Uterine Polyps

Understand

Overview

A uterine polyp (endometrial polyp) is a localized, usually benign overgrowth of the glands and stroma of the uterine lining (endometrium) that forms a projection bulging into the uterine cavity — attached by a stalk (a pedunculated polyp) or a broader base. Unlike uterine fibroids, which arise from smooth muscle, and ovarian cysts, which form within the ovary itself, a polyp develops exclusively from the lining of the uterine cavity — a third, biologically distinct category of gynecological findings, even though in everyday conversation these three phenomena get lumped together as 'something found on a pelvic ultrasound'.

Endometrial polyps are surprisingly common — depending on the population studied and the diagnostic method, they're found in a few to several percent of women undergoing ultrasound or hysteroscopy for another reason, and the detection rate rises with age, peaking around the perimenopausal period. A substantial share remain completely asymptomatic and are discovered incidentally during an ultrasound done for another reason — a routine gynecological check-up, an infertility workup, or surveillance of another pelvic finding.

In women who do have symptoms, the dominant one is abnormal uterine bleeding — most often irregular intermenstrual spotting, heavier or prolonged periods, and, in women past menopause, any bleeding from the genital tract at all, which is by definition already abnormal and warrants evaluation. Polyps are also sometimes an incidental finding during an infertility workup, since even a small polyp projecting into the uterine cavity can interfere with embryo implantation.

Diagnosis starts with transvaginal ultrasound, which in most women allows a reasonably sensitive suspicion of a polyp, especially in the second half of the cycle when the endometrium is thinner and the contrast with the polyp is clearer. Saline infusion sonohysterography (ultrasound with saline instilled into the uterine cavity) significantly improves diagnostic accuracy by outlining the lesion against the distended, saline-filled cavity. The definitive diagnostic-and-therapeutic gold standard is hysteroscopy — a procedure that allows the polyp to be directly visualized, sent for histopathology, and removed in the same session, combining diagnosis with treatment in a single step.

The most important clinical question when a polyp is found isn't 'is this dangerous', but what the real malignancy risk is for this specific lesion in this specific patient — and that depends above all on menopausal status. A large meta-analysis by Lee and colleagues, covering 17 studies and 10,572 women who underwent polypectomy, found neoplasia (malignant or premalignant) in 5.4% of polyps in postmenopausal women versus 1.7% in premenopausal women — nearly a fourfold difference in risk. Abnormal bleeding was also moderately associated with higher malignancy risk, though the effects of menopausal status and bleeding weren't found to be additive. Polyp size itself, in this meta-analysis's pooled data, wasn't clearly linked to malignancy risk, though some individual studies point to higher risk above 1.5 cm, especially in postmenopausal women.

Not every polyp needs immediate removal. Research on the natural course of asymptomatic polyps shows that a substantial share regress spontaneously within a year of follow-up, which is a strong argument for watchful waiting in selected, low-risk patients rather than automatically referring every woman with an incidentally found polyp for a procedure. The decision to remove one depends on a combination of factors: the presence and severity of symptoms (especially abnormal bleeding), menopausal status, lesion size, fertility plans, and additional risk factors such as tamoxifen therapy or prolonged, progestin-unopposed estrogen exposure.

It's worth stressing the distinction from two other frequently confused gynecological findings covered in our articles on uterine fibroids and ovarian cysts: fibroids arise from the uterine smooth muscle rather than the lining, with a completely different hormonal and symptom profile (mainly pressure symptoms and heavy bleeding tied to tumor size, not intermenstrual spotting); ovarian cysts form within the ovary itself, independent of the uterine cavity, and carry a different risk spectrum (including acute events like ovarian torsion). Polyps, fibroids, and ovarian cysts are three separate entities that can coexist in the same woman but require separate evaluation and separate treatment approaches.