PELVIC AND PROSTATIC TRAUMA
Penetrating trauma to the prostate gland is rare as it is protected from penetrating objects by the surrounding bony pelvis. However, penetrating injury to the prostate is possible from broken pelvic bones as a consequence of pelvic fracture. The real concern with prostatic trauma, however, involves injury to the posterior and prostatomembranous urethra that lie superior to the urogenital diaphragm. This is most commonly a consequence of forceful blunt trauma to the pelvis.
Posterior urethral injuries may occur in three
ways: (1) Internal trauma with perforation of the membranous and prostatic
urethra during unskilled use of rigid endoscopy instruments such as sounds or
cystoscopes. This usually results in only temporary injury to the prostatic
parenchyma but can lead to more long-term “acquired” diverticula, prostatic
abscess, or prostatorectal fistula. (2) External trauma with direct injury to
the prostatic capsule by either missiles or sharp objects through the perineum.
Although rare, these usually involve injury to Colles fascia and to the
urogenital diaphragm (see Plate 2-19) as well. (3) The most common and
clinically important injuries involve damage to the prostatomembranous urethra
from fractures of the bony pelvis. The prostate is firmly held in a relatively
fixed position by the dense puboprostatic ligaments that attach its anterior
surface to the under surface of the os pubis (see Plate 4-1) and by its attachment by the
urethra to the pelvic diaphragm inferiorly. However, the prostatomembranous
urethra, measuring 1 cm long between the apex of the prostate and the
urogenital diaphragm, is very fragile and easily subjected to disruption from
shear force. Pelvic fracture and particularly separation of the symphysis pubis
often dislocates the prostate and severs the prostatomembranous urethra from
the urogenital diaphragm. Alternatively, bony os pubis fragments from the rami
and ischium may sever the prostatomembranous urethra. Lastly, any injury
violent enough to disrupt the puboprostatic ligaments usually also injures the prostatomembranous
urethra, even with minimal bony fractures.
Prostatomembranous urethral rupture should be
considered in all cases of trauma to the pelvic girdle. The inability to
urinate and blood at the urethral meatus are particularly important symptoms and
signs. A rectal examination may reveal superior displacement of the prostate
from its normal position, often to the point at which it becomes nonpalpable. A
retroperitoneal hematoma or urine extravasation may also accumulate and, when
significant, may be palpated as a soft mass on rectal examination. Urethral
catheterization should not be attempted in cases of pelvic injury and blood at
the meatal tip unless retrograde urethrogram imaging reveals an intact urethra,
as this procedure could convert a partial to complete urethral disruption.
The majority of posterior urethral injuries
usually require urgent treatment of shock, bleeding, and fracture management.
With urethral bleeding, the possibility of a coexistent intra- or
extraperitoneal bladder rupture must also be considered. With an intact urethra
and a small extraperitoneal bladder rupture, the simple insertion and
maintenance of catheter drainage may be sufficient for early management. For
intraperitoneal bladder rupture, surgical exploration and repair is generally
needed.
With complete prostatomembranous urethral
disruption, primary surgical reanastomosis of the urethra or primary
realignment of the urethral ends over a catheter, performed immediately or in a
delayed fashion, are necessary. Primary surgical repair is performed through
perineal, transpubic, or suprapubic exposure and is partly determined by the
limitations of patient positioning resulting from pelvic fracture and
stability. Evacuation or drainage of extravasated urine is also advised.
Failure to anastomose or accurately
approximate the severed urethral ends leaves a mucosal defect that results in
extensive cicatrix and stricture formation in the urethral gap. A significant
delay in urethral realignment because of other life-threatening conditions
allows a displaced prostate to become fixed by fibrous tissue, and complicates
alignment surgery. In addition to urethral stricture formation, erectile
dysfunction is a common complication of this form of urethral injury.
