Viva Practice for the FRCS(Urol) and Postgraduate Urology Examinations, 2nd ed.

Urethral Trauma

Q. What constitutes the anterior and posterior urethra and how are they most commonly injured?

A.

Anterior urethra (bulbar and penile and navicular) - straddle/fall astride mechanism is the most common cause of injury, which usually results in bulbar urethral damage. Penile fracture, obviously affecting the penile urethra, is another cause.

Posterior urethra (prostatic and membranous) - pelvic fracture (due to road traffic accidents or fall from heights) is the cause of injury in virtually all cases (of blunt trauma). Complete injury occurs due to the shearing effects of bone disruption. Thus the prostate, attached to the puboprostatic ligaments, moves in one direction and the membranous urethra, fixed in the urogenital diaphragm, moves in another. Partial injury results from ligamentous avulsion.

Q. What is the AAST classification of urethral injuries?

A. The AAST classification is demonstrated in Table 8.4.

Table 8.4 The American Association for the Surgery ofTrauma (AAST) urethral trauma severity scale

Q. What is the ‘butterfly’ pattern of perineal bruising following anterior urethral injury?

A. In order to explain this one must understand the fascial layers of the scrotum and anterior abdominal wall.

In the anterior abdominal wall the subcutaneous fatty layer is known as Camper’s fascia. Scarpa’s fascia lies deep to this. Scarpa’s fascia is attached to the coracoclavicular ligaments superiorly. Inferiorly, it fuses with the deep fascia of the thigh (fascia lata) 1 cm below the inguinal ligament. Medially, Scarpa’s fascia is continuous with Colles’ fascia in the perineum. Colles’ fascia attaches to the posterior edge of the urogenital diaphragm and perineal body and the inferior ischiopubic rami. Colles’ fascia is continuous with the dartos fascia of the penis and scrotum.

In the penis, Buck’s fascia lies beneath the dartos fascia (which as already mentioned is continuous with Colles’ fascia). Buck’s fascia is attached distally to the base of glans (coronal sulcus) and laterally to pubic rami, ischial spines and tuberosities.

If the anterior urethra has ruptured but Buck’s fascia is intact, e.g. as may occur in a penile fracture, then urine and haematoma are confined in a sleeve-like or tubular configuration along the length of the penis.

If, however, Buck’s fascia is breached or ruptured or the bulbar urethra is injured, e.g. as may occur in a straddle injury to the bulbar urethra, blood and urine extravasation are limited by the attachments of Colles’ fascia, i.e. their spread is limited by the fusions of Colles’ fascia to the ischiopubic rami laterally and to the posterior edge of the urogenital diaphragm and perineal body posteriorly - the subsequent bruising is There fore butterfly shaped. Bruising and urine can also travel up the anterior abdominal wall beneath Scarpa’s fascia to the clavicles (coracoclavicular ligaments) but extravasation will not extend down the leg or into the buttock.

A posterior urethral injury will only be associated with a butterfly distribution of bruising if the pelvic fracture has resulted in urethral disruption with the tear extending below the urogenital diaphragm into the bulbar urethra.

Q. A 40-year-old farmer is brought into A&E after being run over by a tractor. He is resuscitated by the trauma team and is now stable. He has a pelvic fracture. What urological injuries could this patient have and how might they present?

A.

Bladder injury characterised by suprapubic pain, inability to void, frank haematuria Urethral injury characterised by blood at external meatus (present in 37%-93% of patients with posterior urethral injury and at least 75% of those with anterior urethral injury), pain or inability to void, palpable bladder (latter two suggest urethral disruption)

Q. How would you assess the patient?

A. As with all trauma cases, ATLS principles guide management. It is important to have a multidisciplinary approach, consulting with emergency, orthopaedic and general surgical colleagues if necessary. The patient should be questioned about previous urological problems.

Positive examination findings include

Blood at the penile meatus.

Bruising in the perineum.

Distended bladder on palpation.

Digital rectal examination (DRE) may demonstrate a pelvic haematoma (soft and boggy swelling) or blood on the glove (latter suggests a rectal injury, which is associated in 5% of cases of pelvic fracture). The classically described ‘high riding prostate’ (which occurs as a result of prostate-membranous urethral disruption with the subsequent haematoma pushing up the prostate) can be difficult to feel due to the associated pelvic haematoma.

Q. The previously discussed patient with a pelvic fracture has blood at the meatus, perineal bruising and a large pelvic haematoma on rectal examination. There is no blood on the glove after DRE. What is the likely diagnosis?

A. This is typical of a posterior urethral distraction injury (pelvic fracture urethral distraction defect [PFUDD]) usually occurring between the prostatic and membranous urethra. As mentioned earlier, the injury occurs due to the severe shearing effects of bone disruption. Thus the prostate, attached to the puboprostatic ligaments, moves in one direction and the membranous urethra, fixed in the urogenital diaphragm, moves in another.

Q. How commonly are pelvic fractures associated with urethral injury?

A. Approximately 3%-25% of pelvic fractures are associated with urethral injury. The incidence of double injuries involving the urethra and bladder is 10%-20%.

