Peritoneal aspiration is a diagnostic test that takes a sample of fluid from the peritoneum to see if it contains cancer cells.

Inside the tummy (abdomen), there is a membrane called the peritoneum. It has two layers. One layer lines the tummy wall and the other layer covers the organs inside the abdominal cavity. The peritoneum produces a fluid that acts as a lubricant and allows the organs to glide smoothly over one another. Sometimes too much fluid can build up between the two layers, and this is called ascites.

The illustration shows a side view of the tummy, which is also called the abdomen. The person is facing to the left. It shows the internal organs in the tummy, including the liver, the stomach and the bowel. These are surrounded by the peritoneum, which is a thin membrane. The peritoneum has two layers. The outer layer lines the wall of the tummy, and the inner layer covers the internal organs. There is a small space between these layers, called the peritoneal cavity.

Your doctor may take a sample of this fluid to send to the laboratory, to see if it contains cancer cells. This is called a peritoneal aspiration.

You may have an ultrasound scan during the test. Ultrasound uses sound waves to build up a picture of the area. This helps guide the doctor to where the fluid is. Your doctor will give you a local anaesthetic to numb the area first. After this, they pass a needle through your skin into the fluid to take a sample.

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