What is hydronephrosis? Causes, symptoms, and treatment
The word hydronephrosis derives from “hydro” meaning water and “nephrosis” meaning within the kidney. It’s only a description of an increased amount of fluids or urine seen inside the kidney on a renal tract ultrasound scan. It is most commonly picked up on ultrasound scans performed on pregnant women with an incidence of 1:500 foetuses, and occasionally, it is picked up on renal tract ultrasound scans performed on babies and children who have had urinary tract infections. When diagnosed pre-natally, it is usually self-limiting and harmless and is thought to be due to the fact that the foetus produced an increased amount of urine in the third trimester of pregnancy. In a minority of cases however, the baby will require further investigation once it’s born. In up to 80% of cases, hydronephrosis is harmless and self-limiting and does not require further investigation.
In the remainder of the 20%, it can be due to a blockage anywhere along the urinary tract and this would include something called a pelvi-ureteric junction obstruction which is a blockage at the level of the kidney. A vesicoureteric junction obstruction which is a blockage of the level of the urether where it meets the bladder or rarely, a condition found in boys, called posterior urethral valves which is a blockage of the bladder. In other cases, it can also be due to vesicoureteric reflux which is kidney reflux or reflux of urine up into the kidney in a backwards fashion. Other causes of hydronephrosis could include double kidneys or duplex systems which can have associated cysts which cause blockage or reflux. These cases will require investigation when the baby is born.
Hydronephrosis in pregnancy or in the foetus is completely asymptomatic. It does not cause any symptoms. We only monitor it with repeat ultrasound scans during the pregnancy.
Hydronephrosis on the newborn baby is also usually completely asymptomatic and does not give the babies any symptoms especially the type of hydronephrosis that is due to get better on its own over the first few months of life. However, hydronephrosis that is due to a blockage or reflux can cause bad urinary tract infections with fever. Sometimes, it can cause flank pain or difficulty voiding or a poor urinary stream. Once again in the majority of cases, kidney function is completely normal.
In the minority of cases with blockage or reflux or posterior urethral valves, then yes, the affected kidney could have reduced kidney function. That is why it is important to pick up hydronephrosis and investigate it if necessary as it is possible to preserve kidney function and avoid the deteriorating further. Hydronephrosis picked up during the pregnancy does not require any treatment. We usually perform serial ultrasound scans just to check for any progression. Very rarely, in a condition called posterior urethral valves, the condition progresses during the pregnancy and may require in utero intervention. This is however very unusual and will require in depth counselling with myself and your fetal medicine team In the rest of the cases, investigations are performed once the baby is born.
We usually start the baby on a very small dose of antibiotic given to the baby every evening just to protect the kidney from getting infection until the investigations are organised. The first investigation will be a renal tract ultrasound scan performed on the baby within the first four weeks of life. I will then review you and the baby with the ultrasound scan and decide whether the antibiotics can be stopped. If the hydronephrosis is still there, I may decide to perform further investigations and these will enable us to carry out a diagnosis. It is therefore important for us to pick up hydronephrosis and investigate it appropriately by an experienced paediatric urologist.
Hello, my name is Dr. Geoffrey Box. I'm a urologist here at The Ohio State University's Wexner Medical Center. I'm an assistant professor in the Department of Urology, and…By: Ohio State Wexner Medical Center
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