How to Read Your Pelvic Ultrasound Report

A pelvic ultrasound report is a radiologist’s written interpretation of the images taken during your scan, and most of the terms in it are less alarming than they sound. The report typically follows a predictable structure: the type of scan performed, the size and orientation of your uterus, the thickness of your endometrial lining, any masses or abnormalities in the uterus or ovaries, and a final impression summarizing the key findings. Once you know what each section is describing and which terms are normal variants versus actual concerns, the document becomes much easier to parse.

Transabdominal Versus Transvaginal Scans

Near the top of your report, you’ll see which type of ultrasound was performed. Transabdominal scans use a probe on the outside of your lower belly, usually with a full bladder to create an acoustic window. Transvaginal scans use a narrow internal probe placed in the vagina, which gets much closer to the pelvic organs. Many reports describe both being done in the same session, and that’s routine. The transabdominal portion gives the radiologist a wide-angle survey of the pelvis, while the transvaginal probe delivers sharper close-up detail of the uterus and ovaries. Early research showed transvaginal image quality was better in roughly 80–87% of scans compared with transabdominal alone, though the wider abdominal view remains useful for orientation and for spotting large masses that extend beyond the transvaginal probe’s range.¹

This distinction matters when you see a finding described as “suboptimally visualized” or “limited exam.” A transabdominal-only scan may miss smaller fibroids or early ovarian cysts that a transvaginal probe would catch. For classifying uterine fibroids specifically, transvaginal ultrasound has been shown to reach about 96% accuracy compared with roughly 71% for the transabdominal approach.² If your report notes a limitation due to body habitus (the radiology term for body size affecting image quality), that’s worth knowing: ultrasound image quality decreases as BMI rises, and this effect becomes especially pronounced above a BMI of 35.³ In those cases, your doctor may recommend follow-up with MRI rather than a repeat ultrasound.

What Uterine Position and Orientation Mean

One of the first descriptors in most reports is the position of your uterus, and this is the term that sends many people straight to a search engine. You’ll see words like “anteverted,” “retroverted,” “anteflexed,” or “retroflexed,” sometimes in combination. These describe two separate things: the version (which direction the uterus tilts relative to the vagina) and the flexion (which direction the body of the uterus bends relative to its own cervix).

An anteverted uterus tilts forward toward the bladder, and this is the most common position, seen in about 65% of women in one three-dimensional ultrasound study.⁴ A retroverted uterus tilts backward toward the spine, which occurs in roughly a quarter of women. Neither position is abnormal. The “anteflexed” or “retroflexed” addition describes whether the upper body of the uterus bends forward or backward at its own midpoint. Some reports document more unusual combinations: a uterus can be anteverted but retroflexed (tilted forward overall, but with the top portion bending backward), and research has linked this particular configuration to prior cesarean delivery.⁵ If your report says “axial,” it simply means the uterus is sitting in a neutral position, aligned with the vaginal canal.

The critical thing to understand: uterine position is a description, not a diagnosis. A retroverted uterus does not cause infertility and is not a medical problem on its own. If your report lists a position and nothing else of note, that line is just the radiologist documenting the anatomy they see.

Uterine Size and Endometrial Thickness

Your report will list the uterus in three dimensions, typically in centimeters (length × width × depth). Normal uterine size varies significantly depending on age, whether you’ve been pregnant, and your hormonal status, so there isn’t one universal “normal” number. Radiologists are more interested in whether the size is changing over time or whether it’s disproportionate in a way that suggests a mass.

The endometrial thickness (often abbreviated ET) is the measurement of the lining inside the uterus. This number fluctuates considerably during a menstrual cycle. In premenopausal women, the lining can range from a few millimeters right after a period to over 14 mm just before ovulation or in the luteal phase. For this reason, a report that says “endometrial thickness 12 mm” in a 30-year-old woman may be completely unremarkable depending on the cycle day.

After menopause, the endometrial lining thins out and stays thin. Studies of postmenopausal women who are not on hormone therapy show an average endometrial thickness of about 2 mm, with the lining thinning slightly in the first five years after menopause and then stabilizing.⁶ A postmenopausal endometrial thickness above 4–5 mm, especially if there’s any bleeding, usually prompts further investigation like a biopsy. If your report flags a thickened endometrium and you’re postmenopausal, that’s worth a follow-up conversation with your doctor, though it’s not automatically a sign of cancer. Polyps, hormone therapy, and even fluid trapped in the uterine cavity can all cause the measurement to read higher.

