SONOGRAPHIC MEASUREMENT OF RENAL LENGTH IN CHILDREN - DOES THE POSITION OF THE PATIENT MATTER

Purpose. This prospective study was designed to determine the effect o f patient positioning on sonographic measurements of renal length in c hildren. Materials and methods. Two dedicated pediatric ultrasonograph ers (observers A and B) measured the sonographic lengths of 48 kidneys in 25 children (two had unilateral renal agenesis). Each observer obt ained the two ''longest possible'' measurements for each kidney with t he patient in three positions: supine? contralateral decubitus, and pr one. Patients with myelomeningocele, hydronephrosis, and renal cysts w ere excluded. Results. Both examiners obtained significantly higher va lues for renal lengths with the children lying supine (observer A P le ss than or equal to 0.0017; observer B P less than or equal to 0.0409) or in contralateral decubitus (observer AP less than or equal to 0.00 01; observer B P less than or equal to 0.0419) than with them lying pr one. There was no significant difference between the supine and decubi tus measurements. The mean difference between the supine and prone mea surements for the observers was 3.0 mm for observer A and 1.8 mm for o bserver B. The mean difference between the contralateral decubitus and prone measurements was 3.0 mm for observer A and 1.6 mm for observer B. Conclusion. Sonographic measurements of renal length made with the patient lying supine or in contralateral decubitus yield slightly high er values than those made with the patient prone.