Uterine polyp

Overview
An endometrial polyp or uterine polyp is a polyp or lesion in the lining of the uterus (endometrium) that takes up space within the uterine cavity. Commonly occurring, they are experienced by up to 10% of women. They may have a large flat base (sessile) or be attached to the uterus by an elongated pedicle (pedunculated). Pedunculated polyps are more common than sessile ones. They range in size from a few millimeters to several centimeters. If pedunculated, they can protrude through the cervix into the vagina. Small blood vessels may be present, particularly in large polyps.

Cause and symptoms
No definitive cause of endometrial polyps is known, but they appear to be affected by hormone levels and grow in response to circulating estrogen. They often cause no symptoms. Where they occur, symptoms include irregular menstrual bleeding, bleeding between menstrual periods, excessively heavy menstrual bleeding (menorrhagia), and vaginal bleeding after menopause. Bleeding from the blood vessels of the polyp contributes to an increase of blood loss during menstruation and blood "spotting" between menstrual periods, or after menopause. If the polyp protrudes through the cervix into the vagina, pain (dysmenorrhea) may result.

Diagnosis
Endometrial polyps can be detected by vaginal ultrasound (sonohysterography), hysteroscopy and dilation and curettage. Detection by ultrasonography can be difficult, particularly when there is endometrial hyperplasia (excessive thickening of the endometrium). Larger polyps may be missed by curettage.

Treatment
Polyps can be surgically removed using curettage or hysterescopy. When curettage is performed, polyps may be missed. To reduce this risk, the uterus can be first explored using grasping forceps at the beginning of the curettage procedure. During hysterescopy, the polyp can be visualized and removed through the cervix. If it is a large polyp, it can be cut into sections before each section is removed. If cancerous cells are discovered, a hysterectomy may be performed. A hysterectomy would usually not be considered if cancer has been ruled out. Whichever method is used, polyps are usually treated under general anesthetic.

Prognosis and complications
Endometrial polyps are usually benign although some may be precancerous or cancerous. About 0.5% of endometrial polyps contain adenocarcinoma cells. Polyps can increase the risk of miscarriage in women undergoing IVF treatment. If they develop near the fallopian tubes, they may lead to difficulty in becoming pregnant. Although treatments such as hysterescopy usually cure the polyp concerned, recurrence of endometrial polyps is frequent. Untreated, small polyps may regress on their own.

Risk factors and epidemiology
Endometrial polyps usually occur in women in their 40s and 50s. Risk factors include obesity, high blood pressure and a history of cervical polyps. Taking tamoxifen or hormone replacement therapy can also increase the risk of uterine polyps. The use of an IntraUterine System containing levonorgestrel in women taking Tamoxifen may reduce the incidence of polyps. Endometrial polyps occur in up to 10% of women. It is estimated that they are present in 25% of women with abnormal vaginal bleeding.

Structure
Endometrial polyps can be solitary or occur with others. They are round or oval and measure between a few millimeters to several centimeters in diameter. They are usually the same red/brown color of the surrounding endometrium although large ones can appear to be a darker red. The polyps consist of dense, fibrous tissue (stroma), blood vessels and glandlike spaces lined with endometrial epithelium. If they are pedunculated, they are attached by a thin stalk (pedicle). If they are sessile, they are connected by a flat base to the uterine wall. Pedunculated polyps are more common than sessile ones.