title: Unilateral renal agenesis: a systematic review on associated anomalies and renal injury.
abstract: BACKGROUND
  Unilateral renal agenesis (URA) is associated with other congenital anomalies of the kidney and urinary tract (CAKUT) and extra-renal anomalies. However, the reported prevalences of these anomalies are highly variable. We estimated the prevalence of associated CAKUT and extra-renal anomalies in patients with URA. Furthermore, we determined the prevalence of renal injury in URA patients.
  
  
  METHODS
  We conducted a systematic review of English and non-English articles using PubMed and Embase.com. Included studies reported at least one of the following items: incidence of URA, gender, side of URA, prenatal diagnosis, performance of micturating cystourethrogram, associated CAKUT, urinary tract infection or extra-renal anomalies. Studies that described a mean/median glomerular filtration rate (GFR) and proportions of patients with hypertension, micro-albuminuria or a decreased GFR were also included.
  
  
  RESULTS
  Analyses were based on 43 included studies (total number of patients: 2684, 63% male). The general incidence of URA was 1 in ∼2000. Associated CAKUT were identified in 32% of patients, of which vesicoureteral reflux was most frequently identified (24% of patients). Extra-renal anomalies were found in 31% of patients. Hypertension could be identified in 16% of patients, whereas 21% of patients had micro-albuminuria. Ten per cent of patients had a GFR<60 mL/min/1.73 m2;.
  
  
  CONCLUSIONS
  These aggregate results provide insight in the prevalence of associated anomalies and renal injury in patients with URA. Our systematic review implicates that URA is not a harmless malformation by definition. Therefore, we emphasize the need for clinical follow-up in URA patients starting at birth.
authors: Department of Pediatric Nephrology, VU University Medical Center, Amsterdam, The Netherlands. r.westland@vumc.nl
authors: Rik
authors: R
authors: Westland
authors: Michiel F
authors: MF
authors: Schreuder
authors: Johannes C F
authors: JC
authors: Ket
authors: Joanna A E
authors: JA
authors: van Wijk
mesh_terms: D000013:Congenital Abnormalities / Q000473:pathology*; D006801:Humans; D007668:Kidney / Q000002:abnormalities* / Q000293:injuries* / Q000473:pathology; D007674:Kidney Diseases / Q000150:complications / Q000151:congenital* / Q000473:pathology; D015201:Meta-Analysis as Topic; D011379:Prognosis; D012196:Review Literature as Topic; D014551:Urinary Tract / Q000002:abnormalities* / Q000293:injuries
keywords: congenital anomalies of the kidney and urinary tract; renal injury; solitary functioning kidney; systematic review; unilateral renal agenesis