The term adnexa refers to accessory structures attached to a main organ. In human anatomy, it is primarily used in gynecology to describe the collective organs and tissues located immediately adjacent to the uterus in the female pelvis. This grouping is also frequently called the adnexa uteri or the uterine appendages. Positioned on either side of the uterus, the adnexa are structurally and functionally linked to it, making them integral to the female reproductive system.
What Structures Make Up the Adnexa?
The adnexa is composed of the paired ovaries, the fallopian tubes, and the supporting ligaments that anchor these structures within the pelvic cavity. These components are enveloped by folds of the peritoneum and connective tissues, providing structural stability and pathways for blood vessels and nerves. The ovaries are almond-shaped gonads situated on the lateral sides of the uterus. They are suspended by the ovarian ligament, which connects them to the uterus, and the suspensory ligament, which attaches them to the pelvic sidewall.
Extending from the upper corners of the uterus toward the ovaries are the fallopian tubes, also known as uterine tubes. These bilateral muscular conduits are about 10 to 12 centimeters long and are divided into distinct segments. These segments include the infundibulum, which features delicate, fringe-like projections called fimbriae.
The tubes are encased by the broad ligament, a large double layer of peritoneum that drapes over the uterus. This ligament provides suspension for the fallopian tubes and ovaries, which are specifically covered by the mesosalpinx and mesovarium. Other supporting tissues, such as the round ligaments, also contribute to the adnexa, ensuring the correct positioning of the uterine appendages.
Essential Functions of the Adnexa
The structures within the adnexa carry out the physiological processes necessary for reproduction and hormonal regulation. The ovaries function as both endocrine glands and producers of female gametes. They secrete the sex hormones estrogen and progesterone, which regulate the menstrual cycle and prepare the uterine lining for potential pregnancy.
The ovaries are also the site of oogenesis, where immature egg cells (ova) are produced and matured. During ovulation, a mature ovum is released from the ovary into the pelvic cavity, where it is captured by the fimbriae of the fallopian tube. The fallopian tubes then transport the ovum toward the uterus through muscular contractions and the sweeping motion of internal cilia.
Fertilization typically occurs in the ampullary region of the fallopian tube. Following successful fertilization, the resulting zygote continues its journey through the tube to the uterus for implantation. The adnexa ensures the maturation, release, transport, and potential fertilization of the egg, while maintaining the necessary hormonal environment.
Why the Adnexa Is Medically Significant
The adnexa is a frequent focus in clinical medicine because it is a common site for various pathologies, which are often grouped under the general term “adnexal mass.” An adnexal mass describes any abnormal growth near the uterus, most commonly originating from the ovaries, fallopian tubes, or surrounding connective tissue. The majority of these masses are benign, with common examples being ovarian cysts, which are fluid-filled sacs that often form as part of the normal menstrual cycle, such as functional cysts.
However, adnexal masses can also represent more serious conditions, including pathological cysts, benign tumors like cystadenomas, or, less commonly, malignant ovarian or fallopian tube cancers. Other urgent medical issues involve the adnexa, such as ectopic pregnancy, where a fertilized egg implants outside the uterus, most often in the fallopian tube, which can be life-threatening if the tube ruptures. Ovarian torsion is another acute concern that occurs when the ovary and sometimes the fallopian tube twist around the ligaments that support them, cutting off the blood supply.
Due to the range of potential diagnoses, the evaluation of the adnexa is a standard part of gynecological and emergency medicine. Diagnostic tools are frequently employed, with pelvic ultrasound being the most common initial method due to its accuracy, safety, and widespread availability for characterizing adnexal masses. Further investigation may involve computed tomography (CT) scans or magnetic resonance imaging (MRI) to better characterize masses that are indeterminate on ultrasound, guiding management from simple observation to surgical intervention.