Endometrial polyps are common structural and epithelial abnormalities of the endometrium that are often encountered by gynecologists in office-based practice. These endometrial growths may be found incidentally in as many as 10% to 15% of asymptomatic women, and between 20% to 30% of women with abnormal uterine bleeding (AUB).1,2 Given their prevalence in patients presenting with AUB, polyps are considered as part of the FIGO classification for causes of abnormal uterine bleeding - PALM-COEIN.3 They may cause a variety of abnormal bleeding patterns, likely due to small muscular arteries found within the growths,4 but they can also be completely asymptomatic. Structural uterine pathologies often cause menstruation that is heavy or prolonged, albeit monthly,5 but polyps can also cause intermenstrual or postmenopausal bleeding.1 Endometrial polyps are usually benign but in 0.5% to 3% of cases, they are malignant.1
Endometrial polyps are thought to impact fertility, and removal is recommended prior to initiating treatment, especially before proceeding with in vitro fertilization (IVF). Some proposed mechanisms by which polyps are thought to impact fertility include inhibition of implantation, endometrial inflammation, mechanical blockage of sperm from fertilization, or changes in endometrial receptivity.6 In the infertile population, prevalence of polyps is thought to be between 11% and 45%, which is higher than in the general population.6,7 Hysteroscopic removal of endometrial polyps found incidentally during fertility evaluation is recommended, with one study showing post-polypectomy implantation rates during IVF to be similar to those in women who do not have endometrial polyps.7
True to their name, polyps may grow on a thin stalk from anywhere within the uterine cavity, or they may appear sessile: smooth and flat with a broad base. They typically measure up to about 3 cm.1 Histopathologically, polyps appear as cystic dilation of glands with mononuclear cells, often filled with mucous.4 They may contain vascular pedicles, connective tissue, and even glandular tissue.3 Their prevalence makes them an important pathology to study, so that proper diagnosis and treatment can be undertaken, with the gold standard being hysteroscopy.1
Making the diagnosis
Because AUB triggers further evaluation of potential etiologies, endometrial polyps are often diagnosed on ultrasound,2 as seen in Figure 1. The sonographic finding suggestive of an endometrial polyp is a bright, hyperechoic area visualized within the endometrium (Table 1).8 Using power doppler sonography may reveal a single-vessel pattern of blood flow to the polyp (sensitivity 81.2%, positive predictive value [PPV] 92.9%) compared to fibroids, which more often show an enhancing rim of vessels.9
If further characterization is needed, office hysteroscopy is considered the gold standard for further evaluation,1,10 however, saline infusion sonography (SIS) is another excellent diagnostic study9 with a sensitivity of 93% and specificity of 81% in diagnosing endometrial polyps.10 Hysteroscopy and SIS are best performed during the proliferative phase of the menstrual cycle shortly after cessation of menses. Hysteroscopy allows for direct visualization of the polyps while SIS with a skillful operator can also provide specific details, such as where the polyp is attached and its size.1 If there is uncertainty about presence of a polyp on transvaginal ultrasound, SIS can be used as the next step for better visualization, with a PPV of 88.5%, compared to only 65.2% with ultrasound alone.2
The authors report no potential conflicts of interest with regard to this article.
- Clark TJ, Stevenson H. Endometrial polyps and abnormal uterine bleeding (AUB-P): what is the relationship, how are they diagnosed and how are they treated? Best Pract Res Clin Obstet Gynaecol. 2017 Apr;40:89-104.
- Fadl SA, Sabry AS, Hippe DS, et al. Diagnosing polyps on transvaginal sonography: is sonohysterography always necessary? Ultrasound Q. 2018 Dec;34(4):272-277.
- Munro MG, Critchley HO, Broder MS, Fraser IS. FIGO classification system (PALM-COEIN) for causes of abnormal uterine bleeding in nongravid women of reproductive age. FIGO Working Group on Menstrual Disorders. Int J Gynaecol Obstet. 2011;113:3–13.
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- Yang JH, Yang PK, Chen, MJ, et al. Management of endometrial polyps incidentally diagnosed during IVF: a case-control study. Reprod Biomed Online. 2017 Mar;34(3):285-290.
- Luerti M, VitaglianoA, Di Spiezio Sardo A, et al. Effectiveness of hysteroscopic techniques for endometrial polyp removal: the Italian Multicenter Trial. J Minim Invasive Gynecol. 2018 Dec 7. pii: S1553-4650(18)31402-X. [Epub ahead of print]
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