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References
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References
1. Pereira BM, de Campos CC, Calderan TR, Reis LO, Fraga GP.Bladder injuries after external
trauma: 20 years experience report in a population-based cross-sectional view. World J Urol.
2013;31(4):913–7. https://doi.org/10.1007/s00345- 012- 0871- 8. Epub 2012 Apr 28
2. Matlock KA, Tyroch AH, Kronfol ZN, McLean SF, Pirela-Cruz MA. Blunt traumatic bladder rupture: a 10-year perspective. Am Surg. 2013;79(6):589–93. https://doi.
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3. Deibert CM, Spencer BA. The association between operative repair of bladder injury and
improved survival: results from the National Trauma Data Bank [Erratum in: J Urol. 2012
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4. Gomez RG, Ceballos L, Coburn M. Consensus statement on bladder injuries. BJU Int.
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5. Simon LV, Sajjad H, Lopez RA, Burns B.Bladder rupture. In: StatPearls [Internet]. Treasure
Island (FL): StatPearls Publishing; 2022.
6. Kong JP, Bultitude MF, Royce P, Gruen RL, Cato A, Corcoran NM.Lower urinary tract injuries
following blunt trauma: a review of contemporary management. Rev Urol. 2011;13(3):119–30.
7. Kang L, Geube A.Bladder trauma. In: StatPearls [Internet]. Treasure Island (FL): StatPearls
Publishing; 2022.
8. Anderson RE, Keihani S, Moses RA, etal. Current management of extraperitoneal bladder
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10. Yeung LL, McDonald AA, Como JJ, Robinson B, Knight J, Person MA, Lee JK, Dahm
P. Management of blunt force bladder injuries: a practice management guideline from the
Eastern Association for the Surgery of Trauma [Erratum in: J Trauma Acute Care Surg 2019
Aug;87(2):511]. J Trauma Acute Care Surg. 2019;86(2):326–36. https://doi.org/10.1097/
TA.0000000000002132.
Part IV
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Urethral Injuries
An injured and obstructed urethra can be compared to a tunnel collapsing
just before the prisoners escape after the unlimited risks and tremendous
efforts to dig it. Yet the distress of the patient unable to void would still be
greater given the agonizing physical pain and direct repercussions to
his health.
Introduction toUrethral Injury
Urethral injuries account for only 4% of genitourinary trauma [1, 2]. Nonetheless,
they are probably the most abundantly studied topic of all urinary tract traumatology because of multiple controversies in their management, and the growing interest of surgeons and researchers in their challenging surgical approach [3]. Indeed,
arguments start from the embryology of the urethra up to the classication and
management of its injuries.
The importance of the urethra can be summarized as being the sole nal outlet of
the whole urinary transportation system which starts from the collecting renal
tubules, and, for males, the exit channel for semen during ejaculation.
The urethra is anatomically divided into two parts, the posterior and the anterior,
and this classication has a great bearing on the causes, mechanisms, and management of its injury. Its posterior part is very difcult to access through open procedures, being conned in an exiguous space between the pubic symphysis and rami,
the vagina and uterine cervix in females, and the rectum in males. Unlike the bladder, and to a lesser degree the ureter, the urethra has very few reserve tissues to
overcome losses.
The posterior urethra is protected by the pubic bones. However, in pelvic frac-
ture or dislocation which is mostly caused by road trafc accidents (RTA), this
protective shield instantly turns into a severing sword or a shredding lever. Replacing
the old term “pelvic fracture urethral distraction defects” (PFUDD) introduced
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by Turner-Warwick [4], the concept of “pelvic fracture urethral injury” (PFUI)
is frequently used nowadays to refer to this anatomopathological entity as current
evidence shows that these injuries are not usually complete nor they are necessarily
distracted [5].
The anterior urethra is protected by the corpus spongiosum of the penis, and its
pendulous part is generally spared from violent blunt trauma such as those arising
from RTA and falling astride. It is however exposed to stab injuries, gunshots, animal or human bites, and iatrogenic injuries. The bulbar part of the anterior urethra
is the segment most prone to straddle injuries and also pays a bitter price to iatrogenic trauma.
