Division of Reproductive Endocrinology and Infertility, University of Iowa Roy J. and Lucille A. Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, Iowa
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IntroductionBoth major tissue types of the uterine corpus-the endometrium and the myometrium-can develop nonmalignant mass lesions, especially during a woman's fertile years. Endometrial polyps, consisting of endometrial glands, fibrotic stroma, and central thick-walled vascular channels, protrude into the uterine cavity (Fig. 1). Polyps can arise from anywhere in the endometrial cavity, and their size can vary from several millimeters to several centimeters in diameter.Leiomyomas consist of clonal expansions of a single myometrial cell along with varying amounts of fibrous tissue. They may grow completely within the uterine wall (intramural or interstitial leiomyomas), protrude into the uterine cavity (submucosal leiomyomas) or peritoneal cavity (subserosal and pedunculated leiomyomas), grow into the broad ligament or pick up a blood supply from other intraperitoneal organs (parasitic leiomyomas), or grow from the uterine cervix (cervical leiomyomas) (Fig. 2). Although uterine leiomyomas are often referred to as myomas, fibroids, or fibromyomas, they will subsequently be referred to in this review as myomas.Thanks to autopsy and ultrasound studies, a past notion that endometrial polyps and uterine myomas most often lead to clinical symptoms has been supplanted by an understanding that most of these benign uterine lesions are asymptomatic. Nevertheless, polyps and myomas are important causes of abnormal uterine bleeding. A better understanding of their pathogenesis, the etiology of clinical symptoms, and optimal treatment regimens will impact the management of this very common gynecologic diagnosis of abnormal uterine bleeding.This review will describe the role played by polyps and myomas in abnormal uterine bleeding. Furthermore, it will outline what is known about the prevalence of these benign uterine mass lesions and who is at risk. Finally, the natural history of each of these lesions, from their onset through their potential growth and possible malignant transformation, will be explored.The Role of Endometrial Polyps in Abnormal Uterine BleedingToday, most authors agree that the majority of endometrial polyps are asymptomatic. When women with polyps do present to their physicians, the most common complaint is abnormal uterine bleeding. Although pre- or postmenstrual spotting has been identified as the classic symptom encountered in women with polyps, a wide range of bleeding problems has been described. Bleeding can be quite heavy (menorrhagia) and/or prolonged (metrorrhagia) and is often associated with dysmenorrhea.1-3Studies differ on the prevalence of polyps in women with abnormal uterine bleeding. Some suggest that an endometrial polyp will be discovered in 25% or more of pre- or postmenopausal women complaining of abnormal bleeding.1,4,5 One study from our institution found a prevalence of polyps of 33% in symptomatic premenopausal women over the age of 29.6 Polyps were more prevalent in symptomatic women than in asymptomatic women (33% versus 10%) and tended to be larger in size.6 Other studies have found the prevalence of endometrial polyps to be closer to 10% in their populations of women with bleeding complaints.7,8Some authors have subdivided polyps into 2 categories based on their response to typical hormonal stimulation. Functional polyps, those that respond to reproductive hormones, are more often seen in younger women and are more often associated with bleeding symptoms. Histologically, these polyps tend to resemble normal endometrium. Nonfunctional polyps, those that tend not to respond to hormonal stimulation, are more often found in older and/or menopausal women and are less often associated with abnormal bleeding. It is in nonfunctional polyps that most carcinomas are discovered.Little is written about the pathogenesis of abnormal bleeding in the setting of endometrial polyps.