1516

PART VIII

GENITOURINARY DISORDERS

Mesonephric

duct

Allantois

Primitive

Bladder

urogenital

Phallus

sinus

Mesonephric

Perineal

Cloacal

duct

body

membrane

Ureteric bud

Urorectal

Hindgut

Anorectal

Urorectal

septum

Ureter

septum

canal

FIGURE 120-1

Division of the cloaca in the urogenital sinus and rectum. A, At the end of the fifth week. B, At 7 weeks. C, At 8 weeks. (Modified from Sadler

TW: Langman’s Medical Embryology, 8th ed. Philadelphia, Lippincott Williams and Wilkins, 2000, p 316.)

development, lateral ingrowth of mesoderm occurs between

submucosal tunnel in the bladder wall.²² With continued ex-

the two layers of the cloacal membrane during the fourth

posure and chronic inflammation, the exstrophied bladder

and fifth weeks of gestation. This results in formation of the

becomes thickened and polypoid (Fig. 120-3). Long-term

lower abdominal wall and pelvis. Subsequent caudal growth

exposure may eventually result in a fibrotic, rigid bladder

of the urorectal septum results in its fusion with the cloacal

plate that is ultimately unsuitable for closure.

membrane, thus fully separating the cloaca into the bladder

anteriorly and the rectum posteriorly (Fig. 120-1). The paired

GENITAL DEFECTS—MALE

genital tubercles, which will give rise to the phallus, migrate

medially to fuse in the midline. Normal perforation of the clo-

In the male infant, the open and everted urethral plate can be

acal membrane occurs after fusion with the urorectal septum,

seen joining the exposed bladder. The penis is characteristi-

at approximately the sixth week, resulting in formation of

cally short with a flattened, everted glans. The prepuce is lo-

separate urogenital and anal openings.¹⁷

cated on the penile ventrum (Fig. 120-4). The ejaculatory

Migratory failure of the lateral mesodermal folds and ab-

ducts are typically normal and exit at the exposed verumon-

normal overdevelopment of the cloacal membrane have both

tanum in the posterior urethra. The base of the penis and scro-

been proposed as potential causes of the prevention of normal

tum are widely separated, with lateral displacement of the

mesodermal ingrowth to the cloacal membrane.^16,18 The lack

corporal bodies and neurovascular bundles. Historically it

of adequate mesodermal reinforcement is thought to result in

was believed that the individual corpora were of normal cal-

premature rupture of the cloacal membrane, the timing of

iber and appeared shortened because of their attachment to

which determines the extent of the abdominal wall defect

the widened pubic diastasis and associated dorsal chordee.

and degree/severity of urogenital tract involvement.¹⁹ Rupture

of the cloacal membrane after fusion with the urorectal sep-

tum results in bladder exstrophy, whereas rupture before fu-

sion gives rise to the more severe presentation of cloacal

exstrophy (see later discussion).

CLINICAL PRESENTATION

In general infants with bladder exstrophy are born full term,

without coexisting anatomic anomalies. At birth, an everted

posterior bladder plate of varying size is seen in the midline

of the lower abdomen. The mucosa of the exposed bladder

in the newborn is typically smooth and pink. The umbilical

cord exits from the superior-most border of the bladder plate,

and a small umbilical hernia may be present (Fig. 120-2). In

addition, there is significant widening of the pubic symphysis

and the anus is anteriorly displaced. The levator ani complex

is also divergent, leading to an inherent weakness in the pelvic

floor and a tendency toward rectal prolapse and varying de-

grees of fecal incontinence. Associated inguinal hernias are

common and have been reported in 82% of boys and 10%

of girls.²⁰ The upper urinary tract is usually normal, though

renal anomalies including ectopic, horseshoe, hypoplastic,

FIGURE 120-2

Typical findings of classic bladder exstrophy in a new-

dysplastic kidneys, and megaureters may be observed.²¹ Vesi-

born male. The bladder plate is small, and a small hernia is evident at its

coureteral reflux occurs in the vast majority of children after

superior border. The penis is foreshortened, with widely splayed corporal

bladder closure, secondary to an exaggerated lateral course

bodies and glanular separation. The urethral plate is short and located on

of the ureters within the pelvis and lack of adequate

the anterior surface of the split phallus.

CHAPTER 120

BLADDER AND CLOACAL EXSTROPHY

1517

GENITAL DEFECTS—FEMALE

The clitoris is bifid, with divergence of the mons pubis, labia,

and clitoral halves (Fig. 120-6). The urethra and vagina are

shortened, and the introitus is anteriorly displaced. The vag-

inal orifice is often stenotic. The uterus and adnexa are typi-

cally normal, though vaginal and uterine duplication have

been reported.^24,25

Uterine prolapse occurs commonly in

female patients, secondary to the inherent weakness in pelvic

floor support.

