Abdominal pregnancy is a rare entity but potentially life
threatening. The reported incidence was between 1 in 4857
to 7931 [1,2] while omental pregnancy is the least common
type. To date, there were only few cases being reported. We
report a case of primary omental ectopic pregnancy based
on the Studdiford's criteria . In this case presentation, we
illustrated the importance of examining the entire abdominal
cavity including the omentum particularly when clinical
findings are highly suggestive of ectopic pregnancy but both
adnexa appeared to be normal at diagnostic laparoscopy.
A 30-year-old Gravida 4 Para 2+1 presented at eight weeks
and five days Period of Amenorrhoea (POA), with sudden
onset of lower abdominal pain for one day. She did not have
vaginal bleeding or history of passing out product of conception.
She had two full term spontaneous vaginal deliveries
and one complete miscarriage at seven weeks POA. She had
laparoscopic cholecystectomy a year ago. Otherwise, there
was no other significant history.
Upon arrival, she was not pale. Her blood pressure was 126/72
mmHg and pulse rate was 88 beats /minute. Abdominal examination
revealed tenderness over supra-pubic region with
rebound tenderness but no guarding. Upon bimanual examination,
the uterus was anteverted, normal size and mobile.
There was positive cervical excitation and both adnexae were
tender. Bogginess was felt at the Pouch of Douglas (POD).
Trans-vaginal scan revealed an empty uterus with endometrial
thickness of 11mm. There was an extra-uterine gestational sac
seen with presence of fetal echo and fetal heart activity. The
crown lump length measured 9.6mm, which corresponded to
seven weeks gestation (Figure 1). Both ovaries appeared normal.
There was presence of free fluid in the POD. Subsequently,
she underwent diagnostic laparoscopy for suspected leaking
Intra-operatively, haemoperitoneum of one litre was noted.
Both fallopian tubes and ovaries were normal. The abdominal
cavity was examined carefully and a 40x 40 mm-dark suspicious
mass, which was actively bleeding, was seen at the momentum
The procedure was then converted to laparotomy, as there was
no immediate expertise available to perform laparoscopic partial
omentectomy. Laparotomy partial omentectomy was then
performed. The resected omentum was then explored. A fetus
in an intact sac was seen within the omental tissue (Figure 3).
Post-operatively, she recovered well without any need for
blood transfusion. Histo-pathological examination of the
partial omentectomy specimen confirmed the diagnosis of
primary omental ectopic pregnancy as the trophoblastic cells
invaded into the omental tissue (Figure 4).
Abdominal pregnancy can be classified as primary or secondary.
The latter is far more common due to re-implantation of
a ruptured tubal ectopic pregnancy . The diagnosis of primary
omental pregnancy was made in our case as it fulfilled
the Studdiford's criteria: 1) both fallopian tubes and ovaries
were normal, 2) there was no uteroplacental fistula, and 3) early
attachment of ectopic pregnancy to a peritoneal surface that
eliminate the possibility of secondary implantation.
Our patient presented as early as eight weeks gestation making
the possibility of secondary implantation less likely. Furthermore,
this is confirmed histo-pathologically as the trophoblastic
cells invaded into the omental tissue. Initial diagnostic
laparoscopy failed to demonstrate the ectopic pregnancy in the
pelvis. Both the fallopian tubes and ovaries appeared normal. A suspicious mass was found at the omentum after further exploration.
Diagnosis of primary omental ectopic pregnancy might be
missed without extensive surgical evaluation. It was reported
that maternal mortality from abdominal pregnancy is 7.7
times higher than tubal ectopic pregnancy and 90 times of a
normal intrauterine pregnancy . Its clinical features are not
specific; trans-vaginal scan might not always be précised and
laparoscopic surgery is rather challenging . It can be easily
overlooked and treated as pregnancy of unknown location
where catastrophe may occur. We perform further exploration
due to the fact that extra-uterine sac with fetal echo and fetal
heart activity were seen during ultrasound scan. A normal
looking ovaries and fallopian tubes with large amount of haemoperitoneum
are highly suspicious of abdominal pregnancy.
Wu, et al.  reported a 27-year-old woman presented 15 days
after methotrexate treatment for persistent ectopic pregnancy
post laparoscopic linear salpingotomy. The patient experienced
severe abdominal pain and haemorrhagic shock. She
underwent laparotomy partial omentectomy and confirmed
to have omental pregnancy. Martelli, et al.  also reported a
similar case of undiagnosed omental pregnancy.
Laparotomy was performed in most of the reported cases [8,9]
because of late presentation, severe haemorrhage encountered
during laparoscopic surgery or lack of immediate expertise.
Laparoscopic surgery for omental pregnancies had been reported
especially in early presentation when the sac is not yet
ruptured [10,11]. Our case successfully illustrates the importance
of having high index of suspicious in managing patients
presented with typical clinical features of ectopic pregnancy
but no adnexal pathology found during laparoscopy. Thorough
assessment of the entire abdominal cavity during laparoscopy
is essential to exclude this rare entity of abdominal
pregnancy, hence minimising further morbidity and litigation.