Hydronephrosis following ureteral reimplantation: when is it concerning?

Abstract

Objectives: Hydronephrosis without obstruction is common prior to ureteral reimplant, especially in patients with high-grade VUR. Consequently, when hydronephrosis is present post-operatively, it is unclear when it should be concerning. We evaluated the finding of hydronephrosis in children undergoing reimplantation and its evolution following surgery.

Methods: After obtaining IRB approval, we identified 938 children who underwent reimplantation at our institution from 1998 to 2006. Their pre- and post-operative US and clinical course were analyzed.

Results: Hydronephrosis was observed in 24% pre-operatively and 21% post-operatively. 52% with pre-operative hydronephrosis had it post-operatively, while 12% without pre-operative hydronephrosis had it post-operatively. 71% of post-operative hydronephrosis resolved on average in 1.36 years. 19% didn't resolve and 0.1% had ureteral obstruction. Risk factors for post-operative hydronephrosis included increasing severity of VUR, and high degree of pre-operative hydronephrosis.

Conclusion: Hydronephrosis following ureteral reimplantation is not rare, and correlated to pre-operative evaluations. Post-operative hydronephrosis is frequently transient and benign, and usually resolves within the first 2 years. These patients do not require follow-up ultrasounds or further imaging, and can be followed clinically. Patients with high-grade VUR and hydronephrosis pre-operatively, however, are at risk for developing worsened hydronephrosis and should be followed with a 3-month post-operative ultrasound.