A pelvic ultrasound uses sound waves to create images of the structures within the female pelvis, primarily focusing on the uterus, ovaries, and fallopian tubes. The procedure is performed using two methods: transabdominal, where the transducer is moved across the lower abdomen, and transvaginal, where a slender probe is gently inserted into the vagina. If your scheduled appointment falls during your menstrual cycle, you may be concerned about the procedure or the accuracy of the results. Having your period is usually not a reason to cancel the appointment, as the test can be safely and effectively performed at any time in the cycle, depending on its specific purpose.
Practical Considerations for the Procedure
The immediate concerns surrounding a pelvic ultrasound during menstruation involve comfort and preparation, which vary depending on the specific technique used. A transabdominal ultrasound requires a full bladder, as the fluid helps push the bowel out of the way and provides a clearer acoustic window to view the pelvic organs. For this procedure, menstrual flow does not interfere with the imaging, and you will lie on the examination table with gel applied to your lower abdomen.
The transvaginal ultrasound provides more detailed images because the probe is placed closer to the reproductive organs, but it requires an empty bladder for optimal visualization. If you are using a tampon, you must remove it just before the examination begins. The probe is covered with a disposable sheath and lubricated with gel before insertion, making the procedure generally quick and often less uncomfortable than a routine Pap smear.
Sonographers and technologists are accustomed to performing this examination on patients who are menstruating. Their focus remains on obtaining the best possible diagnostic information while ensuring patient comfort and maintaining a professional environment. Wearing comfortable, two-piece clothing can simplify the process, as you will typically only need to remove your lower garments.
How Menstruation Affects the Scan Results
The primary way menstruation affects the ultrasound results is through changes to the uterine lining, known as the endometrium. During the period, the endometrium is actively shedding, appearing thick, irregular, and bright on the ultrasound image. This appearance can create diagnostic challenges when the physician is looking for small growths or abnormalities within the uterine cavity.
A shedding or thickened lining can occasionally obscure or mimic true pathology, such as small endometrial polyps or submucosal fibroids. These structures are easiest to detect when the lining is thinnest, which typically occurs immediately after the period ends, around Cycle Days 5 through 10. If the scan is performed during the period, the presence of blood or shed tissue may make a definitive diagnosis of these subtle abnormalities impossible.
The presence of menstrual fluid can also slightly complicate the visualization of other structures like the ovaries and adnexa. For many conditions, such as ovarian cysts, fibroids not in the uterine cavity, or overall organ size, menstrual blood does not significantly impact the diagnostic accuracy. If the purpose of the scan is to evaluate the cause of abnormal bleeding, the physician may prefer a follow-up scan when the lining is thin to confirm any findings.
Clinical Reasons for a Period-Timed Ultrasound
In some medical situations, the ultrasound is not merely tolerated during menstruation but is specifically required for accurate assessment. This timing is frequently utilized in fertility monitoring and treatment, where baseline scans are ordered for Cycle Days 2 to 5. During this early follicular phase, the uterus has completed shedding, and the endometrium is at its thinnest.
Scanning during this narrow window allows physicians to accurately assess the ovaries before the dominant follicle begins its rapid growth. This includes performing an Antral Follicle Count (AFC), a measure of ovarian reserve that requires counting the tiny, resting follicles. If the scan is done later, a developing follicle or corpus luteum from a previous cycle could obscure the view or be mistaken for a cyst.
Another procedure requiring a thin endometrial lining is the preparation for a Saline Infusion Sonohysterography (SIS). The SIS involves injecting sterile salt water into the uterus to expand the cavity, which helps outline the lining and detect small polyps or fibroids. This test is scheduled immediately after the period to avoid interference from a thick lining and ensure accurate results.
When Should You Consider Rescheduling?
While most routine pelvic ultrasounds can proceed during menstruation, there are specific circumstances where discussing rescheduling with your provider is prudent.
Reasons to Consider Rescheduling
If the reason for your scan is specifically to evaluate the uterine lining for small, subtle pathology, such as a polyp, the diagnostic quality is significantly better a few days after your bleeding has stopped. Your doctor may prefer to wait until Cycle Days 5 through 10 to ensure a definitive result.
You should also contact the clinic if your flow is unusually heavy, involving significant clotting, as this may increase discomfort or potentially interfere with the transvaginal imaging.
If your ultrasound is for a non-gynecological reason, such as checking your kidneys or gallbladder, but you are experiencing severe menstrual pain, rescheduling may be appropriate for your comfort alone.
Open communication with the scheduling staff or your physician is the best way to determine the optimal timing for your individual situation.