Fibroids on Your Report

Fibroids (also called leiomyomas or myomas) are among the most common findings on a pelvic ultrasound, appearing in a large proportion of women by their forties. If your report mentions fibroids, it should describe their number, size, and location. The location matters because it determines symptoms and treatment options. The International Federation of Gynecology and Obstetrics (FIGO) developed a classification system that radiologists are increasingly expected to use, numbering fibroids from Type 0 through Type 8 based on where they sit relative to the uterine cavity, the muscle wall, and the outer surface.⁷ Not every report will use this numbering system, but the trend is toward standardized descriptions so that surgeons can plan procedures more effectively.⁸

In plainer terms, a submucosal fibroid bulges into the uterine cavity (the inside where the lining grows), an intramural fibroid sits within the muscle wall, and a subserosal fibroid protrudes outward from the uterine surface. A pedunculated fibroid hangs on a stalk, either inside or outside the uterus. Submucosal fibroids tend to cause the most trouble with heavy bleeding and fertility, even when small. Subserosal fibroids can grow quite large before causing symptoms because they expand outward rather than compressing the cavity.

You may also notice a fibroid described as “heterogeneous” or with “areas of degeneration.” This sounds worrying but usually means the fibroid has outgrown its blood supply in spots, causing parts of it to break down. This is common in larger fibroids and is a benign process, though it can cause pain.

Polyps Versus Fibroids

Reports sometimes mention endometrial polyps, which are growths of the uterine lining itself rather than the muscle wall. Distinguishing a polyp from a submucosal fibroid on ultrasound can be tricky because both appear as masses inside the uterine cavity. There are clues the radiologist uses: polyps tend to look uniformly bright (hyperechoic) on ultrasound, while fibroids tend to be larger and show multiple feeding blood vessels on Doppler.⁹ Power Doppler blood flow mapping helps distinguish between the two, since their vascular patterns differ.¹⁰ If the report can’t definitively distinguish the two, it may recommend a saline infusion sonogram (where sterile fluid is injected into the uterus to separate the walls and give a clearer view) or a hysteroscopy.

Adenomyosis and What “Heterogeneous Myometrium” Means

If your report describes a “heterogeneous myometrium” or “myometrial cysts,” you may be looking at adenomyosis. This is a condition where tissue similar to the uterine lining grows into the muscle wall of the uterus. Unlike fibroids, which are distinct round masses, adenomyosis tends to infiltrate the muscle diffusely, making the uterine wall look uneven or mottled on ultrasound.

Radiologists look for a cluster of ultrasound signs to diagnose adenomyosis. These include tiny cysts within the muscle wall, bright spots (hyperechoic islands), striations radiating from the lining into the muscle, asymmetric thickening of one uterine wall compared to the other, and a blurred border between the lining and the muscle.¹¹ A “question mark sign,” where the uterus curls into a question mark shape due to thickened and stiff posterior walls, is another recognized marker.¹² No single sign is definitive on its own. A large multicenter study found that combining the most accurate individual signs, specifically subendometrial microcysts, myometrial cysts, and a heterogeneous myometrium, pushed specificity to about 86%, which is far better than relying on any one feature alone.¹²

If your report mentions several of these signs together, the radiologist is building a case for adenomyosis rather than making a definitive pathologic diagnosis. Definitive confirmation only comes from examining tissue, but ultrasound gets close enough that many gynecologists will treat based on imaging findings and symptoms alone.

Ovarian Cysts and What the Descriptions Mean

Ovarian findings are often the part of the report that causes the most anxiety, but the vast majority of ovarian cysts are physiologic, meaning they’re a normal part of your menstrual cycle and will resolve on their own. A “simple cyst” is the most reassuring descriptor: it means a thin-walled, fluid-filled sac with no internal structures, no solid parts, and no blood flow within it. In premenopausal women, a simple cyst under 3 cm is almost always a normal follicle or corpus luteum and doesn’t even need follow-up.

