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[Effects of preventive double-J stent placement in ureteral obstruction treatment with metal stents on animal model].

OBJECTIVES
The purpose of this experimental study is to assess the additive effects of temporary JJ stent placement together with metal stents (MS) in the treatment obstructive uropathy, in order to reduce urothelial hyperplasia formation.


METHODS
Twenty-four pigs were included, and an experimental model of obstructive uropathy was created. Six weeks after obstructive uropathy model induction, ureteral obstruction was confirmed using ultrasonography, ureteropyelography and endoluminal ultrasound. Afterwards, animals were randomly distributed into 2 groups. Group I underwent covered MS placement and JJ ureteral stenting for 3 weeks. Animals in Group II received the same MS without simultaneous JJ stenting. The follow-up was at 3 weeks and at 6 months.


RESULTS
Incidence of urothelial hyperplasia was higher in Group I than Group II, but without statically significant differences. On the other hand, Group II showed a significantly higher degree of obstruction severity due to hyperplasia. The migration rate in both groups was 33.3% at the end of the study. Significant differences were shown on animals showing urinary tract infection (UTI) and hyperplasia against those with hyperplasia but no infection. There was a high rate of correlation between UTI and obstructive urothelial hyperplasia.


CONCLUSIONS
Placement of JJ ureteral catheter does not inhibit urothelial hyperplasia associated with placement of metal mesh stents, although it significantly reduces its obstructive severity in long-term follow-up. Urinary tract infection is directly related to the development and magnitude of the urothelial hyperplasia.