The term adnexa refers to the structures connected or appended to a main organ. In the context of the female body, it describes the appendages of the uterus. This area is located within the pelvis and plays a role in reproductive health and hormonal balance. The adnexa consists of paired structures situated next to the uterus, including the organs responsible for producing eggs and the conduits through which those eggs travel. This anatomical region is a frequent site for various medical conditions, ranging from common cysts to serious emergencies.
Defining the Structures of the Adnexa
The adnexa includes structures that facilitate female reproduction, primarily the ovaries and the fallopian tubes. The ovaries are small, almond-shaped organs that produce ova (eggs) and synthesize the reproductive hormones estrogen and progesterone. The fallopian tubes, also known as oviducts, are hollow, muscular channels extending outward from the top of the uterus. Their function is to capture the ovum released during ovulation and transport it toward the uterine cavity. Fertilization typically occurs within the ampullary region of the tube before the fertilized egg continues toward the uterus for implantation.
A network of supporting ligaments provides structural stability and a pathway for blood vessels and nerves. The broad ligament is a wide double-layer of peritoneum that anchors the uterus to the pelvic sidewalls. The ovarian ligament connects the ovary to the uterus, while the suspensory ligament (infundibulopelvic ligament) extends from the lateral pelvic wall and carries the ovarian artery and vein.
Precise Anatomical Location
The adnexa is situated within the true pelvis, the space bordered by the hip bones and lower spine. The complex is suspended within the pelvic cavity, maintaining a close spatial relationship with the bladder anteriorly and the rectum posteriorly. The ovaries generally rest in a shallow depression on the lateral pelvic wall known as the ovarian fossa. This location is bounded by major blood vessels, including the obliterated umbilical artery and the ureter.
The ligaments help stabilize the position of the ovaries and tubes, even though the uterus is relatively mobile. The fallopian tubes arch over the ovaries and extend back toward the uterus. This close proximity to the pelvic sidewall means that conditions affecting the adnexa often present with unilateral or bilateral pain in the lower abdomen or groin region.
Common Medical Conditions Involving the Adnexa
The adnexa is a frequent site for various pathologies, often presenting as an adnexal mass (a lump or growth near the uterus). The most common mass is an ovarian cyst, a fluid-filled sac that develops on the ovary. Many cysts are functional and resolve spontaneously, but pathological cysts, such as endometriomas or benign tumors, may grow larger and cause symptoms like pelvic pain or a feeling of pressure.
One serious condition is an ectopic pregnancy, where a fertilized egg implants and grows outside the uterus, most frequently within a fallopian tube. This is a medical emergency because the growing embryo can rupture the tube, leading to severe internal bleeding and acute pelvic pain. Another acute condition is adnexal torsion, where the ovary and sometimes the fallopian tube twist around their blood supply ligaments.
This twisting action cuts off the blood supply, causing sudden and severe lower abdominal pain often accompanied by nausea and vomiting. Chronic infections can also affect the adnexa, falling under Pelvic Inflammatory Disease (PID), typically caused by a bacterial infection ascending from the lower genital tract. Untreated PID can lead to a tubo-ovarian abscess, a pus-filled pocket that severely damages the tubes and ovaries, potentially causing long-term fertility issues and chronic pelvic discomfort.