An assembly of disposable and reusable devices designed to obtain a submucosal tissue specimen from the rectum using suction [rectal suction biopsy (RSB)], typically for histopathological analysis [e.g., to help diagnose Hirschsprung's disease (HD)]. It typically consists of dedicated disposable capsules (e.g., plastic cylinder-shaped devices with a small hole at their closed end that contain a metallic cutting blade), suction tubing with negative pressure manometers, and a reusable handpiece.