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Paediatric Hydronephrosis: Causes, Types, Symptoms, Diagnosis And Treatment

Hydronephrosis is a condition, affecting about 1 in 100 babies, where urine overfills or backs up into the kidney. It causes the kidney to swell up and become abnormally dilated. Hydronephrosis can affect one (unilateral) or both (bilateral) kidneys, and it resolves on its own in most of the cases.

The severity of the condition depends on the extent of blockage and the degree to which the kidney is stretched, ranging from mild to severe. In most of the cases, it is the blockage at the top of the ureter near the kidney, an area known as the ureteropelvic junction (UPJ) that leads to abnormalities which can impair foetal lung development [1] [2] .

The condition can affect the infant's ability to drain urine from the urinary system - affecting the kidneys, bladder, ureters and urethra. Hydronephrosis isn't a primary disease, but a secondary condition that results from some other underlying diseases [3] .

Causes Of Paediatric Hydronephrosis

It is not a disease. Hydronephrosis can arise due to internal and external conditions that affect the kidney and the urinary system of the infant. One of the most common causes of hydronephrosis is acute unilateral obstructive uropathy [4] . It can also develop due to any abnormal developments or formations of the kidney in the absence of obstruction or reflux. There are few genetic causes of hydronephrosis, which can also act as the reason behind the condition developing in the child.

Studies point out that about 2 per cent of prenatal ultrasound examinations reveal some degree of hydronephrosis, making it one of the most commonly detected abnormalities in pregnancy. It is unclear as to why the ureter becomes blocked during development.

Hydronephrosis is increasingly reported in males rather than females [5] .

Some of the common causes of hydronephrosis are as follows [6] :

  • Congenital blockage (a defect that is present at birth)
  • Scarring of tissue
  • Tumour or cancer

Types Of Paediatric Hydronephrosis

There are three major categories of paediatric hydronephrosis and they are as follows [6] :

Vesicoureteral reflux: This develops when the urine flow from the kidneys to the bladder gets disrupted and abnormally backs up into the ureter.

Blockage/obstruction: This occurs due to four different causes and in different locations and that is, where the kidney meets the ureter, where the ureter meets the bladder, within the urethra and when there is an incorrect attachment of the ureter to the bladder.

Idiopathic hydronephrosis: The reason behind this type of hydronephrosis is not yet clear, however, it resolves on its own before or after birth.

Symptoms Of Paediatric Hydronephrosis

Newborns and infants with hydronephrosis usually show few or no symptoms at all. However, some of the signs of the condition are as follows [7] :

  • Cloudy urine
  • Painful urination
  • A weak urine stream
  • A fever
  • Chills

Diagnosis Of Paediatric Hydronephrosis

Your physician can usually detect hydronephrosis through a routine prenatal ultrasound during the second trimester. Ultrasound can detect the foetal kidneys and bladder by 14 or 15 weeks gestation, though 20 weeks of pregnancy is the ideal time to detect hydronephrosis. Because, during this period, the foetus is larger and the kidneys are producing urine [8] .

If the condition is detected, your doctor will ask you to carry out the following tests:

  • Diagnostic imaging of the kidneys to assess function and proper urine drainage
  • X-ray of the bladder to check for vesicoureteral reflux

Babies with severe cases of prenatal hydronephrosis have an ultrasound of the kidneys and bladder a few days after birth.

Treatment For Paediatric Hydronephrosis

The medical care for the condition depends on the severity of hydronephrosis in your baby. The treatment methods for paediatric hydronephrosis are as follows [9] [10] :

  • Surgery to repair any urinary tract blockage, in more severe cases
  • Foetal surgery to place a drainage tube in your baby's bladder, in the most severe cases
  • Antibiotics will be prescribed after your baby is born to prevent infection
  • Close observation for mild or moderate cases, including ultrasounds before and after birth

On A Final Note...

Many cases of hydronephrosis resolve on their own before the baby's birth. Studies point out that most cases of hydronephrosis at birth will resolve over time with the kidneys working normally.

View Article References
  1. [1] Riccabona, M., Avni, F. E., Blickman, J. G., Dacher, J. N., Darge, K., Lobo, M. L., & Willi, U. (2008). Imaging recommendations in paediatric uroradiology: minutes of the ESPR workgroup session on urinary tract infection, fetal hydronephrosis, urinary tract ultrasonography and voiding cystourethrography, Barcelona, Spain, June 2007. Pediatric radiology, 38(2), 138-145.
  2. [2] Woodward, M., & Frank, D. (2002). Postnatal management of antenatal hydronephrosis. BJU international, 89(2), 149-156.
  3. [3] Silay, M. S., Undre, S., Nambiar, A. K., Dogan, H. S., Kocvara, R., Nijman, R. J., ... & Radmayr, C. (2017). Role of antibiotic prophylaxis in antenatal hydronephrosis: A systematic review from the European Association of Urology/European Society for Paediatric Urology Guidelines Panel. Journal of pediatric urology, 13(3), 306-315.
  4. [4] Martín‐Solé, O., Soria‐Gondek, A., Pérez‐Bertólez, S., Paredes, P., Tarrado, X., & García‐Aparicio, L. (2019). Value of supranormal function on 99mTc‐mercaptoacetyltriglycine renal scan in paediatric patients with obstructive hydronephrosis. BJU international.
  5. [5] Zee, R. S., Herbst, K. W., Kim, C., McKenna, P. H., Bentley, T., Cooper, C. S., & Herndon, C. A. (2016). Urinary tract infections in children with prenatal hydronephrosis: A risk assessment from the Society for Fetal Urology Hydronephrosis Registry. Journal of pediatric urology, 12(4), 261-e1.
  6. [6] Baskin, L. S. (2017). Postnatal management of fetal hydronephrosis. UptoDate 2016.
  7. [7] Perlman, S., Roitman, L., Lotan, D., Kivilevitch, Z., Pode‐Shakked, N., Pode‐Shakked, B., ... & Gilboa, Y. (2018). Severe fetal hydronephrosis: the added value of associated congenital anomalies of the kidneys and urinary tract (CAKUT) in the prediction of postnatal outcome. Prenatal diagnosis, 38(3), 179-183.
  8. [8] Zee, R. S., Herndon, C. A., Cooper, C. S., Kim, C., McKenna, P. H., Khoury, A., & Herbst, K. W. (2017). Time to resolution: A prospective evaluation from the Society for Fetal Urology hydronephrosis registry. Journal of pediatric urology, 13(3), 316-e1.
  9. [9] Wilkins, J., Lambert, H., & Robson, S. (2019). G235 (P) Isolated fetal hydronephrosis: sonographic predictors of adverse postnatal outcome.
  10. [10] Baskin, L., Mattoo, T. K., & Wilkins-Haug, L. (2018). Overview of fetal hydronephrosis. Accessed August, 14.
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Story first published: Monday, December 16, 2019, 16:00 [IST]
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