Is pre-stenting necessary for Direct In-Scope Suction (DISS)? Real world practice outcomes from a global prospective multicentre study by EAU Endourology
This global prospective multicentre study demonstrates that routine pre-stenting prior to Direct In-Scope Suction (DISS) flexible ureteroscopy is unnecessary, as it fails to improve stone-free rates or reduce complications despite facilitating ureteral access sheath placement and increasing post-operative stent symptoms.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Kidney stones are a common and painful problem where hard mineral deposits form inside the kidney, blocking the flow of urine. When these stones grow too large to pass on their own, doctors often use a procedure called flexible ureteroscopy. In this delicate operation, a thin, flexible tube with a camera and a laser is threaded up through the bladder and into the kidney. The laser breaks the stone into tiny dust-like particles, which are then flushed out or vacuumed away. To make this process safer and more effective, surgeons sometimes place a small, temporary plastic tube, known as a stent, inside the ureter a few days before the main surgery. This pre-stenting is intended to gently stretch the narrow passage, making it easier to insert the surgical tools and clear the stone. However, this extra step also causes discomfort and requires an additional procedure, leading many to wonder if it is truly necessary for every patient.
A large international team of researchers recently set out to answer this question specifically for patients undergoing a newer, advanced version of this surgery that uses direct suction through the scope itself. They gathered data from over 500 patients across sixteen medical centers in fourteen countries to see if placing that pre-operative stent actually improved the final results. The study compared two groups: those who received a stent beforehand and those who went straight to the surgery without one. The researchers found that while the pre-stented patients did have an easier time getting the surgical tools into place, the final outcome was remarkably similar for both groups. The rate at which patients were left completely free of stone fragments after thirty days was nearly identical, regardless of whether they had a stent or not.
The study involved 540 patients, with 356 undergoing the procedure without a pre-operative stent and 184 receiving one. The group with pre-stents was generally more complex; they had larger stones, more infections, and more urgent medical needs, which is why surgeons had chosen to stent them in the first place. Despite these challenges, the surgeons were able to clear the stones just as effectively in the non-stented group. In fact, the pre-stented patients spent more time in the operating room, averaging sixty minutes compared to forty minutes for the others, and they were more likely to have a larger access sheath placed during the surgery. The researchers noted that the pre-stented group also reported more frequent discomfort related to the stent itself after the operation, such as pain and urinary urgency, whereas the non-stented group had fewer of these specific complaints.
When the researchers looked closely at the data to see what actually predicted a successful outcome, they found that the size of the stone was the most important factor, not the presence of a pre-stent. Larger stones were harder to clear completely, but whether a patient had a stent beforehand made no statistical difference in the final success rate or the risk of complications. The study suggests that the modern suction technology used in these procedures is powerful enough to clear debris effectively without the need for the extra step of pre-stenting in most cases. While pre-stenting remains vital for specific emergency situations or when a surgeon has failed to access the kidney in a previous attempt, the evidence indicates that it is not a required step for everyone. For the average patient, skipping the pre-stent may mean a shorter hospital stay, fewer extra procedures, and less post-operative pain, without sacrificing the chance of leaving the operating room stone-free.
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