Solving the Dilemmas of PUL (Pregnancy of Unknown Location)

Initial Assessment in the Emergency Room

When women come to the emergency room for this problem, 15 to 26% of them have normal or negative initial ultrasound examination.

A normal pelvic examination at presentation does not exclude an ectopic pregnancy.

We need to assess the hemodynamic stability of the patient and in a stable patient, we could repeat the ultrasound until the HCG reaches the discriminatory zone, which has now been pegged to 3000 million international units.

It used to be that if there's no gestational sac in the uterus by 2000 million international units, then we assume that we are dealing with a failed pregnancy.

But now there is the new standard that says you have to wait until 3000 million international units before you could declare the pregnancy as having failed.

Follow-up Ultrasound and HCG Monitoring

If no intrauterine gestational sac is seen, when a discriminatory zone has been met, then a follow-up ultrasound examination and HCG level is performed in 48 hours for information.

You can also repeat the ultrasound in three to four days because a normal gestational sac grows at a rate of one millimeter per day and we can usually see a three millimeter sac and therefore waiting three to four days should be enough to show you an intrauterine early gestational sac.

When you do follow ups, about 11 to 16% of women will be diagnosed with an ectopic pregnancy on the follow up examination when the initial ultrasound is negative.

Bottom line, you should never treat with methotrexate, systemic methotrexate or DNC based only on the HCG levels without doing an ultrasound follow up examination.

Normal Intrauterine Pregnancy Appearance

Here's what a normal intrauterine pregnancy should look like.

And when you refer to this diagram obtained from Moore's Human Embryology, you can see how the potential endometrial cavity and the relationship of the cavity to the early pregnancy would lead to the eccentric appearance of the gestational sac.

So for every in vaginal ultrasound done for this, that this diagnosis, you have to always look for this line.

This line marks the endometrial cavity.

It might contain some fluid sometimes in women with a small implantation hemorrhage, but the whole idea is that you should see the gestational sac in an eccentric location relative to the endometrial cavity.

Sometimes you can see what we call a double deral sign.

There is the decidua that surrounds the developing pregnancy.

The decidua capis is seen on this diagram from wars embryology.

That is the deral layer immediately surrounding the fluid collection.

On the other side of the potential endometrial canal is the decidua vera or peritus, and the two will form two very echogenic rings, which we designate as the double deral sign.

Timing and Sensitivity of Signs

Now at three to five weeks you might see a fluid collection, which we said is suggestive of pregnancy in the vast majority of women.

The yolk sac, however, has to develop for you to confirm that it is indeed an intrauterine pregnancy.

The eccentric intraprocedural sign is only sensitive in 48 to 68% of cases, and the double decidual sign may be seen at four to nine weeks, but more helpful at an earlier time because the embryo is not typically seen at this time.

So these two signs are important before you can demonstrate a yolk sack or an embryo.

And when you see these two signs, you can feel pretty confident that you are proudly dealing with a normal intrauterine pregnancy before you see a yolk sack or an embryo.

Ectopic Pregnancies

The Pseudo-sac

What about ectopic pregnancies?

The pseudo sac is a fluid collection inside the urine cavity seen in about 20% of women with ectopic pregnancies.

It is centrally located, so the endometrial stripe or the endometrial cavity leads up to the collection.

It is surrounded by decidua and not by the chorionic ring that typically surrounds a developing gestation.

So this is all deidra echogenicity you see in at the chorionic ring.

So you don't have the double decid sign.

If you try to compress the sack with your probe, it can change in shape and sometimes when they contain blood, as you see here, it might a pain.

It might appear complex because of the blood products within it.

Locations of Ectopic Pregnancies

Ectopic pregnancies can occur in many places, and if you say that the vast majority of ectopics are tubal in origin, you'll be right about 95 to 97% of the time.

And as you can see, the most common site will be the ampullary region of the tube.

But it can also occur in the ovary in the cervix, although they're rare.

And we of course have specific types of tubal pregnancies, the most disastrous of which will be the interstitial or corneal pregnancy.

Another diagram barred from Dr. Philippe Genti with his permission shows you the different location of the unique or unusual pregnancies.

We have the angular pregnancy, which is really an intrauterine pregnancy, but implanted right at the angle before it becomes the interstitial portion of the tube.

We have different kinds of tubal pregnancies, so interstitial is one of them, then followed by the isthmic and the ampullary and the fibrile.

A very unusual pregnancy is the abdominal pregnancy that can implant anywhere in the abdomen or pelvis.

So you might have a pregnancy developed under the liver, under the spleen in the mesentary attached to bowel in the fundus of the uterus.

And these are pregnancies that either resulted from a rupture in the tube and the fertilized egg basically escapes out of the tube to implant in other places or, or there's also a theory where the fertilized egg, instead of proceeding towards the uterus, can have reverse peristalsis and exit the tube through the fia, and therefore the fertilized egg is free to roam around the peritoneal cavity looking for a nurturing environment on which to grow.

Pregnancy of Unknown Location

So in a patient that appears to have a perfectly normal pregnant, intrauterine stripe and has no signs of intrauterine or a nexel mass, both trans abdominally and endo vaginally, you could see a thin stripe.

And if the pregnancy test is positive, you know that this uterus does not look like it could nurture or provide a good environment for a developing pregnancy.

So this is where you have to come into the algorithm of the pregnancy of unknown location.

In this particular case, there is no free fluid in the cul-de-sac, so that does not support the possibility of a ruptured ectopic pregnancy.

The next thing you should do is to look for the ovaries or look at the ad nexa.

So these are your normal images of the left ovary where the patient was symptomatic.

And for all intents and purposes, this left ovary appears normal.

However, if you continue to evaluate the left adnexa, you'll appreciate the fact that in a place where there is no ovary, there is a developing gestational sac with a very thick rim of chorionic tissue.

And as you can see, the Probe that passes from front to back that assesses the whole left. A nexa will usually find the ectopic pregnancy unrelated to the uterus or the normal left ovary that we have previously demonstrated.

Again, there is no free fluid in the pelvis suggesting that this ectopic pregnancy is intact.

Case Example: Tubal Pregnancy

How about this patient that has a very thick deidra that looks like it is well prepared to provide a good environment for the development of a gestational sac?

You would think that there will be a normal pregnancy that will result from this.

However, this is always not a guarantee because in this patient a beautiful tubal pregnancy is seen between the uterus and the normal appearing ovary and it has the so-called ring of fire, which is increased flow around the chorionic ring.

And in fact, the embryo, if you can see on this real time, has a heart motion that you could document on M mode at a normal rate of 114 beats per minute.

So the appearance of the uterus does not predict whether or not you'll have an ectopic pregnancy or a normal intrauterine gestation.