Wet suction technique

Dr. AttamRajeev Attam, MD, from the Southern California Permanente Group, Kaiser Permanente, in Downey, California, USA discusses this Original Article “‘Wet suction technique (WEST)’: a novel way to enhance the quality of EUS-FNA aspirate. Results of a prospective, single-blind, randomized, controlled trial using a 22-gauge needle for EUS-FNA of solid lesions.”

Wet suction technique involves replacement of column of air within the FNA needle with a column of saline prior to performing needle puncture. The technique, developed by our group, is a simple modification of conventional FNA technique and does not require specialized or more expensive FNA needles. In our study, we have compared our novel wet suction technique of EUS fine needle aspiration (FNA) to the conventional methods of EUS FNA. The focus of our study was to compare the cellularity, bloodiness, and specimen adequacy of the aspirate obtained using the novel wet suction technique to the aspirate from conventional FNA technique.

Figure 1
Figure 1. Wet suction technique needle preparation with saline solution (A) and loading suction syringe in the locked position (B).

As we developed wet suction technique, we found improvement in the quality of aspirate in terms of cellularity and specimen adequacy without adding significant cost or time to the FNA procedure. We therefore embarked on a study comparing this novel technique to conventional FNA technique.

To remove any bias, we sampled all study lesions with both the wet suction and conventional FNA techniques and also used the same needle for both techniques. The lesions were randomized to first pass with wet suction vs. conventional FNA technique. Subsequent passes were made in alternating manner.

A total of 117 lesions were sampled, and their cell block was later evaluated by the study cytopathologist who was blinded to the type of FNA technique. The aspirates were graded for cellularity, bloodiness, and adequacy. Aspirates obtained using novel wet suction technique had a significantly higher cellularity and specimen adequacy as compared to the conventional FNA technique. The 2 techniques were similar in the bloodiness of the aspirates. In multiple cases where specimens from the conventional technique was nondiagnostic or inadequate, aspirates obtained using the wet suction technique were able to provide a definitive cytological diagnosis. A larger proportion of aspirates with the wet suction technique were read as moderate and high cellularity compared with the conventional FNA technique.

The study clearly shows wet suction technique to be superior to the conventional FNA technique in sampling of solid lesions using a 22-gauge needle.

Figure 2
Figure 2. Column of saline solution (arrow) moving into the suction syringe as FNA is performed.

This was the first study evaluating a new technique and more studies are needed before a widespread change in FNA practice is advocated. Future studies evaluating wet suction technique using different needle sizes will be helpful.

Wet suction technique is an easy way of improving the quality of EUS FNA aspirate. It does not add additional costs or time to the procedure of EUS FNA.

Read the abstract for this article here.

The information presented in Endoscopedia reflects the opinions of the authors and does not represent the position of the American Society for Gastrointestinal Endoscopy (ASGE). ASGE expressly disclaims any warranties or guarantees, expressed or implied, and is not liable for damages of any kind in connection with the material, information, or procedures set forth.

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