Kidney Swelling - Hydronephrosis

Hydronephrosis, or kidney swelling, occurs when there is a build-up of urine in the kidney.

What is Hydronephrosis?

Hydronephrosis is characterised by kidney swelling or distention as urine builds up in the kidney. This is due to a partial or complete obstruction of the flow of urine at the upper end of the ureter (the tube that brings the urine from the kidney to the bladder). Hydronephrosis can sometimes develop in children; however, most babies who have the condition were born with it. It is considered one of the most common abnormalities of the urinary tract in children. 

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If hydronephrosis is left undiagnosed and untreated, some children will present a large stomach bulge and perhaps pain from a huge, swollen kidney. Often when discovered at this stage, there is not much kidney function left in that kidney. However, the other kidney usually functions normally. 

Hydronephrosis Causes and Risk Factors

Hydronephrosis of one kidney is most commonly caused by an incomplete blockage at th junction between the kidney urine collecting system, and the urine drain pipe (pelvicalyceal system and ureter). This is called a PUJO. This is an in-born condition and is not known to be inherited or related to the mother’s food intake or behavior during her pregnancy.

Other causes of the condition include the backflow of urine from the bladder into the kidneys or a blockage of the lower end of the ureter. 

Hydronephrosis Diagnosis

In unborn babies, this condition can be diagnosed by an ultrasound scan of the expectant mother. Hydronephrosis does not usually affect the pregnancy, and the baby’s delivery should proceed as planned. The condition will then be confirmed by a repeat ultrasound of the baby’s kidney on the second or third day after his birth. If hydronephrosis is confirmed, the baby’s kidney tissue may be distended and squashed, and the urine drainage system will appear very ballooned and dilated. 

Hydronephrosis Treatment

Babies with hydronephrosis need regular kidney ultrasounds and kidney function scans. Sometimes, the baby (and the kidney) improve with time without the need of surgery. Generally, a few investigations will be needed over time before it can be known if an operation is required. 

Treatment of hydronephrosis depends on the underlying cause. For example, in the case of children diagnosed with PUJO, an operation called a pyeloplasty will be needed if the hydronephrosis causes back pressure on the kidney. While this is a major operation, it has a high cure rate and a low chance of any complications. 

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