Pre-operative factors associated with the development of distal ureteral stump syndrome after upper pole heminephrectomy

IntroductionFor children with duplex systems and severe hydroureteronephrosis of the upper pole, heminephrectomy is one of many suitable treatments, particularly if there is no associated lower pole reflux. Distal ureteral stump syndrome (DSS) is a very difficult complication and manifests as stump empyema, urinary tract infection and/or vulvar discharge and can occur months to years later in 10 to 20 percent of patients. Secondary distal ureterectomy is an extremely difficult surgery due to inflammation and adhesions. To avoid DSS, distal ureterectomy at the time of heminephrectomy can be performed concurrently but carries a risk of lower pole ureter devascularization and injury. Current literature on DSS has shown associations with subtotal ureterectomy or long ureteral stumps. We hypothesized that there may be preoperative variables prior to heminephrectomy that are associated with the development of DSS.ObjectiveIdentify pre-operative risk factors for the development of DSS in pediatric patients who underwent upper pole heminephrectomy for duplex kidneys.Study MethodsRetrospective analysis of pediatric patients who underwent upper pole heminephrectomy at single, academic institution from 1999 to 2021. Pre-operative patient age, gender, history, imaging, and lab results were extracted from patient charts to assess for factors that may predict the development of DSS. Patient groups with and without DSS were compared using Fischer’s Exact Test.ResultsFive (14%) of 36 patients developed DSS and required secondary distal ureterectomy at a median time of 22 months (IQR 6—27) after heminephrectomy. The presence of ureteral debris (80% of DSS) on preoperative ultrasound (p<0.001), reflux into the upper pole (p=0.005), and mucus discharge (100% of DSS) (p<0.001) prior to surgery were found to be significantly associated with those who developed DSS, compared to those who did not. These three pre-operative factors had high specificity (97-100%) and negative predictive value (94-97%).DiscussionSubstantial experience has shown that less than 20% of patients benefit from distal ureterectomy during upper heminephrectomy. Whether using an open or laparoscopic approach, selection of at-risk patients should lower operative time and avoid injury and devascularization of the lower pole ureter for most patients.ConclusionThe presence or absence of ureteral debris, mucus discharge and/or upper pole reflux prior to heminephrectomy may be useful guides in selecting which patients would benefit from concurrent distal ureterectomy and conversely which patients may safely avoid the additional dissection.