The urachus or
median umbilical ligament is an epithelial tubular structure located in the midline
that spreads from the anterosuperior part of the bladder to the umbilicus,
connecting the apex of the urinary bladder with the allantois in the fetus, and
is involved in forming the umbilical structures. It is the embryological
remnant of the cloaca and the allantois. The lumen of the urachus usually
becomes obliterated during embryonic development. Descent of the bladder toward
the pelvis stretches the urachus, eventually leading to obliteration of its
lumen. The median umbilical ligament is the resultant fibrous cord that runs
from the umbilicus to the dome of the bladder. Occasionally, this obliterative
process is incomplete, leading to a persistent urachal remnant (UR)1.
UR diseases are rare and typically present in early childhood with unspecific
symptoms such as abdominal pain or urinary problems. Urachal anomalies can be
classified into congenital and acquired anomalies.
It is of four
types:
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1.
Persistent
urachus, which communicates the bladder with the umbilicus;
2.
Urachal
cyst (54%), a part of the urachal canal without any patent connection with the
bladder or the umbilicus;
3.
Vesicourachal
diverticulum, a structure that opens within the bladder;
4.
Urachal
sinus (30%), which is a form of a cyst communicating with the umbilicus.
Acquired
anomalies are infections and malignant degeneration. Remnants found in neonates
<6 months old usually resolve spontaneously without the need for surgery5.
Case report
A 40 year old
woman presented to OP with complaints of abdominal pain in the umbilical region
for 2 weeks with foul smelling purulent discharge from the umbilicus for 1week.
There were no urinary symptoms, and she was afebrile. Physical examination revealed
periumbilical tenderness and minimal guarding. Ultrasound scan revealed
umbilical abscess. On exploration abscess was drained and a striated structure
was seen between the bladder and the umbilicus. It is found to be the patent
urachal structure connecting the two. The urachus is resected and sent for
pathological analysis. Postoperatively the patient condition improved and there
were no urinary complaints. The pathological report revealed the patent
urachus. With the advice to review regularly, the patient was discharged.
Fig
1.1 This shows the umbilicus being dissected and the patent urachus as a tube
like structure extending from the bladder to the umbilicus (arrow pointed)
Fig
1.2., shows after resection, the remanant of the patent urachus being attached
to the urinary bladder.
Discussion
The urachus is a
fibrous remnant of the cloaca and the allantois, which in adults, connects the
dome (anterosuperior part) of the bladder with the anterior abdominal wall (umbilicus).
The allantois is a fingerlike projection from the yolk sac, which is contiguous
with the ventral cloaca at one end and the umbilicus at the other. The cloaca,
in the fetal life, is the cephalic extension of the urogenital sinus (a
precursor of the fetal bladder) and the allantois. The ventral portion of the
cloaca develops into the bladder after cloacal division by the urogenital
septum. Between the 4th and the 5th months of gestational age, the bladder
drops toward the pelvis, and the urachus prolongs and narrows until it turns
into an epithelialized fibromuscular cord. It lies in the space of Retzius,
extending between behind the transversalis fascia and anterior to the parietal
peritoneum, and is bordered laterally by the obliterated umbilical arteries (medial
umbilical ligaments) 2. The size of the urachus can range between
3 cm and 10 cm in length and 8 mm and 10 mm in diameter. After birth it
obliterates, forming the median umbilical ligament. However, a vestigial small
lumen lined by a transitional epithelium is seen commonly in the fully
developed infant3. Occasionally, the urachus may merge with one or
both of the obliterated umbilical arteries, and there may be a slight deviation
to the right or left of the mid line4.
Those found in
older patients require management and needs resection, as chronic exposure to
urinary stasis leads to infection and inflammation, and has an increased risk
of neoplastic differentiation. Clinical symptoms of an urachal infection are
fever, abdominal pain, urinary problems and sometimes, a suprapubic palpable
mass. Spontaneous resolution without the need for further intervention has been
reported6.
It is unclear
whether all URs or a subset of symptomatic URs should be resected. With an
increase in incidental diagnosis, non-operative management has become more
common. Ueno et al 3 reviewed the ultrasound reports of 3400
patients and found that 56 children had a UR. Of these, 44 patients were
followed up without surgical resection. In 9 cases, URs disappeared during the
follow-up period. Only 1 patient had recurrent symptoms, which were treated
conservatively.
Galati et al7
retrospectively reviewed 23 patients treated for a UR, and found that overall
50% and in children less than 6 months of age 80% of URs resolved non-operatively.
Lipskar et al 8 reviewed their experience in managing 15 children
with URs. 8 patients underwent surgical excision, while 7 were managed non-operatively
for 26 months.
There is not
enough information in describing postoperative complications after UR
resection. McCollum et al2 reported on excision of 26 URs with 1
wound infection and 1 bladder leak. Cilento et al9 reported 45 UR
excisions with three postoperative wound infections.
Urachal
anomalies are twice as common in men as those in women4, and are
rarely observed in adulthood. Modes of presentation differ from those seen in
children. Urachal cancer (51%) and urachal cyst (35%) are the most frequent modalities
diagnosed in adults 5. Some patients with URs are asymptomatic,
but still carry a high risk for infection or cancer.
First, urachal
anomalies are rarely observed clinically, with only eight of 40,000 cases being
admitted to a surgical department10. Second, the urachus is
located in a clinically silent area, in the space of Retzius. As a consequence,
possible symptoms and clinical signs of inflammation as well as of tumors are,
in most cases, nonspecific or delayed, or even absent.
Typical clinical
manifestations of patent urachal pathologies are umbilical discharge, abdominal
pain and tenderness, erythema, or a mass within the umbilicus. The differential
diagnosis should include, mainly acute appendicitis, cystitis, inflammatory bowel
disease, strangulated umbilical hernia, hematoma, pelvic or intra-abdominal
abscess, and Meckel's diverticulum5
The diagnostic
tools include USG, contrast enhanced CT abdomen or sometimes sinogram.
Additional studies, including voiding cystourethrogram or cystoscopy, play very
little roles in an otherwise asymptomatic patient. Treatment of symptomatic URs
remains surgical. For the uncomplicated patent urachus, usually a one-stage
procedure will suffice2.
When urachal
cancer cannot be excluded, cystoscopy with biopsy and urine cytology should not
be omitted. Cytology is positive in 38% of patients with urachal carcinoma. If
urachal pathology appears with signs of infection, a two-stage treatment is
recommended: initially, administration of antibiotics and resolution of
inflammation, associated with the draining of the cyst or purulent collection, followed
by surgical removal. In benign urachal anomalies, complete excision, with or
without the cuff of the bladder, is sufficient. It is not necessary to remove
the umbilicus. The surgical treatment prevents the possibility of a malignant
degeneration. In case of urachal cancer, partial or radical cystectomy should
be considered. Partial cystectomy with en bloc resection of the urachus with
cancer within the bladder dome provides similar oncologic outcomes to radical
cystectomy. Reports on laparoscopic partial cystectomy with urachus removal
have been published5.
Patent urachus
and other congenital urachal anomalies in adulthood are rare. Often it present as
acute abdominal pain which may be inconspicuous. So it may cause many
diagnostic problems. The differential diagnosis should include mainly acute
appendicitis, cystitis, inflammatory bowel disease, strangulated umbilical
hernia, hematoma, pelvic or intra-abdominal abscess, and Meckel's diverticulum.
The patient's clinical history and thorough physical examination are important
for the correct diagnosis. It is crucial to have an understanding of the
embryology, anatomy, presentation, and relevant investigations for these
anomalies.
