A vaginal ultrasound (also called a transvaginal ultrasound or TVS) is an internal imaging procedure in which a small, wand-shaped probe is gently inserted into the vagina to produce detailed images of the uterus, ovaries, fallopian tubes, and surrounding pelvic structures. It uses high-frequency sound waves, not radiation, and is the most precise way to examine the female reproductive organs.
In fertility care, it is used at nearly every stage: to assess ovarian reserve before treatment, to monitor follicle growth during IVF stimulation, to measure the uterine lining before embryo transfer, and to confirm early pregnancy. The procedure is not painful. Most women feel mild pressure or a sensation similar to a pelvic examination, which passes within seconds.
Why a Vaginal Ultrasound Gives Better Images Than an Abdominal One
Many women coming to a fertility clinic for the first time wonder why a transvaginal scan is used rather than the abdominal ultrasound they may have seen in pregnancy contexts. The answer is straightforward.
A transvaginal ultrasound positions the probe directly at the back of the vagina, immediately adjacent to the uterus and ovaries. From that position, the sound waves travel a very short distance to reach the target organs, producing images that are far more detailed and precise than what an abdominal probe can achieve from outside the body.
An abdominal probe has to transmit sound waves through layers of skin, fat, and muscle before reaching the reproductive organs. This reduces resolution, particularly in women with a higher BMI or in early pregnancy when structures are very small. The transvaginal approach eliminates those barriers entirely. For measuring follicle sizes during IVF stimulation, where accuracy down to individual millimeters determines the timing of the trigger shot, transvaginal ultrasound is the clinical standard.
What Is a Vaginal Ultrasound Used For?
A vaginal ultrasound is used across a wide range of clinical situations, both in general gynaecology and in fertility care specifically.
In General Gynaecological Care
Doctors request a vaginal ultrasound to investigate or monitor the following:
Pelvic pain. When a woman experiences unexplained pain in the lower abdomen or pelvis, a transvaginal scan helps identify the cause, including ovarian cysts, fibroids, endometriosis, or pelvic inflammatory disease.
Abnormal uterine bleeding. Irregular, heavy, or postmenopausal bleeding often prompts a transvaginal scan to check the uterine lining for polyps, fibroids, or thickening that may indicate endometrial abnormality.
Ovarian cysts. Cysts identified on examination or through symptoms can be assessed for size, structure, and whether they are likely to resolve on their own or require further investigation.
Uterine fibroids. The location, size, and number of fibroids within or around the uterus are mapped with transvaginal ultrasound to guide treatment decisions.
Endometriosis assessment. Transvaginal ultrasound can detect ovarian endometriomas (chocolate cysts) and deep infiltrating endometriosis affecting the uterosacral ligaments and posterior compartment.
Ectopic pregnancy. When pregnancy is confirmed but the embryo’s location is uncertain, a transvaginal scan determines whether implantation has occurred inside or outside the uterus. This is a clinical emergency when ectopic pregnancy is suspected.
IUD placement check. An intrauterine device can be confirmed in the correct position, or investigated if a woman reports symptoms suggesting displacement.
Early pregnancy monitoring. A transvaginal ultrasound can confirm a gestational sac and fetal heartbeat from approximately 5 to 6 weeks of pregnancy, earlier and more reliably than an abdominal scan.
In Fertility Treatment and IVF Care
A transvaginal ultrasound is used at multiple points throughout an IVF cycle. According to StatPearls at NCBI, the key roles of ultrasound in fertility care include:
Baseline assessment. At the start of a cycle, typically on days 2 to 5 of the menstrual period, a baseline scan checks that the uterus is normal, that the ovaries are quiet with no residual cysts, and measures the antral follicle count (AFC), which estimates how many follicles are available for stimulation.
Ovarian stimulation monitoring. During the stimulation phase of IVF, most patients have two to five transvaginal scans spaced two to three days apart. The doctor tracks the number and size of growing follicles. In a stimulated cycle, follicles typically grow at approximately 1.7 to 2.0 mm per day. When the leading follicles reach 17 to 20 mm in diameter, the trigger injection is timed.
