• Abnormal enlargement of a kidney, which may be caused by blockage of the ureter (such as by a kidney stone) or chronic kidney disease that prevents urine from draining into the bladder.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• Abnormal enlargement or swelling of a KIDNEY due to dilation of the KIDNEY CALICES and the KIDNEY PELVIS. It is often associated with obstruction of the URETER or chronic kidney diseases that prevents normal drainage of urine into the URINARY BLADDER.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• Dilation of the urinary collecting space in the kidney.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• Distention of the pelvis and calices of the kidney with urine, as a result of obstruction of the ureter, with accompanying atrophy of the parenchyma of the organ.
  CRISP Thesaurus
  National Institutes of Health, 2006
• Severe distention of the kidney with dilation of the renal pelvis and calices.
  Human Phenotype Ontology (HPO)
  The Human Phenotype Ontology Project, 2021
• Hydronephrosis is swelling of one or both kidneys. Kidney swelling happens when urine can't drain from a kidney and builds up in the kidney as a result. This can occur from a blockage in the tubes that drain urine from the kidneys (ureters) or from an anatomical defect that doesn't allow urine to drain properly.
  Mayo Clinic
  Mayo Foundation for Medical Education and Research