Pelvic ultrasound in gynaecology: technique and indications
In brief
Pelvic ultrasound is the basic imaging test in gynaecology: it uses sound waves, not X-rays, to show the womb, its lining (endometrium) and the ovaries. It is mostly done through the vagina (transvaginal ultrasound), which is more precise, and sometimes through the abdomen (transabdominal route). Painless and quick, it is the first test used to investigate pain, bleeding, a cyst or a fibroid.
What is a pelvic ultrasound?
Ultrasound is an imaging test that uses sound waves: a probe sends out waves that bounce off the organs and create a real-time image. It does not use X-rays and can be repeated safely.
In gynaecology, it shows the womb (its muscle, the myometrium, and its lining, the endometrium), the ovaries and, indirectly, the fallopian tubes when they are abnormal. It is the first-line imaging test in gynaecology; it is also used to plan a possible operation (see Gynaecological surgery).
Transvaginal or abdominal ultrasound: what is the difference?
| Transvaginal scan | Transabdominal (suprapubic) scan | |
|---|---|---|
| How it works | A slim probe, covered with a sheath and gel, is inserted into the vagina | The probe is placed on the lower abdomen, above the pubic bone, with gel |
| Precision | Very good, because the probe is close to the womb and ovaries | Broader view, less detailed |
| Bladder | Empty | Often full, to act as an acoustic window |
| Preferred situations | Most gynaecological scans | Patients who have never had sex, who decline or find the vaginal route painful, a large womb or a large mass |
The two routes are often combined: the vaginal route for detail, the abdominal route for an overview of the pelvis. The choice is always explained to you, and your consent is asked before a transvaginal scan.
When is a pelvic ultrasound needed?
Examining the ovaries
The ovaries are hard to feel during an examination: ultrasound is the first-line test when an ovarian problem is suspected. It distinguishes a fluid-filled structure, which most often suggests a functional cyst or a benign organic cyst, from a solid or mixed mass, which needs further assessment. The 2021 European ESGO, ISUOG, IOTA and ESGE consensus stresses assessment by an experienced sonographer and the use of standardised rules and models to estimate the risk of cancer. See our article on benign ovarian cysts.
Examining the womb
- Fibroids: number, size and location, giving a useful map before any treatment.
- Endometrium: thickness and appearance, interpreted according to the point in the cycle and hormonal status.
- Malformations: septate uterus, bicornuate uterus, etc.
- Coil (IUD): checking its position.
Investigating symptoms
- Pelvic pain, sudden or long-standing (see lower abdominal pain).
- Heavy periods, bleeding between periods or after the menopause.
- Suspected endometriosis, as a first-line test.
- Early pregnancy: location and viability, especially to rule out an ectopic pregnancy.
Supporting fertility treatment
During ovarian stimulation or in vitro fertilisation (IVF), ultrasound tracks the growth of the follicles and guides egg collection. It is also used to count follicles at the start of the cycle, one element of the ovarian reserve assessment.
How do I prepare for a pelvic ultrasound?
- For a transvaginal scan: come with an empty bladder. No fasting is needed.
- For an abdominal scan: you are often asked to drink before the test and not to pass urine, so that your bladder is full. Follow the instructions given when you book.
- Timing in the cycle: depending on the question, the doctor may ask for a specific date, for example early in the cycle to assess the endometrium or count follicles. Otherwise, the scan can be done at any time, including during your period.
- Bring your previous scans, reports and test results, so that changes can be compared.
- Practical arrangements at the practice: appointments can be booked on Doctolib or on 01 43 79 59 79, with an average wait of one week to 10 days, except during holiday periods.
What happens during a pelvic ultrasound?
You lie on your back, with your knees bent and apart for the transvaginal route. The probe, covered with a single-use sheath and gel, is inserted gently; it is slimmer than a speculum. The doctor moves the probe to examine each organ and takes measurements. Light pressure may be applied to your abdomen to bring the ovaries closer to the probe.
The scan is painless in the vast majority of cases, and sometimes slightly uncomfortable if you have endometriosis or an infection. It takes a few minutes. The results are explained to you at the end of the scan and you are given a report.
How do I understand my ultrasound report?
