Champion speaks of a woman who became pregnant although her hymen was intact.

She had been in the habit of having coitus by the urethra, and all through her pregnancy continued this practice.
Houghton speaks of a girl of twenty-five into whose vagina it was impossible to pass the tip of the first finger on account of the dense cicatricial membrane in the orifice, but who gave birth, with comparative ease, to a child at full term, the only interference necessary being a few slight incisions to permit the passage of the head.

Tweedie saw an Irish girl of twenty-three, with an imperforate os uteri, who had menstruated only scantily since fourteen and not since her marriage.

She became pregnant and went to term, and required some operative interference.

He incised at the point of usual location of the os, and one of his incisions was followed by the flow of liquor amnii, and the head fell upon the artificial opening, the diameter of which proved to be one and a half or two inches; the birth then progressed promptly, the child being born alive.
Guerard notes an instance in which the opening barely admitted a hair; yet the patient reached the third month of pregnancy, at which time she induced abortion in a manner that could not be ascertained.