Review Question - QID 108725

This patient has intermittently profuse vaginal discharge that is clear, viscous, and odorless, most consistent with ovulation. The high estrogen levels associated with ovulation result in increased electrolyte content of the cervical mucus with an “egg white” quality.

Even without an ovulation predictor kit, it is likely that this patient is ovulatory since she has regular periods and premenstrual symptoms. This young woman states that her last period was 2 weeks ago, which suggests that she is currently ovulating (i.e., cycle day 14 in a cycle of 28 days). Her symptom of intermittently increased odorless discharge suggests ovulatory cervical mucus. Known as “spinnbarkeit,” this mucus is a result of increased estrogen leading to the LH surge that triggers ovulation. Because of the mucus’s increased water content during this phase of the cycle, the mucus is thin and serous, resulting in the “egg white” appearance and the formation of a “string” when stretched. There is also increased electrolyte content, causing precipitation in a fern pattern on wet mount (Figure A). This helps increase the movement of semen in the vaginal canal for fertilization of the ovulated ovum. The decreased acidity of this mucus prevents degradation of sperm and thus further increases fertility.With ovulatory mucus, as in this patient, there is no associated abdominal pain, pelvic, or skin irritation. The patient should be reassured that this discharge is normal, and no additional follow-up is needed.

Figure A shows a wet mount with ferning, due to increased electrolyte content of the mucus and subsequent salt precipitation on the slide. Illustration A shows clue cells with bacterial stippling of epithelial cells on wet mount in BV. Illustration B shows flagellate trichomonads on wet mount in trichomonas vaginalis.

Incorrect Answers:
Answer 1: Alteration of the vaginal flora is the cause of bacterial vaginosis (BV). Although this patient does have a recent history of antibiotic use (a risk factor for BV), her discharge is odorless in contrast to the classic “fishy” smell of BV. In addition, wet mount would show clue cells (Illustration A) and should be treated with metronidazole.

Answer 2: Increased FSH levels are found at ovulation, as the negative feedback from estrogen is switched to positive feedback at high estrogen levels. However, FSH is not known to have a direct effect on cervical mucus and is not the cause of this patient’s discharge.

Answer 4: A sexually transmitted disease (STD) is a possibility in this patient who is having unprotected intercourse with a new partner. Trichomonas vaginalis is a common STD that causes abnormal discharge that can be clear and watery, but it typically causes vulvar irritation, which is absent in this patient. Furthermore, this patient’s symptom is intermittent, while Trichomonas would be continuous. Trichomonas often has flagellate trichomonads on wet mount (Illustration B) and should be treated with metronidazole.

Answer 5: Increased progesterone levels are present in the last half of the menstrual cycle during the luteal phase, when a pregnancy could already possibly be established. This causes a thickening of the cervical mucus to prevent transport of semen and bacteria through the vaginal canal. The mucus is also more acidic, resulting in decreased sperm survival. Women on progesterone-containing oral contraceptives or with levonorgestrel intrauterine devices may experience this type of cervical mucus.

Bullet Summary:
During ovulation at the middle of the menstrual cycle, high estrogen levels cause cervical mucus to be thin, clear, and profuse. Its high electrolyte content causes ferning on wet mount.