A uterine polyp is a soft, fingerlike growth that forms on the inner wall of the uterus. It develops when the endometrium, the tissue lining the inside of the uterus, overgrows in one spot and forms a small protrusion. Polyps can be as small as a sesame seed or as large as a golf ball, and you can have one or several at a time. Most are benign, but they can cause irregular bleeding and, in some cases, affect fertility.
How Uterine Polyps Form
The endometrium thickens and sheds every menstrual cycle in response to hormones, particularly estrogen. A uterine polyp forms when a small area of that lining grows excessively and doesn’t shed normally. The result is a rounded or elongated growth attached to the uterine wall by a thin stalk or a broad base. Polyps stay confined to the inner surface of the uterus, though occasionally a large one can extend through the cervix.
The exact trigger isn’t fully understood, but estrogen appears to play a central role. Because estrogen drives the monthly thickening of the endometrium, prolonged or elevated exposure to it likely encourages polyp growth.
Who Is Most at Risk
Age is the strongest predictor. Uterine polyps are most common in women in their 40s and 50s, around the transition to menopause, though they also occur after menopause. Several other factors increase your risk, all of which relate to higher or more prolonged estrogen exposure:
- Obesity or overweight. Fat tissue produces estrogen, raising overall levels in the body.
- High blood pressure. The connection isn’t entirely clear, but it consistently appears as a risk factor in large studies.
- Tamoxifen use. This breast cancer medication blocks estrogen in breast tissue but can act like estrogen in the uterus, promoting polyp growth.
- Hormone replacement therapy involving high doses of estrogen.
- Genetic conditions such as Lynch syndrome or Cowden syndrome, which raise the risk of several types of growths.
Common Symptoms
The hallmark symptom is abnormal uterine bleeding. That can look different depending on your situation:
- Bleeding between periods
- Periods that are unusually heavy, irregular, or unpredictable in length
- Vaginal bleeding after menopause
- Light spotting outside your normal cycle
Some women with polyps have no symptoms at all. In those cases, a polyp is often discovered incidentally during an ultrasound or fertility evaluation. The presence or absence of symptoms doesn’t reliably predict whether a polyp is harmless or needs attention, which is why further evaluation is usually recommended once one is found.
How Polyps Are Diagnosed
A standard transvaginal ultrasound is typically the first step. A small probe placed in the vagina uses sound waves to create an image of the uterus. A polyp may show up directly, or the image may reveal a thickened area of the lining that warrants a closer look.
If the ultrasound is inconclusive, a saline infusion sonography (also called sonohysterography) can provide a clearer picture. A small amount of sterile salt water is injected into the uterus through a thin tube, which expands the uterine cavity and makes polyps easier to distinguish from the surrounding lining.
Hysteroscopy offers the most direct view. A thin, lighted telescope is passed through the vagina and cervix into the uterus, allowing the doctor to see polyps in real time. This procedure doubles as a treatment option because polyps can be removed during the same session. An endometrial biopsy, where a small tissue sample is collected with a suction catheter, can sometimes confirm a polyp, though it may miss one entirely since the catheter samples at random.
Cancer Risk: Low but Not Zero
The vast majority of uterine polyps are benign. In premenopausal women, only about 1 to 2 percent of polyps turn out to be cancerous or precancerous. In postmenopausal women, that figure rises to roughly 5 to 6 percent.
Several factors increase the chance that a polyp contains abnormal cells: being over 60, being postmenopausal, having abnormal uterine bleeding, having large polyps, or having polycystic ovarian syndrome. When any of these risk factors are present, removal and laboratory analysis of the polyp tissue become more important.
Treatment Options
For small, asymptomatic polyps in women who are not at elevated risk for cancer, watchful waiting is a reasonable approach. Some small polyps resolve on their own, and monitoring with periodic ultrasounds can be sufficient.
When polyps cause symptoms, are large, or carry risk factors for malignancy, the standard treatment is hysteroscopic polypectomy. During this procedure, the hysteroscope is guided into the uterus and the polyp is removed, usually with a small surgical instrument or a wire loop. The tissue is then sent to a lab to check for cancerous or precancerous cells. The procedure is minimally invasive, often performed as an outpatient visit, and most women return to normal activities within a day or two.
Impact on Fertility
Uterine polyps can interfere with conception, likely by disrupting embryo implantation. Research consistently shows that removing polyps improves pregnancy rates. In one study, infertile women who had polyps removed achieved a pregnancy rate of 78 percent, compared to 42 percent in women with a normal uterine cavity. Other studies have reported post-removal pregnancy rates ranging from 50 to 76 percent within 12 months.
Location matters. Polyps sitting at the junction where the fallopian tubes meet the uterus had the highest pregnancy rates after removal (about 57 percent), possibly because they were physically blocking the path between egg and sperm. Polyps on the anterior wall of the uterus had the lowest rates after removal (around 15 percent).
For women undergoing intrauterine insemination (IUI), a randomized trial found that removing polyps beforehand nearly doubled the cumulative pregnancy rate: 41 percent versus 22 percent. The picture is more nuanced for IVF. Several studies have found that small polyps (under 15 to 20 millimeters) discovered during an IVF cycle don’t significantly affect pregnancy or implantation rates whether they’re removed or left in place. However, leaving polyps in place may increase the miscarriage rate, so many fertility specialists still recommend removal before proceeding with embryo transfer.
Recurrence After Removal
Polyps can come back after removal, though recurrence is less common than many women expect. In a large study tracking over 1,400 patients, about 6 to 7 percent developed a recurrent polyp. Of those who did have a recurrence, 86 percent experienced only one, and it typically appeared within about four to six months of the original removal. The wide range reported in the medical literature (from 0 to 44 percent) reflects differences in follow-up length and how closely patients were monitored.
If you’ve had a polyp removed, your doctor will likely schedule a follow-up ultrasound within several months to check for regrowth. Women with ongoing risk factors, particularly those taking tamoxifen or those who are postmenopausal, may benefit from more regular monitoring.