Which position is primarily used for rectal exams and utilizes body weight on the knees and chest?

The knee-chest position is specifically designed for procedures such as rectal examinations. In this position, the patient kneels on the examination table with their body weight supported on their knees and chest, allowing for maximum access to the rectal area. This positioning helps the healthcare provider perform the examination effectively while also providing comfort and stability for the patient.

The other positions listed do not offer the same advantages for rectal exams. The supine position involves lying flat on the back and does not provide the necessary access. The dorsal recumbent position, while it involves lying on the back with knees bent, does not utilize the chest and knees to the same degree as the knee-chest position. The lithotomy position is typically used for gynecological exams and procedures, offering access to the pelvic area rather than specifically facilitating rectal examinations.