Measurement and Comparison of Kidney Dimension Using Ultrasonography and Computed Tomography Scan

The measurement of renal size is of utmost importance in patients with renal failure, especially azotemia. The present study aimed to assess and compare kidney size using ultrasonography and computed tomography (CT) scans.

This cross-sectional study was conducted on subjects over 18 years of age who were referred to Hajar Hospital of Shahrekord for an ultrasound and CT scan of the kidney or abdomen with a time interval of less than one week. Kidney dimensions were measured by transabdominal ultrasound model Mindray DC-60Exp with 2-5 MHz probe in supine position and oblique if needed. After less than a week, the dimensions of the kidneys were determined by a Siemens 16-slice CT scan machine (with reconstruction at different stages). Data were analyzed in SPSS software using statistical tests.

Right and left kidney dimensions using ultrasonography were obtained at 103.46±13.53 and 107.44±12.15 mm, respectively. These dimensions were 103.10±15.76 and 108.81±14.77 mm, respectively, using a CT scan. The agreement between the ultrasonography and CT scan in determining right and left kidney dimensions was higher than 95% in 96.7% and 95% of all cases, respectively. Sensitivity, specificity, false positive value, negative-positive value, positive predictive value, and negative predictive value for right kidneys were reported as 82.4%, 92.6%, 7.4%, 17.6%, 73.7%, and 95.4% using ultrasonography. These values for the left kidney were 88, 88.6, 11.4, 11, 45.8, and 98.5%, respectively.

Regarding the importance of kidney size in determining renal failure, it seems that in some cases, reliance on ultrasonography is unclear, and it is recommended that kidney size be determined using a CT scan in patients with suspected kidney failure