Christopher Amling, MD, FACS
Nicholas Cowan, MD
BASICS
DESCRIPTION
• Prostatic calculi are extremely common and rarely symptomatic
• Most stones are discovered incidentally
• Treatment typically reserved for severely symptomatic men
• Stones within the prostatic urethra rare and likely due to bladder or upper tract stones that become trapped in the prostatic urethra
• Reports of calculi in the prostatic urethra following transurethral resection of the prostate
EPIDEMIOLOGY
Incidence
• 7% in pathologic specimens
• 20% in autopsies
• 30% in radiologic studies, with higher percentages in ultrasound scan exams
Prevalence
• Small areas of microcalcification can be seen in 2nd and 3rd decades of life
• Almost all men (99%) have some degree of prostatic calcification noted at autopsy
– Stone burden and size typically increase as a man ages
RISK FACTORS (1)
• Intraprostatic calculi:
– Recurrent urinary tract infections (UTIs)
– Pelvic radiation (for prostate cancer)
– Studies are mixed on role of inflammation in stone development
• Prostatic urethral calculi
– Urolithiasis
– Enlarged prostatic utricle
– History of transurethral resection of the prostate
Genetics
N/A
PATHOPHYSIOLOGY
• Urinary intraprostatic reflux implicated in stone formation
• Intraprostatic calculi presumed to form by the precipitation of prostatic secretions and calcification of the corpora amylacea under inflammatory conditions
– Inspissation of prostatic secretions within the prostatic ducts
– Concentric layering of calcium phosphate and calcium carbonate on inspissated core result in growth
– Stone elements may contain constituents found only in urine and not in prostatic secretions
• Stones may harbor bacteria and serve as source for relapsing UTI
• For prostatic utricle stones, prostatic utricle distends during voiding and then passively drains.
– Impaired emptying results in urinary stasis stone formation. Patients present clinically with chronic UTI, hematuria, urethral discharge, epididymitis, and voiding dysfunction.
ASSOCIATED CONDITIONS
• Chronic pelvic pain syndrome
• Prostatitis
• No association between prostate calculi and risk of prostate cancer
• Hypospadias (enlargement of the prostatic utricle, a Müllerian duct remnant)
GENERAL PREVENTION
No known preventative strategies
DIAGNOSIS
HISTORY
• Typically stones are asymptomatic
• Evaluate for history of lower urinary tract symptoms (LUTS) (2)
– Patients should complete the international prostate symptom score (IPSS)
– Presence of large calculi associated with moderate LUTS
• 25–47% of men with chronic pelvic pain have significant prostatic calcifications
– Correlation seen with stone size, not number
• Prostatitis history
• With prostatic utricle stones patients typically present with chronic UTI, hematuria, urethral discharge, epididymitis, and voiding dysfunction. Often a history of hypospadias is present
PHYSICAL EXAM
• Genitourinary exam including DRE
– DRE unlikely to localize stones
• Presence of hypospadias
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Urine culture
– Escherichia Coli, enterococci, and Klebsiella spp. more common
• Expressed prostatic secretions
– May see increased leukocytes
• PSA optional
– PSA levels not influenced by presence or volume of prostatic calculi, but infection related to chronic nidus may falsely elevate PSA (3)
Imaging
• Stones often identified incidentally
• Transrectal ultrasound (TRUS)
– Highly sensitive for large calculi
• Sometimes seen on plain film
Diagnostic Procedures/Surgery
• Postvoid residual (PVR)
• Uroflow if significant obstructive voiding symptoms present
• If intraurethral stones are suspected, cystoscopy is diagnostic
Pathologic Findings
• Majority of calculi are found in the posterior and posterolateral zones of the prostate
– Rare to find large stones obstructing the urethra
DIFFERENTIAL DIAGNOSIS
• Benign prostatic enlargement (BPE)
• Calcified prostatic utricle cyst or utricle stone
• False prostatic calculi: Calculi trapped in dilated prostatic urethra or in dilated prostatic utricle
• Prostate cancer
• Prostatitis
• Seminal vesical calculi
• UTI
TREATMENT
GENERAL MEASURES
Evaluate and treat coexisting conditions such as UTI, prostatitis, and BPO
MEDICATION
First Line
Culture-directed antibiotic therapy if urine culture positive
Second Line
N/A
SURGERY/OTHER PROCEDURES
• Surgery rarely indicated and is typically for severely symptomatic patients
• Transurethral resection of the prostate
– Unroof stone containing cavities where nidus of infection is thought to exist
– Stone burned usually visible on TRUS
• Open prostatolithotomy for large stones
• Cystoscopy with lithotripsy for stones within the prostatic urethra or prostatic utricle
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
N/A
Complementary & Alternative Therapies
N/A
ONGOING CARE
PROGNOSIS
Excellent, as majority of stones are asymptomatic
COMPLICATIONS
• Rarely results in urinary obstruction
• May predispose to chronic UTI.
FOLLOW-UP
Patient Monitoring
• No follow-up necessary for asymptomatic incidentally identified stones
• Consider postoperative PVR or uroflow if surgical intervention undertaken
Patient Resources
N/A
REFERENCES
1. Klimas R, Bennett B, Gardner WA Jr. Prostatic calculi: A review. Prostate. 1985;7(1):91–96.
2. Kim WB, Doo SW, Yang WJ, et al. Influence of prostatic calculi on lower urinary tract symptoms in middle-aged men. Urology. 2011;78(2):447–449.
3. Lee SE, Ku JH, Park HK, et al. Prostatic calculi do not influence the level of serum prostate specific antigen in men without clinically detectable prostate cancer or prostatitis. J Urol. 2003;170:745–748.
ADDITIONAL READING
• Geramoutsos I, Gyftopoulos K, Perimenis P, et al. Clinical correlation of prostatic lithiasis with chronic pelvic pain syndromes in young adults. Euro Urol. 2004;45:333–337.
• Kirby RS, Lowe D, Bultitude MI, et al. Intraprostatic urinary reflux: An aetiological factor in abacterial prostatitis. Br J Urol. 1982;54:729–731.
See Also (Topic, Algorithm, Media)
• Corpora Amylacea
• Prostate, Benign Hyperplasia/Hypertrophy
• Prostate, Nodule
• Prostatic Utricle Anomalies
• Prostatitis, Acute, Bacterial (NIH I)
• Prostatitis, Chronic, Bacterial (NIH II)
• Prostatitis, General
• Urinary Tract Infection, Adult Male
CODES
ICD9
• 599.0 Urinary tract infection, site not specified
• 599.70 Hematuria, unspecified
• 602.0 Calculus of prostate
ICD10
• N39.0 Urinary tract infection, site not specified
• N42.0 Calculus of prostate
• R31.9 Hematuria, unspecified
CLINICAL/SURGICAL PEARLS
Prostate calculi are very common and rarely require treatment.