An adnexal mass is a common finding in women’s health, referring to a growth or lump found near the uterus. The term describes the location of the growth, not what the mass is composed of or its potential nature. The overwhelming majority of adnexal masses are benign, meaning they are noncancerous, particularly in women of reproductive age. Many of these growths are temporary, resolving on their own within a few menstrual cycles without the need for intervention.
Defining the Adnexal Region
The adnexal region is the anatomical area located adjacent to the uterus on both the right and left sides of the pelvis. This area includes the uterine appendages: the ovaries, the fallopian tubes, and the supporting ligaments and connective tissues. While the most common origin of these masses is the ovary, they can also arise from the fallopian tubes or the broad ligament that supports the uterus. Adnexal masses are physically categorized as either cystic (fluid-filled sacs) or solid (denser tissue composition).
Common Etiologies and Classifications
Most adnexal masses are related to the normal function of the reproductive system, stemming from the monthly cycle of ovulation. These include functional cysts, such as follicular cysts that form when a follicle fails to release an egg, or corpus luteum cysts that result from the breakdown of the hormone-producing structure after ovulation. These functional cysts are almost always self-limiting and resolve within one to three months.
Other benign ovarian masses are also frequent, including endometriomas, often called “chocolate cysts,” which are blood-filled cysts that form on the ovary as a result of endometriosis. Mature cystic teratomas, commonly known as dermoid cysts, are another common benign tumor arising from germ cells, often containing various tissues like hair or fat.
Masses can also originate from non-ovarian structures within the adnexal region. A hydrosalpinx involves a fallopian tube that has become blocked and swollen with fluid. Uterine fibroids, which are benign muscle tumors of the uterus, can sometimes grow on a stalk (pedunculated) and extend into the adnexal area. In reproductive-aged women, an ectopic pregnancy must also be considered, as it requires immediate attention.
Masses are classified based on their potential for malignancy into three categories: benign, borderline, and malignant. A mass is considered to have a higher risk of being malignant if it appears in a postmenopausal woman or a prepubertal girl, or if it has complex features like solid components or irregular walls on imaging. Conversely, a simple, fluid-filled cyst in a reproductive-aged woman is highly likely to be benign.
Diagnostic Evaluation Procedures
Transvaginal ultrasound (TVS) is the primary initial imaging tool used for characterizing the mass. TVS provides a detailed view of the mass’s internal structure, allowing doctors to assess its size, whether it is cystic or solid, and if it contains internal walls called septations or papillary projections.
Features such as thin, smooth walls and purely fluid contents suggest a benign simple cyst, regardless of the patient’s age. Conversely, the presence of thick, irregular septations, solid components, or abnormal blood flow detected via Doppler ultrasound increases suspicion for malignancy. If the ultrasound is inconclusive or the mass is very large, additional imaging like Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) may be used to better define the mass’s origin and characteristics.
Laboratory tests often include measuring the serum level of Cancer Antigen 125 (CA-125), a protein that can be elevated in ovarian cancer. CA-125 is not a definitive marker for cancer, as it can be elevated by many common benign conditions, including endometriosis, uterine fibroids, and pelvic inflammatory disease. The predictive value of an elevated CA-125 level is higher in postmenopausal women than in premenopausal women.
Treatment and Monitoring Strategies
The management of an adnexal mass is determined by its characteristics on imaging, the patient’s menopausal status, and the presence of any symptoms. Observation, or watchful waiting, is the most common strategy for small, asymptomatic masses that appear benign on ultrasound. Simple cysts under 10 centimeters, even in postmenopausal women, can often be safely monitored.
Monitoring typically involves a repeat ultrasound, often scheduled for six to twelve weeks after the initial discovery, to confirm that the mass is shrinking or has resolved. Many functional cysts and other benign lesions will spontaneously disappear within this timeframe, avoiding unnecessary surgery. Lack of resolution for a mass that remains stable and benign-appearing is not necessarily cause for concern.
Surgical intervention is generally reserved for masses that are causing persistent pain, are very large, or show suspicious features on imaging like solid components or complex architecture. Surgery aims to remove the mass while preserving the ovary and fallopian tube, if possible, especially in premenopausal women. Minimally invasive techniques like laparoscopy are often used for benign masses, while open surgery may be necessary for very large or highly suspicious lesions. Masses with a high likelihood of malignancy often require referral to a gynecologic oncologist for specialized surgical management.