2 Normal Endometrium and Infertility Evaluation General Considerations in Histologic biopsy or curettage is part of a comprehensive Evaluation . 8 workup of the patient in the operating room Histologic Dating of the Normal, that includes laparoscopy, hysteroscopy, or Cycling Endometrium . 10 hysterosalpingography to assess the presence Proliferative Phase Endometrium . 11 or absence of uterine or tubal lesions that con- Secretory Phase Endometrium . 12 tribute to infertility. In these cases, the endome- Menstrual Endometrium . 19 trial sampling may not be timed as precisely for Pitfalls in Dating . 21 the mid- to late luteal phase. Nonetheless, his- Artifacts and Contaminants . 23 tologic evaluation provides the gynecologist Luteal Phase Defect and Abnormal with information regarding the response of the Secretory Phase Patterns . 26 Clinical Queries and Reporting . 29 endometrium to hormonal stimulation, includ- ing indirect evidence of ovulatory function. The secretory phase is constant in the normal cycle, lasting 14 days from the time of ovula- The histologic features of what constitutes tion to the onset of menstruation.1 Variations in “normal” endometrium change with a woman’s cycle length occur because the proliferative age, through the premenarchal, reproductive, phase of the cycle varies, both between cycles perimenopausal, and postmenopausal years.1–3 and between women. Accordingly, the gynecol- During the reproductive years, the cyclical hor- ogist correlates the cycle date by histology with monal changes of the menstrual cycle provide the woman’s cycle date based on the time of a continuously changing morphologic pheno- onset of the upcoming menstrual period, not type that is “normal.” In biopsy specimens, the the last menstrual period. Ovulation with se- combination of these cyclical changes along cretory endometrial changes ceases in most with artifacts and limited sampling can make women by age 53, although rarely ovulation normal patterns difficult to interpret. During with secretory endometrium and a confirmed the reproductive years, deviations from normal, corpus luteum of the ovary has been seen up to either in histologic pattern or in temporal rela- a least age 56 (personal observation). tionship to ovulation, often indicate underlying The biopsy findings help confirm that ovula- abnormalities that may cause female infertility. tion occurred, and indicate whether there was The endometrial biopsy is an important part sufficient secretory effect, mediated by proges- of the evaluation of the woman with infertil- terone, during the luteal phase. To utilize fully ity.4;5 Biopsies for the evaluation of infertility the morphologic interpretation, the gynecolo- often are performed in the office using a small gist compares the histologic date to the clinical curette or a Pipelle aspirator and therefore data, including the date of the rise in the basal the specimens tend to be small.6 Occasionally, body temperature, the time of the serum 7 8 2. Normal Endometrium and Infertility Evaluation luteinizing hormone (LH) surge, transvaginal The subsurface endometrium is divided into ultrasound evaluation of follicular or corpus two regions, the functionalis (stratum spongio- luteum development, serum progesterone sum) and the basalis (stratum basale) (Fig. 2.1). level, or subtraction of 14 days from the onset The functionalis, situated between the surface of menses.4;7–9 Consequently, the biopsy typi- epithelium and the basalis, is important to cally is timed to coincide with the luteal (secre- evaluate because it shows the greatest degree tory) phase of the cycle. In addition to defining of hormonal responsiveness. The size and the precise histologic date, an endometrial distribution of glands as well as the cytologic biopsy is part of the infertility workup to features of the glandular epithelial cells exclude other organic uterine abnormalities. are important features in the histologic evalua- This chapter reviews the morphologic varia- tion. Under normal conditions, the glands tions caused by ovarian hormonal stimulation should be regularly spaced and have a per- that provide a background for the interpreta- pendicular arrangement from the basalis to tion of endometrial biopsies in infertility the surface epithelium. In the secretory phase, patients. These patterns include changes result- the endometrium also shows a stratum com- ing from normal hormonal fluctuations during pactum, a thin region beneath the surface the menstrual cycle and variations in normal epithelium. In the stratum compactum the development that are caused by abnormalities stroma is dense and the glands are straight in the endogenous ovarian hormonal levels and narrow, even when the glands in the during the reproductive years. The latter