Back in the 1960’s, third year students at the Indiana University School of Medicine, spent three months on the Obstetrics and Gynecology service. Our rotations were called services, I suspect, because as students we were providing free service to the patients for whom we cared in exchange for them allowing us to learn from them. These practical experiences were also called clinical clerkships. The first question our professor asked us was “What’s the most frequent cause of amenorrhea?” To answer that question, one first had to know the definition of amenorrhea. Amenorrhea is the absence of female menstrual blood flow, or more commonly, it means a woman with amenorrhea has no periods.
This is a trick question because the answer is PREGNANCY! Yes, the absence of periods most often occurs when a woman is pregnant. But many other, far less common conditions also cause it. Fortunately, for most women this is a good cause because it results in the birth of a baby. However, other causes don’t always have the happy ending of a pregnancy.
This blog talks about the more common things that cause women to not have periods.
AMENORRHEA can either be:
PRIMARY—a woman never starts having periods.
OR
SECONDARY—a woman who has had periods stops having them.
Female menstrual flow usually begins around age 15. The term for starting periods is MENARCHE. During adolescence, a change occurs in girls, and boys, called Thelarche. This is the time young girls develop breasts and pubic and underarm hair. Usually, 12-24 months later, menarche occurs, ie. periods begin. If they don’t begin, the young woman has Primary Amenorrhea and the search for a cause begins.
Primary amenorrhea occurs because there is either an obstruction to the menstrual flow, or the hormonal mechanism that causes periods fails to work. That is blood either cannot get out or the hormones that cause periods are blocked, inadequate, or not being produced. The causes of these situations are numerous.
Causes of Obstruction of Menstrual Flow:
The Hymen is Intact—It covers the vaginal opening
The Uterine Cervix is closed—Cervical Stenosis
Congenital Absence of Uterus, Tubes, and/or Ovaries
Other congenital anatomical abnormalities
Causes of Hormonal Failure to Produce Periods:
Primary Ovarian Failure—The ovaries fail to respond to stimulus from the pituitary
gland and don’t produce the hormones needed for ovulation and menstrual flow. Or
the ovaries simply don’t work.
Pituitary Gland Disorders—Hormones (FSH, LH) produced by the pituitary, needed
for ovulation, aren’t produced. There are numerous reasons for this most of which
are quite rare.
Hypothalamic (Deeper brain structure) disorders
Other Endocrine (Glandular) Causes—Adrenal gland insufficiency
Effects of Chronic Disease or Chronic Illness—Diabetes, Thyroid disease
Psychosocial Stressors
Medication Use—Oral birth control pills
Physiologic—unknown cause
Secondary Amenorrhea occurs when previously regular periods
stop. Again, the causes are many, but the number one cause is Pregnancy.
Other causes of Secondary Amenorrhea are:
Ovarian Failure
Pituitary Failure
Other Endocrine Disorders
Medications—Oral contraceptives
Chronic illness/disease
Hysterectomy
Psychosocial Stressors
Many of the same conditions cause both primary and secondary amenorrhea. It’s easy to differentiate between 1° and 2°, but finding the underlying cause can be a complex trail of tests and special procedures. The most common cause, pregnancy, is quite easy to diagnose by urine or blood pregnancy tests, pelvic examination, or pelvic ultrasonography. The other causes are far more elusive and require a good knowledge of reproductive endocrinology. If one doesn’t have that information at hand, the diagnosis will be much harder to make.
Dr. G’s Opinion: Deciding between primary and secondary amenorrhea is an easy decision, but after ruling out pregnancy, discovering why a woman has stopped menstruating, or never started, is a difficult challenge. If I was unable to tell with simple testing, I never hesitated to refer to an OB-GYN who I knew would be more adept at deciding what was wrong and what to do about it. The process of ovulation and the menstrual period cycle is complicated and effective treatment depends totally on getting the reason right. If I felt uneasy about my investigation, I would consult knowledgeable physicians. It’s better to admit you don’t know and ask for help, than to prescribe something that might do harm.
References: Klein DA, Paradise SL, Reeder RM Amenorrhea: A Systematic Approach to Diagnosis and Management, Am Fam Phys 2019 July 1;100(1):39-48.
