Abdominal ultrasound scan: preparation, what happens and what it shows

The NHS explains that an ultrasound scan is used to see images of the inside of your body, such as muscles, organs, or a baby in the womb. For the abdomen, Guy’s and St Thomas’ describes it as a widely used diagnostic test to examine the abdominal organs (liver, kidneys, pancreas, gallbladder, spleen and aorta) and soft tissues of the body. It can help find the cause of a problem and can also be used to monitor an existing condition.

The scan is carried out by a sonographer or radiologist, both trained professionals in this type of scan. A probe is moved over the skin, the sound waves bounce back from the organs, and the machine builds a picture from the echoes.

The NHS lists general reasons for an ultrasound referral: to investigate symptoms you have had, such as pain or a lump, to monitor a condition, to help a health professional see inside the body during a procedure, or to check a baby during pregnancy. The Cambridge University Hospitals leaflet adds that the scan may identify the cause of your symptoms or help to rule out conditions that could cause them.

Reasons for an upper abdominal scan can include persistent upper tummy pain, abnormal liver blood tests, jaundice and questions about the gallbladder or kidneys, but the exact reason is decided by the doctor who refers you. You are entitled to ask what the scan is looking for.

Preparation varies slightly between hospitals, so follow your appointment letter. Guy’s and St Thomas’ asks patients to fast for 6 hours before the appointment, not to eat any food, and to drink clear fluids only, avoiding milky drinks, fizzy drinks and alcohol. Cambridge University Hospitals also asks for no food for six hours and clear fluids only (water or squash), explaining that this helps to improve the quality of the images, particularly of the gallbladder.

You can continue to take any medicines prescribed by your doctor, according to Guy’s and St Thomas’. Wear comfortable, loose-fitting clothing. If you have diabetes and fasting will cause problems, contact the department in advance; Guy’s and St Thomas’ says people with type 1 diabetes should have an early morning appointment, and Cambridge asks people to get in touch if they take time-sensitive medicines such as insulin.

Tell the department beforehand if you need extra time, are pregnant, cannot lie flat, need a chaperone, hoist, interpreter or transport. The NHS adds that you can ask for a chaperone, a person you know or a member of staff, to be in the room.

You will lie on a couch with your clothing moved or removed from your abdomen. Paper tissue protects your clothing from the gel, and the lights are dimmed so the screen is easier to see. Gel, which may feel cold, is applied to your skin and a small handheld probe is moved across it.

You may be asked to breathe in and hold your breath several times, or to turn on your side so views can be taken from different angles. The practitioner takes pictures and measurements, may ask about your symptoms and history, and then gives you tissue to wipe off the gel.

Some people feel mild pressure from the probe. The NHS notes that an external probe might be uncomfortable if pressed on an area that is already painful. You are in control and can ask them to stop at any time.

The NHS says the sound waves used in ultrasound scans are safe, and ultrasound does not use any radiation. Guy’s and St Thomas’ describes the scan as very safe with no side effects, and Cambridge notes a very low risk of infection from the gel, reduced by wiping it off thoroughly. You can usually return to normal activities straight afterwards.

Guy’s and St Thomas’ notes that depending on your symptoms another test such as a CT or MRI scan may be suggested, and that another scan may sometimes be needed in addition to the ultrasound.

Guy’s and St Thomas’ says the scan will be reviewed and most often reported on the same day, with the result sent to your doctor. If your GP referred you it suggests booking an appointment about 2 weeks after the scan. Cambridge says results are sent to the referring clinician within approximately 7 to 10 days. The NHS says some results are available at the end of the appointment but it can take a few weeks, and that if you have not heard anything after a few weeks you should contact the specialist or your GP surgery.

A normal scan does not rule out every problem, and an abnormal finding does not always mean serious disease. Your doctor will explain what it means and whether you need other tests, such as blood tests, CT, MRI or endoscopy.

On the NHS, an abdominal ultrasound is requested by a GP or hospital doctor, and waiting times vary by area and urgency. Private imaging centres also offer abdominal ultrasound, which may offer a quicker appointment and a report that you can bring to your GP.

The NHS pages read for this guide do not compare the two routes. Whichever you choose, tell your GP about any private scan result so that it can be considered alongside your symptoms and other tests, and follow the preparation instructions you are given.

A scan appointment is not an emergency pathway. Severe, sudden or worsening tummy pain, vomiting blood, black stools, fainting, a rigid tummy or a high temperature with abdominal pain needs same-day assessment through NHS 111, A&E or 999 rather than waiting for a booked scan.