Girth measurement is not a reliable investigation for the detection of intra-abdominal fluid.

Routine measurement of abdominal girth after suspected trauma is still recommended as a predictor of intraperitoneal bleeding but there is little evidence to support its accuracy. Girth measurements were taken on 12 recumbent adult patients by independent observers and repeated after infusion of 550 ml aliquots of dialysate to a maximum of 2000 ml. Girth increase per 500 ml infusion varied from -0.46 cm to 2.1 cm (mean 0.84 +/- 0.65 SD) giving a range in excess of 2.5 cm. In some cases the girth decreased after a further 500 ml infusion. A change in patient position altered the girth at a constant volume by 1.32 cm (+/- 0.75 SD). Observer error was low at 0.33 cm (+/- 0.35 SD). These results preclude girth as a reliable clinical indicator of intraperitoneal haemorrhage.