Kidney Stone

Kidney stones (calculi) are hardened mineral deposits that form in the kidney.

The kidneys filter waste products from the blood and add them to the urine that the kidneys produce. When waste materials in the urine do not dissolve completely, crystals and kidney stones are likely to form. These stones may stay in the kidney for a long time or they may pass out of the kidney and become lodged in the tube that carries urine from the kidney to the bladder (ureter). If left untreated, the kidney may swell and lose its function.

Stone Formation

Kidney stones form

Urine normally contains chemicals—citrate, magnesium, pyrophosphate—that prevent the formation of crystals. Low levels of these inhibitors can contribute to the formation of kidney stones. Of these, citrate is thought to be the most important.

Signs and Symptoms

Stones that lodge in the tube that carries urine from the kidneys to the bladder (ureter) results in severe pain that begins in the loin and lower back and radiates to the groin or front of the lower abdomen.

A ‘small’ stone (usually 4 mm in diameter or less) has a 90% chance of spontaneous passage. Stones larger than 6 mm in diameter has less than 10% chance of passage.

Other symptoms of kidney stones may include the following:

Diagnosis

Diagnosis of renal stone disease involves

Laboratory tests include urinalysis to detect the presence of blood (hematuria) and bacteria (bacteriuria) in the urine. Other tests include blood tests for creatinine (to evaluate kidney function) and a complete blood count ( to detect infection).

Imaging tests

Imaging tests used to diagnose kidney stones include:

• Ultrasound

Ultrasound can detect a dilated (swollen)) upper urinary tract and kidney caused by a stone lodged in the ureter, but usually cannot detect small stones, especially those located outside the kidney (in the ureter). It is the preferred imaging method for kidney stone patients who are pregnant.

• Intravenous Pyelogram (IVP)

This test involves taking a series of x-rays after injecting a contrast agent (dye) into a vein. Most kidney stones can be precisely located using this procedure. There is a slight risk for an allergic reaction to the contrast agent during this procedure and overall kidney function must be normal.

• Retrograde Pyelogram

This procedure eliminates the risk for an allergic reaction to the contrast agent because the dye does not reach the bloodstream, but it may require anesthesia. While retrograde pyelogram is the most reliable method for visualizing the urinary system and detecting stones, it is generally used only when other imaging methods are inadequate or unsuccessful.

• Computerized tomography (CT Scan)

This test uses a scanner and a computer to create images of the urinary system. It is performed quickly. CT scan can also help identify medical conditions (e.g., ruptured appendix, bowel obstruction) that cause symptoms similar to kidney stones. The non-contrast CT scan is the most common imaging test used to evaluate a possible kidney stones.

Treatment

Indications for surgical intervention include

Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal Shock wave lithotripsy uses shock waves to break stone smaller than 2 cm into small fragments that can more easily flushed out of the urinary tract and pass out from the body. After identification of the position of the stone with X-ray or ultrasound, shockwaves are applied to fragment the stones. ESWL treatment can be used to treat urinary stones in the kidney and ureter (urine pipe that brings urine from kidney to bladder).

This procedure takes about 45 minute’s to1 hour, and is often done as an Outpatient Procedure. Intravenous analgesia is given to ensure a pain free experience. This procedure is very safe and causes no significant damage to the kidney. It can be repeated and may have to be repeated for larger or harder stones. Main drawback of the procedure is some stone are not well seen and some are hard to break.

Surgical intervention

• Ureteroscopy – Involves the use of a scope that can be inserted up the urethra, through the bladder and into the ureter without an incision. Stones are fragmented using Holmium laser at Apollo Hospitals, chennai.Laser is universal energy source that breaks all stones. Laser breaks stones into powder and it has an added advantage that the fragment need not be removed from the ureter .There is no pain in the postoperative period as there is no fragments to pass as in case of standard lithoclast used for stone fragmentation.

• Open Surgery – Ureterolithotomy refers to the open surgical removal of a stone from the ureter.

• Percutaneous surgery (PCNL) – Under anaesthesia a nephroscope is passed through an incision made in the flank area to locate and remove the stone. For larger stones, an ultrasonic probe may be needed to break the stone into small pieces.

• ESWL (Extracorporeal shock wave lithotripsy) – In ESWL, shock waves that are created outside the body travel through the skin and body tissues until they hit the stones. The stones break down into sand-like particles that are easily passed out through the urine.
• Repeat ESWL sessions may be necessary.

Laser

MINI PCNL

RIRS

Staghorn Calculi (Large stones, more than 2cm)

Staghorn Calculi – Treatment

Combinations of percutaneous stone removal and extracorporeal shock-wave lithotripsy (ESWL) are used remove staghorn calculi

How can I avoid getting more kidney stones?