As administered in the Western Church today according to the rite of the Roman Ritual, the sacrament consists (apart from certain non-essential prayers) in the unction with oil, specially blessed by the bishop, of the organs of the five external senses (eyes, ears, nostrils, lips, hands), of the feet, and, for men (where the custom exists and the condition of the patient permits of his being moved), of the loins or reins; and in the following form repeated at each unction with mention of the corresponding sense or faculty: "Through this holy unction and His own most tender mercy may the Lord pardon thee whatever sins or faults thou hast committed [quidquid deliquisti] by sight [by hearing, smell, taste, touch, walking, carnal delectation]". The unction of the loins is generally, if not universally, omitted in English-speaking countries, and it is of course everywhere forbidden in case of women. [italics and bold added for emphasis]
http://www.newadvent.org/cathen/05716a.htm This could well have changed with Vatican II; I have no idea. I also have no idea "where the custom exists" or existed. The wondrous Catholic Encyclopedia, of course, dates from 1917.