Q. What investigation would you do?

A. Immediate retrograde urethrogram.

Note: In an unstable patient, one careful attempt can be made to pass a urethral catheter. If there is any resistance a suprapubic catheter is inserted (either via ultrasound scan [USS] guidance or via a formal open approach) and a retrograde urethrogram performed later. It is extremely unlikely that gentle passage of a urethral catheter would convert a partial injury into a complete injury.

Q. How is the urethrogram performed?

A.

I am aware that in a normal situation, the patient should be positioned in a 30% oblique position with bottom leg flexed at hip and knee, but in this pelvic trauma case, as the hips and knees may not be able to be flexed, I would perform supine with anterior-posterior views, with an option to use the C-arm obliquely, to make sure that extravasation from the bulbar urethra is not masked. This is because in the AP views, the bulbar urethra is superimposed upon itself.

A 12F catheter is placed in the fossa navicularis and the balloon inflated with 2 mL water to create a seal preventing leakage of contrast.

Then 20-30 mL of full-strength water-soluble contrast is injected slowly into the urethra using fluoroscopic guidance. If fluoroscopy is not available, then a series of plain x-rays using 10 mL aliquots each time gives sufficient information.

Q. How would you treat a partial urethral injury?

A. Partial urethral injuries can be managed with a suprapubic catheter (SPC) or urethral catheter for 4 weeks. If an SPC is in situ, voiding cystourethrography is then performed. If there is neither contrast extravasation nor stricturing, the SPC can be safely removed and normal voiding can be re-established.

If a urethral catheter is in situ a urethrogram can be performed via a 6 Fr nasogastric (NG) tube inserted alongside the urethral catheter. Contrast can then be passed down the NG tube to exclude extravasation (one uses the same method to perform a retrograde urethrogram following urethroplasty when the urethral catheter is in situ).

Q. What does the antegrade urethrogram in Figure 8.10 show?

Figure 8.10

A. Figure 8.10 shows an antegrade urethrogram demonstrating complete disruption of the posterior urethra with extravasation of contrast due to a pelvic fracture urethral distraction injury. This occurs in 65% of urethral injuries. Partial injuries make up the remaining 35%.

Q. How would you manage the above patient initially?

A. SPC drainage of the bladder to minimise urinary extravasation and broad-spectrum antibiotics.

Q. What difficulties might be anticipated in performing the suprapubic puncture?

A. The bladder may not be palpable. The pelvic haematoma can cause significant distortion of the anatomy and difficulty identifying the normal tissue planes. Thus one must never insert an SPC blindly in this situation. Ultrasound can be used to guide the puncture, otherwise open cystotomy is recommended.

Q. On inserting the SPC into the bladder via USS guidance, the urine is found to be blood stained. What do you suspect and how will you manage this?

A. A combined urethral and bladder injury. A cystogram should be performed via the SPC and the bladder injury dealt with accordingly.

Q. What is the next step in the management of the PFUDD following an antegrade urethrogram?

A. A more detailed urethrogram - the up-and-downogram (i.e. simultaneous retrograde and antegrade urethrogram) - is performed to assess the site, severity and length of the urethral defect.

Definitive reconstruction is performed between 3 and 6 months post-injury (deferred treatment).

Q. Why wait prior the reconstruction?

A.

1. To allow the patient to recover from major trauma.

2. To allow the pelvic haematoma and any urinary extravasation to resolve. This reduces the length of the defect, and allows the tissue planes to return to normal.

Q. What operation is used to re-establish urethral continuity (following the above PFUDD) and what steps can be used to bridge the urethral defect?

A. Bulbo-prostatic anastomotic (BPA) urethroplasty via a perineal approach. It is sometimes necessary to use a combined abdominal and perineal approach.

The steps used to deal with the defect include bulbar urethral mobilisation and if necessary, midline separation of the corporal bodies, inferior pubectomy, and supracorporal urethral rerouting. Defects up to 7 cm can be dealt with using these manoeuvres in sequence.

Q. What are the approximate success rates for deferred treatment and how is the outcome of urethral reconstruction following pelvic fracture judged?

A. The success rate of deferred BPA approaches 95%. The outcome is judged by observing restricture rates (<10%), incontinence (5%) and erectile dysfunction (ED) (20%).

Q. Is there a role of ‘early’ urethral realignment following PFUDD?

A. Early realignment is performed either by open or endoscopic surgery. Immediate open repair is associated with a high incidence of strictures (70%), incontinence (20%) and ED (44%).

Although the incidence of incontinence and ED is reported to be less with endoscopic realignment, there are high restricture rates requiring multiple follow-up procedures. This is an acceptable initial treatment if carried out expeditiously.

Due to the relatively poor outcomes of early surgical realignment, deferred repair is preferred in specialist centres in the United Kingdom.

The only indications for early realignment are concomitant bladder neck or rectal injury. These injuries require immediate open exploration and repair. Bladder neck injury combined with PFUDD will result in incontinence in most cases so repair is essential. Early realignment is recommended in these cases.

Q. How are fall astride injuries managed?

A. The principles are similar to the management of PFUDDs. However, the injury differs in that it is due to a crushing force on the bulbar (anterior) urethra which results in an obliterative stricture and loss of normal urethral length. Deferred treatment is again recommended with initial suprapubic diversion to minimise extravasation, antibiotics to minimise infection and abscess formation, and time to allow bruising and haematoma to resolve. After 3 months stricture excision and primary anastomosis can be performed.