Anorectal ultrasound scan

An ultrasound uses sound waves to build up a picture of the tissues inside your body. An anorectal ultrasound scan takes pictures of your rectum and anus.

A smooth probe the size of a finger is placed in the anus that can use high-frequency sound waves to build up a picture of the layer of tissue beneath the surface of the rectum on a computer screen. Your doctor may do a biopsy (take samples of tissue) during the scan using a small needle attached to the probe.

You may need to have an enema to clear out your back passage before an anorectal scan. This is a liquid-filled pouch with a nozzle on the end. You put the nozzle into your back passage and squeeze so that the liquid goes into your body. 

No.

An anorectal ultrasound can be uncomfortable or may cause you some pain, depending on where the tumour is. You may also feel some discomfort if your doctor takes a tissue sample (biopsy) during the test.

About 20-30 minutes.

You may feel a little sore after the test. There is also a risk of infection if you have a biopsy, so you may be prescribed antibiotics to protect against this.