Most people begin by seeing their GP when they have symptoms. Your GP will examine you and may arrange for you to have some tests or x-rays. You may be referred to hospital for these tests and for specialist advice and treatment. At the hospital, the doctor will take your medical history and occupational history before doing a physical examination.

A chest x-ray will be taken to check for any abnormalities in your lungs, such as thickening of the pleura or fluid around the lungs. However, there can be other causes of thickening of the pleura and peritoneum (and fluid around the lungs or in the abdomen) apart from mesothelioma.

The following tests may also be needed to diagnose mesothelioma, and your doctor may arrange for you to have one or more of them at the hospital.

A CT scan (computerised tomography scan) takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. The scan is painless but takes from 10 to 30 minutes. CT scans use a small amount of radiation, which will be very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan.

CT scans of the chest and of the abdomen will show the size and position of the mesothelioma and whether it has spread to other parts of the body.

You may be given a drink or injection of a dye that allows particular areas of your body to be seen more clearly. For a few minutes, this may make you feel hot all over. If you are allergic to iodine, or have asthma, you could have a more serious reaction to the injection, so it is important to let your doctor know beforehand.

You will probably be able to go home as soon as the scan is over.

If there is fluid in your chest or abdomen, the doctor can take a sample by using a local anaesthetic and passing a needle through the skin into the fluid. Some of the fluid is then drawn off into a syringe and can be analysed in the laboratory to look for mesothelioma cells.

Taking fluid from between the pleura is known as a pleural aspiration and taking fluid from the abdomen is known as drainage of ascites (or peritoneal aspiration).

If you need a biopsy, your doctor will take a sample of tissue from the thickened pleura or peritoneum. A local anaesthetic is used to numb the area and a special type of needle is passed through the skin into the tumour. The needle has a tip that can cut out a sample of the tumour. The doctor may use ultrasound or a CT scanner to position the needle accurately. An ultrasound uses sound waves to build up a picture of the organs in a part of the body. A small device is passed over the skin to show the doctor where the tumour is and guide the needle into the right place.

Sometimes the doctor will want to look at the area of the pleura or the peritoneum directly to get a sample of tissue from the right area. This is done by using a thin flexible tube with a light and camera at the end. The tube (endoscope) can be passed through the skin of the chest, where it is called thoracoscopy, or the abdomen, where it is called laparoscopy. The procedure is done under a general anaesthetic by a surgeon. You will usually be able to go home the same day.

Your doctors may want to check for any signs of spread of the cancer to the nearby lymph glands in the centre of the chest. This central area, around the lower part of the windpipe, is called the mediastinum and the lymph glands which are found there are the mediastinal lymph nodes. This test is called a mediastinoscopy. The test is done under a general anaesthetic and will mean a short stay in hospital. A small cut is made through the skin at the base of the neck. A tube, like a small telescope, is passed into the chest through the hole created by the cut. The doctor can use this tube to examine the area. Samples can be taken for examination under a microscope.

Analysing the biopsy in the laboratory is the only way your doctors can make the diagnosis of mesothelioma. Sometimes, even after taking a biopsy, the doctors may not be sure of the diagnosis, because mesothelioma can be very difficult to distinguish from other illnesses. In this situation, the biopsy samples may be sent to other laboratories to confirm the diagnosis, some of your tests may need to be repeated or you may be referred to another hospital for a second opinion.

It will probably take several days for the results of your tests to be ready and a follow-up appointment will be arranged for you before you go home. This waiting period is likely to be an anxious time for you and it may help to talk things over with a close friend or relative. You may want to ring our cancer support service to ask any questions you may have.