The Core Differences Between Uterine Fibroids and Polyps

Abnormal uterine bleeding can be frustrating, disruptive, and difficult to interpret. Two of the most common causes are uterine fibroids and endometrial polyps. Because both are non-cancerous growths that can cause unexpected bleeding, many women assume they are the same condition.

In reality, they are very different.

Although their symptoms may overlap, fibroids and polyps develop from different tissues, behave differently, require different imaging studies, and are treated using completely different approaches. Understanding these distinctions is the first step toward receiving the right diagnosis and the most appropriate treatment.

Already familiar with fibroids? For a complete overview of their causes, symptoms, diagnosis, and treatment options, read our Uterine Fibroids guide.

Muscle vs. Lining: The Fundamental Difference

The most important distinction between fibroids and polyps is where they develop within the uterus.

Uterine Fibroids: Growths Within the Muscle

Fibroids develop from the myometrium, the thick muscular wall of the uterus. Because they consist of smooth muscle and fibrous tissue, they are firm, dense, and capable of growing quite large.

Depending on their location, fibroids may remain within the uterine wall, project into the uterine cavity, or grow outward toward surrounding pelvic organs. Some become large enough to noticeably enlarge the uterus and create pressure throughout the pelvis.

Endometrial Polyps: Growths of the Uterine Lining

Endometrial polyps develop from the endometrium, the inner lining of the uterus that thickens and sheds during each menstrual cycle.

Rather than forming dense muscle masses, polyps are soft, vascular growths that extend from the lining into the uterine cavity. Most remain relatively small, although even small polyps can trigger significant bleeding because they contain numerous blood vessels.

Unlike fibroids, polyps rarely change the overall size or shape of the uterus.

How Symptoms Differ

Although both conditions commonly cause abnormal uterine bleeding, the pattern of symptoms often provides important diagnostic clues.

Fibroids Usually Cause Heavy Menstrual Bleeding

Because fibroids can interfere with the uterus’s ability to contract normally, they often cause:

• Exceptionally heavy menstrual periods
• Periods lasting longer than normal
• Passage of large blood clots
• Iron-deficiency anemia from chronic blood loss

Women frequently describe needing to change pads or tampons every hour or experiencing bleeding severe enough to interfere with work and daily activities.

Polyps More Often Cause Irregular Bleeding

Since polyps grow directly from the uterine lining, they are more likely to produce bleeding outside of normal menstrual cycles.

Common symptoms include:

• Spotting between periods
• Unpredictable bleeding
• Bleeding after intercourse
• Irregular menstrual cycles
• Postmenopausal bleeding

The bleeding may be light but persistent, making it especially noticeable even when menstrual flow itself is relatively normal.

Pelvic Pressure and Pain

The physical composition of these growths also affects how they feel.

Fibroids Frequently Cause Pressure Symptoms

As fibroids enlarge, they occupy space within the pelvis and can press against nearby organs.

Women may experience:

• Constant pelvic pressure or fullness
• Lower abdominal heaviness
• Lower back pain
• Frequent urination
• Difficulty emptying the bladder
• Constipation from pressure on the bowel

These “bulk symptoms” become more common as fibroids increase in size.

Polyps Rarely Cause Pressure

Because polyps usually remain small, they seldom create pelvic pressure.

Instead, symptoms are generally limited to:

• Mild uterine cramping
• Occasional discomfort during bleeding
• Little or no sensation of pelvic fullness

Large symptomatic polyps are uncommon compared with large fibroids.

How Doctors Tell the Difference

Since symptoms alone cannot reliably distinguish fibroids from polyps, imaging plays an essential role in diagnosis.

Transvaginal Ultrasound

A transvaginal ultrasound is usually the first imaging study performed for abnormal uterine bleeding.

It can identify both fibroids and polyps, but there are limitations. Small fibroids that protrude into the uterine cavity may sometimes resemble polyps on standard ultrasound images.

For that reason, additional imaging is often necessary.

Saline Infusion Sonography (SIS)

A saline infusion sonogram improves visualization of the uterine cavity by introducing sterile saline during the ultrasound examination.

The saline gently expands the cavity, allowing physicians to clearly identify soft endometrial polyps that may otherwise be difficult to distinguish from surrounding tissue.

This study is particularly valuable when abnormal bleeding suggests a problem within the uterine lining.

Pelvic MRI

When fibroids are suspected, pelvic MRI provides the most comprehensive evaluation.

MRI offers detailed information about:

• The exact number of fibroids
• Their size
• Their location within the uterus
• Their blood supply
• Their relationship to nearby pelvic structures

This level of detail is especially important when determining whether a patient is a candidate for minimally invasive treatments such as Uterine Fibroid Embolization (UFE).

Why Treatment Depends on the Diagnosis

Because fibroids and polyps are biologically different, their treatments are not interchangeable.

Treatment for Endometrial Polyps

Symptomatic polyps are generally removed through hysteroscopic polypectomy, a minimally invasive procedure in which specialized instruments are inserted through the cervix to remove the growth.

Removal is recommended not only to relieve symptoms but also because polyps carry a small risk of containing precancerous or cancerous changes, particularly in women after menopause.

Treatment for Fibroids

Fibroids require an entirely different strategy.

Because fibroids rely on a substantial blood supply, many women can be treated with Uterine Fibroid Embolization (UFE), a minimally invasive outpatient procedure performed by an interventional radiologist. During UFE, tiny particles are used to block the arteries feeding the fibroids, causing them to shrink over time while preserving the uterus.

Unlike surgery, UFE treats the fibroid by targeting its blood supply rather than removing uterine tissue.

Importantly, UFE is not a treatment for endometrial polyps, which is why establishing the correct diagnosis is so important before beginning treatment.

Expert Diagnosis for Abnormal Uterine Bleeding in Louisville

Heavy periods, irregular spotting, pelvic pressure, and chronic bleeding should never be dismissed as simply “part of getting older.” While fibroids and polyps can produce similar symptoms, they are fundamentally different conditions that require different diagnostic evaluations and treatment plans.

At Precision Vascular Kentucky, Dr. Ryan Jean-Baptiste, a Yale- and Mayo Clinic-trained interventional radiologist, specializes in advanced pelvic imaging to accurately determine the underlying cause of abnormal uterine bleeding. For women diagnosed with uterine fibroids, he offers Uterine Fibroid Embolization (UFE), a proven, minimally invasive alternative to hysterectomy that can relieve symptoms while preserving the uterus.

If you’re experiencing persistent abnormal bleeding or have been told you may have fibroids, schedule a consultation with Precision Vascular Kentucky to receive an accurate diagnosis and personalized treatment plan designed around your condition, not just your symptom