Urine flows from the kidney through the ureter into the bladder. In the process, the urine is transported in individual waves through the muscular ureteral tube to the bladder. Since the ureter is very slender, it can easily become obstructed, causing hydronephrosis.

Questions about the diagnosis and treatment of hydronephrosis

Hydronephrosis is always the result of an obstruction in the ureter inhibiting drainage.

In most cases, the cause is urinary stones that slide from the kidney into the ureter and then block it. However, obstructions in or around the ureter can cause urinary stasis. In both cases, urine cannot flow away from the kidney, which is also called hydronephrosis.

If hydronephrosis occurs acutely, the patient feels a strong, colicky pain in the side, which can radiate into the lower abdomen or the genital region, as is usually the case with ureteral stones. In contrast, the slow-onset, chronic congestion of the urine can remain completely unnoticed. For example, this can occur in the case of ureteral masses.

An ultrasound examination of the kidneys can detect dilatations of the renal calyceal system. X-ray examinations are necessary to distinguish between a possibly harmless dilatation and a real hydronephrosis in case of doubt.

Here, the clear answer is yes. Hydronephrosis must be identified and usually also treated. If left untreated, they can lead to kidney failure, infections, and even life-threatening blood poisoning.

Urinary obstructions are usually treated by inserting a thin ureteral catheter, known as a double-J stent. This only serves as an acute treatment because it does not eliminate the cause. The follow-up treatments take some time and depend on the cause of the congestion. Causes can range from stones to renal pelvis outlets or ureteral stricture, and also to tumours.

A double-j stent is a soft, thin plastic catheter that extends from the kidney through the ureter into the bladder. In this way, it “splints” the ureter and ensures the unobstructed flow of urine. The name comes from the fact that the tube curls in a J-shape in both the kidney and the bladder to prevent it from slipping. It is also known as a pigtail or ureteral stent.

A double-j stent is typically inserted while the patient is under short anaesthesia. This is done via a cystoscopy. In the bladder, the orifice of the ureter is located, and double-j stent is pushed up past the obstacle, into the renal pelvis. The stent follows the natural course of the organs, so to speak. In rare cases, insertion of a double-j stent is not possible, in which case the kidney can also be punctured directly through the skin in a more “artificial procedure.”

Double-j stent removal is performed by means of a 1-2 minute cystoscopy under local anaesthesia as an outpatient procedure.

About this page:


Prof. Dr. med. Sven Lahme
Urology specialist

Medical director of the Goldstadt-Privatklinik.
Specialist for Urology, Mini-PCNL and robot-assisted da Vinci procedures.

Member in Scientific Societies and Reviewer of scientific journals.

Creation Date: 08.03.2020Modification date: 08.03.2020