Using the criteria of a prostate volume > 30 mL and a moderate or high American Urological Association Symptom Score (see table American Urological Association Symptom Score for Benign Prostatic Hyperplasia), the prevalence of BPH in men aged 55 to 74 without prostate cancer is 19%. But if voiding criteria of a maximal urinary flow rate < 10 mL/sec and a postvoid residual urine volume > 50 mL are included, the prevalence is only 4%. Based on autopsy studies, the prevalence of BPH increases from 8% in men aged 31 to 40 years to 40 to 50% in men aged 51 to 60 years and to > 80% in men > 80 years.
American Urological Association Symptom Score for Benign Prostatic Hyperplasia
The etiology is unknown but probably involves hormonal changes associated with aging.
Multiple fibroadenomatous nodules develop in the periurethral region of the prostate, probably originating within the periurethral glands rather than in the true fibromuscular prostate (surgical capsule), which is displaced peripherally by progressive growth of the nodules.
As the lumen of the prostatic urethra narrows and lengthens, urine outflow is progressively obstructed. Increased pressure associated with micturition and bladder distention can progress to hypertrophy of the bladder detrusor, trabeculation, cellule formation, and diverticula. Incomplete bladder emptying causes stasis and predisposes to calculus formation and infection. Prolonged urinary tract obstruction, even if incomplete, can cause hydronephrosis and compromise renal function.
Symptoms of benign prostatic hyperplasia (BPH) include a constellation of symptoms that are often progressive, known collectively as lower urinary tract symptoms (LUTS):
Frequency, urgency, and nocturia are due to incomplete emptying and rapid refilling of the bladder. Decreased size and force of the urinary stream cause hesitancy and intermittency.
Pain and dysuria are usually not present. Sensations of incomplete emptying, terminal dribbling, overflow incontinence, or complete urinary retention may ensue. Straining to void can cause congestion of superficial veins of the prostatic urethra and trigone, which may rupture and cause hematuria. Straining also may acutely cause vasovagal syncope and, over the long term, may cause dilation of hemorrhoidal veins or inguinal hernias.
Some patients present with sudden, complete urinary retention, with marked abdominal discomfort and bladder distention. Retention may be precipitated by any of the following:
Symptoms can be quantitated by scores, such as the 7-question American Urological Association Symptom Score (see table American Urological Association Symptom Score for Benign Prostatic Hyperplasia). This score also allows doctors to monitor symptom progression:
On digital rectal examination, the prostate usually is enlarged and nontender, has a rubbery consistency, and in many cases has lost the median furrow. However, prostate size as detected with digital rectal examination may be misleading; an apparently small prostate may cause obstruction. If distended, the urinary bladder may be palpable or percussible during abdominal examination. Firm or hard areas in the prostate may indicate prostate cancer.
The lower urinary tract symptoms of benign prostatic hyperplasia (BPH) can also be caused by other disorders, including infection, prostate cancer, and overactive bladder. Furthermore, BPH and prostate cancer may coexist. Although palpable prostate tenderness suggests infection, digital rectal examination findings in BPH and cancer often overlap. Although cancer may cause a stony, hard, nodular, irregularly enlarged prostate, most patients with cancer, BPH, or both have a benign-feeling, enlarged prostate. Thus, testing should be considered for patients with symptoms or palpable prostatic abnormalities.
Typically, urinalysis and urine culture are done, and serum prostate-specific antigen (PSA) levels are measured. Men with moderate or severe symptoms of obstruction may also have uroflowmetry (an objective test of urine volume and flow rate) with measurement of postvoid residual volume by bladder ultrasonography. Flow rate < 15 mL/sec suggests obstruction, and postvoid residual volume > 100 mL suggests retention.
Interpreting prostate-specific antigen (PSA) levels can be complex. The PSA level is moderately elevated in 30 to 50% of patients with BPH, depending on prostate size and degree of obstruction, and is elevated in 25 to 92% of patients with prostate cancer, depending on the tumor volume.
In patients without cancer, serum PSA levels >1.5 ng/mL (1.5 mcg/L) usually indicate a prostate volume ≥ 30 mL. If the PSA level is > 4 ng/mL (4 mcg/L), further discussion/shared decision-making regarding other tests or biopsy is recommended.
For men < 50 or those at high risk of prostate cancer, a lower cutoff (PSA > 2.5 ng/mL [2.5 mcg/L]) may be used. Other measures, including rate of PSA increase, free-to-bound PSA ratio, and other markers, may be useful. (A full discussion of prostate cancer screening and diagnosis can be found elsewhere in THE MANUAL.)
Transrectal biopsy is usually done with ultrasound guidance and is usually only indicated if there is suspicion of prostate cancer. Transrectal ultrasonography is an accurate way to measure prostate volume.
Clinical judgment must be used to evaluate the need for further testing. Contrast imaging studies (eg, CT, intravenous urography [IVU]) are rarely necessary unless the patient has had a urinary tract infection (UTI) with fever or obstructive symptoms have been severe and prolonged. Upper urinary tract abnormalities that usually result from bladder outlet obstruction include upward displacement of the terminal portions of the ureters (fish hooking), ureteral dilation, and hydronephrosis. If an upper tract imaging study is warranted due to pain or elevated serum creatinine level, ultrasonography may be preferred because it avoids radiation and IV contrast exposure.
