Abdominal CT with Contrast: What to Expect

Abdominal CT with Contrast: What to Expect During the Scan

An abdominal CT with contrast is used to create highly detailed images of abdominal organs and other tissues within the abdominal cavity. Contrast helps highlight tissue changes in more detail, making them easier to spot than on a CT scan (CAT scan) without contrast.

Here, we’ll explore why you might need an abdominal CT scan with a contrast material, what to expect, how to prepare and what happens after your CT scan.

Understanding an abdominal CT scan with contrast

An abdominal and pelvic CT scan (computed tomography scan) uses X rays and computer technology to create detailed, 3D images of the tissues and organs in your abdomen and pelvis.

The radiation exposure during this imaging test is considered low and generally safe. However, to avoid exposing you to unnecessary radiation, a CT scan will only be recommended if there’s a clinical need.

Purpose and common uses in diagnosis

Contrast material is used during CT imaging to improve image quality and help diagnose conditions more easily.

These medical conditions include bowel conditions, such as appendicitis, colitis, diverticulitis, inflammatory bowel disease and bowel obstructions and perforations.

Abdominal CT with contrast is also useful for detecting tumours, particularly in early stages when they’re small. What’s more, the use of contrast media can help define blood vessels to diagnose conditions such as an abdominal aortic aneurysm, aortic dissection and gastrointestinal bleeding.

How contrast material enhances imaging

The contrast used in a CT imaging test is usually either iodine-based or barium sulphate. Both iodine and barium absorb more X rays.

As a result, when contrast temporarily accumulates in tissues, they absorb more X rays during CT scanning. This causes the tissues to appear brighter and whiter on CT images. This enhanced contrast results in more detailed pictures.

Types of contrast used in abdominal CT scans

Oral contrast versus intravenous (IV) contrast

When contrast dye is needed for an abdominal CT scan, there are 2 options: oral contrast material and intravenous contrast material. They are named according to the method of contrast administration.

IV contrast is given via an injection into a vein, usually in your arm. This feels like a pin prick. Oral contrast is swallowed, usually as a drink.

Oral contrast is used to investigate conditions affecting the gut, such as bowel blockages (intestinal obstruction) and leaks (bowel perforations).

IV contrast is used to investigate a range of medical conditions affecting different organs in the abdomen, not just the gut. This includes inflammation of internal organs such as the pancreas or bowel, infections, growths and blood vessel problems.

How to prepare for an abdominal CT scan with contrast

Fasting guidelines and eating restrictions

If you need to have a contrast dye, you’ll be asked to fast for a certain number of hours before your scan. This means you should not eat or drink anything other than water.

Your care team will tell you how many hours prior to your scan to fast for. If you have diabetes, you’ll have your scan in the morning and will be asked to bring a snack to eat after your scan.

What to expect before your appointment

You’ll be asked to remove any metal objects from your body. This includes hair accessories, piercings, and clothes with metal zips and buttons, including bras with a metal underwire.

You will be asked about your health and given a hospital gown to change into. It’s advisable to wear loose clothing that you can easily change out of.

The scan procedure will be explained to you, and you’ll have the chance to ask any questions. You will then be asked to give your consent to have the scan.

What happens during the abdominal CT scan procedure

Before your scan, you’ll be given a contrast agent. This will either be injected into a vein or you’ll be asked to swallow a drink containing contrast.

Shortly after, you’ll be asked to lie back on a narrow table, which will be slowly slid into the ring part of the CT scanner.

The ring will release beams of X rays into your body. It will then detect the X rays that pass through. Dense tissues or tissues containing contrast absorb more X rays and, therefore, appear brighter and whiter on CT images.

The X-ray signals are sent to a computer and processed to form a grayscale, 2D cross-section through the body – these are called slices. Multiple images in 2D are collected and processed again. They form a detailed 3D image, which can be viewed on a computer monitor.

CT sensations: warm sensation and other effects

If you have IV contrast, you may feel a warm sensation similar to a hot flush as the contrast goes in. You may also feel nauseous, notice a salty or metallic taste in your mouth, and/or develop a brief headache. These effects usually only last a few minutes.

If you have oral contrast, you may have an aftertaste of the contrast in your mouth for a short while. Barium sulphate contrast is a thick, white liquid with a chalky taste. Iodine-based contrast is thinner and has a bitter taste.

Patient safety and considerations with contrast material

If you have an iodine allergy, tell your care team before you attend your scan appointment. Depending on the severity of your allergy, you may not be able to have an iodine-based contrast.

Your care team may be able to use a different contrast. If you have an allergic reaction to one type of contrast, it doesn’t mean you’ll have an allergic reaction to all types of contrast.

Alternatively, they may suggest a different scan or other tests to investigate your symptoms.

Pregnant women can have an abdominal CT scan with contrast if there’s a medical need. However, extra precautions and consent may need to be taken during the scan.

You should avoid contrast if you have poor kidney function, for example, due to chronic kidney disease or other kidney problems. This is because contrast places greater strain on your kidneys.

After your abdominal CT scan with contrast

After your scan, you’ll be asked to remain at the imaging facility for around 30 minutes. This is to make sure you don’t develop an allergic reaction to the contrast. Symptoms include difficulty breathing, sweating and feeling weak.

The vast majority of people don’t develop an allergic reaction, and when it does happen, it’s usually mild and easily treatable.

Over the next 1-2 days, the contrast will pass out of your body in your urine.

At Vista Health, we aim to provide a report of your CT scan results within 3 working days. This will be sent to you via email and can also be sent to your NHS GP.

Alternatively, you can book a private GP consultation with one of our experienced Vista Health GPs who will explain what your results mean for you and any next steps.

Need an abdominal CT scan?

If you have unexplained abdominal symptoms, a private CT scan can help you get definitive answers.

Take the first step to getting the insights you need by booking a private GP consultation with Vista Health. One of our experienced GPs will discuss your symptoms to find out if an abdominal CT scan is appropriate and if contrast is needed.

Alternatively, if you already have a referral letter from a doctor, you can email this to our team. We can then help you book your private abdominal CT scan at one of our nationwide imaging clinics.

If contrast is needed, you will need a recent kidney function blood test, which you can also arrange with Vista Health.