Ovulation -- Normal and Abnormal
from the book How to Have a Baby:
by Dr. Aniruddha Malpani, MD and Dr. Anjali Malpani, MD.
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Normally, one of the ovaries releases a single mature egg every month, and
this is called ovulation. Women may notice pain or abdominal discomfort at the
time of ovulation and occasionally have some slight vaginal bleeding. The
presence of regular periods, premenstrual tension and dysmenorrhoea (period
pains) usually indicate that the menstrual cycles are ovulatory.
Eggs are stored in the ovaries in follicles. Follicles exist in two major
categories – growing and non-growing ( primordial ). Eggs in the primordial
follicle are in a very immature form. In this state they are not capable of
being fertilized by a sperm until they undergo a maturing process which
culminates in their release from the ovary at the time of ovulation. Egg
maturation and ovulation is stimulated by two hormones secreted by the pituitary
- follicle stimulating hormone (FSH) and luteinizing hormone (LH) . These two
hormones must be produced in appropriate amounts throughout the monthly cycle
for normal ovulation to occur. Every month, at the start of the menstrual cycle,
in response to the FSH produced by the pituitary gland, about 30-40 primordial
follicles start to grow. Of these, only one matures to form a large fluid-filled
structure, called a Graafian follicle which contains a mature egg, while the
others die ( a process called atresia). The mature egg is released from the
follicle when the follicle ruptures in response to a surge of LH produced by the
After ovulation has occured, the follicle from which the egg has been
released forms a cystic structure called the corpus luteum. This is responsible
for progesterone production in the second half of the cycle.
Most women who have regular periods have ovulatory cycles. Women who fail to
ovulate or who have abnormal ovulation usually have a disturbance of their
menstrual pattern. This may take the form of complete lack of periods (amenorrhoea),
irregular or delayed periods (oligomenorrhoea) or occasionally a shortened cycle
due to a defect in the second part (luteal phase) of the cycle.
Fig 1. Schematic of the ovarian follicle during its
Fig 2. The hormonal changes which occur during a normal
ovulatory cycle, if pregnancy occurs. The purple line marks the point when the
Detecting ovulation – do you ovulate?
Menstrual period timing ( Calendar method)
To determine the length of the menstrual cycle, one only needs to note the
date of the beginning of the menstrual period (first day of flow) for two
consecutive periods, and then count the day from one date to the next. Keeping
track of the length of menstrual cycles will help determine the approximate time
of ovulation, because the next period begins approximately two weeks from the
date of ovulation.
The rough rule to calculate the approximate date of ovulation is : NMP minus
14 days, where NMP is the ( expected) date of the next menstrual period. This is
because the luteal phase for most women is 14 days long.
Keeping track of the menstrual cycle by charting it can indicate other
ovulatory disturbances . For example, if a menstrual cycle that is normally 28
days starts to occur every 35 or 40 days, this may mean that ovulation is
disturbed, and an evaluation is needed.
Basal Body Temperature (BBT) chart
During the luteal phase of the cycle, the corpus luteum produces the hormone
progestrone, which elevates the basal body temperature. When the basal body
temperature has gone up for several days, one can assume that ovulation has
occurred. However, it is important to remember that the BBT chart cannot predict
ovulation - it cannot tell you when it is going to occur !
The basal temperature chart can be a useful tool. It allows the patient to
determine for herself if she is ovulating as well as the approximate date of
ovulation, in retrospect. Basal body temperature charts are easy to obtain and
the only equipment required is a special BBT thermometer.
General instructions for keeping a basal body temperature chart include the
- The chart starts on the first day of menstrual flow. Enter the date here.
- Each morning immediately after awakening, and before getting out of bed or
doing anything else, the thermometer is placed under the tongue for at least
two minutes. This must be done every morning, except during the period.
- Accurately record the temperature reading on the graph by placing a dot in
the proper location. Indicate days of intercourse with a cross.
- Note any obvious reason for temperature variation such as colds, or fever
on the graph above the reading for that day.
The major limitation of the BBT is that it does not tell you in advance when
you are going to ovulate - therefore its utility in timing sex during the
fertile period is small. Interpreting the BBT chart can be tricky for many
patients - rarely do the charts look like those you see in textbooks! Also,
keeping a BBT chart can be very stressful - taking your temperature as the first
thing you do when you get up in the morning is not much fun. What is worse is
that you start to let the BBT chart dictate your sex life. This is why though
the BBT chart used to be a useful method in the past, it's utility is limited
today - and newer methods are available which are more accurate are available.
