3D Pelvic Sonography: Routine or Selective - HD

Introduction

Hi, I'm Rochelle Andrea from Vanderbilt University Medical Center, and I will be speaking today on the topic of 3D ultrasound of the pelvis and whether it should be routine or selective.

Before we start, I just need to disclose that I have been a speaker for a Phillips healthcare user course.

I'd like to give you some perspective from our experience at Vanderbilt regarding the use of 3D reconstructions in the pelvis.

The objectives will be to discuss the reasons to consider the use of 3D ultrasound of the uterus as a routine part of a gynecologic ultrasound study, and then also to discuss the alternative of a selective use only when specific indications arise.

Why Has Pelvic Volume Imaging Gained in Popularity?

Volume imaging has advantages.

First, it potentially decreases the amount of time required to perform the study, and it does this by retrospectively reviewing and manipulating reconstructed images in any plane, including planes that may be unavailable to 2D imaging.

However, there is a potential problem with this because a workstation is necessary to save these volumes and perform the reconstructions retrospectively, and these are not available in all the practices.

Popularity in the pelvis revolves around the reconstructed coronal plane, and this is usually the reconstructed coronal plane of the uterus, which has become the most useful application.

This is because this cannot usually be visualized using traditional 2D imaging due to the constraints of the vaginal probe, but it does answer important questions that could not be previously addressed with traditional 2D imaging.

Our 3D reconstruction of the uterus as you see here.

Routine Uses of 3D Reconstruction

Routine uses of this technique would include uterine shape anomalies and IUD localization, and these actually have become part of standard imaging protocol at many institutions.

Other uses include evaluation of the endometrial cavity for endometrial polyps, fibroids, adhesions, or even for the evaluation of interstitial ectopic pregnancies.

Should the Coronal View Be Performed Routinely?

Technical Considerations

First there's some technical considerations.

Image quality. You need a good 2D image to obtain a good 3D image.

Obesity, prior surgery, shadowing artifact, these will all degrade the image in 2D and 3D and 2D is always the better image because we use mechanical sweeps with a single elevation focus.

Resolution outside of the focal zone is degraded.

Artifacts, any type of artifacts, shadowing enhancement, volume averaging may be more confusing or compounded with 3D reconstructions.

If the 2D image is poor, then it's probably no reason to pursue the 3D image.

For example, here we have a 2D image of the uterus in sagittal plane and there's a lot of shadowing artifact.

This is poor image quality on 2D imaging.

Let me just show you the 3D image that we reconstructed from this uterus.

You could see that we can't even see the delineation of the endometrial cavity because of the shadowing.

This image is even worse using the 3D reconstruction.

Evidence for Routine Use

What evidence do we have for routine use of the coronal plane?

In pelvic imaging, more specifically imaging of the uterus, we found that we can better characterize some uterine abnormalities, may occasionally detect unsuspected abnormalities.

But when 2D imaging is normal, this is less likely to be contributory.

In some studies done at our institution and also another done by Dr. Beryl, RAF and her group, additional findings were seen in 29% of 90 consecutive patients at Vanderbilt and in 23% of 64 consecutive patients in Dr. Serf's group.

However, when the 2D image was normal, there were very few additional findings.

Only 2% of patients had additional findings in our study and about 5% in Dr. RAF's study.

What's interesting is the majority of these additional findings were an arcuate uterus.

You may ask, what is the importance of an arcuate uterus?

Do we really need to find these?

It is the mildest form of a septate uterus and it's commonly considered a normal variant.

Its significance is really debatable, but there have been reports of significant increased risk of second trimester loss in preterm labor in some studies.

Findings in the Coronal Plane When 2D Imaging Is Normal

If there are normal 2D imaging findings, is there anything else that we may find in the coronal plane besides an arcuate uterus?

Here we have a normal appearing uterus in the sagittal view and the transverse view.

We perform our routine 3D reconstruction, and lo and behold, this is a uterine abnormality.

We have a unicorn uterus, so this is an unsuspected finding when 2D imaging is normal.

Another patient presents with infertility and we have a uterus with a pretty normal appearing proliferative endometrium.

We perform our 3D reconstruction and we see that we have adhesive bands crossing the endometrial cavity, which were not at all suspected on the 2D image.

A third patient 2D imaging of the uterus and endometrium shows pretty normal uterus.

Normal endometrium.

We perform our 3D reconstruction and we see a small polyp in this patient who presents with some abnormal uterine bleeding.

One more patient with an IUD, 2D imaging shows a very nicely placed shaft within the endometrial cavity.

On our transverse view, we can see the arms that seem to be normally placed in the fundal cavity.

We perform our 3D reconstruction in this patient who's presenting with pelvic pain.

We actually see that a large portion of this IUD the right arm is embedded within the lateral myometrium.

A reason for the patient's pelvic pain, which was not at all suspected on the 2D imaging.

There are missed findings when there is normal 2D imaging.

As we just reviewed, these include the arcuate uterus, unicorn uterus, uterine synechiae, small polyp, and IUD malposition.

Uterine Shape Abnormalities and IUD Evaluation

I mentioned before that uterine shape abnormality evaluation and IUD evaluation may be part of standard imaging protocol at many institutions.

