Stones in Urinary Tract

Kidney Stones

What are kidney stones?

Stones form in the kidney when certain organic and inorganic crystals amalgamate with proteins and precipitate in the urine under favourable conditions, for example, persisting states of dehydration. This initially results in crystal formation, but when favourable conditions persist it results in formation of larger stones.

Calcium stones are the most frequent type accounting for nearly 80%.

How common are kidney stones?

The true incidence of kidney stones in India is not really known but is far more prevalent than quoted in the literature from the West. It is estimated that 1 in 10 people at any point of time are likely to be harbouring a kidney stone.

It is more common in males (3:1) but this may be slowly getting equal with increasing lifestyle changes, obesity and renal diseases.

The lifetime risk of developing renal colic is 5-10%. Once there has been a stone episode, the lifetime risk of recurrence is 50-70%.

The risk of stone formation is increased with the following:

living in hot climes
working in hot environment eg. chefs, manual labourers
poor fluid intake
recurrent urinary infections
kidneys with scars or cysts
strong family history of kidney stones
several uncommon conditions like hyperparathyroidism, hyperoxaluria, hyperuricemia and cystinuria
rarely, with certain medications (eg. diuretics, anti-HIV drugs)

What are the symptoms of kidney stones?

Pain is the most common symptom. Stone in the kidney can cause pain in the back / side (flank or loin) of the abdomen. Whilst this is typical, occasionally it can manifest with vague pain in the front of the abdomen.

Kidney pain can sometimes be confused with lower back pain and vice versa. Stones can also result in passage of blood in the urine (haematuria).

If the stone blocks the drainage of urine from the kidney it can cause serious / life threatening infection which may manifest with high-grade fever, loin pain and chills / rigors. If untreated this may result in loss of kidney or even life.

If stones are present in both kidneys they might affect kidney function and hence, patient may manifest with symptoms of kidney failure.

What are the symptoms of stone in the ureter?

Once a stone forms in the kidney it may dislodge from its place of origin and drop into the pelvis or ureter. The ureter then tries to push this down. Also, this blocks the passage of urine. The combination results in renal or ureteric colic, the worst pain that could be suffered by humans.The distribution of pain is illustrated in the picture here (Source: Medscape). Therefore, patients may present with pain in the flank, groin, testicle or labia, which can be quite excruciating. This is commonly associated with severe nausea and vomiting.

Otherwise a stone in the ureter causes all the symptoms mentioned above for kidney stones.

How do I find out if I have kidney or ureteric stones?

If your doctor or urologist suspects that you may have stones, you are likely to undergo a combination of any of the following:
x-ray of the kidney, ureter, bladder area (KUB)
Ultrasound KUB
CT scan KUB or a CT urogram
Intravenous urogram (IVU – this has been replaced by CT in all premier centres)

How do I find out if I am at increased risk for forming stones?

If you form a stone for the first time without any additional risk factors, then standard practice is to check the blood for calcium and uric acid in addition to the usual blood tests (creatinine, urea, electrolytes, complete blood count +/- CRP).

If there are additional risk factors (recurrent stone former, suggestion of underlying disease, strong family history of kidney stones, major component of stone is uric acid or cystine, urine examination suggestive of cystine crystals, etc), then additional tests including 24 hour urine collection may be undertaken.

How are kidney / ureteric stones managed?

KIDNEY STONES

If the stone(s) are tiny and do not cause any symptoms, it may be managed by merely watching them. Of course, if there are certain risk factors or the patient is in a high-risk occupation (airline pilot, deep sea diver, etc) the urologist may advise intervention (see below).

URETERIC STONES

If the stone(s) causes renal or ureteric colic it will be treated with painkillers and drugs to control the nausea / vomiting, if present. In addition, your urologist may give you an additional tablet to facilitate the passage of stone if it is in the ureter and nearing the bladder.

The majority of stones that drop into the ureter if less than 5 mm in size are likely to be passed spontaneously with conservative treatment. This is usually limited to a maximum of 4-6 weeks depending on individual circumstances. If during this period of conservative management the patient develops fever or starts getting unwell, it is an indication for urgent intervention.

The need for surgical intervention in ureteric stones depends on several factors –size of the stone, presence of stones in both sides, kidney function, presence of sepsis, etc.

SURGERY FOR STONES

Surgical intervention involves the following in the management of stones:

Stenting of the ureter
Extracorporeal shockwave lithotripsy (ESWL)
Ureteroscopy (rigid or flexible)
Percutaneous nephrolithotomy (PCNL)
Open or laparoscopic pyelo or nephrolithotmy (rare)
Open or laparoscopic nephrectomy
All these procedures are explained in detail – see SURGERY FOR STONES – pt guide

What can I do to prevent recurrence of a kidney stone?

The single most important thing one can do to prevent recurrence is increase water intake. Rather than aim for a specific volume per day (eg. 3-4 litres / day), an easy rule of thumb to remember is to aim for passing either colorless or very light wine colored urine every 3 hours or so. In certain recurrent stone formers fluid intake needs to be continued in the night as well.

A healthy and regular intake of citrate helps prevent stone formation – homemade lemonade (without salt) is an excellent and cheap source of citrate.
There is a mistaken belief that calcium intake needs to be reduced but this is absolutely wrong! In fact, reducing calcium intake, paradoxically, increases the risk of stone formation. Therefore, it is important to maintain a healthy amount of calcium and Vitamin D in the diet.
In general, it is useful to avoid salt rich food items (most off the shelf or readymade meals are salt rich).

High volume meatintake increases the risk of stone formation and is best restricted. White meat (fish) is better and if red meat is partaken it needs to be less than a quarter of a dinner plate.

For those with uric acid stones, urinary alkalinisation is usually recommended and if needed, a tablet to reduce uric acid in the blood. For those with specific risk factors help of a dietician is useful. Also, specific medications may be prescribed to reduce the risk of recurrence.

It is useful to watch what one eats and maintain a healthy balanced diet.

Bladder Stones

What causes bladder stones?

Stones that form in the bladder – primary bladder stones – used to be common in malnourished children, related to their diet. This is quite uncommon these days.

It is more common to come across secondary stones in the bladder ie stones that have been formed in the kidney and have dropped down the ureter and lodges in the bladder. Most young people will pass these stones naturally if they have reached the bladder.

In some elderly men, with obstruction from a large prostate, the stone is retained and starts increasing in size. More commonly, due to poor emptying of the bladder, whether due to enlarged prostate or spinal disease, crystals in the urine start aggregating that result in stone formation.

Rarely, stones can form over foreign bodies that are left in the bladder, eg. over catheter tips

What are the symptoms of bladder stones?

They can cause a variety of symptoms:

Excruciating pain in the lower part of the abdomen. This is usually associated with passing urine. In some, changing the position, for example, when turning in bed may bring it on.
Urinary frequency
Urgency and urge incontinence
Blood in the urine

Surprisingly, in some patients, even large stones (like in the picture above) do not cause any pain. They may have lower urinary tract symptoms (see PROSTATE-LUTS-BPH – pt guide)

How is bladder stone managed?

Treatment is usually surgical. Depending on patient, stone and other factors it can be dealt with using a telescope and laser (endocystolithotomy) or may require a small cut in the lower abdomen to remove the stone (open cystolithotomy). In men with associated enlargement of the prostate causing obstruction, a TURP (see TURP – pt guide) may be carried out at the same time.