Benign prostatic hyperplasia (BPH) is nonmalignant adenomatous overgrowth of the periurethral prostate gland. Symptoms are those of bladder outlet obstruction—weak stream, hesitancy, urinary frequency, urgency, nocturia, incomplete emptying, terminal dribbling, overflow or urge incontinence, and complete urinary retention. Diagnosis is based primarily on digital rectal examination and symptoms; cystoscopy, transrectal ultrasonography, urodynamics, or other imaging studies may also be needed. Treatment options include 5α-reductase inhibitors, α-blockers, tadalafil, and surgery.
Using the criteria of a prostate volume > 30 mL and a moderate or high American Urological Association Symptom Score (see Table 1: Benign Prostate Disease: 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 yr to 40 to 50% in men aged 51 to 60 yr and to > 80% in men > 80 yr.
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 obstruction, even if incomplete, can cause hydronephrosis and compromise renal function (see Obstructive Uropathy).
Symptoms and Signs
Symptoms include progressive urinary frequency, urgency, and nocturia due to incomplete emptying and rapid refilling of the bladder. Pain and dysuria are usually not present. Decreased size and force of the urinary stream cause hesitancy and intermittency. 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. The constellation of symptoms that develop when BPH causes progressive obstruction is sometimes referred to as lower urinary tract symptoms (LUTS).
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 1: Benign Prostate Disease: American Urological Association Symptom Score for Benign Prostatic Hyperplasia). This score also allows doctors to monitor symptom progression: Scores > 8 but < 20 suggest moderate symptoms, and scores ≥ 20 suggest severe symptoms.
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.
The lower urinary tract symptoms of BPH can also be caused by other disorders, including infection and prostate cancer. 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 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 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 usually indicate a prostate volume ≥ 30 mL. Typically, if the PSA level is > 4 ng/mL or if the digital rectal examination indicates an abnormality (other than smooth, symmetric enlargement), then a transrectal biopsy is recommended. For men < 50 or those at high risk of prostate cancer, a lower cutoff (PSA > 2.5 ng/mL) may be used. Other measures, including rate of PSA increase, free-to-bound PSA ratio, and other markers, may be useful (for full discussion of prostate cancer screening and diagnosis, see Genitourinary Cancer: Diagnosis).
Transrectal biopsy is usually done with ultrasound guidance. Transrectal ultrasonography can also measure prostate volume.
Clinical judgment must be used to evaluate the need for further testing. Contrast imaging studies (eg, CT, IVU) are rarely necessary unless the patient has had a 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.
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, sympathomimetics, and opioids should be stopped, and any infection should be treated with antibiotics. For patients with mild to moderate obstructive symptoms, α-adrenergic blockers (eg, terazosin, doxazosin, tamsulosin, alfuzosin) may decrease voiding problems. The 5α-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 improve 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 UTI, urinary calculi, severe bladder dysfunction, or upper tract dilation. Transurethral resection of the prostate (TURP) is the standard. 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%. About 10% of men undergoing TURP need the procedure repeated within 10 yr because the prostate continues to grow. Various laser ablation techniques are being used as alternatives to TURP. Larger prostates (usually > 75 g) require open surgery via a suprapubic or retropubic approach. All surgical methods require postoperative catheter drainage for 1 to 7 days.
Less invasive procedures include microwave thermotherapy,electrovaporization, high-intensity focused ultrasound (not available in the US), transurethral needle ablation, radiofrequency vaporization, 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.
Last full review/revision January 2013 by Gerald L. Andriole, MD
Content last modified January 2013