Solving the Dilemmas of PUL (Pregnancy of Unknown Location)

Ovarian Ectopic Pregnancies

What about ovarian ectopic pregnancies?

These are very rare, extremely rare
and may only be diagnosed at surgery.
Sometimes the diagnosis could be difficult.
At laparoscopy it's usually mistaken
for a corpus lithium cyst or an ovarian malignancy.
And when the pregnancy is excised,
the ovarian tissue is seen to attach to the wall
of the gestational sac.
So you usually will have a rim of normal ovarian tissue
right next to the gestational sac.

So here are two examples.
This is the pregnancy, this is the ovary,
and it's growing right at the edge of the ovary.
And you can still see follicles here.
The same thing here, gestational sac ovary,
and you can see the rim of the ovary going around the sac.
So you will find this gestational sac within
the normal location of the ovary surrounded
by ovarian tissue
and attached to the uterus by ovarian ligament.

Heterotopic Pregnancies

What about heterotopic pregnancies?
Heterotopic pregnancies are pregnancies
where you have a concurrent intrauterine,
an extrauterine pregnancy.
So in this particular example,
you have an embryonic pole within the uterus
and another one in the adnexa, which is ectopic.
We are seeing more and more of these lately
because of increasing in vitro fertilization and
therefore, even if you see an intrauterine pregnancy,
you should always investigate the adnexa just in case you
might be dealing with a heterotopic pregnancy.
The presenting symptoms are the same as other ectopics.

Another case of heterotopic pregnancy,
here's a yolk sac within the uterus
and a yolk sac within the adnexal mass
that turned out to be the ectopic pregnancy.
In this particular case, there is an intrauterine pregnancy
that is larger than the ectopic pregnancy.
Because the ectopic pregnancy has died,
you can see there is no blood flow
around this developing sac
or within the embryo, whereas the
embryo within the intrauterine cavity was viable.
In this particular case, the obstetricians chose to
do a laparoscopy
and excise a tubal pregnancy
and allowed intrauterine pregnancy to continue.
So if detected early, it is possible to save
the normal intrauterine pregnancy.

Cervical Ectopic Pregnancies

What about cervical ectopic pregnancies?
They could be difficult to differentiate from a pregnancy
that is undergoing spontaneous abortion
because you can see the gestational sac in the cervix
and it could be mistaken to be within the cervical canal,
but you can see a yolk sac within the fluid collection
and therefore that is definitely
an intact gestational sac and not an incomplete abortion
or an abortion in progress.

They could be subtle like in this particular
transabdominal ultrasound.
All you see is a very small suggestion
of a fluid collection in the cervix.
And when you do the endovaginal examination,
then you can see actually that there is a yolk sac
and an embryo where the heartbeat was
112 beats per minute.
So an intact gestational sac implanting in the region
of the cervix is a cervical pregnancy versus
an incomplete abortion or an abortion in progress.
And as you can see, the difference in resolution
between the transabdominal images
and the transvaginal images
is quite significant.

Hysterectomy Scar or Cesarean Section Pregnancies

A very unusual case is the hysterostomy
hysterectomy scar pregnancy
or the cesarean section pregnancy.
This particular case when done transabdominally created a
confusing picture because this patient has never had a prior
ultrasound examination
before she got pregnant, so we did not know
that her uterus is severely retroflexed
and that we were really looking at the fundus
of the uterus over here and
where we thought the pregnancy was
here was not within the uterus
but bulging out of the uterine scar.

So this is the sagittal view vaginally.
You can see the intact gestational sac with blood flow
around it protruding out of the cesarean section scar.
This is the uterus with hemorrhage within the uterine cavity
and this was initially felt to be an adnexal hematoma
with an intrauterine pregnancy,
but when the realtime
clips were obtained, you can see cardiac activity
in this intact gestational sac
and you can see how the gestational sac is documented
to protrude from the site of the cesarean section scar.
And the hematoma within the uterine cavity
is more posterior since it's in a
retroflexed uterine fundus.
So it could create a very confusing picture,
but just bear in mind that women
with prior cesarean sections
can develop a hysterectomy scar pregnancy.

