Obstetric/Gynaecologic Ultrasound

An obstetric/gynaecologic ultrasound (USG) is a scan that uses safe sound waves — not radiation — to produce live images of the uterus (womb), ovaries, and, during pregnancy, the developing baby.

A small handheld device called a transducer sends sound waves into the body. Those waves bounce back from organs and tissues, and a computer turns the echoes into a moving picture on a screen. The doctor can measure structures, watch the baby move, check blood flow through vessels, and spot changes in tissue — all in real time, without any cuts or needles.

Doctors use obstetric/gynaecologic ultrasound both to monitor healthy pregnancies and to investigate symptoms or suspected conditions of the female reproductive system. The scan is requested for a wide range of situations.

• Confirming a pregnancy and checking that it is inside the uterus (not an ectopic pregnancy, where the embryo implants outside the womb)
• Dating the pregnancy and estimating the due date
• Checking fetal (baby's) heartbeat, growth, position, and movements
• Screening for structural differences in the baby, such as neural tube defects (problems with the spine or brain development) or heart abnormalities
• Monitoring the placenta (the organ that feeds the baby) and amniotic fluid (the fluid surrounding the baby)
• Investigating abnormal or heavy periods
• Evaluating pelvic pain or pressure
• Detecting fibroids (non-cancerous growths in or on the uterus), ovarian cysts (fluid-filled sacs on the ovaries), or polyps (small tissue outgrowths inside the uterus)
• Assessing suspected endometriosis (tissue similar to the uterus lining growing outside it)
• Guiding procedures such as egg retrieval for IVF (in vitro fertilisation) or a biopsy (tissue sample)
• Investigating infertility (difficulty conceiving)

There are very few situations where this ultrasound cannot be used. However, the image quality may be limited in patients with a high body-mass index (BMI), or when the bowel contains a lot of gas. In such cases, the doctor may recommend a transvaginal ultrasound (where a slim probe is gently inserted into the vagina to get a closer view) or a different imaging method.

Obstetric/gynaecologic ultrasound is one of the safest imaging methods available. It uses sound waves rather than X-ray radiation, and decades of use in pregnancy have not shown any harm to mothers or babies.

• Mild discomfort during a transvaginal scan (when a probe is used inside the vagina), which usually passes immediately after the probe is removed
• A full bladder required for some abdominal scans can feel uncomfortable to hold during the procedure
• Very rarely, slight spotting (light bleeding) after a transvaginal scan — this usually stops on its own within a short time
• Ultrasound gel used on the skin is water-based and rarely causes skin irritation; it wipes off easily
• In rare cases, the scan may not give a clear enough image, and an additional scan or a different test may be needed

Preparation depends on which type of ultrasound is planned. Your care team will give specific instructions beforehand, but the following are common guidelines.

For an abdominal (over-the-skin) pelvic ultrasound, most hospitals ask the patient to drink several glasses of water and avoid urinating for about an hour before the appointment. A full bladder pushes the uterus and ovaries into a better position for imaging. For a transvaginal ultrasound, the bladder is usually emptied first. Fasting is generally not required for either type, unless the scan is combined with another procedure. There are no restrictions on smoking or alcohol specific to this scan, though standard healthy habits are always encouraged during pregnancy.

Some doctors order blood tests before or around the time of the scan — for example, a beta-hCG (a hormone that confirms pregnancy) blood test, or hormonal tests when investigating menstrual problems or infertility. The ultrasound itself does not require anaesthesia (sedation or sleep medicine).

During the scan, the steps typically follow this order:

• The patient lies on an examination table, usually on their back.
• For an abdominal scan: the sonographer (the specialist who performs the scan) applies a warm gel to the lower abdomen and moves the transducer gently across the skin.
• For a transvaginal scan: the patient is asked to undress from the waist down and bend their knees; a slim, covered probe is gently inserted a short distance into the vagina.
• The doctor or sonographer watches the images on a monitor, takes measurements, and records pictures or short video clips.
• The gel is wiped away, and the patient can dress and, if needed, use the bathroom.
• The whole appointment usually takes between fifteen and forty-five minutes, though complex assessments may take longer.

Because obstetric/gynaecologic ultrasound is non-invasive (nothing cuts the skin) and uses no radiation, there is virtually no recovery period. Most patients return to their normal activities immediately after leaving the appointment.

• No rest period is needed after a standard abdominal scan; the patient can eat, drink, and go about their day straight away.
• After a transvaginal scan, very mild pelvic discomfort or light spotting (faint bleeding) can occasionally occur; this usually settles within a few hours. If bleeding is heavier or pain is significant, the patient should contact their doctor.
• If the bladder was kept full for the scan, the patient can use the bathroom as soon as it is finished.
• The sonographer or radiologist (a doctor who interprets medical images) will analyse the pictures; results are usually discussed with the referring doctor, who will then explain the findings to the patient.
• Follow-up scans may be scheduled — for example, repeat ultrasounds at key stages of pregnancy, or monitoring after treatment for a cyst or fibroid.
• In pregnancy, the doctor will advise on how often further scans are needed based on individual circumstances.
• No wound care, special diet, or medication changes are required specifically because of this scan.