Uterine cancer occurs when malignant cells form in the tissues of the uterus, the hollow organ where a fetus grows. Over 90% of cases begin in the lining of the uterus, known as endometrial cancer. Uterine sarcoma, which arises from the muscle wall or connective tissue, is a much rarer form. The diagnostic process moves from initial suspicion based on symptoms and history to definitive confirmation through tissue analysis.
Initial Clinical Assessment and Patient History
The diagnostic process begins with a detailed assessment of a patient’s symptoms and medical background, which establishes the initial level of suspicion. The most common warning sign of uterine cancer, present in 75 to 90% of cases, is abnormal vaginal bleeding. This often manifests as bleeding between menstrual periods in premenopausal women or, more frequently, any bleeding that occurs after menopause.
A thorough patient history also focuses on known risk factors that increase the likelihood of the disease, including age, polycystic ovary syndrome, obesity, diabetes, and a family history of certain cancers. Following the history, a physical examination is performed, including a pelvic exam. During the exam, the provider checks the uterus and surrounding organs for any unusual masses, tenderness, or changes in size and shape.
Visualizing the Uterus: Role of Imaging
Once initial suspicion is raised, the next step involves non-invasive imaging to visualize the internal structure of the uterus. Transvaginal ultrasound (TVUS) is typically the preferred initial modality due to its accessibility and ability to provide clear images of the pelvic organs. A small, wand-like transducer is gently inserted into the vagina, using sound waves to create a detailed picture of the uterus and the ovaries.
The primary focus of the TVUS is to measure the thickness of the endometrium. In postmenopausal women experiencing bleeding, an endometrial thickness greater than 4 to 5 millimeters is considered an abnormal finding that warrants further investigation. Other imaging technologies, such as Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans, are generally reserved for later to determine if cancer has spread beyond the uterus.
Tissue Confirmation: Biopsy Procedures
Although imaging can raise suspicion, uterine cancer cannot be definitively diagnosed without analyzing a tissue sample under a microscope. This tissue analysis, called a biopsy, is the final step required to confirm the presence of malignant cells. The most common initial procedure for obtaining this sample is an office-based endometrial biopsy.
During an endometrial biopsy, a thin, flexible tube is inserted through the cervix into the uterine cavity, and gentle suction is applied to collect tissue from the lining. This quick procedure is often performed without anesthesia and provides enough tissue for a pathologist to make a preliminary diagnosis in many cases. However, this method is considered a blind sampling, meaning the provider cannot see exactly where the tissue is being collected, which can sometimes result in an insufficient or non-diagnostic sample.
If the office biopsy is inconclusive, or if the provider needs a better view of the uterine cavity, a more involved procedure is performed using a hysteroscope. Hysteroscopy involves inserting a small, lighted telescope through the cervix, allowing the doctor to directly visualize the entire inner lining of the uterus. This allows for a targeted biopsy of any suspicious lesions or growths observed, which is a more accurate diagnostic approach than blind sampling.
When the cervix needs to be slightly widened (dilated) to gain access, the procedure is combined with dilation and curettage (D&C) to collect a larger amount of tissue. In a D&C, a specialized instrument called a curette is used to gently scrape tissue from the endometrial lining for laboratory analysis. The final diagnosis relies on the pathologist, who examines the cells to confirm cancer, determine the specific type, and assign a grade indicating how quickly the cancer might grow.