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354 Disorders of the Umbilicus

• An omphalomesenteric duct cyst, in which the proximal and distal
ends have obliterated but a remnant persists in between; this may
present with an infection or obstruction and is quite rare.
Diagnosis of an omphalomesenteric remnant is generally made
on physical exam. An ultrasound may show a loop of bowel present
under the umbilicus, but is not diagnostic and usually not necessary. A
fistulogram may be helpful in clarifying the diagnosis.
All omphalomesenteric duct remnants should be surgically resected.
A Meckel’s diverticulum should be amputated at its base, the intestine
closed transversely, and the vitelline artery ligated. A broad-based
Meckel’s diverticulum may require a formal resection with a primary
anastomosis. Meckel’s diverticula may contain ectopic gastric or
pancreatic tissue on histology. 1,2,7
Umbilical Polyp
An umbilical polyp (Figure 57.3) is a round, reddish mass at the base
of the umbilicus that comprises embryologic remnants of the omphalo-
mesenteric duct or, less commonly, the urachus. It is often brighter red
and slightly larger than an umbilical granuloma. Unlike a granuloma,
it does not respond to silver nitrate and must therefore be surgically
excised and histologically evaluated to confirm the diagnosis. If an Figure 57.3: Umbilical polyp.
umbilical polyp is diagnosed, further work-up for an underlying
omphalomesenteric duct or urachal remnant is warranted. One author
reported a 30–60% chance of finding an underlying omphalomesenteric
duct anomaly if an umbilical polyp was identified. 1,7,10,14
Urachal Anomalies
In the foetus, the urachus is the embryonal duct connecting the dome of
the urinary bladder to the umbilical ring. It is normally obliterated prior
to birth, forming the median umbilical ligament. It forms in the pre-
peritoneal space between the transversalis fascia and the peritoneum.
Nonclosure of the entire tract leads to a patent urachus, whereas closure
on the bladder side creates an umbilical sinus (Figure 57.4). Closure
of both ends but patency of the tract in between may trap fluid in an
urachal cyst (Figure 57.5), which is the most common urachal anomaly.
A bladder diverticulum results when the distal tract involutes; it is the
rarest urachal anomaly.
Both a patent urachus and a urachal sinus may present with clear
drainage from the umbilicus, and careful examination demonstrates a
sinus at the base of the umbilicus. A patent urachus drains urine and
may predispose to cystitis or recurrent urinary tract infections. A urachal Figure 57.4: Urachal remnant.
cyst most commonly presents once it has become infected. An affected
patient will present with infraumbilical swelling, abdominal pain, and
erythema. The symptoms may mimic appendicitis. Patients with delayed
separation of the umbilical cord may have a urachal anomaly. 9
Ultrasonography is often useful in diagnosing a urachal cyst, and
will show a cystic hypoechogenic lesion in the preperitoneal space.
The presence of a longitudinal double line from the bladder dome to
the umbilicus is indicative of a urachal remnant. A sinogram may be
used to identify the presence of a patent urachus or an urachal sinus.
For a patent urachus, a voiding cystourethrogram (VCUG) should be
obtained to exclude the presence of posterior urethral valves (back-up
pressure from the distal obstruction may be keeping the urachus patent).
Treatment involves complete resection of any part of the tract that
has failed to completely obliterate. It is important to remove a cuff of
bladder when excising the urachus to prevent the risk of developing a
urachal adenocarcinoma later in adulthood. 1,2,7
Umbilical Hernia
An umbilical hernia is a full-thickness protrusion of the umbilicus with
an associated fascial defect; it may contain peritoneal fluid, preperito-
neal fat, intestine, or omentum.
In children, umbilical hernias often close spontaneously. Small
defects (<1 cm) are much more likely to close than large defects (>2
cm). Meier et al. reported that umbilical hernias continue to close Figure 57.5: Urachal cyst (intraoperative).
16
until the age of 14 years in African children. The skin overlying an