Bladder outflow obstruction due to the bladder neck

Aetiology

This condition usually occurs in men, but can rarely affect children of both sexes and women. It may be due to muscular hypertrophy, or fibrosis of the tissues at the bladder neck following TURP.

Clinical syndromes

1. Due to muscle hypertrophy or dyssynergia. Marion described a series of cases in which muscular hypertrophy of the internal sphincter in a young person had resulted in the development of a vesical diverticulum or hydrone­phrosis (Marion’s disease or prostatism sans prostate). It is thought that dyssynergic contraction of the smooth muscle of the bladder neck (bladder neck dyssynergia) may account for some cases of bladder outflow obstruction.

2. Due to fibrosis. The symptoms are similar to those of prostatic enlargement, but are a consequence of scarring after TURP

Treatment

The management of these patients depends on achieving an accurate diagnosis. For this, urodynamic investigation is often necessary, which should demonstrate raised voiding pressures and diminished flow rate.

Drugs

The presence of alpha-adrenergic receptors in the region of the bladder neck and prostatic urethra allows pharmacological manipulation of the outflow to the bladder. Alpha-blocking drugs: alfuzosin — 2.5 mg b.d. to t.d.s. (to a total maximum of 10 mg/day); doxazosin — 1 mg nocte (up to maximum of 8 mg/day); indoramin — 20 mg b.d. (increased to total maximum of 100 mg/day in divided doses); prazosin 500 mg b.d. (maintenance up to 2 mg/day); and terazosin 1 mg nocte (to a total maximum of 10 mg/day) can be very useful, causing relaxation of the bladder neck. These drugs are not target specific and the patients must be warned of the possibility of possible postural hypotension.

Transurethral incision

Transurethral incision of the bladder neck is the operation of choice. Sometimes symptoms recur, but this is usually due to inadequate division of the fibres of the bladder neck.

Congenital valves of the prostatic urethra

See Chapter 60.