What is a rectal examination?
It is an examination where the doctor puts a finger inside the rectum to feel if there is any abnormality. The Latin word for finger is digitus, so it is also called a digital rectal examination or DRE.
The rectum is the last (or distal) part of the large bowel (colon) through which solid waste (stools or faeces) pass to the outside of the body. The distal colon has an S-shaped part (the sigmoid, from the Greek word for the letter S) which passes on to the rectum (from the Latin word rectus, straight). The opening of the rectum on the outside is called the anus. This is surrounded by a ring of smooth muscle (the anal sphincter) which keeps it closed. When the rectum becomes filled with faeces, the person can choose to relax the anal sphincter, then the smooth muscles of the rectum contract automatically, forcing the stools to the outside (defecation).
Why is rectal examination performed?
Rectal examination involves looking at the area around the anus to see if there are any abnormalities, for example haemorrhoids, which are enlarged or dilated veins (varicose veins) of the lower rectum. With the finger placed through the anus the doctor feels if there is any abnormality inside the rectum or in the prostate gland, which is located below the bladder neck just in front of the rectum.
There are mainly three reasons for performing a DRE:
- Complaints (symptoms) that raise suspicion of a bowel problem.
- Symptoms suggesting a prostate problem.
- In men over the age of 50, without any symptoms, to feel if there is cancer in the prostate.
Complaints suggesting a bowel problem include
- passing blood from the rectum (haematochezia),
- pain on defecation,
- infrequent and difficult passing of stools (constipation),
- frequently passing loose or watery stools (diarrhoea),
- pain in the stomach,
- not wanting to eat (anorexia),
- nausea, vomiting and loss of weight.
Symptoms suggesting a prostate problem include
- passing urine very often during the day (frequency) and night (nocturia),
- feeling a great urge to pass urine immediately when the bladder is full (urgency),
- having to wait long before the urine stream starts (hesitancy),
- pushing or straining to pass urine,
- a weak urinary stream (stranguria),
- stopping and starting of the stream (intermittency),
- a feeling that the bladder is not empty after urination,
- involuntary passing of urine (incontinence),
- pain during urination (dysuria) and
- blood in the urine (haematuria).
Prostate cancer is one of the most common types of cancer in men over the age of 50, and the risk of developing prostate cancer increases rapidly with age. Early stage prostate cancer does not cause any symptoms, and the easiest way to detect it is with DRE.
How is a rectal examination performed?
The doctor should tell you if a rectal examination is necessary, using words such as "I have to examine your back passage" or "I have to feel your prostate". The doctor will usually ask you to turn over on your left or right side, rest your head on a pillow, bend your hips and draw your knees up against your belly, so that you are lying in a curled-up position.
DRE can also be performed in other positions, depending on the doctor's preference. You may be asked to lie on your back, draw your knees up and open your thighs, or you may be asked to turn over on your knees and elbows on the examining table, or you may be asked to stand up and bend forwards over the table, resting on your elbows.
The doctor may touch your buttocks to open them in order to inspect the area around the anus. The doctor puts a glove on and smears lubricating jelly on the index finger, which is then inserted through the anus into the rectum. You may be asked to relax completely, to breathe in and out deeply, or to push down like when you are passing a stool. Usually the doctor will insert the finger quite slowly, giving the anal sphincter time to relax.
After feeling the prostate and the inside of the rectum, the doctor removes the finger and looks to see if there is any blood on the glove. He may also test the faeces sticking to the gloved finger with a test strip to see if it contains blood which is not visible (occult blood). The doctor will then usually wipe the anal opening with a piece of paper, or give you some paper and ask you to wipe yourself.
How should I prepare?
Many patients are embarrassed about undergoing a rectal examination, or are afraid that it will be painful. It is important to realize that your doctor has performed this examination many times before, and it is not really different from examining any other part of your body or looking into your mouth or ears. It is also important to realize that when passing a stool, the anal sphincter is able to relax and pass a solid body which is considerably thicker than the doctor's index finger.
It is not necessary to take a laxative or have an enema before a DRE. It is important to relax completely during the examination, and especially to relax the muscles of your buttocks and anal sphincter. When you feel the finger touching your anus, it helps to push down slightly, like when you are passing a stool. Although DRE may be slightly uncomfortable, it should be no more so than passing a stool. It should not be painful, unless there is a problem such as a raw area (fissure) in the anal canal, haemorrhoids which have thrombosed (become clotted) or acute infection of the prostate.
What are the risks?
Apart from embarrassment and slight discomfort, DRE is completely safe and risk-free.
What are the limitations of the procedure?
DRE is not very reliable in detecting early stage prostate cancer, therefore it is necessary to also do a blood test, prostate specific antigen (PSA), which becomes elevated if there is prostate cancer. However, some men have prostate cancer with a low PSA, and in such cases DRE is the only way to find out if they have cancer.
In patients with bowel symptoms, DRE often does not make a definitive diagnosis, but it can rule out conditions such as cancer of the anus or rectum, or detect the presence of occult blood in the stool, which may indicate cancer of the colon. If the diagnosis is still unsure after DRE, further investigations may be necessary.