An endometrial biopsy is done whenever it is important to know the microscopic status of the uterine lining, also known as the endometrium.

The uterine lining is influenced by hormones. During the reproductive years, the lining is stimulated by estrogen to grow, thicken and proliferate. With ovulation, progesterone is produced by the ovaries and this progesterone causes the thickened, soft uterine lining to stabilize and begin secreting from its glandular elements. These two phases, Proliferative endometrium and Secretory endometrium, can be easily distinguished based on their microscopic appearance.

Proliferative endometrium consists of dense connective tissue with tubular glands made up of simple columnar cells.

Secretory endometrium contains glands that are larger, longer and more branching. The glandular cells will contain clear vacuoles, and the interior of the glands will contain secretions.

During menopause, the endometrial lining becomes quite thin and loses most of it’s glands, although this appearance can be different if the woman is exposed to hormones.

If exposed to unbalanced amounts of estrogen and progesterone, or estrogen alone, the endometrium over time can develop hyperplasia, or abnormally increased growth. In the case of simple hyperplasia, the endometrium is both anatomically thickened, and microscopically altered, with enlarged, irregular glands, some of which may have unusually prominent collections of secretions within the glands. While associated with abnormal bleeding, this reversible abnormality is not immediately threatening to the patient.

However, if untreated, simple hyperplasia can develop into complex hyperplasia, with very crowded glands with many side buds. The glands have angular contours and irregular architecture. Particularly if cellular atypia is present, this change is considered premalignant, though still able to be arrested with proper therapy.

Should further time elapse without treatment and the predisposing factors remain unchanged, many of these patients will develop endometrial cancer.

At times, it can be medically important to know exactly what the endometrium is doing on a microscopic level. The two primary reasons are to evaluate abnormal bleeding and to assess the hormonal support of ovulation.
For example, a perimenopausal woman with spotting may have endometrial hyperplasia, although endometrial polyps, cancer, cervicitis and anovulation are all capable of causing this symptom. An endometrial biopsy can resolve this diagnostic uncertainty.

Among infertility patients, it is sometimes valuable to confirm with an endometrial biopsy that the ovary is providing consistent hormonal support of the endometrium following ovulation. In the case of a luteal phase defect, it is believed by many physicians that progesterone production among these women is insufficient to support the endometrium, a condition that can be corrected with medication. A timed endometrial biopsy can be used to identify this condition.
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Start with a bimanual exam to determine the position and attitude of the uterus and rule out other palpable pelvic pathology. It is particularly important to note the amount of anteflexion or retroflexion present. For a safe procedure, your biopsy instrument should follow the normal internal anatomy.
Next, position a vaginal speculum to allow a clear and unobstructed view of the cervix.

This procedure is usually performed as an outpatient in a provider’s office or ambulatory medical center. If you use no anesthetic for this procedure, it will typically cause mild to moderate pelvic cramping for a few minutes but then the discomfort will resolve.

You can administer a paracervical block, resulting in excellent anesthesia, but the paracervical block itself is somewhat painful to receive and can have systemic effects ranging from annoying but common bradycardia, tinnitus and postural hypotension, to very serious but rare vascular collapse.
As an expedient compromise, I’ve personally had very good results with 20% topical benzocaine gel, swabbed around the entire cervix and lateral vaginal fornices, and also pushed into the endocervical canal. It takes effect within about 30 seconds and lasts about 15 minutes. There is very little systemic absorption and it can reapplied if necessary. Using this technique, about half my patients report no pain whatsoever during the biopsy, and the other half report very mild but tolerable cramping that lasts a few minutes and then resolves.

Some providers recommend pretreatment of the patient with oral ibuprofen, 600 to 800 mg orally, one hour prior to the procedure to minimize pain through analgesia and by blocking prostaglandin release during cervical manipulation.

After achieving adequate anesthesia, I recommend stabilizing the cervix with a single-toothed tenaculum, usually on the anterior lip of the cervix. If the uterus is retroverted, then the tenaculum should go on the posterior lip.

There are a variety of endometrial biopsy instruments that can provide good results. Their differences are primarily their relative flexability and diameter. The thinner, more flexible biopsy tubes provide good specimens but with less patient discomfort and have some ability to bend around small turns on the way into the uterus. The larger and less flexible tubes also provide good specimens but because of their rigid shape, they can be manually directed around bends in the cervical canal, albeit with somewhat more discomfort.
Self-contained biopsy tubes, such as the Pipelle, are inserted into the uterine cavity and held in place while the central stiffener and vacuum applier is withdrawn. This creates a small amount of suction within the catheter that enables it to pull in small bits of endometrium, facilitated by rotating the catheter.

Older catheters, such as the Novak curette, are inserted into the uterine cavity and suction applied with an attached syringe while the curette is scraped in and out of the cavity. This mini-curettage is more painful but may be necessary if the endometrium is very thin and not obtainable with the gentler suction of Pipelle-like devices.

After stabilizing the cervix, hold the biopsy catheter like a pencil and slide it through the cervix and into the endometrial cavity. You will meet with resistance when the catheter hits the fundus and you should stop at that point to avoid perforating the uterus.

Then apply suction and rotate the catheter a number of times.
Keeping the suction applied, withdraw the catheter and inject the contents into a pathology jar for later processing and pathology evaluation.
Remove the tenaculum, check for excessive bleeding from the tenaculum sites, and then withdraw the vaginal speculum. A small amount of bleeding can be anticipated over the next few hours which should spontaneously resolve.

Some providers always sound the uterus with a uterine sound prior to inserting the biopsy catheter. Others simply use the catheter as the uterine sound. Still others occasionally use a uterine sound to better delineate the contour of the cervical canal prior to inserting the endometrial catheter.
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There are some risks associated with this procedure, but they are usually small. Aside from the annoying side effects of pelvic cramping and vasovagal reaction, uterine perforation occurs about once in every thousand procedures. Infection is extremely rare, and antibiotic prophylaxis is usually not recommended unless the patient has a complicated cardiac history or has prosthetic valves.

Endometrial biopsy should not be done during pregnancy. You should take appropriate steps to make sure the patient is not pregnant.
Endometrial biopsy usually should not be done in the presence of active infection of the genital tract, although there might be occasional exceptions where the need for the information is urgent or the infection is not one that can be significantly improved or resolved.