Bladder stones

Urinary bladder stones or calculi are classified on the basis of the type of constituents. Sometimes the bladder calculi can have more than one component and in such cases, it is referred to as a mixed bladder stone. Following are the commonly encountered types of bladder stones:

• Uric acid bladder stone: This is the most common type of bladder stones found in more than half of all adult cases. It may or may not be related to hyperuricemia (raised blood levels of uric acid) or gout.
• Calcium oxalate bladder stone: This is one of the most common types of bladder stones that occur in children. There is some association of such stones occurring with a diet of vegetables rich in oxalates (spinach, beets, potatoes, okras, etc), which can cause an increase in the excretion of oxalate crystals through urine.
• Calcium phosphate bladder stone: Calcium oxalate and calcium phosphate mixed stones are also common.
• Ammonium urate bladder stone: A diet consisting of foods low in phosphorus, like polished rice, can cause an increase in ammonia excretion in the urine, leading to the formation of stones in children.
• Cysteine bladder stone: This is a relatively uncommon type of bladder stone and occurs with inborn problems of cysteine metabolism.
• Magnesium ammonium phosphate bladder stone: This type of bladder stone is more commonly seen in the setting of urinary tract infections.
• Jackstone calculus: This rare type of bladder stone refers to the shape rather than the composition of the calculus. They are usually composed of calcium oxalate and have a spiculated structure that makes them very responsive to lithotripsy treatment.

Although some bladder stones can remain asymptomatic and only be diagnosed incidentally on imaging studies done for other unrelated conditions, most cases of urinary bladder stones are reported by patients due to the signs and symptoms that arise with them. The following clinical presentation usually accompanies bladder stones:

• Pain: It is experienced, most commonly, in the pelvic area above the bladder. Pain can also be perceived in the tip of the penis, scrotum, perineum, back or hip. The pain can either be mild discomfort or a sharp shooting sensation that can be made worse with sudden movements or exercising. In some cases, the pain is noted to reduce on lying down.
• Problems urinating: Some or all of the following problems can be associated with bladder stones:
  • Increased frequency of urination, especially at night
  • Pain, discomfort or a burning sensation while urinating
  • Inability to void fully
  • Hesitancy or inability to start a stream of urine even with the urge to urinate
  • Intermittency or intermittent stoppage of the flow of urine in the middle
  • Children may experience occasional bedwetting or enuresis
  • Male children may experience priapism at times which is a painful, persistent, asexual erection of the penis (Read more: Pain in penis)
• Change in colour of the urine: The urine can appear cloudy or bloody (gross haematuria)

Certain underlying disorders, diseases and infections can predispose people to develop bladder stones. Some common causes of bladder stones include:

• Infections: Urinary tract infections cause inflammation of the urinary tract, which causes the solutes (minerals, salts and metabolic byproducts) to supersaturate the urine, crystallise and clump together to form stones. It is one of the most common causes of urinary bladder stones, especially in children. Schistosomiasis, also known as snail fever or bilharziasis, an infection caused by small parasitic worms (schistosoma) that affects the urinary tract and often presents with bloody urine, is an important cause of infection-induced bladder stones.
• Prostate enlargement: Bladder outlet obstruction, due to enlargement of the prostate gland (as with Benign Prostate Hypertrophy or BPH) is the most common cause of bladder stones in adult males. The enlarged prostate prevents the urine from flowing freely through the sphincter at the urinary bladder neck, causing urinary retention and stagnation, which can allow solutes to form stones. Additionally, the residual volume of urine retained within the bladder can also act as a reservoir for infection to set in.
• Dehydration: Poor nutrition and inadequate hydration of young children in developing countries is also a significant cause for bladder stones in the population. (Read more: Malnutrition)
• Neurogenic bladder: Some disorders, injuries and diseases of the brain, spinal cord or nerves, can cause people to lose control of their bladder and subsequently develop stagnation of urine in it. Neurogenic bladder can develop in newborns and infants due to birth defects affecting the spinal cord, like spina bifida, as well. As the urine flow is impeded, stones develop. Conditions that can lead to neurogenic bladder in adults include, but are not limited to:
  • Spinal cord Injury
  • Multiple sclerosis
  • Parkinson’s disease
  • Diabetes mellitus (diabetic neuropathy is a complication of long-standing uncontrolled diabetes mellitus)
• Augmentation cystoplasty: A type of surgical procedure used in adults and children who lack adequate bladder capacity or bladder muscle compliance. This type of operation aims to correct urinary incontinence but can be associated with the complication of bladder stone formation.
• Radiation cystitis: The treatment of certain types of pelvic cancer tumours requires radiation therapy to the pelvis. An unfortunate side effect of this radiation therapy is radiation cystitis or inflammation of the urinary bladder due to radiation. Radiation cystitis induced inflammation can cause bladder stones to form as well.
• Vesicular diverticula: Diverticula (or outpouchings) of the urinary bladder wall can be present since birth or develop later in life in some individuals. This anomaly can cause urine flow to reduce and stones to form in such bladders. (Read more: Diverticulitis)
• Cystocele: Sometimes, after giving birth, women can develop weakness of the urinary bladder wall that causes it to fall into the vaginal cavity. This is known as a cystocele, or prolapsed bladder, that needs surgical repair. Urine stagnation in this bulging bladder can cause stones to form as a complication.
• Medical devices: Patients who require long-term indwelling urinary catheters are at risk of developing urinary bladder stones if the catheter is not changed in a timely manner. The catheter can act as a foreign body in the bladder, providing a scaffolding for salts, minerals and other wastes to crystallise upon.
• Kidney stones: Although the presence of concomitant kidney stones does not increase the risk of formation of stones in the urinary bladder, occasionally certain types of kidney stones that form in the kidney can travel downstream and settle in the urinary bladder.

