Abdomen and Pelvis Scan

An abdomen and pelvis scan is not a single test. The phrase can mean an ultrasound, a CT scan, or an MRI, and the three work in very different ways, need different preparation, and carry different considerations around radiation. This guide helps you work out which scan you have been booked for, what each one involves, and what the results are used for, so you can walk in knowing what to expect.

First, work out which scan you are having

The single most useful thing you can do is read your appointment letter or referral carefully. The type of scan is usually named there, and the preparation instructions are a strong clue. If it mentions drinking water for a full bladder and no mention of radiation, it is likely an ultrasound. If it mentions a contrast injection, dye, or a dose of radiation, it is likely a CT. If it mentions a long time in a tunnel-shaped machine, removing all metal, and loud noises, it is likely an MRI. When in doubt, phone the imaging department and ask.

Each option answers slightly different questions, which is why a doctor chooses one over another. Below we walk through all three so you can match your booking to the right description.

Abdomen and pelvis ultrasound

Ultrasound uses sound waves to build real-time images and is often the first test for abdominal and pelvic symptoms. It looks at organs such as the liver, gallbladder, kidneys, spleen, bladder, and the pelvic organs. Preparation commonly involves fasting for the abdominal views and a full bladder for the pelvic views. It is painless, uses no radiation, and usually takes 20 to 45 minutes. Our dedicated explainer on the ultrasound of the abdomen and pelvis covers this option in full, and the broader guide to diagnostic ultrasound explains the technology.

CT scan of the abdomen and pelvis

A CT scan uses X-rays and a computer to produce detailed cross-sectional images. It is fast and excellent for many questions, including trauma, suspected appendicitis, kidney stones, and staging some conditions. A CT of the abdomen and pelvis often involves an oral contrast drink, an injected contrast dye, or both, and you may be asked to fast beforehand. Unlike ultrasound and MRI, CT uses ionising radiation, so doctors weigh the benefit against the small dose and reserve it for when its detail is needed. Our explainers on the CT scan of the abdomen and pelvis and CT scans in general go deeper.

MRI of the abdomen and pelvis

An MRI uses a strong magnetic field and radio waves, not radiation, to create very detailed soft-tissue images. It is often chosen to characterise a finding seen on another scan, to assess the liver, pelvis, or bowel in detail, or when repeated imaging without radiation is preferable. An MRI takes longer, requires you to lie still in a tunnel-shaped scanner, is noisy, and demands that all metal is removed. Some MRI scans use a contrast agent. Our MRI scan guide describes the experience and the safety checks in detail.

How the three compare

No single scan is best for everything. In broad terms:

• Ultrasound: no radiation, widely available, great first look, but limited by gas and body habitus.
• CT: fast and highly detailed, ideal in emergencies, but uses radiation and often contrast.
• MRI: no radiation and superb soft-tissue detail, but slower, noisier, and not suitable for everyone with certain implants.

Your doctor picks the test that best answers the clinical question with the least downside. Sometimes more than one is used over time, for example an ultrasound first, then a CT or MRI to clarify a finding. If you are comparing places to have a scan, our guides to a diagnostic center near you and radiology services near you explain what to check.

Preparing for your scan

Because preparation depends entirely on the scan type, follow your own instructions rather than general advice from friends or the internet. As a rough guide:

• Fasting may be needed for ultrasound, CT with contrast, or some MRI scans.
• A full bladder is often requested for pelvic ultrasound.
• Contrast for CT or MRI may require a kidney function blood test first and a check for allergies.
• Metal and implants must be declared before an MRI, and pregnancy must be declared before any CT or X-ray.

Understanding the results

Whichever scan you have, a radiologist reviews the images and writes a report for the doctor who referred you. Results are rarely given during the appointment, and the staff performing the scan are usually not the ones who issue the interpretation. The report describes what was seen and whether anything needs further tests, but it is your doctor who explains what it means for you, alongside your symptoms and other results.

Please do not try to diagnose yourself from the scan name, the images, or an offhand remark during the test. A finding can sound alarming out of context and turn out to be minor, and a normal scan does not exclude every possible condition. The RadiologyInfo abdominal imaging resources are a reliable place to read more, and the NHS CT scan page explains radiation considerations plainly.

Frequently asked questions

Is an abdomen and pelvis scan an ultrasound, CT, or MRI?

It can be any of the three. The phrase describes the body regions being examined, not the technology. Check your appointment letter, which names the scan type and gives preparation instructions, or phone the imaging department to confirm.

Which abdomen and pelvis scan uses radiation?

CT uses ionising radiation because it is based on X-rays. Ultrasound uses sound waves and MRI uses a magnetic field and radio waves, so neither of those uses ionising radiation. Doctors choose CT when its speed and detail are genuinely needed and weigh the small dose against the benefit.

Do I need to fast or have a full bladder?

It depends on the scan. Fasting may be needed for ultrasound or a contrast CT, and a full bladder is often requested for pelvic ultrasound. Follow the exact instructions on your appointment letter and call the department if anything is unclear.

Should I mention pregnancy before my scan?

Yes, always. Tell the imaging team before any CT or X-ray if you are or might be pregnant. They will decide whether the scan is still appropriate or whether an alternative without radiation, such as ultrasound or MRI, is better for you.

When and how will I get the results?

A radiologist reviews the images and sends a report to your referring doctor, who explains it in the context of your symptoms and other tests. Results are usually not given on the day. If you have not heard back within the expected time, contact the referring clinic.