Müllerian anomalies are very common, and a frequent cause of infertility. The most used classification system until now, proposed by the American Society for Reproductive Medicine in 1988, categorizes comprehensively uterine anomalies but fails to classify defects of the cervix or vagina. This is based on a developmental theory that postulates that müllerian duct fusion is unidirectional, beginning caudally and extending cranially, which does not account for isolated cervical or vaginal defects. More recently, the European Society of Human Reproduction and Embryology has developed a consensus, which allows for independent cervical anomalies. We present a case of a 39-year-old woman with secondary infertility, found to have a cervical duplication in an anteroposterior disposition, which puts into question the principles of embryology formerly known, but supports the theory that development happens in a segmentary fashion.
Female genitourinary tract malformations are extremely
common, being found in around 5.5% of the general
population and 8% of infertile women, specifically affecting
as many as 25% of women with infertility due to
miscarriage (1). The real prevalence may be even higher,
considering most of them will go undiagnosed either for
being asymptomatic or because of having no access to
methods for accurate diagnosis. The spectrum of these
malformations is enormous, and although there have been
several attempts to catalogue them-the most utilized until
recently being the classification by the American Society
for Reproductive Medicine (ASRM) from 1988 (2),
which included mostly uterine anomalies-it is still necessary
to extend the list for a more complete record. Over
the years reports of types of malformations have arose,
not included in this classification system, predominantly
of associated or isolated cervical and vaginal anomalies.
We present a case of a cervical duplication with a normal
uterus and normal vagina, but with an anteroposterior
disposition of the cervix, which supports the theory that
isolated segment defects may occur. This case questions
the embryology theory that has supported the ASRM classification
A 39 year-old woman was referred to our institution due
to secondary infertility. Menarche was at 14 years of age,
with regular cycles and slight dysmenorrhoea. She had
experienced a term caesarean section 8 years prior due
to failure to progress, and had been trying to get pregnant
for 3 years. Her past medical history was unremarkable.
On gynaecological examination external genitalia and vagina
were normal; two cervical orifices in an anteroposterior
disposition were clearly visualized (Fig .1)-this was
confirmed with curetting of the posterior canal, which
revealed “normal endocervical mucosa”, excluding other
pathologies such as uterovaginal/cervicovaginal fistulae.
Menstrual blood was observed exiting both cervical orifices.
Hysterosalpingography (HSG) revealed a normal
uterine cavity and tubes, although contrast was visualized
exiting the posterior endocervical canal (Fig .2). Transvaginal
ultrasound revealed a normal retroverted uterus, with
one internal cervical OS and two endocervical canals diverging
from it in an anteroposterior arrangement (Fig .3).
Because both these exams did not suggest a uterine cavity
defect, we chose not to pursue with further tests such
as magnetic resonance imaging (MRI) or hysteroscopy,
having to subject the patient to bothersome and invasive
testing that would not alter clinical conduct. Consent form
was obtained and completed by participant.
Hysterosalpingogram showing a normal uterine cavity with contrast
extravasation through a posterior cervical canal (black arrow).
Transvaginal ultrasound displaying one internal cervical os (black arrow)
and two cervical canals (white arrows).
An extremely rare müllerian malformation is described,
which questions classical knowledge of developmental
embryology. An extensive literature search was conducted
revealing only a few similar cases (3, 4), one in
a 4-month infant with other multiple malformations, and
another with a side-by-side disposition of the cervix. Only
one other case anatomically similar to ours is depicted in
the literature (5).
The aetiology for most of the congenital anomalies of
the female genital tract is unknown. The importance of
normal embryological development lays in its reproductive
consequences, and also in concomitant urological abnormalities
(which are more common with more proximal
defects) and in quality of life (for possible dysmenorrhoea
or dyspareunia in obstructive defects). In 1988 the ASRM
attempted to classify these anomalies (2), however it
documents only the more common uterine anomalies, not
including rarely occurring cervical or vaginal defects (6).
