An endometrial biopsy is a procedure where a small tissue sample is taken from the lining of the uterus, known as the endometrium. This sample is examined under a microscope to identify any cellular changes. The primary purpose of the biopsy is to investigate the cause of specific symptoms and check for the presence of abnormal cells.
Reasons for an Endometrial Biopsy
A physician may recommend an endometrial biopsy for several reasons, most often related to unusual bleeding patterns. For postmenopausal women, any instance of vaginal bleeding is a primary indicator for a biopsy. In premenopausal women, symptoms such as heavy menstrual bleeding, bleeding between periods, or prolonged periods can warrant this investigation. These symptoms are collectively known as abnormal uterine bleeding (AUB).
Another reason for an endometrial biopsy is the discovery of a thickened endometrial lining during a pelvic ultrasound. An ultrasound might be ordered to investigate pelvic pain or other symptoms, and if it reveals an endometrium that is thicker than expected for a person’s age and menstrual cycle phase, a biopsy is used to determine the cause. The procedure is also used to check for uterine infections, such as endometritis, or to monitor the uterine lining’s response to certain hormone therapies.
Understanding the Results of an Endometrial Biopsy
The majority of endometrial biopsies have benign, or non-cancerous, findings. For premenopausal women undergoing a biopsy for abnormal uterine bleeding, over 95% of samples reveal a benign pathology. For postmenopausal women who experience bleeding, about 9% are diagnosed with endometrial cancer. The percentage can vary based on the reason for the biopsy and individual risk factors.
A benign result means no cancerous or pre-cancerous cells were found. The report might identify a non-cancerous cause for symptoms, such as an endometrial polyp or uterine fibroids. In other cases, the findings may show normal endometrial tissue responding to hormonal fluctuations, or tissue that is thin and atrophic, a common finding in post-menopausal women.
Some biopsy results may indicate endometrial hyperplasia, a thickening of the uterine lining. This condition is pre-cancerous and is categorized based on the appearance of the cells. Hyperplasia without atypia involves an overgrowth of normal-looking cells and has a lower chance of progressing to cancer. Hyperplasia with atypia involves cells that are structurally abnormal and carries a higher risk, with some studies suggesting that up to 50% of these cases may have a concurrent underlying cancer or a high risk of developing it.
A result of cancerous cells is known as endometrial carcinoma. This is the most common type of cancer affecting the female reproductive organs. Nearly all of these cancers begin in the glandular cells of the endometrium and are called endometrioid adenocarcinomas. Early detection through a biopsy allows for more effective treatment planning and a better prognosis.
Factors Influencing Cancer Risk
The likelihood of an endometrial biopsy revealing cancer is influenced by personal health factors and the reason for the procedure. The risk is higher for postmenopausal bleeding compared to abnormal bleeding in premenopausal women. Age is also a significant factor, as endometrial cancer is rare before age 45 and most often diagnosed in people around age 60.
Certain medical conditions and lifestyle factors can elevate the risk. These include:
- Obesity, because excess body fat can lead to higher estrogen levels, which can stimulate the growth of the endometrium.
- Conditions like Polycystic Ovarian Syndrome (PCOS) and diabetes.
- The use of estrogen-only hormone replacement therapy without a progestin to balance it.
- Lynch syndrome, a hereditary condition, which significantly increases the lifetime risk of developing endometrial cancer.
- A personal history of related cancers, such as colorectal cancer, or a family history of uterine cancer.
Conversely, factors like the use of combination oral contraceptives can be protective.
Next Steps After Receiving Biopsy Results
The follow-up actions after an endometrial biopsy are guided by the findings in the pathology report. If the results are benign, the focus shifts to managing the symptoms that prompted the biopsy. This could involve a procedure to remove a polyp or fibroid, or medical management for hormonal imbalances. When no specific cause is found, monitoring may be all that is needed.
For a finding of pre-cancerous endometrial hyperplasia, the management strategy depends on the type. If there is no atypia, treatment may involve progestin therapy, which is a hormonal treatment designed to thin the uterine lining and reverse the hyperplasia. When atypia is present, the risk of progression to cancer is higher, and the recommendation is often a hysterectomy (surgical removal of the uterus) for those who have completed childbearing.
When a biopsy confirms a diagnosis of endometrial cancer, the next step is further evaluation to determine the extent of the disease. This involves a referral to a gynecologic oncologist, a specialist in cancers of the female reproductive system. Additional imaging tests, such as an MRI or CT scan, are ordered to stage the cancer, which assesses its size and whether it has spread beyond the uterus. This information is necessary to formulate an appropriate treatment plan.