What position may be used to examine the rectum or vagina by having the resident lie on her abdomen?

The knee-chest position is specifically designed to facilitate examination of the rectum or vagina, providing the healthcare professional with easier access to these areas. In this position, the resident kneels on the examination table with the thighs straight up and the chest and abdomen resting on the table, allowing for optimal visualization and examination. This position can also assist in certain procedures, such as rectal examinations or vaginal examinations, due to the increased pelvic tilt it provides.

The other positions mentioned do not serve the same purpose effectively. For example, the dorsal recumbent position, where the individual lies on their back with knees bent and feet flat on the surface, is typically used for different types of examinations and can restrict access to the rectal and vaginal areas. The supine position, which involves lying flat on the back, is not conducive for rectal or vaginal exams either, as it similarly limits visibility and access. Lastly, the sitting position does not provide the necessary positioning for these specific examinations, as it does not bring the pelvis into the best angle for assessment. Thus, the knee-chest position is the appropriate choice for the procedure described.