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 mm(2) versus 11.5 mm(2); 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.