal vein compression by the aorta (Ao) and superior mesenteric artery (SMA) where the vein courses the fork formed at the origin of the artery. This phenomenon has been known to cause hematuria resulting from venous congestion in response to obstruction of the vein at the site of compression by the SMA. Recently some authors have reported that ultrasonography can reveal the nutcracker phenomenon by visualizing both the collapsed left renal vein at the segment of compression and its distention distaly. We suspected, however, that this "nutcracker sign" is not caused by the compression by the arteries, but by compression of the abdominal wall through the transducer. A consecutive series of 34 patients (1-16 years of age) without hematuria and 13 patients (3-13 years of age) with hematuria was examined to evaluate the relationship between the caliber of the left renal vein and the pressure load through the transducer. The greater the load through the transducer, the higher the incidence of the nutcracker sign. No relationship between the hematuria and the nutcracker sign is noted. Therefore it can be said that this sign can be easily induced by manual compression, at least in the pediatric age group.