A medical assistant should place a patient in which of the following positions for a vaginal examination?

The left lateral position involves the patient lying on their side, which is not advantageous for a vaginal examination. While this position can be useful for certain medical procedures and assessments, it does not provide the necessary access needed for a thorough examination of the vaginal and pelvic areas.

Fowler's position, where a patient is seated upright, is helpful for assessing respiratory issues and certain cardiovascular conditions. However, it is unsuitable for a vaginal examination as it restricts access to the pelvic region, making it difficult for the healthcare provider to conduct a proper examination.

The supine position, or lying flat on the back, is commonly used in many medical examinations. While it offers some access to the pelvic area, it is not the most effective position for a vaginal examination, as it does not provide the same level of access and visibility as the lithotomy position.