Cyst-to-kidney volume ratio in the sonographic diagnosis of unilateral multicystic dysplastic kidney in children.

AIMS: To evaluate the usefulness of the cyst-to-kidney volume ratio determined by ultrasonography (US) in unilateral multicystic dysplastic kidney (MCDK) in children.

MATERIAL AND

METHODS

Our study group included 21 children (average age: 431 days) with unilateral MCDK and 22 children (average age: 440 days) with unilateral grade IV hydronephrosis due to ureteropelvic junction obstruction as the control group. All the children underwent transabdominal US. In children with MCDK, we calculated cyst-to-kidney volume ratios (volume of the largest cyst/volume of the MCDK) and in the control group the volume ratios of the renal pelvis and the largest calyx (volume of the pelvis or largest calyx/volume of the ipsilateral hydronephrotic kidney). Ellipsoid formula was used to calculate kidney and pelvis volumes. Sphere volume formula was used to calculate the largest cyst and calyx volumes.

RESULTS

The mean cyst-to-kidney volume ratio (0.38±0.21) was significantly higher than the mean volume ratios of the renal pelvises (0.10±0.05) and the largest calyces (0.04±0.02) (p<0.05). There was no significant correlation between cyst-to-kidney volume ratio and the ages of the children (r=0.141, p=0.541).

CONCLUSIONS

With the aid of both the qualitative sonographic criteria and the newer data that we have proposed, US is a useful tool in the initial diagnosis of MCDK and for differentiation of MCDKs from grade IV hydronephrotic kidneys in children. The cyst-tokidney volume ratio is independent of age and thus, it can be helpful in the diagnosis of unilateral MCDK at any age.