Historically, urethral injury was almost always fatal because of the inability to
pass urine, the hematoma, and the secondary urine extravasation and infection. With
the progress of modern medicine, urethral injuries not only are no longer fatal per
se but also rarely jeopardize renal function since a rapid suprapubic catheterization
is an easy, effective, and safe way to protect the upper urinary tract. Nonetheless,
injury to the urethra exposes the patient to prolonged morbidity related to the mechanism (pelvic fracture) and other possible associated injuries (rectum, vagina, penis)
and yields a high rate of functional complications (urinary incontinence, impotence).
The diagnosis of urethral injury is mainly reached through retrograde urethrography which can be combined with an antegrade urethrography in patients with
complete disruption of the urethra provisionally treated with an SPC.
The repair of posterior urethral injuries requires a complex technique where
there is almost no room for a pedicled graft or a free ap and efforts have to be made
to approximate the urethral ends even when the gaps are long, by mobilizing the
bulbar urethra. However, repair of anterior urethral injuries with long gaps is frequently performed using various interposition of inlay or onlay grafts.
The average total cost of the management of a urethral injury and stricture widely
varies from publications and depends on the management strategies. It was estimated to be as low as $3000 for a simple anterior stricture requiring a mere urethrotomy/urethral dilatation, to as high as around $170,000 for a complex posterior
urethral injury repair [6–10]. It is important to remember that this cost does not
include the loss of productivity and quality of life.
Urethral Injuries
References
1. McGeady JB, Breyer BN.Current epidemiology of genitourinary trauma. Urol
Clin North Am. 2013;40(3):323–34. https://doi.org/10.1016/j.ucl.2013.04.001.
Epub 2013 Jun 12.
2. Alwaal A, Zaid UB, Blaschko SD, Harris CR, Gaither TW, McAninch JW,
Breyer BN.The incidence, causes, mechanism, risk factors, classication, and
diagnosis of pelvic fracture urethral injury. Arab J Urol. 2015;13(1):2–6. https://
doi.org/10.1016/j.aju.2014.08.006. Epub 2014 Sep 16.
Urethral Injuries
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3. Barbagli G, Sansalone S, Djinovic R, Romano G, Lazzeri M.Current contro-
versies in reconstructive surgery of the anterior urethra: a clinical overview. Int
Braz J Urol. 2012;38(3):307–16; discussion 316. https://doi.org/10.1590/
s1677- 55382012000300003.
4. Turner-Warwick RT.Principles of urethral reconstruction. In: Wesbter G, Kirby
R, King L, editors. Reconstructive urology. Oxford: Blackwell Scientic
Publications; 1993. p.609–42.
5. Gómez RG, Mundy T, Dubey D, El-Kassaby AW, Firdaoessaleh, Kodama R,
Santucci R. SIU/ICUD consultation on urethral strictures: pelvic fracture
urethral injuries. Urology. 2014;83(3 Suppl):S48–58. https://doi.org/10.1016/j.
urology.2013.09.023. Epub 2013 Nov 8.
6. Tausch TJ, Lotan Y, Zhao L, Morey AF.Decision analysis model comparing
cost of management strategies for pelvic fracture urethral injuries. Urol Pract.
2016. https://doi.org/10.1016/j.urpr.2016.07.004.
7. Johnsen NV, Penson DF, Reynolds WS, Milam DF, Dmochowski RR, Kaufman
MR. Cost-effective management of pelvic fracture urethral injuries. World J
Urol. 2017;35(10):1617–23. https://doi.org/10.1007/s00345- 017- 2022- 8. Epub
2017 Feb 22.
8. Rourke KF, Jordan GH.Primary urethral reconstruction: the cost minimized
approach to the bulbous urethral stricture. J Urol. 2005;173(4):1206–10. https://
doi.org/10.1097/01.ju.0000154971.05286.81.
9. Osterberg EC, Murphy G, Harris CR, Breyer BN.Cost-effective strategies for
the management and treatment of urethral stricture disease. Urol Clin North
Am. 2017;44(1):11–7. https://doi.org/10.1016/j.ucl.2016.08.002.
10. Greenwell TJ, Castle C, Andrich DE, MacDonald JT, Nicol DL, Mundy
AR.Repeat urethrotomy and dilation for the treatment of urethral stricture are
neither clinically effective nor cost-effective. J Urol. 2004;172(1):275–7.
https://doi.org/10.1097/01.ju.0000132156.76403.8f.