Manufacturers have now incorporated a microprocessor along with the digital
thermometer, to create an electronic fertility management device , called The
Bioself Fertility Indicator . This makes calculation of the "fertile
days" much easier, because it combines and optimises both the basal body
temperature and calendar method of ovulation prediction.
Fertility Software Programs
Newer software programs ( easily available on the internet ) , such as
CycleWatch, help you learn about your body's fertility signs by giving you the
tools to document and analyze your observations. For women who are comfortable
with computers, this is a useful tool to organize your cycle data and analyze
your cycles to determine fertile times
After ovulation, the endometrium is prepared for implantation of the
fertilized egg by the progesterone secreted by the corpus luteum. In order to
determine if ovulation is occurring normally, an endometrial biopsy may be done.
During this procedure, a small amount of endometrium from inside the uterine
cavity is extracted and sent for pathologic examination under a microscope. This
is a standard procedure usually done just before the period begins. It can be
done in the doctor's office or in an operating theater. No anesthesia or
hospitalisation is needed. However, it does cause discomfort during the
procedure (about as much as a severe menstrual cramp) and an analgesic can be
taken a half-hour prior to the procedure to decrease this discomfort.
When examining the endometrial biopsy, the pathologist looks for the
influence of the estrogen and progesterone hormones on the endometrial glands.
If progesterone has been produced in that cycle, the endometrial glands show
secretory changes . In fact, the effect of progesterone on the endometrium is so
predictable, that the biopsy can be "dated" - that is, the pathologist
can predict on which day the next period will start! If there is a
"lag" between the predicted day and the actual day, then this suggest
a luteal phase defect, which means that the production of progesterone is
deficient. If no progesterone at all has been produced, then the endometrium
will be reported as being proliferative (under the influence of only estrogen) -
which suggests that the cycles are anovulatory (i.e., ovulation did not occur in
A curetting used to the commonest procedure done for infertile patients. In
fact, a number of infertile patients will request that a curetting be done for
them, since they feel that the curetting will "clean out" the dirt
they have in their uterus and allow them to conceive. This is an old wive's tale
and is based on " I know someone who got a baby after a curetting".
The correct technical term for curetting is D and C - dilatation and curettage -
which means the cervix is stretched (dilated) and the uterine cavity scraped
(curetted) to collect the endometrium) . This is an obsolete procedure for an
infertile woman, and can actually be harmful. The only use of a D&C is to
provide endometrial tissue which can be examined under the microscope to see if
the woman is ovulating or not. It has absolutely no fertility-enhancing role
whatsoever. Since this endometrium can be obtained much more easily, safely and
cheaply with an endomterial biopsy (in which only a strip of endometrium is
removed) there should rarely be any need to do a D&C for an infertile woman.
Patients have often have repeated D&Cs - and these can actually damage the
cervix and even block the tubes, if infection occurs after surgery. The only
possible role for a D&C today is when tuberculosis of the uterus is
Blood test for progesterone
The progesterone level in the blood may be measured to confirm that ovulation
has taken place. This test is done on Day 21 of the cycle (about 1 week after
the expected date of ovulation) . A high level indicates that the corpus luteum
is producing enough progesterone, and is good retrospective evidence that
ovulation occurred. A very low level means that the cycle was most probably
anovulatory. An intermediate level may suggest a luteal phase defect (in which
the corpus luteum does not secrete enough progesterone).
While the above tests will tell a women whether or not she ovulates, the
following symptoms and tests which can be used in order to determine when you
ovulate are of greater importance, since they provide information which can be
used to identify the "fertile period" prospectively.
Cervical mucus (Billing’s method)
By checking your cervical mucus daily, as described in the chapter on the
cervical factor, you can determine when you ovulate. Just before ovulation, your
cervical mucus is thin, profuse, clear and stretchy, like raw egg whites. After
ovulation, the mucus becomes thick, tacky, scanty and sticky. You can learn to
appreciate this change in your mucus (by seeing and feeling it) and this allows
you to predict when ovulation occurs quite accurately.
Approximately 25 percent of women may experience a pain on one side of the
abdomen that is associated with ovulation. This is called mittelschmerz (a
German word, which means midcycle pain) and is usually related to the release of
an egg from the rupturing follicle. It is a good idea to mark the date when it
occurs since this information is helpful in determining when ovulation occurs.
by Dr. Aniruddha Malpani, MD and Dr. Anjali Malpani, MD.
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