kidney Stone

Kidney Stone

The urinary tract consists of a pair of kidneys which are two bean shaped organs situated in the back on either side, behind all the abdominal

organs. The kidneys have a rich supply of blood, and this blood is "filtered" through a system of tiny tubes within the kidney called the "nephrons" or "renal tubules". The waste matter filtered out of the blood is drained out as urine. In each kidney the urine draining out from the tubules is collected into a branching system of larger tubes called the minor and major calyces. The calyces join together to form the renal pelvis and from the renal pelvis the urine is carried down by a small tube called the ureter down into the bladder. From the bladder the urine is drained out by the urethra.

Kidney stones

An overview

The urine which is filtered from the kidneys contains minerals like calcium, phosphorus, sodium, uric acid, oxalates. If the saturation of these minerals increases in the urine because of increased solutes content or decreased water  or if the flow of urine is retarded  for any reason there is a risk of deposition and aggregation of these minerals resulting in stone formation. Stone formation is influenced by dietary factors, nature and amount of fluid intake, age, sex, climate, geography, hygiene, race, occupation.

Where do stones form?

Virtually all stones are formed in the kidneys, initially as small particles. These particles grow within the kidney to varying sizes, often filling up the whole kidney as a branched stone (the staghorn calculus). Sometimes they move out of the kidney when relatively small, and then migrate down the ureter into the bladder. As they migrate down the ureter they may get stuck in any part of ureter and block it causing obstruction to the flow of urine: Larger the stone and higher the location of stone in ureter, higher is the chance of getting it blocked, this results in pain which may be very severe (colic). Ureteric orifices in bladder are very narrow openings around 2-3mm, so stones up to the size of approx 4mm may pass spontaneously. Some reach the bladder, and lodge there, growing larger and larger. Rarely they block the urethra causing a painful retention of urine.

Symptoms of urinary calculi

Pain : it characteristically starts from the back or lower part of the abdomen and spreads to the entire side . Sometimes it is also referred to the external genitalia and thighs The location and severity of the pain depends upon the location of the stone in the urinary tract, the degree of obstruction, and kidney function. Poorly functioning kidneys cause less pain.

Other symptoms include

  • Blood in urine
  • Fever which indicates infection
  • Urinary trouble
  • Nausea and vomiting
  • Tenderness in the abdomen and on the sides of the spine

Diagnosis

Ultrasound : A widely available investigative modality, detects stones in the kidney with reasonable accuracy. It can also detect the dilated kidney and ureter thus indicating obstruction in the urinary tract. It is less sensitive in localizing ureteral stones, many times fails to see ureteric stones because of abdominal gas.

X-ray KUB : It can detect stones that are radio opaque (i.e. Seen on x-ray). However the accuracy of x-ray depends upon the amount of gases present inside the abdomen and density of the stone.

Intra Venous pyelography(IVP) : This test involves taking a series of x-rays after injecting contrast (dye) into the vein. The contrast flows through the veins and is excreted by the kidneys. As it can be seen on the x-ray, the whole urinary tract containing the contrast can be delineated. Any obstruction in the urinary tract can be picked up. It can also indicate the kidney function and level of stone. A normal kidney function test is a pre requisite to perform IVP.

CT Scan : A non contrast CT scan is the fastest and most accurate investigation for urinary calculi. It can be performed without the need for contrast and thus is safe in patients with history of radio-contrast allergy. It also gives an opportunity to screen other abdominal organs at the same time. Ct scan is now a days investigation of choice for urinary stone disease.

Treatment of kidney stones

Treatment of urinary stones depends upon

  • Size of stone,
  • Number of the stones
  • Location
  • Kidney function
  • Severity of symptoms
  • Presence of infection
  • Anatomy of the urinary tract

Treatment modalities

  • ESWL or Extra-corporeal Shock Wave Lithotrips
  • PCNL or Per Cutaneous Nephrolithotomy
  • URS or Ureterorenoscopy
  • RIRS or Retrograde Intrarenal Surgery
  • Laparoscopic surgery
  • Open surgery

ESWL

This procedure focused shockwaves from outside the body to crush stones in the urinary tract. The stone breaks according to its hardness. Soft stones break into sand like particles which pass in the patient’s urine. It is used for stones upto 1 cm in the kidney and upper parts of the ureter. More than one session may be required for breaking the stone. It should not be used in pregnant women. Sometimes the stone pieces get stuck while coming out and may require a ureteroscopic removal or temporary insertion of a stent. Success rate depends upon size, location and hardness of stone. Overall success rate is only around 70%. Not a preferred mode of treatment now a days

PCNL

This is one of the most common methods currently employed in the removal of kidney stones. This procedure involves establishing a tract /puncture from the skin into the kidney through which fine nephroscope (telescope) is passed inside into kidney and the stone is broken into smaller pieces with lithoclast/laser and removed. It can be used for stones of any size. Multiple tracts maybe required for complex/larger stones. The incision used for making these tracts is 5 to 10 mm. and does not require to be stitched usually. Hospitalization is usually required for 2 to 3 days and the patient can resume normal work in a weeks time. It has highest success rate approaching upto 95%- 100% for any size of the stone. The only major risk of this operation is bleeding which is unpredictable and can occur in upto 1- 3 % of the patients requiring blood transfusion. Sometimes may require 2nd sitting of PCNL for large stone burden or if unpredictable bleeding occurs Now a days with advancement of technologies mini-PCNL and micro-PCNL are also done

URS

As the name suggests it involves insertion of fine instrument through the penis into the ureter. The stone can be visualized, broken by lithoclast/ laser and removed. It is indicated for the treatment of ureteric stones which are stuck up in ureter, obstructing urine flow and causing sever pain, infection or haematuria. Sometimes in the presence of infection or very tight ureter the procedure is done in two stages. A ureteric stent is usually required to be placed at the end of the procedure which is removed after two weeks.

RIRS

This is a form of uretero-renoscopy, here the instrument used is flexible and thus can negotiate most parts of the ureter and kidney from below. It obviates the need for puncturing the kidney for small renal stones which cannot be taken care of by simple lithotripsy. As it uses fiberoptics and delicate instruments cost of the surgery is high. It is indicated for smaller (<1.5cm) kidney stones. Success rate depends upon size and location of stone. Overall success rate is around 90% but lesser for lower calyceal (pole) stone

Open/Laparoscopic Surgery

These modalities are rarely used currently, however they have their own place in certain special situations.

Is there a medicine for stones?

There is no known medicine that dissolves urinary stones consistently and predictably. One should drink plenty of fluids, and the doctor will advise you about a specific diet if indicated

Prevention of stone disease

No discussion on urinary stones is complete without an information on their prevention. The recurrence rates over a period of ten years is upto 50%. General preventive measures are increased intake of fluids, citrus fruit juices and limiting intake of salt, meat, chocolate, dry fruits, high oxalate containing vegetables like spinach, cauliflower, tomato, bringle etc. Urinary tract infections and other abnormalities should also be corrected. The patient should drink enough fluids so as to produce a urine output of more than 2 litres. Special tests like stone analysis and metabolic work up help in finding the cause of kidney stones in an individual. Contrary to the popular belief beer is not helpful in the prevention and expulsion of stones.