Some other clinical problems can also present with features similar to that of bladder calculi, especially on imaging investigations, and need to be ruled out in order to arrive at the correct diagnosis and provide accurate treatment. Few conditions that need to be ruled out include, but may not be limited to:

• Bladder calcifications:
  • Urachal carcinoma
  • Schistosomiasis
• Pelvic calcifications:
  • Prostate calcification
  • Calcified uterus fibroids
• Filling defects in the bladder:
  • Blood clot
  • Fungus ball
  • Ureterocele
  • Tumour

The doctor will begin by taking a thorough medical history of the patient consisting of their current chief complaints, dietary history and past medical history, paying close attention to a history of previous pelvic surgery. Afterwards, a comprehensive clinical physical examination will be conducted. The pelvis will be palpated by the doctor and it may be found to be tender or full. Occasionally a distended bladder may be felt in case of acute urinary retention. In women, a vaginal examination can reveal a bladder prolapse. In case of urinary diversion surgery, or neobladder, the stoma is also examined for stenosis or hardening. A complete neurological examination is carried out in order to diagnose a possible neurogenic bladder. Following history and examination, certain investigations may be necessary to complete the evaluation and arrive at a diagnosis before proceeding with treatment.

(Read more: Ureterosigmoidostomy)

The following investigations are used routinely to diagnose and confirm a case of bladder stones:

• Blood tests
  • Full blood count, or complete blood count, can reveal an elevated level of white blood cells, which are indicative of infections including those affecting the urinary tract.
• Urine tests
  • Urinalysis: A urine sample is collected from the patient and then the following tests are performed on it.
    • Urine dipstick test: A rapid, but non specific, investigation that can indicate the possible presence of a bladder stone if tests positive for leukocyte esterase, nitrites and blood.
    • Urine routine microscopy: Red blood cells and pus cells can be demonstrated. Crystals specific to the type of bladder stone can also be detected.
    • Urine pH: It may be low, or acidic, in the case of uric acid stones.
    • Urine specific gravity: It may be lower than normal in case of dehydration.
  • Urine culture and sensitivity: It can diagnose a urinary tract infection and provide information on which antibiotics to use.
• Radiological imaging tests: While many modalities are available, CT scan is the most useful for diagnosing urinary tract stones.
  • X-ray KUB (kidney ureter and bladder): It may be done but is not a very useful imaging tool as some types of stones are radiolucent; that is, they do not appear on X-ray film and can be missed. 
  • Ultrasound: It can diagnose both radiolucent and radiopaque types of bladder stones. 
  • CT scan: Overall, this is the top choice for diagnosing urinary tract stones, including bladder stones. It can detect all types of stones. Contrast-enhanced CT (CECT) scans are not recommended for stones as they may get obscured by the dye. Low dose CT scans can also effectively diagnose bladder stones while exposing the patient to lesser radiation.
• Cystoscopy: Cystoscopy is the most common imaging investigation done to confirm the presence of a bladder stone and arrive at a definitive diagnosis. A scope, or tube, equipped with a camera is inserted through the urethra into the bladder and the stones and surrounding tissue is visualised, confirming the diagnosis.

In order to treat the patient, the underlying cause of bladder stones (infection, benign prostate hypertrophy, etc.) is treated and the stone itself is removed. The possible ways to remove a bladder stone include:

Medical management: Few types of stones can be dissolved using medicines. Uric acid stones, associated with an acidic pH, can be dissolved by alkalinising the pH of the urine with potassium citrate. However, treatment should be carried out carefully to not over-alkalise the urine.

Surgical management: Three types of surgical procedures are available to remove bladder stones:

• Transurethral cystolitholapaxy: Being a less invasive procedure, associated with a shorter hospital stay, it is the preferred technique, when feasible, in both adults and children. Cystoscopy is done to visualise the bladder stone and then using an external energy source (or lithotripter), like ultrasound waves, the stone is broken. The fragments are expelled through urine.
• Percutaneous suprapubic cystolitholapaxy: This method uses the same principle as the previous procedure but intervention is made by the percutaneous route (i.e. through the skin). It is usually done in children.
• Open suprapubic cystotomy: Open surgical method in which an incision is given to access the urinary bladder and remove the stone manually.

(Read more: Bladder infection)

After appropriate treatment, the prognosis of bladder stones is very good. Future stones can be prevented in some cases by maintaining adequate hydration and following a diet low in oxalates and animal proteins.

(Read more: Kidney stone diet)