Kidney STONE Calculator for Percutaneous Nephrolithotomy
Please enter the following CT scan-based information to assess the chance of a stone-free outcome after PCNL:
Important Note
This calculator uses the **STONE nephrolithometry scoring system**, designed to estimate the success rate of **Percutaneous Nephrolithotomy (PCNL)**, a surgical procedure for kidney stone removal.
Here's what each parameter means:
- Stone size (mm²): Calculated by multiplying the longest length and width of the stone on a CT scan. Larger stones are harder to remove entirely.
- Tract length: The distance from the skin to the stone. Longer tracts are technically more challenging during surgery.
- Obstruction (hydronephrosis): Indicates if the kidney is swollen due to blocked urine. Severe obstruction complicates treatment.
- Number of calyces with calculi: More affected calyces (branches of the kidney) indicate a more complex stone pattern. A staghorn stone fills much of the kidney.
- Stone density (Hounsfield Units): Measured on a CT scan; denser stones are harder to break during surgery.
The total score ranges from **5 to 13**, and a **lower score** is associated with a **higher chance of being stone-free** after PCNL. While this tool provides valuable insight, it’s not a replacement for a detailed evaluation by a healthcare professional.
Percutaneous Nephrolithotomy
Percutaneous nephrolithotomy (PCNL) is a type of kidney stone removal procedure. It is typically used for large stones (greater than 1.5 cm) or when other, less-invasive methods have failed or are not suitable.
The Procedure - Step by Step
PCNL is usually performed under general anesthesia. Below are the key steps involved in the procedure:
- Insertion of the sheath: A tube (sheath) is inserted through a small incision on the patient's back, reaching the kidney's calyx.
- Insertion of instruments: Surgical instruments are passed through the sheath. These may include:
- A telescope to visualize the stone,
- A laser or other tools to break the stone into smaller pieces,
- And devices to remove the fragments from the body.
- Drainage placement: A nephrostomy tube and/or ureteral stent is often placed to allow proper urine flow after the procedure. These are removed in follow-up visits.
Potential Complications
Like all medical procedures, PCNL may come with some risks. Potential complications include:
- Bleeding
- Injury to the kidney or nearby organs
- Infection
- Failure to remove the stone completely
This is a medical support tool inspired by peer-reviewed clinical studies. For decisions related to your health, always consult a licensed urologist or healthcare professional.