URETHRAL
ANOMALIES, VERUMONTANUM DISORDERS
Diverticula are
outpouchings of the urethral lumen that occur in both the anterior and
posterior urethra. They may be congenital or acquired. The congenital variety,
usually located in the penile urethra, is more frequent. Diverticula are
further divided into true and false (pseudodiverticula) forms. The true
diverticulum is generally congenital in origin and has a mucous membrane lining
continuous with that of the urethra, whereas the wall of the false type is
initially an unlined pouch as a result of a neoplastic or inflammatory process.
Destruction of the mucosal lining of a true diverticulum by inflammation may
render the two types indistinguishable. A false, acquired diverticulum may
become epithelialized following surgical drainage of a periurethral abscess and
may be interpreted as a true variety. Acquired diverticula are frequently
observed in spinal cord injury patients who develop painless, undetected
periurethral abscesses from chronic urethral catheters. These are “false” at
the onset but appear “true” after epithelialization. Acquired pseudodiverticula
are frequently found in the posterior urethra following instrumental trauma,
whereas congenital diverticula are almost always located on the ventral wall of
the anterior urethra.
Difficult
urination (stranguria) or recurrent urinary tract infections are the most
common presenting symptom. In addition, a common history is that during
micturition, a mass appears in the perineum, scrotum, or under the penis that
slowly disappears with dribbling of urine from the urethra. The condition is
suspected by observation and palpation of the diverticular mass and the
diagnosis is confirmed by urethroscopy and antegrade or retrograde
urethrography. Diverticula are rarely asymptomatic and are best treated by
complete excision and reconstruction of the urethral channel.
The
accessory or duplicated urethra is very rare and has an unknown embryologic
origin. They end blindly, generally at a depth of 3 to 10 mm (incomplete form,
Effman Type I), but can be much longer and connect with the urinary tract
(complete form, Effman Type II). They can communicate with the true, orthotopic
urethra and for the most part are located ventral (hypospadiac) to the true
urethral channel. When found dorsal to the true urethra, they are termed
epispadiac duplicated urethrae. The most common type of urethral duplication is
the Y type, in which a perineal meatus accompanies the usual orthotopic penile
meatus. Retention of inflammatory exudates within these accessory structures can
lead to recurrent abscess formation and intermittent purulent discharge.
Infected anomalous tracts may require complete marsupialization or excision to
eradicate the chronic inflammation.
Disorders
of the verumontanum can be found in all age groups. The verumontanum represents
the fusion of the terminal müllerian ducts (see Plate 2-12) and is located in
the posterior urethral floor proximal to the external urethral sphincter. The
only known function of this structure is to direct the semen during
ejaculation. Congenital hypertrophy of the verumontanum is probably caused by
maternal estrogens. It may be quite enlarged in young children and may nearly
obstruct the prostatic urethra. Obstructive urinary symptoms such as stranguria
and urinary frequency occur, until over- flow incontinence develops. This form
of incontinence in this age group can often be confused with benign enuresis.
When severe, the back pressure induced by this obstruction on the upper urinary tract results
in renal damage, especially if urinary tract infection is present. Surgical
removal of the histologically normal but enlarged verumontanum by transurethral
resection is usually curative but renal damage may persist.
Verumontanitis,
or inflammation of the verumontanum, is usually due to underlying inflammation
from chronic prostatitis, urethritis, or seminal vesiculitis. Visible changes
include simple vascular engorgement or congestion, with or without edema.
Chronic cases assume
a granular and cystic appearance. Verumontanitis in adults can provoke abnormal
sexual symptoms, such as pain with ejaculation or hematospermia, and can cause
urinary symptoms such as frequency and urgency. The ejaculatory ducts may be
obstructed, leading to seminal vesicle dilation and pain radiating to the low
back, perineum, scrotum, and rectum. The diagnosis is generally made by
urethroscopy and treatment is directed at the underlying obstructive or
inflammatory
condition.