PELVIC DEFECTS

Some degree of widening of the pubic symphysis is present in

all cases of bladder exstrophy and contributes to outward ro-

tation and eversion of the pubic rami at their junctions with

the ischial and iliac bones (Fig. 120-7). Using computed to-

mography (CT), Sponseller and colleagues further character-

ized the pelvic anatomy of a large group of exstrophy

patients, noting a significantly increased distance between

the triradiate cartilages (31%), external rotation of the anterior

pelvis (18%), and 30% shortening of the pubic rami.²⁶ On the

FIGURE 120-3

When the bladder has been exposed for at least 1 week

basis of three-dimensional models generated by CT, Stec and

after birth and the mucosa is subjected to continued exposure and inflam-

colleagues observed that among children with exstrophy, the

mation, polypoid excrescences typically appear, as in this female infant.

levator ani muscles were more posteriorly positioned and out-

wardly rotated. Furthermore, the puborectal sling had a more

More recently, an MRI-based study by Silver and colleagues of

flattened configuration and supported twice the body cavity

adult men with exstrophy and age-matched controls found

area in exstrophy patients.²⁷ As mentioned previously, these

that although the length of the posterior corporal bodies

pelvic floor defects predispose to pelvic organ and rectal

was the same between groups, anterior corporal length in

prolapse in this patient population.

men with exstrophy was nearly 50% shorter than that of con-

trols.²³ Therefore the penis appears shortened not only second-

PRENATAL DIAGNOSIS

ary to corporal divergence, dorsal chordee, and abnormal

crural attachments to the corpora cavernosa but also because

The use of prenatal ultrasound (US) and MRI has improved

of an inherent deficiency of corporal tissue (Fig. 120-5). The

the antenatal diagnosis of bladder exstrophy, allowing for ap-

testes may appear to be undescended, but in most cases they

propriate parental counseling and planning of postnatal man-

are actually retractile and will eventually reside in the scrotum

agement. The prenatal diagnosis of bladder exstrophy may be

without the need for formal orchiopexy. Should it be required,

suggested on US by failure to visualize the bladder in the pres-

orchiopexy is performed in conjunction with inguinal hernia

ence of normal kidneys and amniotic fluid.^28-30 In a review of

repair.

prenatal US studies from 25 women who delivered infants

FIGURE 120-4

Classic exstrophy in the male. The penis is pulled downward to expose the dorsal aspect, revealing the urethral plate leading to the

exposed bladder. 1, umbilical cord; 2, bladder mucosa; 3, paraexstrophy tissues; 4, left ureteric orifice; 5, verumontanum; 6, urethral plate; 7, glans penis.

1518

PART VIII

GENITOURINARY DISORDERS

FIGURE 120-5

Penile configura-

tion in classic bladder exstrophy.

Normal male perineum (A) and with

bladder exstrophy (B). Note the loss

of the normal triangular shape of

the perineum and widening of the

pubic symphysis. In the setting of

exstrophy, the corpora cavernosa

are widely separated and are intrin-

sically shorter.

1, corpus caverno-

sum of the penis; 2, glans penis;

3, corpus spongiosum;

4, bul-

bospongiosus muscle;

5, ischium;

6, ischiopubic ramus;

7, pubis;

ischio-cavernosus muscle and crus

of penis; 9, urogenital diaphragm;

10, anus and external anal sphincter.

with exstrophy, Gearhart and colleagues observed the follow-

be accomplished in a multi- or single-stage (complete) repair.

ing features: absent bladder (71%), lower abdominal bulge

Multiple contemporary approaches including the modern

(47%) and anteriorly displaced scrotum with small phallus

staged reconstruction of exstrophy

(MSRE) and complete

in male fetuses (57%), low-set umbilical cord (29%), and

primary reconstruction of exstrophy (CPRE) along with War-

abnormal widening of the iliac crest (18%).³¹

saw,³² Erlangen,²⁴ Mainz,³³ and Kelly³⁴ techniques have been

published; however, for the purposes of this review, only the

major principles of MRSE and CPRE are discussed.

SURGICAL RECONSTRUCTION

Surgical management of classic bladder exstrophy consists of

functional closure of the native bladder, closure of the epispa-

dic urethra and genitalia, and creation of a continence mech-

anism to allow for proper urine storage. Reconstruction may

FIGURE 120-6

Typical appearance of classic bladder exstrophy in a fe-

FIGURE 120-7

Plain radiograph of a neonate with bladder exstrophy

male. Note the widely divergent labia and anterior displacement of the

demonstrates the soft tissue mass effect of the exposed bladder, the wide

vaginal introitus and anus.

diastasis of the symphysis pubis, and the posterior rotation of the

acetabula.

1520

PART VIII

GENITOURINARY DISORDERS

FIGURE 120-9

Sequence of repair of bladder exstrophy in a male. A, Completion of the dissection around the periphery of the bladder and the urethral

plate. B, Inversion of the bladder plate and approximation of the corpora as a first stage in epispadias repair. Also note the inferior paraexstrophy incisions.

C, Further closure of the skin over the corpora and their partial freeing from the pubis. D, Placement of a suprapubic drainage tube. E, Further closure of the

skin inferiorly, with approximation to the urethral plate. Creation of the paraexstrophy flaps is now evident. F, The urethral plate is prepared for tubular-

ization over a catheter. G, The urethral plate is now tubularized, and ureteral catheters are placed bilaterally and brought out on each side of the bladder.

The bladder is also in the process of being tubularized. H, Completion of tubularization of the bladder and urethra, and location of the various drainage

tubes. I, After two-layer closure of the bladder and urethral plate, the bladder is reduced into the pelvis and fixed with sutures. J, Sutures are placed to

encourage approximation of the pubic halves. K, Drainage tubes are brought out superiorly, and fascia, subcutaneous tissue, and skin are approximated.

Approximation of the pubis helps protect the bladder closure and the abdominal wall closure.