Endometrial thickness assessment. The uterine lining must reach an adequate thickness, generally at least 7 mm and ideally in a trilaminar (triple-line) pattern, to support embryo implantation. The transvaginal scan measures this precisely before embryo transfer is scheduled.
Egg retrieval guidance. The egg retrieval procedure is guided by real-time transvaginal ultrasound, allowing the doctor to visualize each follicle and direct the needle precisely.
Embryo transfer guidance. Abdominal ultrasound is typically used alongside the transfer to confirm catheter placement in the uterus, but transvaginal monitoring throughout the cycle has established the timing and lining readiness beforehand.
Early pregnancy confirmation. After a positive pregnancy test, the first ultrasound to confirm the pregnancy is growing in the correct location and that a heartbeat is present is done transvaginally.
How the Procedure Works: Step by Step
Understanding exactly what happens during a vaginal ultrasound removes much of the anxiety that comes from not knowing. The procedure is routine and takes 15 to 30 minutes from start to finish.
Before the scan. For a transvaginal ultrasound, you do not need a full bladder. In fact, an empty bladder gives a clearer view. Remove your lower clothing and underwear, and you will be given a sheet or gown to cover yourself. If you are menstruating, you do not need to reschedule. The scan can be done during your period and in many fertility contexts is specifically timed to occur during your cycle.
Positioning. You lie on your back on an examination table with your knees bent, similar to the position used for a pelvic examination or cervical smear. Your feet may rest in stirrups or simply lie flat on the table.
The probe. The transvaginal probe (transducer) is shaped like a thin wand, approximately the width of two fingers at its widest point, significantly narrower than a speculum. It is less than 1.5 inches in diameter at the tip. The probe is covered with a protective sheath (similar to a condom) and coated with lubricating gel before insertion.
Insertion. The doctor or sonographer gently inserts the probe approximately two to three inches into the vagina. You may be offered the option to insert it yourself if you prefer. Once in place, the probe is slowly angled and rotated to bring each organ into view. The entire imaging phase takes only a few minutes, though the full appointment including preparation and documentation takes 15 to 30 minutes.
During the scan. Real-time images appear on a monitor. In many clinics, you can see the screen as well. The sonographer will measure structures on-screen. If Doppler imaging is used to assess blood flow, you may hear a rhythmic sound.
After the scan. There is no recovery period. You can dress immediately and return to normal activities. There are no documented adverse biological effects on patients from the ultrasound intensity levels used in diagnostic scanning. Some women notice a small amount of gel or light spotting afterward, particularly during early pregnancy when the cervix has increased blood supply. This is normal.
Is a Vaginal Ultrasound Painful?
The direct answer is: no, a transvaginal ultrasound is not painful for most women.
Medical News Today, reviewed by a PA-C and updated in July 2024, states that transvaginal ultrasounds typically do not cause pain. Most women feel a sensation of mild pressure when the probe is inserted or repositioned, which is brief and passes quickly. MedlinePlus describes it as “mildly uncomfortable but will not hurt.”
Research published in the Australasian Journal of Ultrasound Medicine found that pain levels with transvaginal ultrasound are typically low. However, the same research noted that only 40% of women who do experience discomfort report it to the sonographer at the time. This matters because if anything feels uncomfortable, saying so allows the operator to adjust the probe position, reduce pressure, or pause briefly. You have the right to stop the procedure at any time.
Factors that may increase the likelihood of discomfort include:
Pelvic pain conditions. Women with endometriosis, pelvic inflammatory disease, or ovarian cysts that are close to the probe pathway may feel more sensitivity during the scan.
Anxiety and tension. Muscular tension in the pelvic floor, which is a natural physical response to anxiety, can make any pelvic procedure feel more uncomfortable. Slow breathing and consciously relaxing the pelvic muscles before and during insertion can make a real difference.
Position of the uterus. A retroverted (tilted backward) uterus may require the probe to be angled more, which some women notice as pressure in a different area than expected.
Previous experiences. Women who have experienced difficult pelvic examinations, sexual trauma, or vaginismus may find the procedure emotionally or physically challenging. Telling your doctor or sonographer in advance allows them to take extra time, go more slowly, and ensure you feel as comfortable as possible throughout.
