Abdominal ultrasound examination was given to 715 (566 male and 149 female) adult non‐manual workers in Tokyo as part of their annually required medical check‐up. Gross abnormalities were found in 44.5% of males and 34.2% of females. The most common finding was fatty liver (15.2%), seen four times as frequently in males as in females. There were 93 elevated lesions in the gall‐bladder in 56 subjects (7.8%); some required follow‐up examinations because malignancy could not be excluded. Small cystic lesions were frequently seen in the kidney (6.4%) and in the liver (4.8%). Gallstones were found in 3.4%. Mild splenomegaly occurred in 3.4%. Ten mass lesions, 8 hyperechoic and 2 hypo‐echoic, were found in the liver, but subsequent imaging studies showed them to be benign haemangiomas. Other changes found included calcific lesions in the liver (2.1%) and in the spleen (0.4%), renal stones (2.0%), thickened wall of the gall‐bladder (3.2%), intramural stones (0.8%) and debris/sludge (0.4%) in the gall‐bladder, dilated pancreatic duct (0.7%) and common bile duct (0.3%), liver cirrhosis (0.4%), hydronephrosis (0.1%), enlarged pancreas (0.1%), small pancreas (0.1%), ovarian tumour (0.1%), uterine tumour (0.1%), abnormally shaped kidney (0.1%) and situs inversus (0.1%). It was concluded that abdominal ultrasound is an important examination for a mass screening or a physical check‐up commonly practised as the ‘human dock’ for adults in Japan.

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