What is hydronephrosis?

Hydronephrosis is swelling in the kidney due to the accumulation of urine which is not infected and it may occur due to resistance in the outflow of urine from the kidney to the ureter or urinary bladder. There are numerous potential causes of hydronephrosis, and each one needs to be addressed.

What causes hydronephrosis, and how common is it?

The most frequent pathological cause of hydronephrosis is Pelvi-ureteric junction blockage (PUJO). Although it can occur on either side, it is more typical on the left. Males are more likely to have it.

The obstruction may be due to blockage in the lumen by stones, stricture or birth defect in the wall where the normal muscle in this region is deficient and replaced by abnormal deposition of fibrous tissue. It may also occur due to pressure from outside lesions like tumours or abnormal blood vessels.


What are the symptoms?

Babies with hydronephrosis may not have any symptoms. This condition may be incidentally diagnosed on ultrasound. At times the baby may have swelling on the belly, on one or both sides in the flanks. This may be detected by the mother while bathing the baby. Fever, difficulty in passing urine (if there is an associated urinary tract infection). Older children may complain of pain in the flanks. It may present with blood in the urine.

How is it diagnosed?

It is diagnosed antenatally by ultrasonography. Serial ultrasonography and radionuclide scans are then performed to monitor blockage and renal function. Typically, hydronephrosis is categorized as mild, moderate, or severe.

Ultrasound scan & radionuclide scan for diagnosis of hydronephrosis & assessment of renal function.


How is hydronephrosis managed before and after birth, and what type of surgery is performed?

Not all cases of hydronephrosis need to be treated. But all those babies who do not require surgery require observation until a particular age. One-sided mild to moderate hydronephrosis is usually observed serially with ultrasound to see their natural progression. Usually, no intervention is done before birth. After delivery, babies undergo USG in the first week of life. Baseline renal functions like blood urea and serum creatinine are checked. This is followed by a renal scan, a test to determine the kidneys' abilities at one month of age. This study shows how slowly urine is outflowing from the kidney to the bladder suggesting the degree of blockage. It also shows differential functions of the kidney. Depending on that, further management is planned. If the function is above or equal to 40% with renal pelvis dilatation in USG 10-15mm, your surgeon may wait for surgery. However, if functions further deteriorate or dilatation further increases, your child will require surgical correction.


Open sad laparoscopic procedures

Sometimes in specific situations, a study called micturating cystourethrogram (MCUG) is done to see for the retrograde flow of urine from the bladder to the kidney.

The surgery performed is known as Pyeloplasty. It may be done by laparoscopic open technique, depending on available expertise and facility. It may also be done using robotic techniques if available. The basic principle of the procedure, however, remains the same, which is the removal of the affected segment and resuturing of the pelvis with a normal ureter. There is an additional advantage of cosmesis and early discharge from the hospital in laparoscopic technique.

Are there any alternatives to surgery?

In cases where the obstruction is proven and the renal function is showing signs of deterioration, there is no alternative to surgery.

What happens after the surgery / what are the possible complications?

A possible complication of this condition may include deterioration of kidney function to a poor level, or the kidney may become non-functioning. This may happen if there are repeated infections or if obstruction is severe. In such a situation, your surgeon may advise the removal of the affected kidney. There can be urine leaking from drain tubes after surgery. This might go away by itself. Your surgeon may put a fine tube across the suturing area (DJ stent), which may remain inside for 6-8 weeks. Subsequently, it will be removed by doing a small procedure called cystoscopy. There may be a wound infection that requires antibiotics. After surgery, the red colour urine may occasionally get better or stay the same. But a second procedure might be necessary if it is worsened or if a lump reappears in the abdomen.

What is the outlook or future of these children?

The success rate of this surgery is high and ~ 95% of children with one-sided hydronephrosis due to PUJO (Pelviureteric junction obstruction) do well after surgery. The hydronephrosis may persist for some time after surgery and should not be a matter of concern initially.

Prophylactic antibiotics may be required for up to six weeks, and follow-up ultrasound scans at three and six months. In severe cases, there may be growth retardation.


Hydronephrosis is a disorder where urine overflows or backs up into the kidney, causing the kidney to enlarge. Prenatal or postnatal diagnoses are both possible for infants with hydronephrosis. Many children who receive a prenatal diagnosis have their disease spontaneously resolved by the time of delivery or shortly thereafter.

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