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.