Groin ultrasound: what the scan shows, how it is done and what happens next

An ultrasound scan produces moving pictures of the inside of the body using high-frequency sound waves. The NHS describes it as a way to see images of structures such as muscles, organs or, in pregnancy, a baby in the womb. In the groin, the structures of interest include the muscle and tendon layers of the lower abdominal wall, the canal through which the spermatic cord passes in men, the blood vessels running down to the leg, and the small lymph glands that sit in the crease between the leg and the trunk.

Ultrasound is often the first imaging test chosen for the groin because it is quick, widely available, painless and does not involve ionising radiation. It also allows the person doing the scan to press on the area, ask you to cough or strain and watch the images change in real time, which is useful when a lump comes and goes.

It is a different test from a testicular ultrasound, which focuses on the scrotum and its contents, and from a dedicated hip or pelvic scan. If your symptoms involve the testicles, the request form may ask for the scrotum to be examined as well.

The NHS lists investigating symptoms such as pain or a lump as a common reason for an ultrasound referral. In the groin, the usual triggers are a visible or palpable lump, a dragging or aching feeling, or pain that does not settle. A doctor may also request a scan when an examination was inconclusive, for example when a lump is only seen on standing or coughing.

• A bulge in the groin that may get bigger when you cough, sneeze or strain and smaller when you lie down, which can be a hernia. The NHS notes that a hernia may cause a lump and a heavy, dragging feeling in the leg.

• Tender or swollen lymph glands. The NHS says swollen glands are usually a sign the body is fighting an infection and often settle within 1 to 2 weeks, but glands that are hard, growing or persistent are checked further.

• Persistent groin pain in people who play sport or do physically demanding work, where the question is whether there is a weakness in the abdominal wall or another cause.

• A swelling that might be a fluid collection, a cyst, a vein problem or, less often, a soft-tissue lump needing further tests.

• Pain or swelling after surgery or injury in the region, to look for a collection or other change.

The hospital or clinic should tell you if there is anything you need to do beforehand. For many external scans of the groin, nothing special is required. Some pelvic scans ask you to drink water and arrive with a full bladder, so read the appointment letter carefully because the instructions depend on exactly which areas are being looked at.

You may be asked to remove clothing from the lower half of the body or to move it out of the way, and a gown or paper sheet is often provided. The NHS notes that you can ask for a chaperone, either someone you know or a member of staff, and this is worth remembering because the groin is a sensitive area. You are also in control of the scan and can ask for it to stop at any time.

You will usually lie on a couch while a slippery gel is applied to the skin over the groin. The person scanning, who may be a sonographer or a radiologist, moves a handheld probe across the area and watches the images on a screen. Paper towel is used to protect clothing from the gel, and the lights may be dimmed so the screen is easier to see.

You may be asked to change position, for example to stand up, roll to one side, cough or bear down, because this can make a hernia or a vein problem more obvious. The probe might feel slightly uncomfortable if it is pressed on an area that is already tender, but it should not usually cause pain. Tell the person scanning if you feel pain, and they will help you feel more comfortable.

The NHS says the whole appointment can take around 10 to 45 minutes. When it is finished, you wipe off the gel and get dressed, and most people leave straight away and can carry on with normal activities.

The scan result is a written report describing what was seen. Common findings include the following, and the same appearance can sometimes have more than one cause, which is why the report is read alongside your symptoms.

• A hernia, where tissue or part of the bowel pushes through a weak area in the abdominal wall. The NHS describes inguinal hernias as occurring where the leg joins the abdomen and femoral hernias as occurring in the upper thigh near the groin.

• Enlarged lymph nodes, which may be reactive to an infection nearby or, less commonly, need further investigation.

• A fluid collection, cyst or an enlarged vein.

• Muscle or tendon changes in people with sports-related groin pain.

• No abnormality. This is a useful result in itself, and the next step is then based on your examination and symptoms rather than the scan.

The NHS explains that you may get the result at the end of the appointment, or it can take a few weeks, depending on why you had the scan. The report is sent to the doctor who referred you, and you may need a follow-up appointment to discuss it. If you have not heard anything after a few weeks, the NHS advises contacting the specialist or your GP surgery about the result and what happens next.

What follows depends on the finding. A hernia that is causing symptoms may be referred for surgery, and the NHS notes that an inguinal hernia may not need treatment if it is not causing symptoms. Enlarged glands with an obvious infectious cause may simply be watched. Some findings lead to other tests, such as blood tests, an MRI scan or a biopsy, and the NHS says that sometimes you may need other tests depending on why you had the ultrasound.

A groin lump should not be ignored if it changes quickly. The NHS says to get help from NHS 111 if you have a hernia and you develop pain in or around the hernia, a bloated tummy, feeling or being sick, vomiting blood, constipation, a high temperature or sudden confusion. These can be signs of a trapped or strangulated hernia, which needs prompt assessment and may need emergency treatment.

For swollen glands, the NHS advises seeing a GP if they are getting bigger or have not gone down within 1 week, feel hard or do not move when pressed, come with night sweats or a very high temperature, or occur without any other sign of infection.

On the NHS, a groin ultrasound is normally requested by a GP or hospital doctor after an examination, and the wait depends on how urgent the request is marked and local capacity. Private imaging services also carry out groin ultrasound, and people sometimes use them to shorten the wait. In either setting the scan should be reported by a suitably trained professional, and the report should go to a doctor who can explain it and arrange follow-up.