title: Symptomatic subcapsular and perinephric hematoma following ureteroscopic lithotripsy for renal calculi.
abstract: OBJECTIVE
  Ureteroscopic lithotripsy (URSL) is believed to be associated with less risk of symptomatic renal hematoma than extracorporeal shockwave lithotripsy (SWL) and percutaneous nephrolithotomy (PCNL). We sought to document the rate of and risk factors for this rare complication following URSL for renal calculi.
  
  
  METHODS
  With Institutional Review Board approval, we reviewed 1087 cases of URSL performed between July 2009 and October 2012 for four surgeons. We identified cases for renal calculi complicated by symptomatic "hematoma" by searching electronic medical records of patients undergoing URSL with a web-based search tool and cross-referencing with a departmental quality improvement database for postoperative complications. Chi-squared tests were used to assess risk factors.
  
  
  RESULTS
  Among 877 renal units exposed to URSL for renal calculi, 4 were complicated by symptomatic subcapsular hematomas (SH) and 3 by symptomatic perinephric hematomas (PH), yielding a 0.5% and 0.3% rate for each complication, respectively. Pain was the primary presenting symptom. Almost all cases presented within 24 to 48 hours postop. Two PH patients required postoperative blood transfusion. Four patients (two SH, two PH) were hospitalized for observation. Ureteral sheaths were used in two cases (one PH and one SH). There was no association with age, diabetes, body mass index (BMI), or operative duration (p-values all>0.05). However, hematoma did correlate with female gender, preoperative hypertension, preoperative ureteral stenting, intraoperative ureteral sheath use, and postoperative ureteral stenting (all p-values<0.0001).
  
  
  CONCLUSIONS
  While symptomatic hematoma is a complication of URSL, the rate of such outcome (0.8%) is far less than that reported by prior series with SWL and PCNL. This may partially be attributable to collection biases, where subclinical cases are not imaged, or anchoring biases, where clinicians attribute symptoms to another possible etiology. This outcome can be morbid, but can often be conservatively managed with observation.
authors.affiliation: Department of Urology, University of Michigan Medical School , Ann Arbor, Michigan.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kozminski
authors.forename: David J
authors.initials: DJ
authors.lastname: Kozminski
authors.forename: William W
authors.initials: WW
authors.lastname: Roberts
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Faerber
authors.forename: John M
authors.initials: JM
authors.lastname: Hollingsworth
authors.forename: J Stuart
authors.initials: JS
authors.lastname: Wolf
mesh_terms: D005260:Female; D006406:Hematoma / Q000000981:diagnostic imaging / Q000209:etiology*; D006801:Humans; D007669:Kidney Calculi / Q000601:surgery*; D008297:Male; D008824:Michigan; D008875:Middle Aged; D009403:Nephrostomy, Percutaneous / Q000009:adverse effects*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology*; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors