Stones in the urinary tract is very common in the Indian subcontinent with a lifetime prevalence of upto 15%. The most common age group affected is 30 to 60 years.
What causes Stone Formation?
The first question that arises in a patient’s mind is “why has my body formed this stone?” The primary cause is genetic (not to be confused with hereditary). Means there is a chemical imbalance in the blood with stone-forming elements(oxalates) being more than the stone inhibitors(citrates). This is the reason that upto 50% of urinary stone patients are recurrent stone formers. Other reasons are hyperuricemia, cystinuria, chronic UTI, Diabetes mellitus, obesity, hypercalciuria, chronic dehydration etc.
Signs and Symptoms
Usually, the first symptom is pain, which is dragging or dull aching if the stone is located in the kidneys but becomes excruciating when the stone gets lodged in the ureter.
The ureters are slender structures measuring around 4-5mm in diameter, making it very difficult to allow passage of bigger stones. Sometimes patients experience a complete inability to pass urine (retention of urine). This happens when the stone gets stuck in the urethra (Passage of urine from the bladder to outside). Blood in urine and urinary tract infection are other possible symptoms. Sometimes, unfortunately, the patient presents very late after the kidneys have been permanently damaged. This happens when the stone has not caused any symptoms or the symptoms have been ignored for long. This is the reason I believe that stones causing pain are good for the patients compelling them to seek treatment early and thus protecting their kidneys.
Diagnosis and Workup
The best modality for diagnosing a stone in the urinary tract is CT Scan (NCCT KUB) with a sensitivity greater than 95%. Ultrasound is a good screening tool though. Any stone removed surgically from the urinary tract should be analyzed for chemical composition. Metabolic investigations of the blood and urine (either spot sample or 24 hours sample depending upon case) is performed to detect any abnormality precipitating stone formation.
Most important precautionary measure is adequate fluid intake. Precisely the amount of fluid taken should be enough to produce around 2 litres of urine. Put simply 2.5 to 3 litres of fluid intake is adequate in people not involved in strenuous physical activities. This amount should be increased proportionally if you are sweating more due to increased sun exposer or physical activity. The next important dietary advice is to limit salt intake. Sodium in salt precipitates oxalate leading to stone formation. Junk food, cola, salted fries, pickles etc should be avoided. Maintain a good intake of dietary calcium (milk, curd etc) but avoid calcium supplements, unless medically indicated. Fresh fruits and vegetables are protective against stone formation. The age-old theory of avoiding fruits and vegetables with seeds is questionable in today’s time. Recent researches prove that the effect of oxalate in seeds is nullified by citrate, magnesium etc present in the rest of the fruit or vegetable. However, calcium oxalate (most common type) stone formers should avoid excessive intake of oxalate-rich foods like black tea, spinach, cocoa, mustard greens, beets, okra, chocolate, nuts, wheat germ, pepper.
Medical treatment of specific conditions if present prevents recurrence. Some examples are hyperuricemia, cystinuria, renal tubular acidosis, hyperthyroidism. Known oxalate stone formers are prescribed citrate medication, usually in syrup form, to be taken for 6 months to 2 years
Larger stones that are stuck in the ureter can damage the kidneys permanently if ignored for more than 2 weeks. The damage is not reversed on removing the stone later on. If such is the case in both the kidneys then the patient may become dialysis-dependent or has to undergo a kidney transplant. Stones lodged in the urethra can cause urethral stricture disease which requires a long treatment including a separate surgical procedure. Ignored stones can be a cause of recurrent urinary tract infections.
Urological stone is one such entity for which innumerable regional medicines and advice are available, ultimately confusing and disappointing the patient. Please remember that any stone in the urinary tract has to either traverse the urinary passage spontaneously to come out or has to be removed endoscopically/surgically. These are real stones and there is no chemical that can dissolve them even if put outside the body so, it’s practically impossible to dissolve urinary tract stones with medicines. Medical expulsive therapy (MET) is prescribed in the case of smaller ureteric stones to relax the passage and facilitate expulsion. Size matters here. Stones upto 5 mm are likely to pass off spontaneously in 80-90% of cases. This probability decreases as the size increases with only upto 10-15% chances of spontaneous passage for stone larger than 7-8 mm. Such stones require intervention endoscopically to prevent any damage to the kidneys.
Miniaturization of endoscopic instruments and lasers have revolutionized the surgical management of urinary tract stones. For stones in the ureter, urethra or urinary bladder a very slender instrument is introduced through the normal urinary passage and the stones removed after fragmenting with laser (URS, RIRS, cystolithotripsy). Larger stones in the kidney are dealt with by making a small hole (15-20mm) in the back and removing the stones with laser fragmentation (PCNL, Mini PCNL) The hospital stay in all these procedures is usually one day and the patient can resume daily activities after discharge.