"How reliable is the woman's menstrual history in determining where she is in her cycle, namely that she is preovulatory? In a study by Novikova et al., they found the history of the first day of the last period to be unreliable 39 percent of the time (Novikova et al. 2007). In addition they found a wide range of cycle lengths with the first day of one period to the first day of the next to be 21 to 35 days. With a longer cycle the woman could be on day 17 of her cycle but still be preovulatory and with a shorter cycle she could be on day 13 of her cycle and be postovulatory. Although one may suspect the woman is approaching ovulation on pelvic exam with the presence of highly fertile mucus at the cervical os, it is impossible for a physician to determine whether the woman is preovulatory on a pelvic exam, in particular in a woman who has just been sexually assaulted. How reliable are LH testing and progesterone levels done stat in the emergency room in determining where the woman is in her cycle? The LH surge goes on over a twenty-four-hour period, and is usually detected by testing a first-morning concentrated urine. A random urine specimen, particularly late at night, may not detect the LH surge. In addition, serum progesterone levels are not emergency tests, and the results often are not available for twenty-four hours, even in major metropolitan hospitals, and even longer in small community hospitals. Therefore, this protocol may not have a timely progesterone level available to help determine if a woman is preovulatory in the emergency room."