URINARY STONES

URINARY STONES

 

Dissolved substances in the urine may become concentrated and form crystals that aggregate to form stones. The majority of stones contain a material called calcium oxalate. Other types are calcium phosphate, uric acid, cystine and struvite.

Some risk factors for urinary stones:

1) Inadequate fluid intake 2) A high-protein diet by increasing acid content in the body and lowering urinary citrate; 3) A high-salt diet, as increased sodium in urine also pulls calcium with it; 4) Intake of oxalate-rich foods such as leafy vegetables, tea or chocolate; 5) A family history and past history of stones

Symptoms of urinary stones:

1)    Pain in the flank or abdomen 2) Hematuria 3) Infection/Fever 4) Renal failure 5) Silent

 

Investigations For Urinary Stones:

1) Blood test for kidney function and to check the level of calcium, phosphate, uric acid; 2) Urinalysis and culture and 24 hour urine sample for calcium, oxalate, uric acid, citrate & phosphate; 3) Intravenous urogram (IVU); 4)Ultrasound/CT scan/Renal dynamic scan (in special situations) 5) Stone analysis

Treatment options for urinary stones:

Stone size, the number of stones, their location and stone composition (if known) are the most important factors in deciding the appropriate treatment for a patient with stones.

 

Shock Wave Lithotripsy (SWL): This is a non-invasive treatment under sedation, useful for stones < 1.5-2 cm in size in the renal pelvis, upper and middle calyx, and < 1 cm in size in the ureter and inferior calyx. Shock waves from a generator are focused to fragment the stone and the fragments are passed out with urination. This is not a good modality for very hard or large stones since they may not clear even with multiple sessions of SWL. Patients are discharged the same day and are back to normal activity in 2-3 days. Potential problems are flank pain, blood in the urine, infection and fever. Repeat sessions of SWL may be required in some cases.

 

Ureteroscopy (URS): This treatment, under anesthesia, uses a rigid or flexible instrument called a ureteroscope, which allows access to stones in the ureter or kidney. Under direct vision the stone is fragmented and/or removed by progressing up the ureter via the bladder. Sometimes a ureteric stent may be required. Patients are discharged the same day and are back to normal activity in 2-3 days. Potential problems include pain, blood in urine, ureteral wall injury and fever.

 

 Percutaneous Nephrolithotomy (PCNL): PCNL, under general anesthesia is the treatment of choice for large stones located in the kidney that are not suitable for SWL or URS. Through a 1-cm incision in the flank, a track is made into the kidney and stones from the kidney or upper ureter fragmented and/or removed under direct vision with an instrument called a nephroscope. Sometimes more than 1 track is made into the kidney. Once the procedure is complete, a tube is left in the flank to drain the kidney. A ureteric stent may also be placed. Patients are discharged in 2-3 days and back to normal activity in 7-14 days. Sometimes relook procedures may be required. Potential problems include, pain, blood in urine, severe bleeding from the kidney which may require transfusions, angiographic embolization or very rarely a nephrectomy, chest complications, urinary infection and fever. Some patients may require combined treatment with PCNL and SWL (sandwich therapy).

 

Open surgery: A large incision in the flank is required and the portion of kidney overlying the stone or the ureteral wall is then cut and the stone removed. At present, open surgery is used only for very complicated cases of stone disease. Patients stay in hospital for about a week and take about 6 weeks to get back to normal activity. Potential problems include wound infection, bleeding and fever.

Things to remember:

1) The risk is higher with more invasive treatments such as PCNL & open surgery than with SWL or URS. With these, the overall mortality is < 1 in a 1000 cases, while the morbidity is about 10%;

2) If a stent is placed it should be removed in a couple of weeks, otherwise serious complications may ensue. Stents are usually well tolerated but sometimes may cause irritative symptoms;

3) Blood/urine test and stone analysis will dictate subsequent measures for prevention of stone recurrence, which can occur in 50% of patients over 10 years. Most cases will require increased water and potassium citrate intake and a decrease in salt and animal proteins in the diet. Reduction of foods rich in calcium or oxalate depends on individual defects or type of stone. Some patients may require additional medication to prevent recurrence or infection;

4) After discharge if you have persistent high grade fever or large amount of blood in the urine or severe pain in the flank or abdomen, report to your doctor immediately;  

5) Patients with renal failure may require dialysis and other special measures;

 6) This is only a brief guide and cannot cover all aspects and eventualities.