Solving the Dilemmas of PUL (Pregnancy of Unknown Location)

Tubal Pregnancies

The fallopian tubes when the ectopic pregnancy settles within the cavity of the tubes could be the site of up to 98% of all ectopic pregnancies.

And as I said earlier, the vast majority of tubal pregnancies will settle within the ampullary portion of the tube as the tube widens.

So on a real time clip, you will see the intact tubal pregnancy typically between the ovary and the tube, and that is where you visualize the vast majority of tubal pregnancies and when they're intact, you can see a mass right next to the uterus and an intact ectopic pregnancy upon surgery.

Signs Suggesting Ectopic Pregnancy

Tubal Ring Sign

What about other signs that could suggest that you're dealing with ectopic pregnancy?

We have the tubal ring sign, which is really the thick echogenic ring made up of Cho tissue that when seen provides a 100% positive predictive value if you see a yolk sack within the fluid collection or a dead embryo.

However, if it is empty, the positive predictive value falls to about 95%.

So therefore, the finding of the tubal ring sign is highly suggestive, but again, not diagnostic of a tubal ectopic without the presence of an embryo or yolk sac.

Masses and Adnexal Masses

What about masses?

Extra ovarian masses could be complex, predominantly cystic or complex, predominantly solid, and be 84% sensitive in 99% specific for tubal pregnancy.

However, follow up is required until the status of the pregnancy or the location of the pregnancy has been confirmed, because these by themselves are not accurate in predicting the ectopic pregnancy.

Sometimes the adnexal masses may be hyper coic.

They could even look tubular, especially in those with hemato cell pinks.

But again, the appearance of these adnexal masses are nonspecific and therefore may only be suspicious or suggestive of an ectopic pregnancy, but without the finding of a sac, with an embryo or yolk sac, they are not confirmatory.

Peritoneal Fluid

Perennial fluid when seen is highly suspicious for an ectopic pregnancy, but it doesn't always mean a ruptured ectopic because it's usually or could be seen in 37% of intact tubal pregnancies.

This is why you should always look for fluid or free fluid in the upper abdomen, under the liver, under the spleen, under the diaphragm, and you should especially be suspicious if it appears echogenic, which means it has blood or occasionally puss within it.

In women with pregnancies of unknown location, echogenic fluid has 56% sensitivity and 96% specificity.

So again, by themselves, without the actual finding of an ectopic sac with a yolk sac or an embryo, it's not a hundred a hundred percent reliable.

When you see hemorrhagic peroneal fluid, we need to evaluate the hemodynamic stability of the patient because if they're unstable, then they should proceed immediately to surgery.

However, if they are stable, then a follow-up ultrasound should be performed until the location of the pregnancy has been determined.

So here are examples of hemorrhagic peritoneal fluid.

You can see real thick are echogenic contents suggesting the presence of blood within the free fluid in the abdomen.

Rare Ectopic Locations

Interstitial Ectopic Pregnancy

Now, there are the rare ectopic locations.

The first one is what we call interstitial ectopic pregnancy.

This could be misdiagnosed as normal intrauterine pregnancies because they implant within the first two centimeters of the tube.

They're still within the limits of the outline of the uterus, but they really are located in the proximal portion of the tube.

They're partially implanted in the endometrium and they are usually discovered at an advanced gestational age.

In a patient's presents with pelvic pain, they're surrounded by myometrium and the pregnancy is seen very close to the cirr.

They have to be differentiated from the corneal pregnancies that are seen by Cornal Ute eye and the angular pregnancies that I showed you earlier that are literally in the uterine cavity, but very close to the IC or the interstitial portion of the tube.

So interstitial pregnancies comprise about 2% of all ectopic pregnancies.

When you look at the coronal image of the uterus, you can see the normal endometrial canal and you can see the gestational sac that bulges beyond the fundal margin of the uterus.

As you can see here, if you trace the myometrium surrounding this interstitial pregnancies, you can see there's less than five millimeters of myometrium because the developing pregnancy bulges around the posterior portion of the sac.

These are specimens of interstitial pregnancies that were intact at the time of surgery, and as you can see, they bulge outside the fundus of the uterus because they are literally within the first two centimeters of the fallopian tube.

Another sign that we follow in interstitial pregnancy is the so-called interstitial line sign.

If you follow the endometrium and follow it to its termination in the region of the urine cornea, you will see that the line points to the ectopic pregnancy.

They usually rupture at less than 12 weeks, but when they do rupture, they're often fatal because they can result in massive hemorrhage.

Here is an example from my institution of an interstitial pregnancy that was difficult to diagnose an ultrasound because of complicating fibroids.

However, this was clearly outside the borders of the uterus.

And when you turn your collar doppler around a suspicious sac, you can see a very elaborate network of vascularity called the ring of fire.

This is the MRI in the same patient.

And as you can see, the ultrasound had such difficulty finding the endometrial cavity in the lower half of the uterus because of multiple uterine myomas that deformed the uterine contour.

But here is the endometrial cavity on a coronal plane, and you can see that the cavity points to this gestational sac in the corneal portion of the uterus.

And so this is the so-called interstitial line sign as interpreted on an MRI exam.

Angular Pregnancy

The angular pregnancy, as we already mentioned, is really an endometrial pregnancy.

It is not within the tube yet, but it is at the angle of the endometrium.

It is not interstitial in location.

It has a thick myometrium around it, definitely more than five millimeters, but it could be easily mistaken for an interstitial pregnancy.

It implants at the lateral angle of the uterine cavity, so it is technically within the uterine cavity, but it is high risk for spontaneous abortion because of its abnormal location.

It can result in uterine rupture in 23% and also has a high incidence of placenta accreta.

Here are two examples of angular pregnancies, and as you can see, there's a thick myometrium surrounding the pregnancy and it is literally within the extreme lateral portion of the fundal endometrial cavity.