Computed tomograpy evaluation of ureteral length in children

Although ureteral length (UL) is highly variable in children, reliable data on this topic are scarce. During urinary tract surgery, the use of an inappropriately dimensioned ureteral stent is associated with adverse effects. This study aimed to evaluate UL as a function of the child's age, using contrast-enhanced computed tomography (CT) of the abdomen and pelvis, and to calculate a new equation for predicting UL (and thus the optimal length of ureteral stents) in children.

A retrospective, single-centre study of children (younger than 16 years) who are free of abdominal mass syndrome and severe scoliosis was conducted. After three-dimensional reconstruction of the CT data, the ureter was measured between the ureteropelvic junction and ureterovesical junction by two observers. The lengths of the right and left ureters were analyzed by age, with at least 10 CT measurements per age class.

The mean ULs on the right and left were, respectively, 9.7 and 9.91 cm before the age of 1 year, 20.10 and 21.08 cm at the age of 7 and 26.55 and 27.46 cm at the age of 16. The interobserver reproducibility of UL determination was high (intraclass correlation coefficient [95% confidence interval]: 0.97 [0.94-0.99]). On the basis of these results, the length of the double-J catheter should be equal to the child's age +12 cm (Table 1).

Computed tomography measurement of the UL in healthy children is reproducible and reliable and enabled the estimation of the UL by age group. This knowledge should facilitate the choice of the stent used in ureteral surgery. To confirm the study results, the stent size suggested here should be evaluated in routine practice.