Andrew Siegel MD 3/11/2023
If you own a pet, you may be aware that your dog or cat can develop painful bladder stones, but did you know that humans — particularly older males — can develop bladder stones? Today’s entry covers this not uncommon problem that keeps urologists busy, drilling away at stones with lasers.
Bladder stones, aka bladder calculi, are concretions of mineral materials that form in the bladder and can cause a variety of symptoms. Bladder stones are often a sign of underlying pathology as most are secondary to another issue that is creating the environment for stone formation. Therefore, the proper treatment involves not only removing the offending stones, but also a thorough urological evaluation to determine the root cause so it can be addressed to prevent recurrences. The average age of a patient with a bladder stone is about 60 years old. Bladder stones happen to be much more common in males and are somewhat unusual in women.
The common denominator underlying most bladder stone formation is urinary “stasis” from incomplete emptying of the bladder. Stasis is a condition in which the urine does not flow properly, analogous to a “pond” versus a “river. With stagnant urine retained in the bladder, salts within the urine can precipitate out of solution and crystalize into particulate matter (crystal nucleation). Thereafter, they can grow and gradually accumulate additional layers with continued exposure to the urine (accretion).
The most common reason for incomplete bladder emptying is benign prostate hyperplasia (BPH) causing obstruction to the flow of urine. Other common causes include neurogenic bladders (e.g., spinal cord injury patients) and bladder diverticula (outpouchings from the bladder of variable size that do not empty well). An uncommon cause of incomplete emptying is a high-grade cystocele (dropped bladder) that may occasionally cause bladder stones in females. The presence of any kind of foreign body (something that should not be there) within the bladder is another reason for having a bladder stone. The foreign body acts as a scaffold for stone formation as it is exposed to the salts in the urine and becomes calcified. Foreign bodies may include retained catheters, retained stents, sutures, meshes, surgical clips, and retained hardware from a prior surgical procedure. Bladder tumors can act as a nidus for calcification and overlying stone formation. A kidney stone that passes into the bladder from the ureters but fails to pass out of the bladder can gradually enlarge and be the source of a bladder stone. Some people –for a variety of reasons — insert foreign bodies into the bladder that end up being a nidus for stone formation, e.g., wires, metallic nuts, bolts, batteries, etc. You never know necessarily what you are going to find at the core of a bladder stone until you break the stone up and discover the source. On rare occasions, an object may erode into the bladder and be the source of calcification that forms on its surface, e.g., a retained vaginal pessary.
A history of prior pelvic surgery should be sought in all patients with bladder stones, particularly when synthetic materials were implanted. Although bladder stones may be asymptomatic, they often present with blood in the urine, particularly occurring after exercise that causes the stone(s) to bounce around and irritate and induce bleeding of the delicate lining of the bladder. Bladder stones often cause irritative lower urinary tract symptoms including urgency, pressure, frequency, incontinence, and at times can cause pain and difficulty urinating. Sometimes, the presence of a bladder stone will give rise to a urinary tract infection.
Bladder stones are readily diagnosed using imaging tests such as sonography or computerized tomography (CT). Cystoscopy will clearly demonstrate the presence, size, number, shape, color, and position of the stones, which can be quite variable. Examination of the urethra, prostate, and bladder will identify strictures (scar tissue), prostatic obstruction, bladder diverticula, and bladder tumors, if present.
Stones can be single or multiple and can vary tremendously in size, ranging from tiny sand-like crystals to a huge stone that occupies virtually the entire bladder. They vary tremendous in hardness, with some soft and others extremely tenacious. Some stones are perfectly smooth and spherical, while others are irregular and jagged. Jackstones resemble the jacks in the jacks game that children used to play back in the day. Most stones are mobile, except those that are fixed because they form on a foreign body such as a suture, clip, stent, or a bladder tumor. I have seen a large bladder stone form on the retained and exposed hardware from a Urolift implant.
Bladder stones can have a variety of chemical compositions. Those that originated as kidney stones are most commonly calcium oxalate stones. Stones that form within the bladder itself are most commonly uric acid stones and are less commonly calcium oxalate, calcium phosphate, ammonium urate, cysteine, or magnesium ammonium phosphate (struvite). It is not uncommon for the core of the stone to consist of one chemical composition and the outer layers of a different chemical composition. Uric acid stone formation is promoted by high urinary acidity, dehydration, and high levels of uric acid in the urine. Struvite bladder stones are known as infection stones and are most commonly seen in the spinal cord injured population.
Tiny stones may pass spontaneously, but the larger ones will not. Most bladder stones are amenable to fragmentation using a laser passed through a cystoscope followed by bladder irrigation and evacuation of the fragments. Some stones are so large or tenacious that they may need to be addressed by an abdominal procedure, typically performed laparoscopically. In the case of a stones due to an enlarged prostate or stones in a bladder diverticulum, the abdominal approach enables removal of the stones in conjunction with performing a simple prostatectomy (removing the obstructing part of the prostate gland and leaving the remaining prostate) and bladder diverticulectomy (surgically removing the bladder diverticulum), respectively. Uric acid stones may be amenable to alkalinizing the urine (making it less acidic) to increase their solubility. Potassium citrate is themedication of choice to help alkalinize the urine.
Wishing you the best of health,
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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery. He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, one of the largest urology practices in the United States. He is the co-founder of PelvicRx and Private Gym. His latest book is Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families.
Video trailer for Prostate Cancer 20/20
Preview of Prostate Cancer 20/20
Andrew Siegel MD Amazon author page
PROSTATE CANCER 20/20 is now available at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours).
Dr. Siegel’s other books:
THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health
MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health
PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food
Our Greatest Wealth Is Health 