Why is that?

You can see here by FS guidelines, Escher guidelines and on netter drawing, the coronal plane best delineates these uterine shape abnormalities.

They are not seen nearly as well on 2D sagittal and transverse images.

You can see an example of this, one of the most useful applications in anomaly evaluation to determine the etiology for two cavities seen on 2D imaging.

As we can see here, three different patients, we can see two cavities on the transverse image, and these represent three different types of uterine shape anomalies with a different management for each.

As you can see, the first patient has a septate uterus when we do the 3D reconstruction, the second uterus didelphys the third an arcuate uterus.

The sub septate uterus could be managed surgically uterus didelphys would be managed just as a high risk pregnancy.

An arcuate uterus most people think is just a normal variant and probably would not need any special management.

Importance of 3D for IUDs

Why is it important to have 3D reconstructions of all IUDs?

First of all, embedded IUDs are a major cause of pain and bleeding.

Using 2D we can see that a portion of the IUD may be embedded within the myometrium, but only with the coronal view can we successfully improve the visualization of the entire IUD, which includes the shaft and arms and see it on a single image.

For example, we have this patient, we can see that a large portion of the IUD is within the endometrial cavity.

On the transverse view though we can see that arms appear to be outside of the cavity.

What's going on here?

Our 3D reconstruction shows that these arms were not deployed satisfactorily.

This would never have been suspected on the 2D images.

Another example, we can see a patient with a portion of the IUD within the endometrial cavity on the 2D image.

In sagittal, we perform our 3D reconstruction, and what we see is that not the shaft of the IUD within the main cavity, but the arms and the shaft is actually projecting out the right cornal area.

This would also never be suspected just looking at the 2D images.

Other Uses of 3D When Abnormality Is Suspected

What are some other uses of a 3D of the uterus when an abnormality is suspected?

We may see a fibroid and the endometrial cavity appears splayed around this fibroid on transverse and sagittal 2D images.

But when we do our 3D reconstruction, we see that the whole fibroid is actually within the endometrial cavity.

With 2D, we could only suspect that at least part of the fibroid was in the endometrial cavity.

Also, we can classify fibroids when there's submucosal as far as whether they would be amenable to hysteroscopic resection, using different classification systems.

This is a recent classification system called the Step W, which looks at different characteristics of the fibroid and we score this fibroid.

It's a fairly small fibroid, so we give it a zero for the size, it's low in the cavity, it gets a zero score for that, but it has a wide base as we can see.

So it gets two points for this extent of the base.

It gets one point for being partially within the endometrial cavity.

In fact, the majority within the endometrial cavity and only a small amount within the myometrium itself.

It's along the lateral wall.

We add up the score, we get four points.

This would be a low complexity hysteroscopic myomectomy.

This fibroid would be amenable to hysteroscopic resection.

This is something that we can evaluate with 3D imaging.

Another patient, 2D imaging of a saline instilled sonohysterogram where we can see some polyps suggested within the endometrial cavity.

But we weren't really able to distend the cavity very well with saline.

We do our 3D reconstruction, however, and we can see that this cavity is full of too many to count polyps as we move through the endometrial cavity.

This is seen much better on our 3D images than we could ever have seen on sagittal and transverse 2D imaging.

Finally we have some examples of two different types of pregnancies.

In the transverse view, they look quite similar.

We can see a gestational sac, we can see the endometrial cavity once again, gestational sac, endometrial cavity.

But when we do our 3D reconstruction, we can see very well that these are two different types of pregnancy.

The first is a pregnancy within the cavity of a uterine anomaly, a septate uterus.

The second is a true interstitial ectopic pregnancy.

This is very well delineated in the coronal plane.

Reimbursement Considerations

Let's just move on to some reimbursement considerations.

Coding, are you gonna get paid for this?

The two different codes refer to whether you reconstruct on a separate workstation or on the ultrasound system itself.

Reimbursement considerations, some payers will reimburse, but prior authorization is usually required.

A failure to reimburse is routinely based upon the high probability of abuse.

In our institution, we perform this study in most patients, barring the technical limitations, but we report it only when it adds information to the study so that we really don't abuse this code.

Support for Routine vs. Selective Use

Finally, what is the support for routine use of 3D of the uterus?

We should use it really only when diagnostic imaging can be obtained, even if we do it routinely.

Don't waste your time when 2D imaging is suboptimal.

It frequently adds information when abnormalities are suspected.

It occasionally demonstrates abnormalities when the 2D imaging is normal.

We find it good practice for obtaining skills that will help with the more difficult reconstructions when they're really needed.

If you're to choose selective use, as I explained, it's standard practice in many places in evaluation of IUDs and suspected uterine anomalies, for the reasons that we discussed.

It should be added when abnormalities involving the uterine cavity are suspected.

The decision to perform 3D would need to be made by the sonographer or sonologist while the patient is available.

Therefore, clear guidelines need to be developed and followed, so that this can be done when needed.

You may miss occasional abnormalities such as the arcuate uterus, unicorn uterus, uterine synechiae, or a small polyp if the 3D reconstructions are not done routinely.

Conclusion

Thank you very much and this is the conclusion of my talk.