Smear for malignant cells test

A smear test may be performed as a screening or diagnostic test:

• Screening test: A screening test helps in determining the presence of a particular disease before the onset of symptoms. It does not prove that the disease is present, but it helps in predicting the occurrence of disease. If a screening test is positive, then doctors further order a diagnostic test. Cytology tests such as Pap smear are mainly used for screening.
• Diagnostic test: A diagnostic test helps to identify and classify a disease correctly. People who show signs and symptoms of a disease are asked to get these tests. For example, women who have a suspicious lump in their breast are advised a fine needle aspiration, which can be used to diagnose breast cancer. 

Consult your doctor if you need special preparations before the test as they will be based on the location of the tissue sample to be collected. For example, if you have to undergo a fine needle aspiration, you will need to sign consent before going for the procedure.

A tissue sample for this test can be obtained by different techniques such as scraping or brushing, surgical biopsy, or fine-needle aspiration depending upon the location of the suspected cancer.

Some of these methods are explained below:

• Cytology tests on body fluids: Body fluids from cavities in the body can be isolated by various procedures such as:
  • Pericardial fluid (fluid from the sac that surrounds the heart) can be withdrawn by inserting a needle through the ribs.
  • Spinal fluid, also known as cerebrospinal fluid or CSF (fluid from the space surrounding the brain and spinal cord) is isolated through a spinal tap.
  • Pleural fluid (fluid from the space around the lungs) - through thoracentesis, inserting a thin needle through your chest
  • Ascitic fluid also called ascites or peritoneal fluid (fluid from the belly) is collected by inserting a needle into the abdomen.
  • Sputum 
  • Urine
• Fine needle aspiration: This procedure is used to collect samples of tissues, fluids or cells. A doctor or lab technician will clean the area to be biopsied with alcohol and numb it with a local anaesthetic. He/she will insert a needle into the tissue and apply suction to collect a tissue sample. Once the required amount of sample is obtained, the technician will remove the needle and send the sample for evaluation.
• Brush/scrape cytology test: In this technique, cells from tissues or organs are scraped or brushed to obtain tissue for testing. For example, a Pap smear test is done by the scraping technique, in which a small brush or a spatula is used to scrape cells from the cervix.

Normal results:

A negative test result indicates that no cellular abnormality was found in the tested sample and that the cells are of normal size and shape and are arranged normally for that body part.

However, a normal cytological result does not eliminate the possibility of cancer.

Abnormal results:

A positive or abnormal result indicates that the cells in the given sample had characteristics different from normal cells in that tissue. Cancer cells can be smaller or larger than normal; their shape may be distorted. The nucleus of the cell (an organelle present inside the cell) may be larger and darker, and the arrangement of the cells could also be different than that of normal cells.

Your doctor will identify the type of cancer, based on which type of normal cells your cells resemble. For example, cancers in which the cells resemble fat or bone tissues are called liposarcomas and osteosarcomas, respectively. Your doctor will also grade the cancer based on how closely they look like normal cells. Cancers that do not look much like normal cells are high grade, while cancers in which the cells look more like normal tissues are classified as low-grade cancers.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.