Page 133 - Clinical Anatomy

ECA2 7/18/06 6:43 PM Page 118

118 The abdomen and pelvis

performing an enucleation of the prostate, the plane between the adenoma-
tous mass and this compressed peripheral tissue is entered, the ‘tumour’
enucleated and a condensed rim of prostate tissue, lying deep to the true
capsule, left behind. The prostatic venous plexus, lying external to this, is
thus undisturbed.

Blood supply

The arterial supply is derived from the inferior vesical artery (a branch of
the internal iliac artery), a branch entering the prostate on each side at its
lateral extremity.
The veins form a prostatic plexus which receives the dorsal vein of the
penis and drains into the internal iliac vein on each side. Some of the
venous drainage passes to the plexus of veins lying in front of the vertebral
bodies and within the neural canal. These veins are valveless and constitute
the valveless vertebral veins of Batson. This communication may explain the
readiness with which carcinoma of the prostate spreads to the pelvic bones
and vertebrae.

Clinical features

1◊◊Prostatectomy for benign prostatic hypertrophy involves removal of
the hypertrophic mass of glandular tissue from the surrounding normal
prostate, which is compressed as a thin rim around it—a false capsule (Fig.
88). This is usually performed transurethrally by means of an operating
cystoscope armed with a cutting diathermy loop. During this procedure,
the verumontanum, (colliculus seminalis), is an important landmark. The
surgeon keeps his resection above this structure in order not to damage the
urethral sphincter. If the prostate is very enlarged, open prostatectomy is
indicated. The gland is approached retropubically, the capsule incised
transversely and the hypertophied mass of gland enucleated.
2◊◊After the age of 45 years some degree of prostatic hypertrophy is all
but invariable; it is as much a sign of ageing as greying of the hair. Usually the
lateral lobes are affected and such enlargement is readily detected on rectal
examination. The median lobe may also be involved in this process or may be
enlarged without the lateral lobes being affected. In such an instance, symp-
toms of prostatic obstruction may occur (because of the valve-like effect of
this hypertrophied lobe lying over the internal urethral orifice) without pro-
static enlargement being detectable on rectal examination.
Anterior to the urethra the prostate consists of a narrow fibromuscular
isthmus containing little, if any, glandular tissue. Benign glandular hyper-
trophy of the prostate, therefore, never affects this part of the organ.
3◊◊The fascia of Denonvilliers is important surgically; in excising the
rectum it is the plane to be sought after in order to separate off the prostate
and urethra without damaging these structures. A carcinoma of the
prostate only rarely penetrates this fascial barrier so that ulceration into the
rectum is very unusual.