The language gets more complex when the radiologist sees features beyond a plain fluid sac. A “complex cyst” can mean many things. Your report might describe internal echoes (debris floating in the fluid), septations (thin walls dividing the cyst into chambers), solid components, or papillary projections (finger-like growths from the inner wall). Each of these features shifts the likelihood of what the cyst is. In peri- and postmenopausal women, complex morphology carries a statistically significant risk of malignancy compared to simple cysts, which show no such association.¹³ But complex does not equal malignant. Hemorrhagic cysts (cysts that have bled into themselves), endometriomas, and dermoid cysts all look “complex” on ultrasound and are benign.

Endometriomas, sometimes called “chocolate cysts,” show a characteristic “ground glass” appearance, which means the fluid inside looks hazy rather than clear. About half present as a single-chambered cyst with this ground-glass echogenicity.¹⁴ Dermoid cysts (mature cystic teratomas) are the most common ovarian tumor and contain a chaotic mix of tissue types, including fat, hair, and sometimes calcifications that cast acoustic shadows. Their ultrasound appearance varies widely depending on the mix of tissue inside.

The O-RADS Score

If your report assigns an ovarian mass a number from 0 to 5, it’s using the O-RADS system, which stands for Ovarian-Adnexal Reporting and Data System. Developed by the American College of Radiology, O-RADS gives radiologists a standardized way to communicate how suspicious an ovarian finding looks and what the next step should be.¹⁵ Think of it as a risk ladder:

• O-RADS 0: The evaluation was incomplete or the lesion couldn’t be adequately assessed.
• O-RADS 1: Normal finding, no adnexal lesion seen.
• O-RADS 2: Almost certainly benign, with less than 1% risk of malignancy. Most simple cysts fall here.
• O-RADS 3: Low risk, roughly 1–10% chance of malignancy. Typical for some complex cysts that need short-term follow-up.
• O-RADS 4: Intermediate risk. Features suggest the mass needs further workup, often MRI or surgical evaluation.
• O-RADS 5: High risk of malignancy. Referral to a gynecologic oncologist is recommended.

O-RADS is applied whenever a non-physiologic lesion is found on ultrasound, and it’s becoming the standard reporting framework in the United States.¹⁶ In comparative studies, the O-RADS system has outperformed older classification approaches in distinguishing benign from malignant masses, particularly when used by less experienced readers.¹⁷ If your report uses the older IOTA simple rules instead of O-RADS, that system also performs well, with sensitivity for detecting malignancy around 92% and specificity around 85% in applicable cases.¹⁸

Polycystic Ovary Morphology

A report that describes “polycystic-appearing ovaries” or notes a high follicle count is describing what the ovaries look like, which is not the same as diagnosing polycystic ovary syndrome (PCOS). PCOS is a clinical diagnosis that also requires hormonal signs or irregular periods. Many women with polycystic ovary morphology on ultrasound have perfectly regular cycles and no hormonal issues.

The thresholds for what counts as a polycystic appearance on ultrasound are not one-size-fits-all. Research shows that both the follicle count and ovarian volume that suggest PCOS decrease with age. For women under 25, the cutoffs are roughly 12 mL of ovarian volume and 13 or more follicles per ovary, while for women aged 35–39, the thresholds drop to about 8 mL and 10 follicles.¹⁹ If your report lists a high follicle count and you’re in your early twenties, it may be a completely normal finding for your age. This is one area where the report alone can mislead if the clinical context isn’t considered.

Doppler Findings and Blood Flow

Many reports include a section on blood flow, assessed using Doppler ultrasound. The probe sends sound waves that bounce off moving blood cells, allowing the radiologist to see how much blood is flowing through a mass and how resistant that flow is. You may see terms like “resistance index” (RI) or “pulsatility index” (PI). The general principle: benign masses tend to have higher resistance blood flow (stiffer vessels, more orderly), while malignant masses tend to recruit new, leaky blood vessels with lower resistance.²⁰

In practice, Doppler doesn’t work in isolation. A low-resistance flow pattern in a simple-looking cyst is managed very differently from the same flow pattern in a solid mass with papillary projections. The Doppler information supplements the shape-and-structure assessment rather than overriding it. If your report mentions “increased vascularity” or “low-resistance arterial flow” in a mass, that finding contributes to the overall risk score (like O-RADS) but doesn’t independently determine whether something is cancerous.