repre- functionalis are tortuous. The basalis adjoins sent the so-called dysfunctional abnormali- the myometrium, serving to regenerate the ties that are, for the most part, due to abnor- functionalis and surface epithelium following malities in ovarian follicular development or in shedding during menses. The endometrium of hormone production by the corpus luteum. the basalis is less responsive to steroid hor- Ovarian dysfunction also can result in abnormal mones, and typically shows irregularly shaped, bleeding, and Chapter 5 reviews dysfunctional inactive appearing glands, dense stroma, and uterine bleeding caused by ovulatory abnor- aggregates of spiral arteries. The spiral arteries malities. During gestation the endometrium of the basalis (basal arteries) have thicker mus- undergoes other “normal,” that is, physiologic, cular walls than those in the functionalis. In alterations as discussed in Chapter 3. biopsies, tissue fragments that contain basalis often do not have surface epithelium. The glands and stroma of the basalis cannot be dated, as they are unresponsive to steroid General Considerations in hormones. A specimen consisting solely of Histologic Evaluation endometrium from the basalis is therefore inadequate for dating. Histologic evaluation begins with identification Tissue from the lower uterine segment or of surface epithelium, a prerequisite for orient- isthmus is another region of the endometrium ing the underlying glands and stroma. The sur- that is less responsive to steroid hormones. In face epithelium is less responsive to sex steroid the lower uterine segment the endometrium hormones than the underlying glands, but it has shorter, poorly developed, inactive glands often shows alteration in pathologic conditions, dispersed in a distinctive stroma (Fig. 2.2). The especially when the abnormalities are subtle or columnar cells lining the glands resemble those focal. For example, during the proliferative of the corpus. Some glands near the junction phase, estrogenic stimulation induces develop- with the endocervix show a transition to muci- ment of ciliated cells along the surface.10 In con- nous endocervical-type epithelium.The stromal trast, ciliated surface epithelial cells are far cells in the lower uterine segment are elongate more frequent in pathologic conditions, par- and resemble fibroblasts with more abundant ticularly those associated with unopposed eosinophilic cytoplasm, in contrast to the oval estrogen stimulation, such as hyperplasia and to rounded stromal cells with minimum cyto- metaplasia.2;3;11–13 plasm seen in the corpus. General Considerations in Histologic Evaluation 9 Figure 2.1. Normal secretory phase endometrium. The basalis in the lower portion of the illustration Surface epithelium orients the tissue.The midportion consists of irregular, closely spaced glands, dense of the tissue consists of functionalis where glands, stroma, and aggregates of arteries. The stratum com- stroma, and blood vessels demonstrate the typical pactum is composed of the surface epithelium and a patterns of maturation through the menstrual cycle. subjacent thin layer of dense stroma. The tangential orientation of the functionalis this instance, gland development can be diffi- in biopsies and the tortuosity of the glands, par- cult to assess. Furthermore, not all fragments of ticularly in the late proliferative phase, often tissue in a biopsy or curettage include surface lead to irregular cross sections of the tissue. In epithelium, which helps to orient the glands. 10 2. Normal Endometrium and Infertility Evaluation Figure 2.2. Lower uterine segment. Small, poorly developed glands are seen in nonreactive stroma that is composed of widely spaced spindle cells. Tissue from the lower uterine segment cannot be dated. Nonetheless, at least focally, portions of better- of the corpus luteum.4 The regular sequence of oriented glands usually can be traced through morphologic changes determined by the fluctu- the functionalis to the surface epithelium, and ating levels of ovarian steroid hormones forms these foci are critical for assessing appropriate the basis for histologic dating. glandular and stromal development. Dating uses an arbitrarily defined “normal” cycle of 28 days, with day 1 the first day of men- strual bleeding.1 Histologic dating is most Histologic Dating of the Normal, precise in the postovulatory secretory phase, Cycling Endometrium as the follicular phase can be highly variable in length. Furthermore, proliferative phase In the ovulatory patient, normal endometrium changes are not as discrete as those in the secre- has two phases.The first is the proliferative (fol- tory phase. The date of the secretory phase is licular or preovulatory) phase characterized by expressed either as the specific day