This patient did not have an ultrasound.
She went straight to have an MRI examination.
But as you can see, it's the same finding.
You have an empty uterine fundus
and a pregnancy that protrudes anteriorly
through the cesarean section scar.
This is the coronal view given the expanded lower uterine cavity secondary
to the site of implantation.

Abdominal Pregnancies

What about abdominal pregnancies?
I told you earlier that these are special ectopic
pregnancies because the fertilized egg finds a
nurturing environment in the abdomen, upper abdomen,
lower pelvis to develop normally
if it has found a good supporting structure.

So at 10 weeks this patient presents
with vaginal bleeding and pain.
You can see there's a lot of fluid posterior
to the uterus in the cul-de-sac.
The uterine cavity has decidua
surrounding a fluid collection that is not eccentric.
So this really satisfied the criteria
for an ectopic pregnancy.
And if you look outside of the uterus, you can see this mass
which is superior to the uterine fundus.
If you look at the real time clip here,
you can appreciate the body of the
fetus and the head of the fetus lying completely
outside of the uterus.
And the sonographer
who performed the examination placed an arrow to point out
to the cardiac activity that is very faintly seen
on this real time clip,
but it again demonstrates the extrauterine nature
of this pregnancy that was intact at the time
of examination.

Even if you do see a little bit of fluid within the
cul-de-sac, this is the corresponding MRI
examination for confirmation.
You can see the vagina, the cervix, the uterus,
the uterine fundus ends here
and above the uterine fundus you will see the
head of the fetus, the body of the fetus,
and the surrounding mass
around the developing abdominal pregnancy.

Summary: Pregnancies of Unknown Location

So in summary, when encountered where the problem
of pregnancies of unknown location
ultrasound remains our most useful imaging modality.

In the 15 to 26% of women with pregnancies
of unknown location, we have to
remember that the ultrasound may be negative.
Initially, the discriminatory zone for the level
of beta hCG where to expect a gestational sac
has now been increased to 3000 from the prior limit
or level of 2000 mIU/mL.

And finding a gestational sac is suggestive
but not diagnostic of a viable pregnancy
because sometimes you could mistake the pseudosac
of an ectopic for a gestational sac.
So therefore follow up examination
or conservative treatment has to be done to make sure
that we are dealing with a viable pregnancy.

Also, the findings of tubal rings
adnexal masses whether cystic or solid are suspicious.
But again, not diagnostic
of ectopic pregnancy together.
However, the finding of an adnexal mass
and echogenic fluid have a higher positive predictive detection rate than either one of these findings alone.

And we always have to remember that only finding a yolk sac
or an embryo within a fluid collection
are confirmatory signs of an intrauterine pregnancy.
Without these two structures, we couldn't be sure
that we are dealing with a true developing pregnancy.

So in summary, the pregnancy of unknown location consists of cases where you have a positive pregnancy test
and a negative ultrasound.
The management should be expectant
and conservative until we can tell for sure
where the pregnancy location is.
Some of them can resolve spontaneously as in abortions
and intervention will only be indicated when the beta
hCG does not decline
after meeting all of the criteria
that we have talked about earlier.

So statistically, the 8% of pregnancies that are diagnosed
as pregnancies of unknown location, vast majority
of them will resolve spontaneously.
27% will end up being normal,
14% will resolve ectopic pregnancy
and about 9% will
develop into spontaneous abortions.

And finally, the new guidelines presented
by the society radiologist
and ultrasound consensus panel should be promulgated
to all specialists of various disciplines who diagnose
and manage problems in the first trimester.
If we could do this, we would definitely improve patient
care and reduce the risk of inadvertent harm to potentially viable or potentially normal pregnancies.

As we have learned in medicine the mantra
of primum non nocere,
or first do no harm, we should always remember
that our primary purpose is to not
prevent the development of a viable pregnancy
by being very aggressive in our management.

So with that, I hope we have decreased the incidence
of pregnancies of unknown location,
which can result in a lot of anxiety
and false positive diagnosis in women in the first
trimester gestation.

Thank you.