Location of the Adnexal Region
The adnexal region refers to the anatomical area containing the ovaries, fallopian tubes, and surrounding supporting structures adjacent to the uterus. 1
Anatomical Components
The adnexa (plural of adnexum, meaning "connected parts") encompasses:
- Ovaries - the primary reproductive organs located on either side of the uterus 2, 3
- Fallopian tubes - extending from the uterine cornua laterally toward the ovaries 1, 4
- Supporting ligaments and tissues - including the broad ligament, infundibulopelvic ligament, and surrounding connective tissue 2, 4
Spatial Relationship to Other Pelvic Structures
The adnexal structures are positioned:
- Lateral to the uterus on both the right and left sides 1
- Within the pelvis, though the ovaries can be displaced higher in late pregnancy 1
- Separate from but adjacent to other pelvic organs, which is why imaging must distinguish adnexal masses from uterine or other pelvic pathology 1
Clinical Imaging Context
When radiologists describe an "adnexal mass," they are referring to a mass arising from or located in this region that is separate from the ovary when the ovary can be visualized, or simply in the adnexal region when the ovary cannot be separately identified 1. The American College of Radiology emphasizes that determining whether a mass originates from the uterus versus the adnexa is a critical diagnostic distinction, often aided by identifying "bridging vessels" connecting a mass to the uterus 1.
Important Anatomical Considerations
- The right adnexa is most commonly involved in torsion cases, which can mimic appendicitis due to its anatomical proximity 4
- In pregnancy, the ovaries may be displaced higher in the pelvis, making transabdominal ultrasound more appropriate than transvaginal imaging for adnexal evaluation 1
- The adnexal region receives dual blood supply from both the ovarian artery and uterine artery, which is why color Doppler may still show flow even in cases of adnexal torsion 4