CT Scan – Groin

About a CT scan of the groin

The groin is the area where the lower tummy meets the top of the thigh. It contains the inguinal canal (a passage through the tummy wall), the main blood vessels and nerves to the leg, lymph nodes, the hip flexor and adductor muscles, and the pubic bones at the front of the pelvis. A CT (computed tomography) scan uses X-rays and a computer to make detailed cross-section pictures of the area.

Most groin hernias are diagnosed by a doctor examining you, and if a scan is needed, ultrasound is usually the first choice. International hernia guidelines say that MRI or CT may occasionally be needed when the diagnosis is still unclear. A groin CT may be used to look at:

• hernias that are hard to confirm by examination or ultrasound, including less common types such as femoral and obturator hernias, and problems after hernia repair
• lumps in the groin and swollen lymph nodes
• the blood vessels, for example a swelling of an artery (aneurysm or pseudoaneurysm) after a procedure, usually with contrast dye
• fractures of the pubic bones, often after a fall in older people
• collections of fluid or pus (abscesses)

For long-lasting groin pain in active people, such as adductor injuries and “sports hernia” (athletic pubalgia), a groin MRI is usually better, as it shows the muscles and tendons in more detail without radiation. For the hip joint, see hip CT. When you book, choose the left or right side.

What happens during the scan

You lie on your back on the scanner bed, with your arms resting on your chest or above your head. The bed moves through a short, open ring while your lower tummy and groin are scanned. To show a hernia, you may be asked to strain or bear down, as if blowing up a balloon, while some pictures are taken. The radiographer controls the scanner from the next room, but can see, hear and talk to you throughout. The scan itself takes only a few minutes.

For some CT scans, an injection of contrast dye is given through a small cannula in a vein, usually in your arm or hand, to make blood vessels and organs show up more clearly. CT contrast contains iodine. As it goes in you may feel warm and flushed, notice a metallic taste, or feel as if you are passing urine; these feelings pass within a minute or two. Allergic reactions are uncommon, and you may be asked to wait for up to 30 minutes afterwards. Where contrast is needed, it is charged separately.

Is CT safe?

CT uses X-rays, which are a type of ionising radiation. A CT of the groin covers part of the pelvis, so the dose is lower than for a full CT of the abdomen and pelvis (about 10 mSv). Because the reproductive organs are close by, the scan is only done when it is likely to help. The risk from a single scan is very small, and every CT scan is checked by a radiologist or radiographer to make sure the benefit of the scan outweighs the risk, as required by the Ionising Radiation (Medical Exposure) Regulations. If you have had other CT scans recently, tell us when you book.