Evaluation of Missed Menstrual Period

Initial Assessment and Diagnosis

The American College of Obstetricians and Gynecologists recommends obtaining a detailed menstrual history, including previous regularity, last menstrual period, and any associated symptoms, to evaluate a 5-month missed menstrual period 1
A pregnancy test should be performed first to rule out pregnancy, as recommended by the American College of Obstetricians and Gynecologists 2
The Endocrine Society suggests assessing for signs of hyperandrogenism, such as hirsutism and acne, and evaluating for galactorrhea, as these can be indicative of underlying hormonal imbalances 1
The use of hormonal contraceptives should be reviewed, as they can affect menstrual regularity, according to the American College of Obstetricians and Gynecologists 2

The American Society for Reproductive Medicine recommends measuring serum FSH and LH levels to evaluate for polycystic ovary syndrome (PCOS) and other hormonal imbalances 1
The Endocrine Society suggests measuring serum prolactin levels to evaluate for hyperprolactinemia, which can cause menstrual irregularity 1
The diagnostic criteria for PCOS include hyperandrogenic chronic anovulation, with laboratory findings of LH/FSH ratio >2, elevated testosterone, and insulin resistance, as defined by the American Society for Reproductive Medicine 3

Pelvic ultrasonography is indicated when clinical features or hormone tests suggest ovarian pathology, and transvaginal ultrasound is preferred over transabdominal for better visualization, according to the American Institute of Ultrasound in Medicine 1
Referral to gynecology/endocrinology is indicated for confirmed amenorrhea of >6 months, abnormal hormone levels suggesting specific pathology, signs of hyperandrogenism with menstrual irregularity, or suspected structural abnormalities on imaging, as recommended by the American College of Obstetricians and Gynecologists 1, 4

PCOS is the most common cause of secondary amenorrhea, affecting 4-6% of the general female population, and is characterized by hyperandrogenic chronic anovulation, according to the American Society for Reproductive Medicine 1, 3
Hypothalamic amenorrhea is associated with weight loss, excessive exercise, or emotional stress, and laboratory findings include low LH and low estradiol, as defined by the Endocrine Society 1, 3
Hyperprolactinemia can cause menstrual irregularity, and prolactin >20 μg/L is considered abnormal, according to the Endocrine Society 1
Primary ovarian insufficiency is characterized by FSH >35 IU/L, and may occur earlier in women with epilepsy than in the general population, as reported by the American Epilepsy Society 1, 3