An adnexal mass is any lump, growth, or swelling that develops in the structures next to the uterus, mainly the ovaries and fallopian tubes. These masses range from completely harmless fluid-filled cysts that resolve on their own to, much less commonly, cancerous tumors that need urgent treatment. Most adnexal masses found in premenopausal women are benign, and even among postmenopausal women the majority turn out to be noncancerous. The challenge for both patients and clinicians is sorting out which masses can be safely watched and which require intervention, and the tools for doing so have improved considerably in the past decade.
What Counts as an Adnexal Mass
The “adnexa” refers to the ovaries, fallopian tubes, and the supporting ligaments and blood vessels that connect them to the uterus. An adnexal mass can be anything from a normal physiological enlargement, like a follicular cyst that forms during ovulation, to a neoplasm that grows independently of the body’s normal cycle.1PubMed Central. Adnexal mass: diagnosis and management Sometimes a mass starts in a nearby pelvic structure and secondarily involves the adnexa, which can make the origin harder to pin down on imaging.
The possible causes break down broadly into gynecological and non-gynecological. The gynecological list includes functional cysts, endometriomas, dermoid cysts (teratomas), tubo-ovarian abscesses, ectopic pregnancies, and various ovarian tumors. Non-gynecological causes can include problems originating in the bowel, bladder, or other pelvic tissues that happen to sit near the adnexa. For most people who hear the term “adnexal mass” for the first time, it comes up after a routine ultrasound or a visit to the emergency room for pelvic pain, and the underlying cause turns out to be something benign.
The Most Common Benign Types
Functional ovarian cysts are by far the most frequent finding. These include follicular cysts, which form when a developing egg follicle does not release and instead keeps growing, and corpus luteum cysts, which develop after ovulation when the empty follicle fills with fluid or blood. Both types typically resolve within one to three menstrual cycles without treatment. Hemorrhagic cysts are a variation where bleeding occurs into a functional cyst. Their contents include blood products, plasma proteins, and other substances that can look alarming on ultrasound but are usually benign.2PubMed Central. Ultrasonography in the Differentiation of Endometriomas from Hemorrhagic Ovarian Cysts: The Role of Texture Analysis
Endometriomas, sometimes called “chocolate cysts,” form when tissue similar to the uterine lining grows on or within the ovary. They get their nickname from the dark, thick fluid inside, which consists of old blood, degenerate red blood cells, and hemosiderin-laden immune cells. Endometriomas can cause pain, especially around menstruation, and are strongly associated with endometriosis elsewhere in the pelvis. They can look similar to hemorrhagic cysts on a standard ultrasound, which is why differentiating them sometimes requires advanced imaging techniques or close follow-up.
Dermoid cysts, formally called mature cystic teratomas, are among the more surprising things you can find in an ovary. They account for roughly 69% of ovarian germ cell tumors in young women and contain tissues derived from all three embryonic germ layers.3PubMed Central. Mature Cystic Teratoma: An Integrated Review That means a single cyst can contain skin, hair, teeth, fat, and even small pieces of bone or cartilage. As odd as they sound, dermoids are overwhelmingly benign. They grow slowly and are usually discovered incidentally, though larger ones may need to be removed because they raise the risk of the ovary twisting on its blood supply.
Masses That Do Not Start in the Ovary
Not every adnexal mass originates from the ovary. Paratubal cysts develop alongside the fallopian tube, usually from embryonic remnants, and are almost always benign. Hydrosalpinx, a fluid-filled, dilated fallopian tube often resulting from prior infection, can also present as an adnexal mass. Proper history-taking and imaging help clinicians distinguish tubal causes from ovarian ones. In younger or never sexually active patients, transabdominal ultrasound or MRI may be more appropriate than transvaginal scanning to assess these abnormalities.4PubMed. Successful term delivery following second-trimester excision of a massive hydrosalpinx presenting as an adnexal mass in pregnancy: management and considerations
Tubo-ovarian abscesses represent an inflammatory mass rather than a neoplastic one. They form when infection, usually related to pelvic inflammatory disease, creates a pocket of pus involving the tube and ovary. Risk factors include intrauterine devices, uterine procedures, multiple sexual partners, diabetes, and conditions that weaken the immune system.5PubMed. High risk and low prevalence diseases: Tubo-ovarian abscess These masses typically cause fever, significant pelvic pain, and elevated white blood cell counts, and they require antibiotics and sometimes drainage rather than the surgical approaches used for tumors.
