A 28-year-old nulliparous woman comes to the office due to clear vaginal discharge for the past 2 days. The patient has had increased vaginal discharge over the last day but no associated odor or irregular vaginal bleeding. Her last menstrual period was 10 days ago, and menses usually occurs every 29 days with 4 days of moderate bleeding. The patient discontinued her continuous oral contraceptive pills 3 months ago as she is trying to conceive with her boyfriend. She has no chronic medical conditions and has had no surgeries. The patient does not use tobacco, alcohol, or recreational drugs. Vital signs are normal. Speculum examination shows clear mucus at the cervical os. Bimanual examination reveals a small, anteverted uterus and no palpable adnexal masses. Which of the following is the most likely explanation for this patient's discharge?
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This patient has an increase in clear vaginal discharge with no associated odor or irregular bleeding. With her relatively recent discontinuation of her continuous oral contraceptive pills (OCPs) and symptoms occurring in the late follicular phase of the menstrual cycle, the most likely cause of this patient's vaginal discharge is ovulation.
Continuous OCPs provide constant estrogen and progestin levels, which exert negative feedback on the hypothalamus and the anterior pituitary gland to decrease gonadotropins (FSH, LH) and prevent the mid-cycle LH surge, thereby suppressing ovulation. When the OCPs are discontinued, physiologic fluctuations in estrogen and progesterone of the menstrual cycle resume. The follicular phase of the menstrual cycle is marked by rising estrogen levels produced by the enlarging dominant follicle, resulting in:
An increase in quantity of cervical mucus, which facilitates the transfer and maturation of sperm for fertilization
A thickened endometrium in preparation for implantation
The cervical mucus in the late follicular phase (10-14 days after the last menstrual period) and leading up to the point of ovulation is clear, thin, elastic, and often perceived by patients as abnormal vaginal discharge (particularly in those who have previously been anovulatory).
After ovulation, the luteal phase begins and is marked by rising progesterone levels (produced by the corpus luteum), which rapidly increase the viscosity of the cervical mucus, resulting in the cyclic nature of the symptoms.
(Choice A) Bacterial vaginosis is caused by overgrowth of anaerobes (eg, Gardnerella vaginalis) and presents with a thin, white vaginal discharge; however, due to the production of amines, the discharge is typically malodorous.
(Choice B) Candidiasis, caused by an overgrowth of Candida albicans, typically causes a thick, white discharge with mucosal erythema rather than clear cervical discharge.
(Choice C) A cervical mucus plug, seen only with pregnancy, serves as a barrier to ascending infection. This brown, red, or yellowish thick mucus is typically shed before or during labor.
(Choice D) In contrast to this patient's physiologic cervical discharge, those with Neisseria gonorrhoeae have a mucopurulent cervical discharge and a friable cervix that can cause irregular or postcoital vaginal bleeding.
Educational objective:
During the follicular phase of the menstrual cycle, rising estrogen levels result in a clear, odorless, physiologic cervical discharge.