US11 - Stone Location and the Degree of Hydronephrosis: Their Role in Postoperative Sepsis After Ureteroscopy with Laser Lithotripsy

Introduction/Purpose: Ureteroscopy with laser lithotripsy is a commonly performed procedure for urinary stone disease of the ureter and kidney. Although relatively rare, ureteral trauma, multi-organ failure, and postoperative sepsis have all been cited as complications of ureteroscopy. A negative urine culture prior to stone surgery is the standard of care in urologic surgery and is proven to reduce rates of postoperative sepsis. However, even following this dogma, the risk of postoperative sepsis is still estimated to range from 0.2% to 17.8%, as sepsis diagnostic criteria vary among studies. Some well-known risk factors for postoperative sepsis include older age, positive preoperative urine cultures, preoperative stent placement, and certain comorbidities such as high body mass index. Many studies have evaluated ways to reduce this outcome, whether it be with prophylactic antibiotics regardless of urine culture results, reducing the amount of indwelling stent time, treating clinically apparent urinary tract infections prior to surgery, or recognizing high-risk characteristics that increase the risk of postoperative sepsis. While studies have helped us identify patients at higher risk of postoperative sepsis, there are additional parameters that have not yet been well studied that could also serve as potential identifiers. The aim of this study is to investigate whether the location of ureteral calculi or the degree of hydronephrosis significantly impacts rates of postoperative sepsis in patients who underwent ureteroscopy with laser lithotripsy for the treatment of kidney stones.

Methods or Case Description: A retrospective review of patients who underwent elective ureteroscopy with lithotripsy from April 2018 to December 2021 at four different hospital sites was retrospectively reviewed. A total of 306 total charts were collected during this time frame. Patients were excluded if urine cultures were mixed/positive and treated with antibiotic therapy, in an inpatient setting, or had percutaneous nephrostomy or prior extracorporeal shock wave lithotripsy. 255 cases met inclusion criteria with 11 operating surgeons. The patient data was collected from the electronic medical record system. The location of each stone was recorded as either intrarenal, ureteropelvic junction (UPJ), proximal, mid-ureteral, distal, or ureterovesical junction (UVJ). The degree of hydronephrosis was recorded as minimal, mild, mild/moderate, moderate, or severe. Both stone location and degree of hydronephrosis were obtained from radiologic reports. Patient charts were analyzed for other factors including stone composition, stone size, stone weight, preoperative urine culture, preoperative antibiotic, stent indwelling time prior to procedure, and whether patients were admitted postoperatively or readmitted within 48 hours after procedure for suspicion of sepsis. Sepsis was defined as two systemic inflammatory response syndrome (SIRS) criteria (temperature >100.4F or < 96.8F, heart rate >90 beats per minute, respiratory rate >20 breaths per minute, and white blood cell count >12,000 cells/mm3), and a source of infection. A one-sided two sample Z-test and Chi-square test were performed to assess the relationship between these variables. Statistical significance was accepted at p < 0.05. The institutional review board reviewed and approved the study protocol (ID: FWA00007111).

Outcomes: Among 255 cases of ureteroscopy with lithotripsy performed, 7.06% developed sepsis postoperatively. There was a 21.4% sepsis rate with intrarenal stones compared to 4.92% distal ureteral stones, 16.13% mid ureteral stones, 7.69% proximal ureteral stones, 1.92% UPJ stones, and none in the UVJ stones. On subgroup analysis based on specific location of stone and rates of postoperative sepsis, a significant association was found for intrarenal stones (p = 0.05) (Table 1). There was no statistical significance between other stone locations and postoperative sepsis. Furthermore, the degree of hydronephrosis was not found to be associated with an increased risk of postoperative sepsis in ureteroscopy with lithotripsy (p = 0.590) (Table 2).





Conclusion: Nephrolithiasis, urolithiasis, and related sequelae cause a significant source of morbidity, and prevalence is continuing to rise globally. Early detection and intervention are vital in preventing further deterioration and complications. While many studies have investigated predictive factors in determining the likelihood of postoperative sepsis following treatment of urinary stone disease, there is limited data surrounding the influence of stone-specific parameters or degree of hydronephrosis. The present study found a statistically significant relationship between stone location and rate of postoperative sepsis in patients undergoing ureteroscopy with laser lithotripsy. The degree of hydronephrosis was not associated with the development of postoperative sepsis.