Alternatively, men whose PSA levels warrant testing can undergo multiparametric MRI, which is more sensitive (although less specific) than transrectal biopsy. Restricting biopsies to areas found to be suspect on multiparametric MRI may reduce the number of prostate biopsies and diagnoses of clinically insignificant prostate cancers, as well as possibly increasing diagnoses of clinically significant prostate cancers (1).
Cystoscopy may help determine the optimal surgical approach and to rule out other obstructive causes such as strictures.
1. Ahmed HU, El-Shater Bosaily A, Brown LC, et al: Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): A paired validating confirmatory study. Lancet 389(10071):815-822, 2017. doi: 10.1016/S0140-6736(16)32401-1
Avoidance of anticholinergics, sympathomimetics, and opioids
Use of alpha-adrenergic blockers (eg, terazosin, doxazosin, tamsulosin, alfuzosin, silodosin), 5 alpha-reductase inhibitors (finasteride, dutasteride), or the phosphodiesterase type 5 inhibitor tadalafil, especially if there is concomitant erectile dysfunction
Transurethral resection of the prostate or an alternative procedure
Significant urinary retention requires immediate decompression. Passage of a standard urinary catheter is first attempted; if a standard catheter cannot be passed, a catheter with a coudé tip may be effective. If this catheter cannot be passed, flexible cystoscopy or insertion of filiforms and followers (guides and dilators that progressively open the urinary passage) may be necessary. (This procedure should usually be done by a urologist.) Suprapubic percutaneous decompression of the bladder may be used if transurethral approaches are unsuccessful.
For partial obstruction with troublesome symptoms, all anticholinergics and sympathomimetics (many available in over-the-counter [OTC] preparations), and opioids should be stopped, and any infection should be treated with antibiotics.
For patients with mild to moderate obstructive symptoms, alpha-adrenergic blockers (eg, terazosin, doxazosin, tamsulosin, alfuzosin) may decrease voiding problems. The 5 alpha-reductase inhibitors (finasteride, dutasteride) may reduce prostate size, decreasing voiding problems over months, especially in patients with larger (> 30 mL) glands. A combination of both classes of drugs is superior to monotherapy. For men with concomitant erectile dysfunction, daily tadalafil may help relieve both conditions. Many OTC complementary and alternative agents are promoted for treatment of BPH, but none, including the thoroughly studied saw palmetto, has been shown to be more efficacious than placebo.
Surgery is done when patients do not respond to drug therapy or develop complications such as recurrent urinary tract infection, urinary calculi, severe bladder dysfunction, or upper tract dilation. Transurethral resection of the prostate (TURP) is the standard (1). Erectile function and continence are usually retained, although about 5 to 10% of patients experience some postsurgical problems, most commonly retrograde ejaculation. The incidence of erectile dysfunction after TURP is between 1 and 35%, and the incidence of incontinence is about 1 to 3%. However, technical advances such as the use of a bipolar resectoscope, which allows use of saline irrigation, have greatly improved the safety of TURP by averting hemolysis and hyponatremia.
About 10% of men undergoing TURP need the procedure repeated within 10 years because the prostate continues to grow. Various laser ablation techniques are being used as alternatives to TURP. Larger prostates (usually > 75 grams) traditionally require open surgery via a suprapubic or retropubic approach, although some newer techniques such as the holmium laser enucleation of the prostate (HoLEP) can be done transurethrally. All surgical methods require postoperative catheter drainage for 1 to 7 days.
Alternatives to TURP include microwave thermotherapy, electrovaporization, various laser techniques, high-intensity focused ultrasonography, transurethral needle ablation, radiofrequency vaporization, pressurized heated water injection therapy, urethral lift, steam injection therapy, and intraurethral stents. The circumstances under which these procedures should be used have not been firmly established, but those done in the physician’s office (microwave thermotherapy and radiofrequency procedures) are being more commonly used and do not require use of general or regional anesthesia. Their long-term ability to alter the natural history of BPH is under study.
1. Parsons JK, Barry MJ, Dahm P, et al: Benign prostatic hyperplasia: Surgical management of benign prostatic hyperplasia/lower urinary tract symptoms (2018, amended 2019, 2020). American Urological Association.
Benign prostatic hyperplasia (BPH) is extremely common with aging but only sometimes causes symptoms.
Acute urinary retention can develop with exposure to cold, prolonged attempts to postpone voiding, immobilization, or use of anesthetics, anticholinergics, sympathomimetics, opioids, or alcohol.
Evaluate patients with a digital rectal examination and usually urinalysis, urine culture, and PSA.
In men with BPH, avoid use of anticholinergics, sympathomimetics, and opioids.
Consider relieving troublesome obstructive symptoms with alpha-adrenergic blockers (eg, terazosin, doxazosin, tamsulosin, alfuzosin), 5 alpha-reductase inhibitors (finasteride, dutasteride), or tadalafil, especially if there is concomitant erectile dysfunction.
Consider TURP or other ablation technique if BPH causes complications (eg, recurrent calculi, bladder dysfunction, upper tract dilation) or if bothersome symptoms are drug resistant.