Anovulatory Cycles
Dr. Nelson Soucasaux , Brazilian gynecologist
As far as the occurrence or non-occurrence of ovulation in the course
of their cycles is concerned, women present both ovulatory (biphasic) and
anovulatory (monophasic) cycles.
In the ovulatory cycles the complete follicular development and transformation
takes place, resulting in the growth of a mature follicle, ovulation and
formation of the corpus luteum. These cycles are considered biphasic because
they present a follicular (estrogenic) and a luteal (progesteronic-estrogenic)
phase. Along the follicular phase, the ovary produces mostly estrogens,
while along the luteal one it produces progesterone and estrogens.
In the anovulatory cycles obviously there is neither ovulation nor formation
of the corpus luteum. They are monophasic, because these cycles present
only the follicular phase, characterized by variable degrees of persistent
estrogenic production.
The recently described cases of "LUF" (luteinized unruptured
follicles), despite also constituting a kind of failure in the ovulatory
process, must not be included in the usual category of anovulatory cycles
because their histological and endocrine features differ too much from the
ones already mentioned, since they are similar to those of the ovulatory
cycles (Note 1, below).
In this way, whenever I speak of anovulatory cycles I mean the specific
kinds of ovarian and menstrual cycles that exhibit only the follicular phase,
in which there is neither ovulation nor formation of the corpus luteum.
Endocrinally and histologically they are monophasic cycles. Only follicles
in variable stages of growth and involution can be found in the ovaries
throughout these cycles.
Anovulatory cycles (monophasic) are physiologically normal soon after
menarche, and are part of the process of maturation of the hypothalamus-hypophyseal-ovaries
axis (or hypothalamus-pituitary-ovaries axis). This maturation is considered
complete with the establishment of regular ovulatory cycles. Even so, we
must remark that the occurrence of anovulatory cycles intermingled with
the ovulatory ones is frequent and normal along the fertile years of a woman's
life. We can say that there are women who ovulate more often, while others
ovulate less often.
In the absence of hyperestrogenism, hyperprolactinemia, hyperandrogenic
syndromes and the usually named "polycystic" pathologies of the
ovaries, the occurrence of occasional anovulatory cycles with a regular
duration intermingled with the ovulatory ones is considered normal (Note 2). We must also remark that in the years that
precede menopause, ovulation gradually becomes less frequent and even rare,
and the anovulatory cycles predominate again.
There are the more varied possible patterns of follicular growth in
the anovulatory cycles, with or without the formation of the mature follicle
(or follicle at the third stage of growth). The duration of these cycles
also can vary greatly, from the average 25-35 days up to short cycles (less
than 25 days) and long ones (35 to 50 days, or even more). Therefore, there
are several kinds of anovulatory cycles.
Though anovulatory cycles often tend to be irregular and exhibit variable
patterns of follicular growth, there are also the common anovulatory cycles,
characterized by the formation of a mature follicle (or almost mature) and
duration within the limits of normality. Anovulatory cycles of this kind
are relatively frequent throughout the menacme (the menovulatory period
of women's lives) and, due to their characteristics, they are not perceived
as such by women, who are ignorant of them. Usually they only can be detected
through a careful gynecologic study.
In these cycles the mature follicle may reach its usual size, but there
is a failure in the ovulatory mechanism that results in the absence of the
hypophyseal ovulatory peak of LH (luteinizing hormone). Because of this,
there is no follicular rupture and the growing follicle persists as such
for more 10 to 14 days, after which its process of follicular involution
and atresia (death) begins. This results in the sudden fall of the estrogenic
levels and the consequent coming of menstruation. Botella Lusiá remarks
that in the common anovulatory cycles, "...the atresia and decay of
the follicle takes place in such a way that the menstrual rhythm does not
alter" ("Tratado de Ginecologia, Tomo 3 Enfermedades del
Aparato Genital Femenino," Editorial Científico-Médica,
Barcelona, 1965). Nevertheless, there are also reports of regular anovulatory
cycles in which signs of mature follicles cannot be detected.
On the other hand, long-lasting anovulatory cycles are often related
to the prolonged persistence of mature follicles or to the usually named
"polycystic" pathologies of the ovaries. Several endocrine disorders
in the hypothalamus-hypophysis-ovaries axis are responsible for chronic
anovulation, long-lasting cycles (oligomenorrhea) and amenorrhea.
It is also important to remark that though many anovulatory cycles progress
normally and without problems (mostly the ones named common anovulatory
cycles), a considerable number of these cycles characterized by absence
of ovulation tend to be associated with several degrees of relative or absolute
hyperestrogenism, a condition that cause endometrial hyperplasia and hypermenorrhea
(excessive menstrual bleeding).
Chronic anovulation which is different from the normal occurrence
of some anovulatory cycles intermingled with the ovulatory ones is
obviously associated with infertility, as well as hyperestrogenism and endometrial
hyperplasia. Endometrial hyperplasia requires special medical attention
in order to prevent the possible development of endometrial cancer.
Note 1: There are cases of luteinization
of follicles that do not ovulate, condition known as "LUF" (luteinized
unruptured follicles). This is a very special sort of failure in the ovulatory
process in which, despite the absence of follicular rupture and ovulation,
the unruptured follicle becomes luteinized under the action of the LH (luteinizing
hormone), giving rise to the corpus luteum. In such cases both the production
of progesterone and the duration of the luteal phase of the cycle may be
normal. Cases of "LUF" constitute, therefore, a very special kind
of ovulatory failure with biphasic cycles.
Note 2: a) Hyperestrogenism: excessive
production of estrogens or excessive estrogenic activity; b) Hyperprolactinemia:
a disorder characterized by an excessive production of prolactin; c) Hyperandrogenic
Syndromes: disorders characterized by an excessive production of androgens;
d) As to the so-called "polycystic" pathologies of the ovaries
("polycystic ovaries syndrome"), I have some personal reservations
about the use of the term "polycystic" for such disorders. I think
they would be much better defined as "polymicrocystic ovaries."
Most of the text above are excerpts from my book "Os
Órgãos Sexuais Femininos: Forma, Função, Símbolo
e Arquétipo"("The Female Sexual Organs: Shape, Function,
Symbol and Archetype"), published by Imago Editora, Rio de Janeiro,
1993. For more information on the book see page http://www.nelsonginecologia.med.br/orgaos.htm
, from my Web site www.nelsonginecologia.med.br
.
Copyright Nelson Soucasaux 1993, 2002
___________________________________________________
Nelson Soucasaux is a gynecologist dedicated to clinical, preventive
and psychosomatic gynecology. Graduated in 1974 by Faculdade de Medicina
da Universidade Federal do Rio de Janeiro, Brazil, he is the author of several
articles published in medical journals and of the books "Novas Perspectivas
em Ginecologia" ("New Perspectives in Gynecology") and "Os
Órgãos Sexuais Femininos: Forma, Função, Símbolo
e Arquétipo" ("The Female Sexual Organs: Shape, Function,
Symbol and Archetype"), published by Imago Editora, Rio de Janeiro,
1990, 1993.
Web site: www.nelsonginecologia.med.br
Email: nelsons@nelsonginecologia.med.br