The third ovary- Superfluous ovary
This is a case of a 25-year-old female with normal female karyotype, who
presented to us with primary infertility. Investigations revealed AMH
level of 9ng/ml. On ultrasound imaging, two ovary-like structure with
follicles on the left (in different planes) and one ovary on the right
were visualized. With this ambiguity, patient consented for diagnostic
laparoscopy.
Intraoperative: there was one, phenotypically normal uterus, 2 fallopian
tubes, all in anatomically normal position were noted. Two ovaries on
the left side, placed at the normal anatomical position were visualized.
Both ovaries had one ovarian ligament each. However, only the lateral
one of the two on the left side was attached with the infundibulopelvic
ligament. Right side had one normally placed ovary with normal
attachments. Biopsy from the ovary without the infundibulopelvic
ligament confirmed ovarian tissue on histopathology. Figure 1 and 2 are
the labelled and unlabelled, respectively, laparoscopic images of our
finding.
The occurrence of more than 2 ovaries is a rare entity. Multiple
theories have been proposed to explain the presence of the third ovary.
Wharton1, in 1959, highlighted the association of
supernumerary ovaries with congenital malformations involving urogenital
system. In 1963, Pearl et al2, suggested that when the
migration of some primitive germ cells is arrested at some point during
the course of normal migration to the gonadal ridges, their inductive
influence on the surrounding epithelium leads to the formation of
ectopic ovarian tissue. In 1973, Printz et al3,
suggested the possibility of gonadal ridge transplantation or migration.
Lachman4, in 1991, hypothesized that supernumerary
ovaries may be secondary to implantation of dislodged ovarian tissue due
to previous pelvic surgery or pelvic inflammatory disease.
With this literature, terminology and classification relevant to our
finding, were suggested which are now commonly used. Those are as
follows:
1. Supernumerary ovaries: ovarian tissue entirely separated from the
normally placed ovary. There is no ligamentous or direct connection with
the ovaries, broad ligament, utero-ovarian ligament or
infundibulo-pelvic ligament and it arises from a separate
primordium1.
2. Accessory ovary: the excess ovarian tissue is situated near the
normally placed ovary, may be connected with, and seems to have
developed from it, possibly from tissue that was split from the
embryonic ovary during early development1.
3. Ectopic ovary: the term was used by Lachman in 1991 to replace both
terms, supernumerary and accessory ovary. It describes any ovarian
tissue additional to normal ovaries with further sub-classification as
post- surgical implant, post-inflammatory implant or true
(embryogenic)4.
The condition that we encountered, does not fit in the above-mentioned
terminologies thereby making it unique. The presence of the third
ovarian ligament excludes this condition to be termed as supernumerary
or duplication or accessory ovary. Hence, the rarity of this observation
or occurrence is worth reporting. We think the term “superfluous
ovary” is a good descriptor of this condition. Embryologically,
superfluous ovary may have developed due to the excessive mesenchymal
proliferation on one side, due to which thicker gubernaculum was formed
that subsequently duplicated. The excess of the mesenchymal cells could
be the reason for double gonadal ridges on one side thereby forming
superfluous ovary on one side only.
The superfluous ovary, in our case, was functional. This could be
explained with the fact that it responded to the ovarian stimulation.
Though the literature suggests that ectopic tissue should be removed due
to their possibility of malignant transformation, we could not justify
removing this unusual presence of a fully functioning superfluous ovary.
Subsequent follow-up will explain the fate of this unique occurrence.
References:
1. Wharton L.R. (1959) Two cases of supernumerary ovary and one of
accessory ovary with an analysis of previously reported cases. American
Journal of Obstetrics and Gynecology, 78, 1101–1109.
2. Pearl M, Plotz EJ. Supernumerary ovary. Report of a case. Obstet
Gynecol 1963;21:253‑6.
3. Printz JL, Choate JW, Townes PL, Harper RC. The embryology of
supernumerary ovaries. Obstet Gynecol 1973;41:246‑52.
4. Lachman M.F. and Berman M.M. (1991) The ectopic ovary, a case report
and review of the literature. Archives of Pathology Laboratory Medicine,
115, 233–235.