Nevertheless, until recently it has been the most commonly
used classification for congenital anomalies.
Two main theories, both described in 1960s, are the
foundations for the classification system of the ASRM.
The first theory, described by Crosby and Hill (7), suggests
that uterine development is a result of müllerian
duct fusion between the 11th and the 13th weeks of embryonic
life, beginning caudally and progressing cranially;
this process is then followed by septal reabsorption,
which begins at any point of fusion and moves in either or
both directions. The downside of this unidirectional theory
is that it does not account for lower segment defects
with normal upper segments, as is the case of vaginal/cervical
duplications with normal uteri. The second theory,
argues that müllerian duct fusion is initiated in the middle
portion, at the uterine isthmus, and proceeds simultaneously
in a cranial and caudal direction, and that the septal
reabsorption follows a similar bidirectional pattern, with
complete uterus formation independently from the formation
of cervix and vagina (8). This theory, which seems to
encompass defects not explained by the first, still does not
justify the existence of a middle segment isolated defect,
as in our case.
Acién et al. (8) advocated that in fact the müllerian ducts
do not contribute to the formation of the vagina, instead
the vaginal walls are formed by cells from the wolffian
ducts and are then covered by cells of the müllerian tubercle.
Therefore the processes of fusion and reabsorption of
the müllerian ducts may affect: i. Both converging and diverging
portions (superior and inferior uterine segments),
ii. Just one of them, or iii. Even just a small specific area,
giving rise to segmentary defects.
More recently, the European Society of Human Reproduction
and Embryology (ESHRE) developed an
anatomy-based consensus on congenital anomalies of the
female genital tract and its related clinical significance,
in a comprehensive and accessible system. Here, cervical
and vaginal anomalies are categorized into independent
sub-classes (9), and a normal uterus can be associated
with either an abnormal cervix or an abnormal vagina,
or both. Therefore, this system encompasses “segmentary
defects”, and supports Acién’s theory. Yet another classification
system, this time by El Saman et al. (10), attempts
to classify müllerian duct anomalies based on both embryological
development and a “treatment-based” categorization,
also including segmentary defects, allowing for
a more comprehensive approach to congenital anomalies.
Embryology of the female genital tract is not completely
understood, as the mechanism of müllerian development
is more complex than previously described. Acién’s
segmentary theory is currently the one that best explains
segment malformations as the one presented here. This
theory puts into question our decade-long understanding
of embryological development of the female reproductive
system, and supports the classification system of müllerian
anomalies of ESHRE. The fact that in our case the
two cervices were displayed in an anteroposterior fashion
also calls into question the fact that development may not
always occur in a side-by-side manner.
Lobo Antunes, I., Tomás, C., Bravo, &., Metello, J., Quintas, A., e Melo, P. (2019). Double Cervix with Normal Uterus and Vagina - An Unclassified Müllerian Anomaly. International Journal of Fertility and Sterility, 13(1), 83-85. doi: 10.22074/ijfs.2019.5524
Isabel Lobo Antunes; Cláudia Tomás; Íris Bravo; José Luís Metello; Ana Quintas; Pedro Sá e Melo. "Double Cervix with Normal Uterus and Vagina - An Unclassified Müllerian Anomaly". International Journal of Fertility and Sterility, 13, 1, 2019, 83-85. doi: 10.22074/ijfs.2019.5524
Lobo Antunes, I., Tomás, C., Bravo, &., Metello, J., Quintas, A., e Melo, P. (2019). 'Double Cervix with Normal Uterus and Vagina - An Unclassified Müllerian Anomaly', International Journal of Fertility and Sterility, 13(1), pp. 83-85. doi: 10.22074/ijfs.2019.5524
Lobo Antunes, I., Tomás, C., Bravo, &., Metello, J., Quintas, A., e Melo, P. Double Cervix with Normal Uterus and Vagina - An Unclassified Müllerian Anomaly. International Journal of Fertility and Sterility, 2019; 13(1): 83-85. doi: 10.22074/ijfs.2019.5524