Endomyocardial biopsy samples are typically how large?

• A. 1-2 mm
• B. 3-4 mm
• C. 4-5 mm
• D. 5-6 mm

Answer: (A)

Endomyocardial biopsy uses very small tissue cores. Each core is kept about 1–2 mm in diameter so that the sampling causes minimal trauma to the thin right ventricular endocardium and reduces the risk of perforation, bleeding, or other complications. Even though the pieces are tiny, they provide enough tissue for histology when multiple cores are obtained, and this approach preserves patient safety while still allowing accurate diagnosis. Larger samples would increase the risk of injury without providing a proportionally greater diagnostic payoff, which is why 1–2 mm is the typical size.