Anatomy oftheUrethra
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26
26.1 Embryology oftheUrethra
The cloacal membrane appears between the fourth and the fth week and separates
the cloaca from the amniotic cavity. Furthermore, the urorectal septum divides the
cloaca into the urogenital sinus and the hindgut, the former being the precursor of
the bladder and posterior urethra [1].
The development of the spongy urethra proceeds through three stages: a solid
epithelial plate, a deep urethral groove, and a fused urethra [2]. Herein a grooved
urethral plate was observed to develop from proximal to distal at 6weeks and to
be completely fused by 8weeks. The glanular urethra development starts also at
6weeks and is a longer process evolving in four stages: a solid epithelial plate (sixth
week), a blind central canal (13th week), a deep glanular groove (14th week), and
the oor from the preputial lamella (14th week) [2].
The distinction between the male and female genital systems is triggered
once the gonad assumes characteristics of the testis or ovary in the eighth week
of gestation. However, the external genital organs acquire specic sexual characteristics only from the 11th or 12th week [3].
The penile urethra was proposed to arise from the fusion of the urogenital swellings with primary luminization, whereas the glandular urethra was created by secondary luminization of the epithelial cord formed by the fusion of the arms of the
genital tubercle, i.e., the glans [4].
An interesting theory, “the double zipper hypothesis”, states that the human
male urethra develops through two mechanisms: an initial “opening zipper” that
produces distal canalization of the solid urethral plate resulting in the urethral
groove, which proceeds through a high rate of epithelial proliferation, and a subsequent “closing zipper” that consists of a fusion of the two epithelial surfaces of the
urethral groove, resulting in the distal extension of the penile urethra [5].
Critical events have been described for the normal development of the urethra
and genitals: (a) development of the external genitalia, (b) cloacal membrane fate,
© The Author(s), under exclusive license to Springer Nature Singapore Pte
Ltd. 2023
S. A. AL-Mamari, Urogenital Trauma: A Practical Guide,
https://doi.org/10.1007/978-981-99-6171-9_26
215
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and (c) distal urethra formation [6]. Hypospadias occurs when there is a faulty ventral opening of the urethra as a result of either a defect in the external genitalia or in
the distal urethra formation.
Does the urethral plate arise from the ectoderm, the mesoderm, or the
endoderm?
There are ongoing controversies not only about the origin of the urethral plate
but also concerning its role in the development of the urethra. However, most
embryologists believe that the epithelial urethral plate is formed by the prolifera-
tion of the endoderm of the anterior cloacal wall, and grows anteriorly in the
mesoderm of the genital tubercle while remaining in contact with the ectoderm
covering the caudal median surface of the tubercle at the cloacal groove [7].
Even if you manage to comprehend the aforementioned sentence, you still won’t
be off the hook, as the role of the urethral plate is also up for debate. Some consider
it to be the precursor of the sole glandular urethra while most of the penile urethra
would develop from the urogenital sinus, and others state that it is the precursor of
the whole penile urethra [7]. However, a consensus exists on the fact that the
urethral plate disintegrates creating the urethral groove which is then transformed into the urethra by fusion of the urethral folds which are present on the
sides of the groove. Yet again, this theory is challenged by some studies which deny
the existence of a groove and folds, calling for revisiting the concept of hypospadias
itself since this is considered to result from the failure of the fusion of the folds [8].
Hynes and Fraher found that the urethral plate is a mere temporary apposition of the
walls of the phallic cloaca in the distal shaft and proximal glans and that the formation of the entire urethra results from a proximo-distal movement of waves of subepithelial migration and fusion of paramedian folds of mesoderm. They described
four pairs of folds being involved in its formation, namely urethral, frenular,
preputial, and lacunar which act in a similar manner to form their corresponding
portions [9].
26 Anatomy oftheUrethra
26.2 Gross Anatomy oftheMale Urethra
Contrary to its female counterpart, the male urethra has a double function: it plays
a key function in micturition as the terminal anatomical channel for urine elimination, but also has an essential role in the male reproductive system by conveying the
semen emitted during ejaculation. It is a relatively long tubular structure whose
length is about 22 cm in the adult male with no signicant correlation with the
patient’s height, weight, body mass index, or age [10].
