A chart audit (pre-intervention, PRE) of endoscopic ultrasound (EUS)-fine needle biopsy (FNB) of solid masses identified a diagnostic yield of 75%. Single needle passes accounted for 56%. To improve diagnostic yield, a quality improvement intervention targeting tissue procurement and processing was developed and trialed (post-intervention, POST). The intervention was to increase needle passes to 3 or more/mass, limit the personnel preparing cytology slides, and replace saline with formalin as medium for cell block preparation. The aim was to optimize the process of tissue acquisition and specimen handling to improve the diagnostic accuracy of EUS-FNB of solid masses by at least 10%.

Three endoscopists were provided results of the PRE, and the intervention. A POST chart audit was undertaken for solid mass EUS-FNB from 01/2024-12/2024, with quarterly reviews. Only a definite diagnosis on pathology was used to calculate diagnostic yield.

241 patients underwent 262 EUS-FNBs. Diagnostic yield was 81% in POST vs. 75% in PRE (p=ns). Single passes decreased to 14% in POST vs. 20% in PRE (p<0.0001), with similar diagnostic yield (57% vs. 56%, respectively). Number of 3 or more passes increased significantly (47% POST vs. 12% PRE, p<0.0001). In POST, 86% of single passes were performed in the first half vs. 14% in the second (p<0.0001). Only 25% of 3 or more passes were performed in the first half vs. 75% in the second (p<0.0001). Diagnostic yield improved significantly between the first and second halves (72% vs. 90%, p<0.0001). Replacing saline with formalin for cell block improved diagnostic yield (57% vs. 75%, p=0.03). Limiting the personnel making slides from 25 nurses (PRE) to 3 endoscopists (POST) had no impact on diagnostic yield.

Critical practice assessment, regular audit, and continued reinforcement led to a significant improvement in EUS-FNB diagnostic yield from 75% to 90% by increasing the number of needle passes to 3 or more/mass. This quality improvement model is easily adaptable in other centres, especially where rapid on-site evaluation is not routinely available, to enhance diagnostic efficiency without requiring additional resources.