Capillary and wet techniques. A pilot study comparing two tissue sampling methods guided by endoscopic ultrasound

There are different techniques for obtaining tissue using a fine needle guided by endoscopic ultrasound (EUS); all aim to obtain the most appropriate material, free of defects, of good quality and in sufficient quantity.

The objective of the study was to determine which of the two EUS-guided techniques (capillary and wet) provides better quality samples for cytopathological analysis and which should be used for obtaining tissue from pancreatic, bile duct, liver, and lymph node tumors.

We conducted a pilot prospective study that included 26 patients with evidence of pancreatic tumor, liver tumor, and/or lymph node metastasis of primary tumor. All patients were subjected to two different tissue sampling techniques, the capillary technique and the wet technique, during the same procedure. Both techniques relied on EUS guidance. The samples obtained for the cytopathological analysis were evaluated in blinded manner by two different pathologists.

Pathologist A was able to make a diagnosis using the capillary technique in 96.15% of the cases and in 88.46% of the cases using the wet technique. Pathologist B was able to make a diagnosis using the capillary technique in 96.15% of the cases and in 92.30% of the cases using the wet technique. The kappa coefficient between observers for histopathological diagnosis was 1 for capillarity and 0.948 for wet technique.

The capillary technique yielded better results than the wet technique in terms of sample quality and cellularity.