Stone disease is among the most prevalent and painful urological disorders. More than a million kidney stone cases are diagnosed each year with an estimated 1 out of every 10 Americans are destined to suffer from kidney stones at some time in their lives.
Kidney stones (calculi) are hardened mineral deposits that form in the kidney. They originate as microscopic particles or crystals and can develop into stones over time. The medical term for this condition is nephrolithiasis or renal stone disease.
Kidney Stone Formation
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 may form. The kidneys must maintain an adequate amount of water in the urine to dissolve all the removed waste products. If dehydration occurs, high levels of substances that do not dissolve completely (e.g., calcium, oxalate, uric acid) may form crystals that slowly build up into kidney stones.
Stones may either pass out of the kidney with normal urination or can become lodged in the kidney or ureter requiring surgical intervention depending on the size and location.
Kidney Stones Signs & Symptoms
Once stones form in the urinary tract, they often grow with time and may change location within the kidney. Some stones may be washed out of the kidney by urine flow and end up trapped within the ureter or pass completely out of the urinary tract. Small, smooth kidney stones may remain in the kidney or pass without causing pain (called silent stones). Stones usually begin causing symptoms when they block the outflow of the urine from the kidney leading to the bladder because it causes the kidney to stretch. The pain is unrelated to the size of the stone and often radiates from the lower back or abdomen and to the side of the affected kidney and possibly into the groin.
The first symptom is extreme, intense pain in the lower back that often begins suddenly as the stone moves in the urinary tract, causing irritation and possible blockage of urine. If the stone is too large to pass easily, pain continues as the muscles in the wall of the tiny ureter try to squeeze the stone along into the bladder. One may feel the need to urinate more often or feel a burning sensation during urination. In a man, pain may move down to the tip of the penis. If the stone is close to the lower end of the ureter at the opening into the bladder, a person will frequently feel like they have not fully completed urination. Sometimes a person will complain of blood in the urine, nausea &/or vomiting and fever &/or chills. Occasionally stones do not produce any signs or symptoms.
Kidney Stone Diagnosis
Kidney stones are found on an X-ray or Ultrasound. These diagnostic images give the doctor valuable information about the stone’s size and location and number of stones present and provides necessary and vital information to the urologist to determine appropriate intervention &/or treatment. Blood and urine tests also help detect any abnormal substance that might promote stone formation.
If your doctor suspects a stone but is unable to make a diagnosis from a simple X-ray, he or she may scan the urinary system with computed tomography (CT) Scan. A CT Scan is an imaging technique that is the gold standard for stone diagnosis as it is an extremely accurate diagnostic tool that can detect almost all types of kidney stones quickly and painlessly. Historically intravenous pyelogram (IVP) was used but this requires intravenous contrast dye and a series X-rays.
Kidney Stone Treatment
Kidney stone treatment depends on the size, location and type of stone present. Stones 4 mm and smaller (less than 1/4 inch in diameter) can usually pass without intervention. Stones larger than 5 mm require some form of treatment (medication or surgical interventions) and those larger than 7 mm rarely pass without a surgical procedure being performed. Patients are advised to increase fluid intake and keep physically active, including walking to promote urine flow and assist in passing of stones.
Extracorporeal Shockwave Lithotripsy (ESWL®)
ESWL® is a completely non-invasive form of treatment for kidney stones and is performed in an outpatient surgery center. Recovery time is short and most people can resume normal activities in a few days. However, one ESWL® session by itself may not free the ureter of all stone material, and either a repeat ESWL® session or treatment with another approach may be necessary. ESWL® is not the ideal treatment choice for all patients. Patients who are pregnant, obese, have obstruction past the stone, have abdominal aortic aneurysms, urinary tract infections or uncorrected bleeding disorders should not have ESWL®. In addition, certain factors such as stone size, location and composition may require other alternatives for stone removal.
Shock Wave Lithotripsy (ESWL®) is the most frequently used procedure for eliminating kidney stones by using shock wave treatment. It works by directing ultrasonic or shock waves, created outside your body (“extracorporeal”) through skin and tissue, until they hit the dense kidney stones. The impact causes stress on the stone. Repeated shock waves cause more stress, until the stone eventually crumbles into small pieces. These sand-like particles are easily passed through the urinary tract in the urine. The technology is only effective if the kidney is functioning well and there is no blockage to the passage of stone fragments.
Ureteroscopy with or without Laser (URS) or Laser Lithotripsy
This treatment involves the use of a very small, fiber-optic ureteroscope allowing your urologist to directly visualize the stone. The thin scope is inserted into the urethra and advanced into the bladder, ureter and kidney, no incisions are necessary and general anesthesia is used to keep the patient comfortable during the procedure.
Once the stone is visualized through the ureteroscope, a small, basket-like device can be used to grasp smaller stones and remove them. If a stone is too large to remove in one piece, it can be fragmented into smaller pieces. Most commonly this is accomplished with laser energy.
Once the stone has been completely treated, the procedure is done. In many cases, the urologist may choose to place a stent within the ureter, to allow any post-operative swelling to keep the ureter open for easy passage of stone fragments.
Percutaneous Nephrolithonomy (PCNL)
Preferred treatment for very large &/or very dense stones located within the kidney that cannot be effectively treated with either ESWL® or URS. General anesthesia is required to perform a PCNL and is performed in the hospital operating room. The main advantage of this approach compared to traditional open surgery is that only a small incision (about one centimeter) is required in the flank area directly behind the kidney. A tube is inserted directly into the kidney under radiographic guidance and directed down the ureter allowing the nephroscope to be inserted through the tube to view the stone. The stone can be removed or fragmentation can then be done using an ultrasonic probe or laser. Because the tract allows passage of larger instruments, your urologist can suction out or grasp the stone fragments as they are produced. This results in a higher clearance of stone fragments than with ESWL® or URS.
Once the procedure is complete, the tube is usually left in the flank to drain the kidney for a period of time, from overnight to several days.
At present, open surgery is used only in extremely rare situations for highly complex cases of stone disease or very large, unpassable stones that cannot be treated with any of the above procedures. Open surgery requires a hospital stay for a few days and full recovery time may take up to 6 weeks.
Open surgery requires a large incision in your side to expose the kidney or portion of ureter that is involved with the stone. Your kidney or ureter is surgically opened were the stone is present and the stone is removed and a drain is placed to assist with urine flow. Once the stone is removed and the tube is placed, dissolvible sutures are used to close the kidney and your wound is closed and the tube is secured with sutures. The tube is removed prior to your discharge from the hospital.