Also Known As
BOO, Lower urinary tract obstruction (LUTO), Bladder neck obstruction, Prostatic obstruction, Urethral obstruction, Obstructive uropathy, Urinary retention - BOO
Definition
Bladder outlet obstruction (BOO) is a blockage at the base of the bladder that reduces or stops the flow of urine into the urethra, the tube that carries urine out of the body.1 This condition results from a variety of etiologies, which may be functional or anatomic in nature. BOO produces compression or resistance upon the bladder outflow channel at any location from the bladder neck to urethral meatus.2 The resulting obstruction frequently produces lower urinary tract symptoms (LUTS), although the degree of bother by these symptoms is highly variable and not predictable based on the specific inciting etiology.2 BOO may also occur in the complete absence of symptoms and be first identified in the scenario of urinary retention or decompensation of the upper urinary tracts.2
Clinical Context
Bladder outlet obstruction is used clinically in the evaluation and management of patients presenting with lower urinary tract symptoms (LUTS).2 These symptoms may be predominantly obstructive, irritative, or often a combination of both. Typically, obstructive symptoms include hesitancy, sensation of incomplete bladder emptying, diminished urinary stream, and post-voiding urinary dribbling. Irritative complaints include urinary urgency, frequency of urination, occasional dysuria, and nocturia.2
In men, BOO is most commonly caused by benign prostatic hyperplasia (BPH), especially in aging populations.1 Other causes include urethral strictures, bladder neck contractures, and prostate cancer. In women, BOO is less common but may result from anti-incontinence procedures, pelvic organ prolapse, or primary bladder neck obstruction.3
Diagnosis typically involves a combination of clinical assessment, uroflowmetry, post-void residual measurement, and in some cases, urodynamic studies which are considered the gold standard for quantitating the degree of obstruction.2 Cystoscopy may also be used to visualize the urethra and bladder neck.
Treatment depends on the underlying cause. For BPH-related obstruction, options include medications (alpha-blockers, 5-alpha reductase inhibitors), minimally invasive procedures, or surgical interventions like transurethral resection of the prostate (TURP).1 For acute obstruction, catheterization is often necessary to relieve the blockage.2 Long-term untreated BOO can lead to bladder decompensation, recurrent urinary tract infections, and kidney damage.2