In fertility clinics, where transvaginal scans are performed frequently across a treatment cycle, staff perform these procedures daily and understand that comfort and dignity matter. You are always entitled to have a chaperone present, to pause the procedure, or to ask questions at any point.
Is a Vaginal Ultrasound Safe?
Yes. Ultrasound uses high-frequency sound waves, not radiation. Unlike X-rays or CT scans, it involves no ionizing radiation. A 2024 review published in PMC confirms that there are no clinical reports of adverse effects from diagnostic ultrasound on pregnant women or their fetuses. Johns Hopkins Medicine confirms there are no documented adverse biological effects from diagnostic ultrasound at the intensity levels used clinically.
The probe is covered with a sterile sheath for each patient, and fresh gel is applied each time. If you have a latex allergy, let your clinic know before the procedure so they can use a latex-free sheath.
There is no evidence that transvaginal ultrasound causes miscarriage, harms embryos, or damages any reproductive tissue. For women going through IVF, where several scans may be needed across a single cycle, the repeated use of transvaginal ultrasound is well established as safe and clinically necessary. The information gathered at each scan directly guides treatment decisions: medication doses, trigger timing, and transfer scheduling all depend on the measurements obtained.
Vaginal Ultrasound Versus Abdominal Ultrasound: Which Is Better?
Neither is universally better. They serve different purposes and are often used together.
| Feature | Vaginal (Transvaginal) Ultrasound | Abdominal Ultrasound |
|---|---|---|
| Image quality for pelvic organs | Higher resolution, clearer detail | Lower resolution for deep pelvic structures |
| Bladder preparation needed | Empty bladder preferred | Full bladder often needed |
| Comfort | Mild internal pressure | Comfortable, external probe only |
| Best for | Early pregnancy, fertility monitoring, ovarian and uterine detail | Later pregnancy, larger structures, embryo transfer guidance |
| Radiation | None | None |
In early pregnancy and throughout IVF stimulation cycles, the transvaginal approach is the clinical preference because of its superior image quality for the specific structures being assessed. In later pregnancy, when the uterus and fetus are large enough to be imaged from outside, abdominal ultrasound becomes the primary tool.
Related Question About Vaginal Ultrasound
Does a vaginal ultrasound hurt?
For most women, no. The procedure causes mild pressure or discomfort when the probe is inserted or repositioned, similar in feeling to a pelvic examination. It is not painful. If you feel significant discomfort at any point, tell the sonographer immediately so they can adjust or pause.
Do I need to shave or prepare in any special way?
No. Your normal grooming is perfectly fine. You do not need to shave before a vaginal ultrasound.
Can I have a vaginal ultrasound while on my period?
Yes, and in fertility monitoring it is often specifically performed during the early days of your period. The presence of menstrual bleeding does not interfere with the scan or cause any clinical concern.
Is a vaginal ultrasound safe during early pregnancy?
Yes. Ultrasound uses sound waves, not radiation, and there is no evidence it harms the embryo, fetus, or mother at any stage of pregnancy. It is actually the preferred imaging method in early pregnancy because it provides clearer images than an abdominal scan at that stage.
How many vaginal ultrasounds will I need during IVF?
Most patients have two to five transvaginal scans during the ovarian stimulation phase alone, spaced every two to three days. Additional scans may be done at baseline and after embryo transfer. The exact number depends on how your ovaries respond to stimulation and the decisions your doctor makes at each monitoring visit.
Can I insert the probe myself?
Yes. Most clinics offer you the option to insert the transvaginal probe yourself if you prefer. Many women find this makes the experience feel more comfortable and within their control. Your sonographer will guide you on how to position it correctly.
What does the doctor look for on a vaginal ultrasound before IVF?
The key measurements are the antral follicle count (number of small follicles in each ovary, an indicator of ovarian reserve), any structural abnormalities in the uterus, baseline ovarian appearance, and endometrial thickness. During stimulation, the main focus shifts to tracking follicle growth and uterine lining development.
Will I get results immediately?
In most fertility clinic settings, the doctor or sonographer interprets the images in real time and can tell you what they are seeing during the appointment itself. If the scan is performed at a diagnostic imaging center, a radiologist reviews the images and sends a formal report to your referring doctor, which may take one to two days.