The report uses technical terms. Here are the most common ones:
| Term | Meaning |
|---|---|
| Anteverted or retroverted uterus | The womb tilts forwards or backwards; both are normal variants |
| Endometrium (thickness in mm) | Lining of the womb; its thickness varies with the cycle, contraception and menopause |
| Homogeneous myometrium | Womb muscle with no visible abnormality |
| Myoma or fibroid (FIGO type) | Benign tumour of the muscle; the classification describes its position relative to the cavity |
| Follicles | Small, normal fluid-filled sacs in the ovary that contain the eggs |
| Functional cyst | A cyst linked to the cycle, which usually disappears on its own |
| Anechoic area | A black area on the screen, meaning it contains fluid |
| Fluid in the pouch of Douglas | A little fluid behind the womb, often normal after ovulation |
If a term worries you, ask for an explanation at your appointment.
What can a pelvic ultrasound miss?
Its main limitations are:
- Small lesions inside the womb cavity: polyps, small submucosal fibroids or adhesions may be missed. A 2020 meta-analysis found a sensitivity for polyps of 55% for transvaginal ultrasound alone, compared with 92% for saline infusion sonography.
- Adenomyosis: ultrasound can suggest it, but MRI is sometimes needed.
- Deep endometriosis: detection depends heavily on the sonographer's experience; an MRI can add information.
- Indeterminate ovarian masses: some of them need an MRI to clarify the risk.
- Technical conditions: excess weight, bowel gas or scars can make the abdominal route harder.
The result is interpreted alongside your symptoms and the clinical examination.
When do I need an urgent pelvic ultrasound?
Some symptoms call for a consultation and an ultrasound without delay:
- sudden, severe pelvic pain, especially on one side, which may suggest ovarian torsion or a ruptured cyst;
- pain or bleeding in early pregnancy, with a risk of ectopic pregnancy;
- fever with pelvic pain;
- very heavy bleeding, with feeling faint.
If you feel faint, have unbearable pain or heavy bleeding, call 15 or 112 in France, or your local emergency number, or go to a gynaecological emergency department.
Frequently asked questions
Is a transvaginal ultrasound painful?
As a rule, no. The probe is slim and lubricated. Some discomfort is possible with endometriosis or an infection; mention it and the doctor will adapt.
Can I have a pelvic ultrasound during my period?
Yes. Your period does not prevent the scan. However, the doctor may prefer a specific point in the cycle depending on the question, for example to measure the endometrium.
Can an ultrasound detect ovarian cancer?
It can detect a mass on the ovary and estimate its risk of being cancerous. However, it is not recommended as routine screening for women without symptoms, and a definite diagnosis relies on tissue analysis.
Can I have a pelvic ultrasound if I have never had sex?
Yes, through the abdomen with a full bladder. This route is less precise, but it is often enough to answer the question asked.
Do I need a full bladder for a pelvic ultrasound?
Only for the abdominal route: you are often asked to drink before the scan and not to empty your bladder. For a transvaginal ultrasound, come with an empty bladder instead. Follow the instructions given when you book.
References
- Timmerman D, et al. ESGO/ISUOG/IOTA/ESGE Consensus Statement on pre-operative diagnosis of ovarian tumors. Int J Gynecol Cancer, 2021. doi:10.1136/ijgc-2021-002565 — PMID 34112736
- Sanin-Ramirez D, et al. Two-dimensional transvaginal sonography vs saline contrast sonohysterography for diagnosing endometrial polyps: systematic review and meta-analysis. Ultrasound Obstet Gynecol, 2020. doi:10.1002/uog.22161 — PMID 32730635
- Brun JL, et al. Management of women with abnormal uterine bleeding: Clinical practice guidelines of the French National College of Gynaecologists and Obstetricians (CNGOF). Eur J Obstet Gynecol Reprod Biol, 2023. doi:10.1016/j.ejogrb.2023.07.001 — PMID 37499278
Dr Olivier KadochObstetrician-gynaecologist and gynaecological surgeon in Paris (16th and 5th arrondissements). Former chef de clinique-assistant (senior registrar) at the Paris public hospitals (AP-HP); individually accredited by the French National Authority for Health (HAS). RPPS 10003957809. Background and practice locations
A question about your situation?Appointments at the practice or by video consultation, usually within one week to 10 days.
Book an appointmentGeneral information article: it does not replace a medical consultation. In an emergency, call 15 or 112 in France, or your local emergency number.