Abstract: ［Abstract］ ObjectiveTo observe the index changes after placement the double J ureteral catheter（DJ） in small infants with severe hydronephrosis and to discuss the clinical application value of this surgical plan.
〖WTHZ〗MethodsTwenty children with severe hydronephrosis less than 3 months were analyzed retrospectively. All the patients were placed ureteral DJ tube retrogradely under cystoscope to analyze the therapeutic effect of hydronephrosis after operation.
〖WTHZ〗ResultsOf 20 children, 2 failed to put the ureteral DJ tube into the nephrostomy, and 2 had ureteral DJ tube obstruction. The ureteral DJ tube recovered well after replacement. The hydronephrosis was aggravated again in 10 cases after 6 months, and the pyeloureteroplasty was performed. 8 cases of hydronephrosis were relieved after removal of ureteral DJ tube, and there was no further aggravation. The effect of internal drainage was good before treatment, 2 weeks after treatment and 6 months after treatment. The degree of hydronephrosis in children after indwelling ureteral DJ tube was obviously relieved（P＜0.01）.
〖WTHZ〗ConclusionThe DJ placement procedure is simple and the operation time is short, which can significantly alleviate the degree of severe hydronephrosis in small infants. After the operation, the children recovers quickly and convenient for nursing. After the removal of the ureteral DJ tube 6 months later, the children have a certain probability of avoiding major surgical trauma, which is worthy of further clinical application.

Key words: severe hydronephrosis, double J ureteral catheter, infant