Stones in the Urinary tract (Kidney, Ureter, Bladder and urethra) are one of the most common afflictions of the developing world with an estimated prevalence of 8-10%. Most common age at presentation is fourth to sixth decade and males are more commonly affected.
Anatomy: Urine is produced in the kidneys and is carried to the bladder by thin tubes called ureters. The urinary bladder stores the urine which is passed out through urethra
The most important cause of stone formation in the urinary system is an imbalance of certain chemicals in the blood, namely citrate and oxalate. This imbalance is present by birth and affects males more than females. Other factors promoting stone formation are dehydration, recurrent urinary tract infection, hyperparathyroidism, Gout, obesity and metabolic syndromes, diabetes and excessive salt intake.
Importance of size:
Stones lesser than 5 mm in the kidneys or ureters have around 70% chances of spontaneous passage. This percentage decreases as the size increases with only 5-10% probability for stones 8mm or bigger. Age of the patient, anatomy of ureters, shape of the stones are other important factors defining spontaneous passage.
Symptoms: Pain is the commonest symptom and uretericstones are known to produce one of the worst pains in humans. There might be blood and burning in urine, fever, retention of urine, nausea and vomiting.
Diagnosis: Ultrasound picks up majority of urological stones but CT scan is more accurate in defining the exact size and location. Urine examination is helpful in determining associated infection and bleeding.
Treatment: Stones less than 5-6mm and patient not in severe pain are given a trial of spontaneous expulsion with medicines. Adequate fluid intake averaging 3litres a day for an adult is very important during this treatment. It is important to understand that endoscopic removal should be done if pain is unbearable. Also, this trial should not be continued beyond 2 weeks as the obstructing stone may lead to permanent damage to the kidneys.
Bigger stones and small stones not responding to medical treatment require endoscopic removal. Majority of them can be removed by very slender scopes passed in through normal urinary passage without the need for a cut or hole(URS,RIRS). Very big and complex kidney stones are removed by making a 10-15mm hole at the back(PCNL). A teflon stent is usually placed after these procedures which is removed after 2-4 weeks.
Prevention: 3 most important prevention tips
- Plenty of oral fluids( 3ltrs a day for an average adult working in moderate climatic conditions)
- Limit salt intake (6gms or one teaspoon a day)
- Citrate supplementing medicines taken for 1-2 years
Medical conditions like hyperparathyroidism, diabetes, obesity, gout etc require specific treatment.