Impact of On-Site Cytologic Assessment of Adequacy of USFNA of Thyroid Nodules - SD

Introduction to the Study

I am going to give a brief presentation on a study that was just completed at our school, University of Southern California, on the impact of onsite cytologic assessment of adequacy of ultrasound guided fine needle aspiration of thyroid nodules.

Background

Ultrasound is routinely used in the guidance of fine needle aspiration for thyroid nodules.

The rate of inadequate specimen is said to vary tremendously in the literature, but has been reported to be as high as 20 or 30% in some series.

While one would intuit that onsite evaluation would decrease the rate of inadequate specimens, there is a paucity of literature confirming this.

Objective

The objective of our study was to compare the adequacy rate of ultrasound guided FNA performed by a single experienced radiologist with and without onsite microscopic evaluation of adequacy of specimens by a cytotechnologist.

Materials and Methods

The data was reviewed retrospectively and IRB approved.

This represented the consecutive evaluation of all ultrasound guided fine needle aspirations performed over a two year period by a single experienced radiologist.

In this particular case, the number of years practicing is probably around 30.

The timeframe for this extended from November 22nd, 2008 until November of 2010.

No onsite microscopic evaluation was performed for the biopsies performed during the first year of the study.

During the second year of the study, all specimens were evaluated by a cytotechnologist with a microscope.

The rate of adequacy of final cytologic diagnosis was compared between these two years.

Procedure Without Onsite Evaluation

Typically, the radiologist mounted or processed material consisted of a biopsy that was done with three passes with a maximum of four.

This, however, was completely determined by the apparent appearance of the specimen at the time of the biopsy by the radiologist.

Normally, the biopsies were performed using a 25 gauge needle.

Occasionally, a 22 gauge needle was used if the aspirate appeared quite scanty.

The technique was performed using suction in all cases using an MRAD syringe holder.

The material thus obtained was extruded onto slides.

The number of slides was basically arbitrary and based on the amount of material aspirated.

The slides themselves, at least one was air dried.

The rest were placed in 95% ethanol fixative.

The syringe was then washed at the end of the procedure at the end of each pass with 95% alcohol and the material sent for cell block.

The initial period of performing the biopsies was observed by an experienced cytopathologist to determine that in fact, the radiologist performing the mounting and processing of the slides was considered adequate at the time.

The typical specimen processing material is shown here.

The syringe is placed into a MRAD suction gun, which is then handheld and suction applied.

The needle is placed on the end of the syringe, and this actually provides guidance for the person performing the evaluation.

The slides you can see are here.

Some of them are mounted in air dried and placed in the cardboard container.

The remains are placed in the ethanol fixatives shown at the left, and, as I mentioned, the specimens after each pass are washed using 95% alcohol for processing into a cell block.

Procedure With Onsite Evaluation

In the biopsies in which the cytotechnologist was present, two initial passes were made just as they were during the non cytotechnologist portion of the study.

These two passes, the material was extruded onto the slides and smears were made.

Stains were then made after drying by the cytotechnologist using H and E technique.

And again, the syringe and needle were washed for cell block.

The cytotechnologist then evaluated for cellularity with an onsite microscope.

If it was felt that the specimen was sufficient after two passes, the biopsy procedure was terminated.

According to the amount of material seen by the cytotechnologist, a third or even fourth pass was occasionally performed, or frequently three passes.

Four was fairly unusual.

In no case did we perform more than four passes on any given patient.

Results

The results of the two years were compared using Fisher's exact test.

The rates of each Bethesda category for the cytologic diagnosis was evaluated, and the average number of slides prepared per case was compared between the two years.

Also, the number of passes made for each procedure was evaluated.

This particular slide sums up pretty much the results.

You can see that for onsite evaluation, we had about 183 patients.

Without onsite evaluation, we had 151, approximately equal number of males and females between the two years.

Age was about equal.

I think obviously the major result is that the number of non-diagnostic or unsatisfactory, or Bethesda classification one, results with onsite evaluation decreased to 1.6% versus those without the onsite evaluation.

The results that were non-diagnostic or unsatisfactory were 7.3%.

You can see in looking at the other Bethesda classifications, the numbers are fairly similar between the two.

You can also see that the average number of slides that were prepared for each biopsy was almost cut in half when the onsite cytotechnologist was present.

So just a couple more going over the results.

To summarize, there were about 334 total specimens.

151 specimens had onsite evaluation 183 or without onsite evaluation.

The rate of inadequate specimens decreased significantly with onsite evaluation decreasing from 7.3% without to 1.7% with cytotechnologist on site with a microscope.

The p value for this is statistically significant.

The average number of slides was decreased by 43% and went from 14 to 7.2.

Again, with the cytotechnologist present, the average number of passes was not significantly changed.

This probably had to do with the fact that when the radiologist performed these alone, almost invariably, they were going to be three passes just done as a routine.

Although a number of patients that had two passes was there were a number of patients who were limited to two passes by virtue of the cytotechnologist demonstrating adequacy of the specimen.

There were probably an almost equal number in which the cytotechnologist recommended that we do a fourth pass.

So the average number of passes still hung around three, both with and without the cytotechnologist being present.

Conclusion

In conclusion, our study shows that the rate of inadequate FNA specimens can be significantly reduced by onsite microscopic evaluation by a cytotechnologist.

Therefore, patients may be spared repeat biopsy or even unnecessary surgery, which will therefore decrease cost by providing onsite evaluation with a microscope.

Thank you.