There are many subdivisions of the male urethra based on embryologic, topographic, anatomic, and clinical criteria. One of the proposals is to divide the urethra
according to the surrounding organs or structures. Hence three portions can be
described, namely the prostatic, membranous, and spongy urethra, in relation to
the prostate gland, the urogenital diaphragm, and the corpus spongiosum, respectively [11].
26.2 Gross Anatomy oftheMale Urethra
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However, most frequently, the male urethra is divided into two parts: The posterior urethra (prostatic and membranous urethra) and the anterior or spongy urethra
(bulbar, penile urethra or pendulous urethra, fossa navicularis, and glandular urethra). The urethral meatus is the exiting orice of the urethra at the tip of the penis.
A pre-prostatic urethra is also described as a very short segment, 0.5–1.5cm long,
embedded within the wall of the urinary bladder before entering the prostate. It is
lined by the same transitional epithelium or urothelium covering the bladder lumen.
It is surrounded by the internal urethral sphincter made of thickened involuntary
circular smooth muscle.
Hereafter is a brief description of the different urethral parts [12–15]:
1. Prostatic urethra: Found within the prostate, measures 3–4cm. It is the widest
portion of the male urethra and contains many structures or appendices:
the urethral crest, seminal colliculus, prostatic utricle, verumontanum, and the
orices of the prostatic ducts. The entrance of the prostatic utricle lies between
the two orices of the ejaculatory ducts. The verumontanum is an important
anatomic landmark serving as the distal limit during prostatic resection to preserve the voluntary striated sphincter which lies just distal to it. It is a prominent
structure visible at the posterior distal prostatic urethra which can also be seen as
a lling defect in urethrography. The prostatic urethra is lined by a continuation
of the urothelium from the bladder and the upper urinary tract. The urothelium
of the prostatic urethra is in direct contact with the glandular and stromal tissue
of the periurethral zone of the prostate.
2. Membranous urethra: It is short, measuring 1–2.5 cm in length. It begins
immediately below the prostate and ends just above the penile bulb. It passes
through the deep perineal pouch, and the perineal membrane and is surrounded
by the external urethral sphincter, which is longer anteriorly and whose
bers do not meet posteriorly. Posteriorly the membranous urethra is in close
contact with the bulbourethral or Cowper’s glands. It is lined by a pseudostratied columnar epithelium. It is closely and intimately attached anteriorly to
the pubis by the suspensory ligaments.
3. Anterior or Spongy urethra: This is the longest segment of the urethra, travel-
ing within the corpus spongiosum of the penis. It has an average length of 15cm
and comprises two widenings at the bulb of the penis and in the glans penis
where it forms the fossa navicularis. Bulbourethral and urethral glands empty in
this portion and can be visualized in urethrography as small dots. It is lined by a
pseudostratied columnar epithelium up to the terminal portion which is lined
by a stratied squamous epithelium. Five layers can be seen in a cross-section
of the anterior urethra: urethral epithelium, lamina propria, corpus spongio-
sum, tunica albuginea, and Buck’s fascia. The bulbar urethra measures
3–4 cm, is located within the bulbospongiosus muscle and extends from the
urogenital diaphragm to the penoscrotal junction. The penile urethra measures
about 15cm, is entirely surrounded by the corpus spongiosum, and dilates as the
fossa navicularis within the glans penis before ending by the external meatus
(Fig.26.1).
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Fig. 26.1 The whole
length of the lumen of the
male urethra exposed by an
incision extending into it
from its dorsal aspect.
(From Ellis H [15], with
permission from Elsevier)
26 Anatomy oftheUrethra
Females have only the posterior urethra, the anterior one being replaced by the
labia minora resulting from the persistent separation of the urethral folds on the
ventral surfaces of the genital tubercle [16].
Unlike other epithelia (e.g., gastrointestinal epithelium), the urethral wall lacks
a supporting muscularis mucosa. Therefore, anteriorly it lies directly on the vascular erectile corpus spongiosum contained within the tight Buck’s fascia. This
direct contact exposes the corpus spongiosum to urine inundation once the urethral
epithelium is breached. Thus, whenever the patient tries to void, the extravasation
will increase inside the corpus spongiosum and the pressure might rupture Buck’s
fascia, allowing further urine extravasation and hematoma to reach the Colles’ fascia, with a characteristic perineal buttery bruising [17, 18].
