Hydronephrosis

Urinary retention is always the result of a drainage obstruction in the ureter.

In the vast majority of cases, the cause is urinary stones that slip from the kidney into the ureter and then block it. However, space-occupying lesions in or around the ureter can also be considered. In both cases, urine cannot drain from the kidney; this is also referred to as hydronephrosis.

If urinary retention occurs acutely, the patient feels a severe, colicky pain in the flank, which can radiate to the lower abdomen or the genital region, as is usually the case with ureteral stones. In contrast, slowly developing, chronic urinary retention can go completely unnoticed, for example in the case of space-occupying lesions in the ureter.

An ultrasound examination of the kidneys can detect dilatations of the renal pelvis and calyx system. In case of doubt, X-ray examinations are necessary to distinguish between a possibly harmless dilatation and genuine urinary retention.

The clear answer here is yes. Urinary retention must always be investigated and usually also requires treatment. If left untreated, it can lead to kidney failure and infections, up to and including life-threatening blood poisoning.

In the acute phase, urinary retention of any cause is usually treated by inserting a thin ureteral catheter, a so-called double-J stent (DJ). This only serves as acute therapy, as it does not eliminate the cause. The follow-up therapies can then wait a little and depend on the cause of the retention. This can be caused, for example, by stones, ureteropelvic junction or ureteral strictures, but also by tumours.

A double-J stent (DJ) 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 that urine can drain without obstruction. The name comes from the fact that the tube is shaped so that it curls into a J shape in both the kidney and the bladder to prevent it from slipping. Other names are pigtail or ureteral stent and have the same meaning.

A DJ stent is typically inserted under short general anaesthesia. This is done via cystoscopy. The opening of the ureter is located in the bladder and the DJ is pushed past the obstruction up into the renal pelvis. The stent follows the natural course, so to speak. If, in rare cases, it is not possible to insert a DJ stent, the kidney can also be punctured directly, but via an "artificial" route through the skin.

The DJ is removed by means of a 1–2-minute cystoscopy under local anaesthesia as an outpatient procedure.