Many patients come to their appointment wondering which probe will be used, and why. In reality, the choice is not arbitrary at all: it simply depends on the medical question being asked.

The myth

"Gynaecological ultrasound is complicated: you never know which probe will be used, or why."

What the science says

In practice, two main approaches complement each other. The first, known as abdominal or suprapubic ultrasound, involves placing the probe on the tummy with a full bladder. It gives an overall view of the pelvis. The transducer is moved across the abdomen after gel has been applied, and a full bladder creates a window that makes it easier to see the structures beneath or around it. This is often the first step, particularly in late pregnancy.

The second approach, transvaginal ultrasound, uses a thin probe inserted into the vagina. It gets directly closer to the uterus and ovaries, which gives a sharper image. The type of examination chosen depends on the images the doctor needs and the reason for the scan. This approach is now the reference method for examining the pelvis in detail: it is recommended that a pelvic ultrasound be carried out transvaginally unless there are contraindications, such as a patient declining or a patient who has never had vaginal intercourse. In that case, a suprapubic ultrasound is discussed to rule out a differential diagnosis.

The two techniques are therefore not opposites: they are often combined during the same appointment. The 2025 guidelines set out the technical details of the examination, including both a suprapubic stage and a transvaginal stage, in order to obtain a complete view of the pelvis.

Why it matters

Understanding this logic changes everything about how the examination is experienced. It is not chance that dictates which probe is used, but the level of precision needed: a wide view to spot an abnormality, a close-up view to analyse it in detail. This document reaffirms the role of transvaginal ultrasound as the first-line examination for diagnosing pelvic endometriosis, which clearly shows that the probe is adapted to the clinical question, not the other way round. Knowing this can help you approach the examination more calmly, without fearing an incomprehensible or disproportionate procedure.

What to remember

Key takeaway

There is no mystery surrounding ultrasound probes: the choice simply follows the medical question being asked, between an overall view and a close-up one, and the two approaches are often combined during the same examination.

Please do not hesitate to ask any questions about how your ultrasound will be carried out at your next appointment.