Kidney stone surgery is a common intervention. Kidney stones are hard masses of crystallized minerals and salts that form inside the kidneys. Surgical removal becomes necessary when a stone grows too large to pass naturally, blocks urine flow, or causes an infection or unmanageable pain. Modern techniques have made stone removal highly effective, minimizing invasiveness compared to traditional open surgery. While the danger is generally low for most patients, understanding the specific risks associated with each method provides a realistic view of the treatment landscape.
The Main Surgical Approaches
The treatment of kidney stones involves three primary approaches, varying in their invasiveness.
Extracorporeal Shock Wave Lithotripsy (ESWL)
Extracorporeal Shock Wave Lithotripsy (ESWL) is the least invasive. It uses focused high-energy shock waves generated outside the body to break the stone into tiny fragments. These small pieces then pass naturally through the urinary tract over days or weeks. ESWL is typically performed on an outpatient basis and does not require a surgical incision.
Ureteroscopy (URS)
Ureteroscopy (URS) is a minimally invasive technique. A small, flexible telescope is inserted through the urethra and bladder, guided up the ureter to the stone location. The stone is then either removed whole with a basket device or broken down using a laser (laser lithotripsy). This method allows for immediate removal of stone fragments and is often used for stones located in the ureter or kidney.
Percutaneous Nephrolithotomy (PCNL)
Percutaneous Nephrolithotomy (PCNL) is the most invasive of the three, reserved mainly for very large or complex stones. The procedure requires a small, approximately one-centimeter incision in the patient’s back to create a tract directly into the kidney. A telescope is passed through this tract to break up the stone and remove the fragments in one session. PCNL offers the highest stone-free rate in a single procedure but involves a longer hospital stay compared to the other two methods.
Potential Complications of Kidney Stone Removal
The main risk across all kidney stone removal procedures is infection, which can escalate to sepsis. The incidence of sepsis varies, ranging from about 0.5% to over 6% for Ureteroscopy and 0.3% to nearly 6% for PCNL. The risk is particularly elevated if the stone is infected, as the procedure can release bacteria into the bloodstream. Patients often receive antibiotics before the procedure to mitigate this risk.
Bleeding is another common complication, especially with the more invasive PCNL, which requires creating a tract into the kidney. Mild blood in the urine (hematuria) occurs in about half of PCNL patients and is expected. Clinically significant bleeding requiring a blood transfusion occurs in approximately 4% of standard PCNL cases, and up to 15% in complex cases involving multiple access points. ESWL can also cause minor bleeding around the kidney, which may result in bruising.
Damage to the urinary tract organs is a specific concern depending on the approach. During Ureteroscopy, there is a small risk of injuring the ureter, potentially leading to swelling or the formation of a ureteral stricture (a narrowing of the tube). PCNL carries a rare risk of injuring surrounding organs, such as the bowel, spleen, or lung; pleural complications like pneumothorax occur in about 1% of cases. Residual stone fragments are a common complication across all procedures, which may require additional treatment to fully clear the kidney.
Variables That Increase Surgical Risk
The overall danger level for kidney stone surgery changes based on several patient-specific factors. Pre-existing medical conditions (comorbidities) significantly increase the probability of complications. Patients with diabetes mellitus, for instance, have nearly double the risk of developing a post-procedure infection. Obesity and heart disease also contribute to higher anesthesia risks and can make the surgical approach more challenging.
The characteristics of the stone itself also elevate the procedural risk. Very large stones, exceeding two centimeters, often necessitate the more invasive PCNL, which has a higher complication profile than ESWL or Ureteroscopy. The stone’s location within the kidney or ureter can make access difficult, increasing the operative time. Increased operative time is an independent risk factor for infectious complications. Stones composed of certain materials, such as cystine, are harder to fragment with ESWL, leading to the need for multiple procedures and prolonged exposure to risk.
The expertise of the medical team is another factor influencing the outcome. The skill and experience of the surgeon can help mitigate the risk of organ injury and minimize the need for multiple access points in PCNL, which correlates with fewer complications. The presence of a known urinary tract infection or a positive stone culture prior to surgery is a major predictor of postoperative sepsis, requiring aggressive antibiotic therapy to manage the increased infectious risk.