Comparison of diagnostic accuracy of laparoscopic 3 mm and 5 mm cup biopsies to wedge biopsies of canine livers

Background Diagnostic accuracy of the 3 mm laparoscopic cup biopsy forceps for collection of tissue samples from canine livers is unproven. Hypotheses/Objectives Compare sample surface area and portal triad count between 3 mm and 5 mm laparoscopic cup biopsies and compare the histologic diagnosis obtained by each instrument to a standard necropsy wedge. The hypothesis was that more portal triads and greater sample surface area would be found with the 5 mm samples and the laparoscopic instruments would not have significantly different levels of agreement with necropsy wedge diagnosis. Animals Twenty‐one client‐owned dogs undergoing necropsy. Methods Prospective ex vivo study. Three samples (3 mm, 5 mm, and wedge) were taken of 2 different hepatic divisions within 24 hours of death. Morphologic diagnosis, World Small Animal Veterinary Association histologic features, surface area, and portal triad numbers were compared among the 3 samples. Results There were significantly more portal triads (mean 21.4 versus 13.8; P < .0001) and a higher surface area (20.3 mm2 versus 11.5 mm2; P < .0001) in the 5 mm samples compared to 3 mm samples. Kappa coefficients and percent agreement for histologic diagnosis as compared to the wedge biopsy were not significantly different between the 2 instrument sizes (κ = 0.383 and 0.436, respectively; 67% and 69%, respectively). Conclusions and Clinical Importance Despite yielding smaller sample sizes, the 3 mm laparoscopic cup biopsy has a similar level of histologic diagnostic accuracy to the 5 mm instrument.