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Hydronephrosis in Child
Other Resources UpToDate PubMed

Hydronephrosis in Child

Contributors: Casey Silver MD, Abhijeet Waghray MD, Catherine Moore MD, Eric Ingerowski MD, FAAP
Other Resources UpToDate PubMed


Hydronephrosis is dilation of the renal pelvis and calyces due to obstruction of urinary flow. This obstruction may occur anywhere along the urinary tract. Increased ureteral pressure leads to changes in glomerular filtration rate, tubular function, and renal blood flow. The obstruction may be acute or chronic, and unilateral or bilateral.

In children, hydronephrosis is most often secondary to an anatomic abnormality such as posterior urethral valves, vesicoureteral reflux, or ureteropelvic junction (UPJ) obstruction. Congenital anomalies account for a higher incidence of hydronephrosis in children compared to adults.

The Society for Fetal Urology (SFU) has developed a grading system for the severity of hydronephrosis. Severity ranges from grade 0 (mild; no renal pelvis dilation) to grade 4 (severe; dilation of the renal pelvis and calyces and thinning of the renal parenchyma).

Patients with isolated hydronephrosis are typically pain free; the presence of pain is usually in the setting of stones, acute bladder distension, or infection. Upper ureteral or renal pelvic lesions typically cause flank pain, whereas lower ureteral obstruction causes pain that radiates to the ipsilateral testicle or labia. Other presenting symptoms include hypertension, change in urine output, hematuria, or new creatinine elevation on routine laboratory studies.


N13.30 – Unspecified hydronephrosis

43064006 – Hydronephrosis

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Congenital posterior urethral valves
  • Vesicoureteral reflux
  • Ureteropelvic junction stenosis (see Ureteropelvic junction obstruction)
  • Bladder obstruction
  • Duplex collecting system (ureteral duplication)
  • Multicystic dysplastic kidney
  • Congenital megaureter

Best Tests

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Management Pearls

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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Last Reviewed:10/14/2019
Last Updated:11/21/2019
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Hydronephrosis in Child
Imaging Studies image of Hydronephrosis - imageId=8359154. Click to open in gallery.  caption: '<span>Transverse grayscale ultrasound image of the left kidney demonstrates moderate to severe hydronephrosis.</span>'
Transverse grayscale ultrasound image of the left kidney demonstrates moderate to severe hydronephrosis.
Copyright © 2024 VisualDx®. All rights reserved.