Lithotripsy procedures have greatly improved the management of painful kidney stones, which form when mineral and acid salts crystallize in the urinary tract. Lithotripsy breaks these stones into smaller, passable pieces, reducing the need for traditional open surgery. Following these fragmentation procedures, patients frequently ask about the need for a ureteral stent, a small, temporary device placed in the urinary system. The decision to place a stent is individualized, balancing the discomfort it may cause against the significant complications it helps to prevent.
How Lithotripsy Works to Clear Kidney Stones
Lithotripsy aims to reduce the size of kidney stones so they can exit the body naturally through the ureter and urethra. Two primary procedures achieve this fragmentation: Extracorporeal Shock Wave Lithotripsy (ESWL) and Ureteroscopy (URS). ESWL is a non-invasive technique using focused high-energy sound waves delivered from outside the body to shatter the stone within the kidney or upper ureter. The goal is to reduce the stone to particles small enough to pass with urine.
Ureteroscopy is a minimally invasive method where a thin, flexible scope is passed through the urethra and bladder into the ureter. Once the stone is located, a laser or other device fragments it, and the surgeon may remove some pieces directly. Regardless of the method used, the procedure creates stone fragments that must travel down the narrow ureter. This passage of fragmented stones is the primary reason for potential complications, leading to stent consideration.
The Primary Function of a Ureteral Stent
A ureteral stent is a thin, hollow tube, typically made of flexible plastic, that is temporarily placed inside the ureter, the duct connecting the kidney to the bladder. The stent has a small coil or curl at each end, often called a Double-J stent, to anchor it in the kidney and the bladder, preventing migration. The stent acts as an internal splint, ensuring the ureter remains open and functional after the stone procedure.
The stent’s main job is to ensure continuous urinary drainage from the kidney to the bladder, bypassing any potential blockage. This drainage is important because the ureter often swells following stone manipulation or fragmentation, a condition known as ureteral edema. By holding the ureter open, the stent prevents urine backup into the kidney (hydronephrosis), which can cause severe pain and potentially damage the kidney.
The stent also creates a clear pathway for stone fragments to exit the kidney without causing obstruction. This is particularly important after ESWL, where numerous fragments are left to pass naturally, potentially forming a “stone street.” Furthermore, the stent prevents ureteral spasms, which can occur after instrumentation and contribute to pain and temporary blockage. Maintaining an open channel mitigates the risks of post-procedure obstruction and infection.
Criteria for Deciding Stent Placement
The decision to place a ureteral stent is determined by the specific circumstances of the procedure and the patient’s individual health factors. While stenting has historically been routine, current practice favors selective placement, especially after uncomplicated procedures. Surgeons use their intraoperative judgment based on how the ureter handled the procedure.
Stent placement is mandatory when the ureter has been injured or perforated during the scope procedure. It is also recommended if the patient had a pre-existing infection or significant kidney swelling (hydronephrosis) before the lithotripsy. These factors indicate a higher risk of complications if the kidney’s drainage is compromised.
In Ureteroscopy cases, a stent is more likely if the stone burden was large or if the surgeon had difficulty removing all fragments. Leaving a stent helps manage the high volume of residual debris that must still pass. Conversely, for smaller stones and uncomplicated procedures, the surgeon may opt for stent omission to reduce patient discomfort, balancing stent morbidity against the risk of post-operative obstruction.
Managing and Removing the Ureteral Stent
Living with a ureteral stent is associated with temporary and manageable side effects during recovery. Common symptoms include flank pain, which may worsen during urination due to urine refluxing up the ureter, and increased urinary frequency or urgency. Many patients also notice blood in their urine (hematuria), which is normal and typically resolves after the stent is removed.
Managing this discomfort involves staying well-hydrated, aiming for at least 100 ounces of fluid daily, which helps flush the urinary system and minimizes clotting risk. Medications may be prescribed to help relax the ureter and bladder, reducing spasms and associated pain. Patients must promptly contact their physician if they develop a fever, uncontrolled pain, or an inability to urinate, as these may signal a serious infection or stent blockage.
The stent is a temporary device and must be removed, usually within a few days to two weeks after the procedure, depending on the case complexity. Removal is typically performed in the doctor’s office using a cystoscopy, where a small camera is inserted into the bladder to grasp and withdraw the stent. In some instances, if an external string was left attached, the patient may be instructed to remove it themselves at home.