Free Fluid in the Pelvis

A small amount of free fluid in the pelvis (sometimes written as “trace free fluid in the cul-de-sac”) is extremely common and usually physiologic. After ovulation, fluid from the ruptured follicle pools in the lowest part of the pelvis, and this is a normal finding, especially in the middle of your cycle. It can also appear during menstruation.

Free fluid becomes more clinically relevant when it’s present in large amounts, when it appears in a postmenopausal woman who isn’t ovulating, or when it’s seen alongside a suspicious ovarian mass. In screening populations, free fluid identified on transvaginal ultrasound has been associated with ovarian malignancy more than with benign tumors, though fluid alone cannot discriminate malignancy from normal physiology.²¹ If your report notes free fluid and nothing else abnormal, it’s almost certainly a normal finding. If it’s mentioned alongside a complex ovarian mass, it adds a piece to the clinical picture your doctor is assembling.

Tubal Findings and Hydrosalpinx

Normal fallopian tubes are too thin and mobile to be seen reliably on a standard pelvic ultrasound. When a tube does appear on a report, it’s usually because something has made it larger than normal. A hydrosalpinx, a tube distended with fluid, is the most common tubal finding. On ultrasound it appears as an elongated, sausage-shaped fluid collection near the ovary, sometimes with incomplete internal dividers that distinguish it from an ovarian cyst. Transvaginal ultrasound detects hydrosalpinx with high sensitivity and specificity when the classic elongated shape and incomplete septations are present.²² If your report mentions a structure described as a dilated tube or tubal-shaped adnexal mass, your doctor will likely want to discuss this further, especially if you’re trying to conceive, since a hydrosalpinx can affect fertility and IVF outcomes.

When Ultrasound Reaches Its Limits

Pelvic ultrasound is the first-line imaging tool for good reason: it’s accessible, affordable, uses no radiation, and performs well for the most common gynecologic conditions. But it has blind spots. Deep infiltrating endometriosis, particularly lesions in the front of the pelvis, the bowel wall, or the ureters, can be missed on a standard transvaginal scan. Research comparing ultrasound and MRI for deep endometriosis has found that transvaginal ultrasound is strong for disease behind the uterus (detecting more rectosigmoid lesions than MRI in one study, roughly 85% versus 65%), but MRI provides better coverage for disease in the anterior pelvis and across multiple compartments.²³ A systematic review concluded the two modalities are genuinely complementary for this condition rather than one being universally superior.²⁴

If your report says “further evaluation with MRI recommended,” that doesn’t mean the ultrasound found something frightening. It usually means the ultrasound found something ambiguous, or clinical suspicion is high for a condition that ultrasound can’t fully characterize. MRI adds tissue-contrast detail that ultrasound simply can’t provide, especially for distinguishing scar tissue from active disease, or for mapping the precise extent of endometriosis or a complex mass before surgery.

Reading the Impression Section

The final section of the report, labeled “Impression” or “Conclusion,” is the radiologist’s synthesis. Everything above it is descriptive measurement and observation; the impression is the interpretive bottom line. It will list findings in order of clinical importance, and it’s the section your doctor reads first. If you see something in the body of the report that isn’t mentioned in the impression, the radiologist considered it incidental or normal.

Impressions are written for your doctor, not for you, so they can feel cryptic. A phrase like “probable corpus luteum cyst, suggest clinical correlation” means the radiologist is fairly confident the cyst is a normal post-ovulation structure but wants your doctor to check whether it fits with your symptoms and cycle timing. “Cannot exclude malignancy” is a legal and clinical hedge that doesn’t mean cancer is likely; it means the imaging alone can’t definitively rule it out, and further workup is warranted. When the impression uses a structured scoring system like O-RADS, the number itself tells you and your clinician where you stand on the risk spectrum without having to decode descriptive language.

One last thing worth knowing: pelvic ultrasound is operator-dependent. The quality of the exam depends heavily on the skill of the person performing it, the equipment used, and factors like your body habitus, bowel gas obscuring the view, or the position of your uterus. If your report notes any technical limitations, those aren’t disclaimers to ignore. They’re context that may affect how much confidence to place in a particular finding, and they may be the reason your doctor orders a follow-up scan or a different type of imaging altogether.