Endometrial dating images
Timing The best way to prove or disprove that ovulation has taken place is to take an endometrial sample on cycle day 22 or later, preferably at the onset of uterine bleeding.
By obtaining samples at the time of early uterine bleeding, the pathologist will be able to determine whether the bleeding is caused by the breakdown of postovulatory, secretory endometrium; by focal necrosis of the endometrium associated with anovulation; by other pathologic states; or by hormone administration.
Because of this interplay of structure, function, and ovarian hormonal stimuli, the endometrium is considered one of the most sensitive indicators of the hypothalamic-pituitary-ovarian hormonal axis. Estradiol promotes endometrial proliferation, whereas after ovulation, progesterone converts estradiol-primed endometrium into secretory tissue.
As a result, morphologic evaluation of the endometrium is used in diagnostic evaluation of infertile patients to determine whether ovulation is occurring (Fig. Postovulatory estradiol amplifies the progesterone effect, and after withdrawal of both estradiol and progesterone, the endometrial mucosa breaks down and regenerates within the period of menstruation.
Method To ensure a good specimen for morphologic interpretation, a biopsy sample should be taken from both the anterior and the posterior endometrium and fixed immediately in 10% buffered formalin.
In current practice, the device that is most often used is the Pipelle endometrial aspirator.
Also, because proliferation precedes the ovulatory period, dating proliferative endometrium gives the clinician no relevant information on whether ovulation is occurring.
Endometrial biopsies are not to be taken at the onset of bleeding in the following two conditions: if luteal phase defect (LPD) is suspected clinically and is desired to be confirmed histologically, when the biopsy should be taken between POD 7 (21st) and POD 9 (23rd) cycle days to demonstrate a 3–4 day delay in endometrial maturation; or if there are asynchrony of gland/stromal development and dissimilar maturation in different regions of the endometrial specimen.
Taking an endovaginal ultrasonography of the uterus may solve this dilemma.
If the aspirator is 'blocked' at the lower uterine segment (internal os), traction may be applied on the uterus with either a single-toothed tenaculum or preferably an Emmet tenaculum placed about half a centimetre into the anterior endocervical canal. The pathology requisition should contain all pertinent information, including date of last menstrual period.
It is not necessary to date the endometrium during the proliferative phase.
During this period, daily morphologic alterations are not sufficiently distinctive to provide adequate benchmarks for accurate dating.