This apical patent allantois becomes stretched

variety of fistulae, the exact type being deter-

and narrowed as the fetus grows and the bladder

mined by the sex of the fetus and the stage of

descends until the patent allantois is totally

development at which time the fistula occurs

obliterated at approximately the fourth month

(see Fig. 1.14).

of fetal life. This “tube like” vestigial remnant of

In the male, such fistulae include: recto-vesical,

the allantois extends extraperitoneally to the

recto-urethral, and recto-perineal fistulae. Their

umbilicus and is known as the urachus. As the

incidence in the presence of rectal atresia or

fetus further develops and the bladder contin-

obstruction is common and occurred in 42% of

ues to descend, the urachus obliterates and

Gross’ series.

forms the urachal ligament.

In the female, the recto-vesical and recto-

urethral fistulae are almost non-existent because

Urachal Anomalies

of the interposition of the vagina and uterus

between the urogenital sinus and rectum (see

Fig. 1.15). However, the result is an even higher

Failure of the urachus to obliterate completely

incidence of recto-vaginal and recto-vestibular

results in one of four basic types of anomalies.

fistulae with an incidence of 60% of such cases

The most common of these is the completely

in Gross’ series.

patent urachus. This condition is commonly

associated with bladder outlet obstruction and

Other Bladder Anomalies

is generally diagnosed shortly after birth with

urinary leakage occurring from the umbilicus.

Other congenital bladder anomalies such as

The diagnosis is confirmed by cystogram and/

agenesis, hypoplasia, duplication, diverticula,

or the use of indigo carmine which confirms

and bladder

extrophy are in

general,

rare.

the drainage to be of urinary origin. Treatment

Agenesis and

hypoplasia are

extremely

rare

consists of correcting the lower urinary tract

and in most cases are associated with either

obstruction and excising the fistula if it does

renal agenesis or other anomalies which are

not close spontaneously. If the anomaly is that

incompatible with life. If the latter is not the

of a partially patent urachus, a mucous fistula is

case, the ureters, generally opens ectopically

generally seen if the patency is at the umbilical

into a dilated urethral pouch or into the rectum

end. If at the bladder end, the apical diverticu-

or vagina.

lum is lined by mucous secreting epithelium

Bladder duplication may be complete in which

that may develop into adenocarcinoma in later

case two entirely separate bladders lie side by

life. A urachal cyst results when the umbilical

side enclosed within a common sheath. Each has

and bladder ends close and a small tube per-

its own ureter and urethra and in the male two

sists centrally. These patients usually present

penises is generally present. In the female, there

with an infra-umbilical midline suprapubic

may also be duplication of the Müllerian duct

mass of various sizes and the treatment is sur-

derivatives and duplications of the large bowel

gical excision.

frequently coexist. In patients with incomplete

duplication, the bladders join at the base and

Cloacal Duct Anomalies

have a common urethra. Other bladder divisions

include the presence of midline sagittal septums

or transverse septums which divide the bladder

Prior to complete division of the cloaca by the

into an upper and lower half.

urorectal septum, which normally has occurred

by the seventh week, a connection remains

Bladder Diverticula

between the rectum and the urogenital sinus

which is known as the cloacal duct. In situations

When a bladder diverticulum is thought to be

where there is associated anal or rectal malde-

of congenital origin, it is believed to be due to

velopment such as stenosis, imperforate anus,

a congenital deficiency in the detrusor muscle.

imperforate anus with blind ending pouch, or

This results in the formation of a diverticulum

normal anus with blind ending rectum, this clo-

in face of normal bladder pressures with mic-

acal duct can fail to close which then leads to a

turition and

no obvious outlet obstruction.