26.4 Congenital Urethral Abnormalities
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26.3 Urethral Blood Supply
The urethra passes through several compartments in the perineum, therefore receiving blood supply from different sources: the inferior vesical artery, bulbourethral
artery, and the internal pudendal artery. Moreover, the anterior urethra and its
surrounding corpus spongiosum receive blood from both antegrade and retrograde
streams mainly from the bulbar and dorsal arteries which arise from the common
penile artery. The common penile artery is a continuation of the internal pudendal artery which divides into bulbar, urethral, and dorsal arteries: the bulbar
arteries are responsible for the antegrade ow to the urethra and corpus spongiosum,
and the dorsal arteries provide the retrograde blood supply starting from the glans
[12, 13].
The venous drainage is organized distally from a plexus within the spongy glans
that develops into periurethral veins running within the corpus spongiosum and
communicating with the deep dorsal vein via multiple circumex veins. Proximally
these veins unite at Santorini’s plexus proximal to the pubic bone and adjacent to
the prostate [13].
26.4 Congenital Urethral Abnormalities
Congenital urethral abnormalities are rare but their anatomopathological forms are
multiple [1, 19]:
1. Hypospadias: This pathology is characterized by abnormal development of the
urethral fold and the ventral prepuce resulting in the urethral opening developing
on the ventral aspect proximal to the penile tip. Hypospadias is classied as
anterior (70%) (glandular and subcoronal), middle (distal and proximal penile
and midshaft), and posterior (penoscrotal, scrotal, and perineal) [20]. The incidence of hypospadias varies from 1/200 to 1/300 boys. The embryological
mechanism of hypospadias is not well understood, and many theories exist stating that it results from the failure of formation of the various primary urethral
folds or from their non-fusion with their counterparts, or from a defect in the
cloacal membrane. Moreover, the chordee associated with hypospadias is
believed to arise from a failure of the increase in volume in the phallic length and
the persistence of the urethral plate [9].
2. Posterior urethral valves (PUV): Occur in 1/5000–8000 newborn boys, and can
have grim consequences such as bilateral renal obstruction, bladder dysfunction,
vesicoureteral reux, bilateral upper tract dilatation (hydroureteronephrosis) and
renal damage [19] (Fig.26.2). Hugh Hampton Young etal. proposed a classication of the PUV into three types in 1919 [21]:
Type I valves (the most common): they develop from the verumontanum and
extend distally attaching the lateral urethral walls as two leaets (type Ia) or
as a unicuspid leaet (type Ib).
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26 Anatomy oftheUrethra
a
b
d
c
Fig. 26.2 Posterior urethral valves (PUV) in a 3-day-old male. Longitudinal grayscale ultrasound
images of the right (a) and left (b) kidneys demonstrate dilation of the pelvicalyceal systems and
right proximal ureter (U). P Renal pelvis, C calyx. (c) Transverse grayscale ultrasound image of
the bladder (B) depicts severe wall thickening with dilation of the distal ureters (arrows). (d)
VCUG image demonstrates marked dilation of the posterior urethra (PU). Arrow indicates the site
of the valves. (From Kassab GH etal. [19], with permission from Springer Nature)
Type II valves: they extend from the bladder neck to the verumontanum. This
type is no longer considered a valve, being regarded as a normal variant.
Type III valves: Appear as a diaphragm xed on the whole circumference of
the urethra, leaving a central hole. These are referred to as type IIIa, or type
IIIb, if they are distal or proximal to the verumontanum, respectively. Cobb
considered the type III valve merely as congenital urethral strictures, and they
are sometimes referred to as Cobb’s collar [22].
3. Anterior urethral valves: These rare anomalies have variable locations, distrib-
uted almost equally between the bulbar urethra (40%), the penoscrotal junction
(30%), and the penile urethra (30%) [19].
4. Prune-Belly Syndrome (PBS): Also referred to by the eponym Eagle-Barret syn-
drome after the authors who rst described it in 1950 [23]. Its incidence is estimated to be 3.8 per 100,000 live male births in the United States, and female
occurrence is extremely rare, representing less than 5% of all PBS cases [24]. It
is characterized by a triad comprising decient abdominal wall muscles,
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