When an Adnexal Mass Is Cancerous
Ovarian cancer is what most people fear when they hear the term adnexal mass, and while the fear is understandable, the actual probability varies greatly depending on age, menopausal status, and what the mass looks like on imaging. In one study, about 8% of adnexal masses in premenopausal women were malignant, compared with roughly 38% in postmenopausal women.6Asian Pacific Journal of Cancer Prevention. Predictive Value of Malignancy Risk Indices for Ovarian Masses in Premenopausal and Postmenopausal Women Even in the postmenopausal group, the majority of masses turned out to be benign.
Ovarian carcinomas are not one disease. The four most common subtypes are serous, endometrioid, clear cell, and mucinous, and they behave very differently from each other. High-grade serous carcinoma is the most common and aggressive subtype and is almost always associated with mutations in the TP53 gene. Compelling evidence now suggests that many of these tumors actually originate from the lining of the fallopian tube rather than from the ovary itself.7Pathology. Morphological subtypes of ovarian carcinoma: a review with emphasis on new developments and pathogenesis This finding has reshaped thinking about prevention, as we will see later. By contrast, endometrioid and clear cell carcinomas tend to present at earlier stages and in many cases arise from endometriosis, while mucinous carcinomas are uncommon, usually one-sided, and develop in a stepwise fashion from a pre-existing benign cyst.
Beyond epithelial cancers, the ovary can produce rarer tumor types. Sex cord-stromal tumors are often found in adolescents and young women and can cause hormonal effects because they may secrete estrogen or testosterone, leading to symptoms like abnormal bleeding or virilization before the mass itself is detected.8PubMed Central. Ovarian Sex Cord-Stromal Tumors And occasionally, cancer from another organ spreads to the ovary. Krukenberg tumors are the most common type of ovarian metastasis and are defined by a specific cell pattern called signet ring cells. The primary cancer is usually in the stomach or colon.9AJR Am J Roentgenol. Krukenberg Tumors: Update on Imaging and Clinical Features
How Doctors Evaluate an Adnexal Mass
Transvaginal ultrasound is the first-line tool. It is widely available, inexpensive, and does not expose the patient to radiation. Over the past two decades, structured approaches to interpreting ovarian ultrasound findings have dramatically improved accuracy. Two systems dominate current practice. The IOTA Simple Rules, developed in Europe, use a set of ultrasound features to classify masses as likely benign or likely malignant. In validated studies, these rules have achieved sensitivity and specificity above 92% in cases where they can be applied.10PubMed Central. IOTA Simple Ultrasound Rules for Triage of Adnexal Mass: Experience from South India
The O-RADS system, endorsed by the American College of Radiology, assigns masses a score from 0 to 5 based on their risk of malignancy and pairs each score with a management recommendation. It was designed to reduce the kind of vague, ambiguous ultrasound reports that used to leave clinicians unsure of what to do next.11PubMed. O-RADS US Risk Stratification and Management System: A Consensus Guideline from the ACR Ovarian-Adnexal Reporting and Data System Committee Recent validation work has shown that both O-RADS and the modified IOTA rules achieve high sensitivity (around 96%) and excellent negative predictive values (around 99%) for detecting malignancy, meaning that when these systems say a mass is likely benign, they are almost always right. Where the systems differ is in specificity: the modified IOTA rules are somewhat better at avoiding false alarms, which supports the recommendation that masses scoring in the intermediate O-RADS categories be evaluated by an expert sonologist.12Clinical Radiology. Validation of O-RADS 2022 risk estimates in surgically treated ovarian/adnexal masses comparing accuracy of O-RADS with modified ultrasound simple rules
MRI comes into play when ultrasound leaves the picture unclear. It is especially useful for large masses, for masses with mixed solid and cystic components, and for cases where the tissue characteristics need further clarification. MRI increases the specificity of imaging evaluation and can often tell clinicians exactly what they are dealing with, allowing women with benign-looking masses to avoid unnecessary surgery.13PubMed Central. Value of MRI in Characterizing Adnexal Masses For the small proportion of cases where the mass is malignant, MRI provides a more timely diagnosis than simply repeating ultrasound scans over time.14PubMed. MR imaging of the sonographically indeterminate adnexal mass
Blood Markers and Their Limits
CA-125 is the blood test most commonly associated with ovarian cancer screening, but its usefulness has clear boundaries. CA-125 can be elevated in many benign conditions, including endometriosis, fibroids, pelvic inflammatory disease, and even menstruation. A second marker called HE4 has been studied extensively as a possible improvement. The Risk of Ovarian Malignancy Algorithm, known as ROMA, combines CA-125 and HE4 with menopausal status to produce a risk score. In postmenopausal women, ROMA has shown sensitivity around 91% and specificity around 66% at commonly used cutoffs.15PubMed Central. HE4 and CA125 as a diagnostic test in ovarian cancer: prospective validation of the Risk of Ovarian Malignancy Algorithm In premenopausal women, both the sensitivity and specificity drop. And in prospective validation, adding HE4 to CA-125 did not consistently improve detection of malignancy over CA-125 alone. Other studies have reported slightly different performance numbers, with sensitivity for premenopausal women reaching about 77% and specificity for postmenopausal women reaching about 75%.16PubMed Central. A novel multiple marker bioassay utilizing HE4 and CA125 for the prediction of ovarian cancer in patients with a pelvic mass The bottom line is that blood markers are helpful in context but are never definitive on their own. They work best as one input alongside imaging and clinical assessment.
