The male
urethra
The most common congenital abnormalities of
the male urethra are:
•
meatal stenosis;
•
congenital urethral stricture;
•
congenital valves;
•
hypospadias;
•
epispadias.
Meatal stenosis
A congenital stenosis of the external urinary
meatus, normally the narrowest part of the male urethra, is associated with
phimosis. After circumcision, meatal ulceration may lead to stricturing of the
meatus. When the meatal opening is reduced to a pinhole there may be chronic
retention of urine with back-pressure effects and eventually chronic renal
failure. Lesser degrees of stenosis lead to loss of the normal urinary stream
with spraying or dribbling.
Treatment by meatotomy or meatal dilatation is indicated for symptomatic stenosis,
if the stricture is sufficient to prevent free drainage of discharge in a
patient with urethritis or there is a need to pass endoscopic instruments
transurethrally.
Meatotomy
The tightened meatus is opened by cutting down
on to a fine probe placed in the anterior urethra. The cut edges of urothelium
and skin are sewn together with absorbable suture. If the stenosis recurs a skin
flap can be laid in as a meatoplasty to
widen the meatus (Fig. 67.1).
Congenital
urethral stricture
This condition is rare. Some cases are
associated with duplication of the urethra. Usually symptoms are delayed until
adolescence, when it may be difficult to be sure that a supposedly congenital
stricture of the bulbar urethra is not due to unrecognised urethral injury in
childhood. A single treatment by optical urethrotomy or dilatation is usually
effective.
Congenital
valves of the posterior urethra
These are symmetrical folds of urothelium
which can cause obstruction to the urethra of boys. They are usually found just
distal to the verumontanum but they may be within the prostatic urethra. They
behave as flap valves so, although urine does not flow normally, a urethral
catheter can be passed without difficulty. In some instances, the valves are
incomplete and the patient remains without symptoms until adolescence or
adulthood. In such cases the prostatic urethra is grossly dilated and saccules
and diverticula are present within it.
The
valves are difficult to see on urethroscopy because the flow of irrigant sweeps
them into the open position. If the bladder is filled with contrast medium, the
dilatation of the urethra above the valves can be demonstrated on a voiding
cystogram.
Treatment
A suprapubic catheter is inserted to relieve
the back pressure and allow the effects of renal failure to subside before
definitive treatment by transurethral resection of the valves using a paediatric
resectoscope.
Hypospadias
Hypospadias occurs in one in 350 male births
and is the most common congenital malformation of the urethra. The external
meatus opens on the underside of the
penis or the perineum, and the inferior aspect of the prepuce is poorly
developed (‘hooded prepuce’).
Hypospadias
is classified according to position of the meatus.
Glandular
hypospadias —
this is the most common type and does not usually require treatment. The normal
site of the external meatus is marked by a blind pit, although it occasionally
connects by a channel to the ectopic opening on the underside of the glans.
• Coronal hypospadias — the meatus is placed at the junction of the
underside of the glans and the body of the penis.
• Penile and penoscrotal hypospadias —
the opening is on the underside of the penile shaft (Fig.
67.2).
• Perineal hypospadias — this is the most severe abnormality. The scrotum
is split and the urethra opens between its two halves. There may be testicular
maldescent which may make it difficult to determine the sex of the child.
The
more severe varieties of hypospadias represent an absence of the urethra and
corpus spongiosum distal to the
Treatment
Glandular hypospadias does not need treatment
unless the meatus is stenosed, in which case a meatotomy is performed. Surgery
is indicated for other forms of hypospadias to improve sexual function and for
cosmetic reasons. A bewildering variety of plastic surgical procedures is
described to correct the chordee and to bring the urethra to an opening at the
tip of the penis. Most of these procedures make use of prepuceal skin and so
circumcision should be avoided until the hypospadias has been repaired.
Operations for hypospadias are best performed by a specialist paediatric
urologist and will not be detailed here.
Epispadias
Epispadias is very rare, occurring in one in
30000 males and one in 400000 females. In penile epispadias the opening on the
dorsum is associated with upward curvature of the penis (Fig.
67.3). Total
epispadias
usually goes with ectopia vesicae and other severe developmental defects.