Ureteroscopy (ureterorenoscopy, URS) for kidney and ureteral stones

URS is the method of choice when a kidney stone is stuck in the ureter. Stones located in the branched renal calyx system can also be treated with a flexible endoscopic instrument. URS treatment is suitable for kidney stones up to a size of 1–2 cm. Larger stones are removed by Mini-PCNL according to Lahme.

The duration of URS depends on many factors such as the size, location and number of stones. However, individual anatomy and stone composition can also affect the duration of the operation. The operation for a small ureteral stone may take only 15 minutes. Removing a large stone in a difficult-to-access renal calyx can take 90 minutes or more.

The stones are accessed with a very thin and long instrument, the ureterorenoscope. This is inserted into the bladder via the urethra. There, either the right or left ureteral orifice is located and the instrument is then advanced through the ureter into the kidney. Flexible instruments can even "look around corners" so that even the furthest corner of the branched renal calyx system can be inspected. In this way, the stones are accessed elegantly via the natural route.

Depending on their size, the stones must first be broken up, as they do not fit through the ureter in one piece. The kidney stones are fragmented with the aid of a laser. The fragmented pieces are normally retrieved with a so-called stone basket, which "captures" the stone as a mesh of very fine wires.

Once all the stones have been removed, it may be necessary to insert a so-called DJ stent. It ensures free urine drainage after the operation.

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, which mean the same thing.

Inserting a ureteral stent is always necessary when an obstruction in the ureter has to be bypassed in order to ensure free urine drainage. This is typically the case when a stone is stuck in the ureter. This causes urinary retention, which manifests itself as renal colic and can be very painful. Immediate surgical removal of ureteral stones is not always advisable, as the ureter is naturally very delicate. In this case, a ureteral stent must be inserted before the stone is removed by URS. This stent for kidney stones defuses the acute situation on the one hand and relaxes the ureter on the other. The stone can then be removed a few days later.

After stone removal by ureteroscopy, swelling of the ureter may occur, which can cause urinary retention again. For this reason, a DJ catheter must be inserted as a precaution during the procedure to prevent pain after the operation.

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 catheter is pushed past the stone up into the renal pelvis.

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

As a rule, a ureteral stent is well tolerated and does not cause any complications. Some patients complain of pain in the lower abdomen or flank, which can be treated well. The treating urologist will explain the possible risks of a kidney stent before the procedure.

URS is performed on the day of admission. After the operation, a bladder catheter is inserted for one night. Patients are usually discharged the day after the operation. Pain is not to be expected after URS. However, if a ureteral stent has been inserted, it may cause certain discomfort such as a feeling of urgency or flank pain during urination. If necessary, painkillers can also be given. Some blood in the urine is possible and no cause for concern.

An outpatient follow-up examination approx. one week after discharge from inpatient treatment is advisable. If a DJ stent was inserted, it must be removed at this point in any case.

With ureteroscopy, a stone-free rate of approx. 90% can be achieved. As a rule, only one operation session is required.