Acute Complications That Bring People to the ER
Two emergencies can arise from adnexal masses, and both tend to announce themselves with sudden, severe pelvic pain.
Ovarian torsion happens when the ovary (and sometimes the fallopian tube along with it) twists on the ligament that carries its blood supply. This cuts off blood flow, leading to swelling, internal bleeding, and eventually tissue death if not corrected quickly. Torsion occurs in roughly 2% to 15% of patients who go on to have surgical treatment for adnexal masses, and having a mass is the primary risk factor.17PubMed Central. A review of ovary torsion The pain often comes in waves as the ovary partially twists and untwists. Early surgery is critical to preserve ovarian function, especially in children and younger women.18PubMed. What every radiologist should know about adnexal torsion On CT imaging, free fluid in the pelvis alongside bleeding within the ovary suggests that the tissue has already begun to die.19PubMed. Deciphering ovarian torsion: insights from CT imaging analysis
Cyst rupture is the other common emergency. When a hemorrhagic cyst or a corpus luteum cyst breaks open, it can spill blood into the abdominal cavity. In most cases, the bleeding is self-limited and management involves monitoring, pain relief, and fluids. But significant blood loss can occur, leading to drops in blood pressure and the potential for shock.20PubMed Central. A Case of Hemorrhagic Ovarian Cyst Rupture Necessitating Surgical Intervention When bleeding does not stop on its own, laparoscopic surgery to remove the cyst wall and evacuate the collected blood is typically the next step.21PubMed Central. Acute hemoperitoneum due to a ruptured hemorrhagic ovarian cyst in a 19-year-old female Delayed recognition of significant intra-abdominal bleeding after a cyst rupture can threaten fertility and, in extreme cases, be life-threatening.22PubMed Central. Hemoperitoneum from corpus luteal cyst rupture: a practical approach in emergency room
Adnexal Masses During Pregnancy
With the widespread use of ultrasound during prenatal care, adnexal masses are being detected in pregnant women more often than in earlier decades. Most of these are simple cysts that disappear on their own as the pregnancy progresses.23Gynecological Surgery. Adnexal masses during pregnancy: management for a better approach Some persist into the second and third trimesters, and those may need monitoring or, occasionally, surgical removal if they grow large enough to press on neighboring structures or if there is concern about torsion.
The vast majority of adnexal masses found during pregnancy are benign. However, ovarian cancer remains the second most common gynecological malignancy during pregnancy after cervical cancer, so persistent or suspicious-looking masses cannot simply be dismissed. Management decisions weigh the tumor’s size, its location, what trimester the mass was found in, and the overall risk to both the pregnant person and the fetus.24PubMed Central. Adnexal masses in pregnancy: An updated review The differential diagnosis is broad and can include unusual entities like hydrosalpinx, which is sometimes mistaken for a simple ovarian cyst during pregnancy.
When Surgery Is Needed and How Fertility Factors In
For masses that do require removal, laparoscopic surgery has become the preferred approach for most benign adnexal masses in women of reproductive age. Compared with open surgery, laparoscopy causes less damage to surrounding reproductive tissue, results in a faster recovery, and is associated with better fertility outcomes.25PubMed Central. Surgical Technique and Fertility Outcomes: A Comprehensive Review of Open and Laparoscopic Cystectomy in Women of Reproductive Age Surgeons generally aim to remove the cyst or mass while preserving as much healthy ovarian tissue as possible, because the remaining ovary continues to produce hormones and eggs.
The tension between thorough removal and preserving the ovary is especially sharp in endometriosis-related masses. A prospective study comparing ovarian preservation with complete removal of the affected ovary found that the preservation group had a significantly higher spontaneous pregnancy rate (about 44% versus 29%) and achieved pregnancy faster (a median of roughly eight months versus eleven months). The trade-off was a higher rate of endometriosis recurrence in the preservation group (about 22% versus 11%).26PubMed Central. Comparison of ovarian preservation versus oophorectomy on fertility outcomes in patients with endometriosis post-laparoscopic surgery: A prospective study For someone who wants to become pregnant, keeping the ovary is generally the better bet despite the higher chance the endometriosis comes back.
Watching and Waiting Safely
Not every adnexal mass needs to come out. For asymptomatic masses that look benign on ultrasound, a growing body of evidence supports conservative management with periodic imaging follow-up. A multicenter Portuguese study that prospectively tracked adnexal masses classified as benign by a validated prediction model found that expectant management was safe for both premenopausal and postmenopausal women, as long as the mass remained stable and the patient stayed free of symptoms.27PubMed Central. Conservative Management of Asymptomatic Adnexal Masses Classified as Benign by the IOTA ADNEX Model: A Prospective Multicenter Portuguese Study Similar conclusions have been reached in earlier prospective work in premenopausal women.28PubMed. Expectant management of adnexal masses in selected premenopausal women: a prospective observational study
There is an important nuance here. While short-term surveillance makes sense, indefinite monitoring of a mass that has already been shown to be stable may do more harm than good. Ongoing ultrasound scans carry their own risks: they can turn up unrelated incidental findings that prompt unnecessary biopsies, they increase the chance of eventually having surgery that was never needed, and they can cause sustained anxiety in patients who live in a perpetual state of uncertainty about whether something inside them might turn cancerous.29PubMed. Potential harms outweigh benefits of indefinite monitoring of stable adnexal masses Guidelines from multiple organizations have increasingly converged on the idea that once a mass has been followed long enough to establish stability and low risk, stopping surveillance is reasonable. The goal is to limit unnecessary imaging follow-up, saving the patient time, money, and worry.30PubMed. Benign-appearing Incidental Adnexal Cysts at US, CT, and MRI: Putting the ACR, O-RADS, and SRU Guidelines All Together
Opportunistic Salpingectomy and Ovarian Cancer Prevention
The discovery that many high-grade serous ovarian cancers begin in the fallopian tube has opened the door to a practical prevention strategy. Opportunistic salpingectomy, the removal of the fallopian tubes during an already planned abdominal or pelvic surgery (such as a hysterectomy or cesarean section), is now offered to women who have completed childbearing. A systematic review encompassing over 150 publications found that salpingectomy has been associated with an ovarian cancer risk reduction of approximately 80%.31PubMed Central. Salpingectomy for the Primary Prevention of Ovarian Cancer: A Systematic Review
A large study following nearly 26,000 individuals who underwent opportunistic salpingectomy found no serous ovarian cancers in the group and fewer epithelial ovarian cancers than expected based on population averages.32JAMA Network Open. Outcomes From Opportunistic Salpingectomy for Ovarian Cancer Prevention This is still a relatively young area of research, and longer follow-up will be needed before we know the full magnitude of the benefit. But for women already undergoing pelvic surgery who have no plans for future pregnancy, the conversation about removing the tubes is becoming standard practice in many institutions. It is worth noting that this strategy applies to women at average risk. Those with known genetic mutations like BRCA1 or BRCA2 are managed through separate, more intensive protocols that may include removal of both the ovaries and tubes at a recommended age.
Incidental Adnexal Cysts and What to Do About Them
Many adnexal masses today are discovered by accident, during an ultrasound, CT, or MRI done for an entirely different reason. A person gets scanned for kidney stones or back pain and learns they also have a cyst on their ovary. This scenario has become common enough that multiple professional organizations have published guidelines specifically addressing it. The consistent message across guidelines from the American College of Radiology, the Society of Radiologists in Ultrasound, and the O-RADS framework is the same: simple-appearing cysts below certain size thresholds in premenopausal women generally do not need any follow-up at all, and even in postmenopausal women, small simple cysts are common and almost never turn out to be anything dangerous.33PubMed. Benign-appearing Incidental Adnexal Cysts at US, CT, and MRI: Putting the ACR, O-RADS, and SRU Guidelines All Together
The psychological dimension is real and under-discussed. Being told you have “a mass” anywhere in your body is inherently alarming, and the clinical terminology does not help. Many patients do not know that “adnexal mass” is often doctor-speak for a fluid-filled cyst smaller than a golf ball that will be gone by the time of their next period. When follow-up is recommended, understanding the reason behind it and the expected timeline can go a long way toward managing the anxiety that comes with the territory. If your provider tells you a cyst looks benign and suggests a single follow-up ultrasound in six to twelve weeks, that is a standard, cautious approach, not a sign that something is likely wrong.