What is a biopsy?
A biopsy is the removal of a tissue sample. The aim is to discover and diagnose pathological changes in the cells through precise microscopic examination of the sample obtained. A small piece of tissue (less than one centimeter) is sufficient for this. The piece of tissue removed is called a biopsy or biopsy specimen.
The biopsy is used to confirm a suspected diagnosis – for example, if the doctor suspects a certain disease based on blood values or an imaging procedure (such as ultrasound, X-ray, computer tomography).
Minimally invasive or surgical
Minimally invasive procedures are often used for a biopsy, such as
- Fine needle biopsy (fine needle puncture, fine needle aspiration)
- Punch biopsy (punch biopsy)
Stereotactic biopsy is a special type of biopsy that is mainly used to obtain tissue samples from the brain. Tissue (such as from a brain tumor) is removed via a small drill hole in the skull at a location calculated with millimeter precision by computer using imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET).
Surgical biopsy procedures, on the other hand, are incisional biopsy, in which the doctor removes part of the tissue change, and excisional biopsy, in which the entire suspicious area is cut out.
Fine needle biopsy and punch biopsy
A punch biopsy follows the same principle as a fine needle aspiration. However, the doctor uses a coarser hollow needle (more than one millimeter in diameter) and a punching device. A punch biopsy is used, for example, if breast or prostate cancer is suspected. The position of the needle is controlled using imaging techniques (e.g. computer tomography) to avoid damaging neighboring tissue structures as much as possible when removing the tissue.
Vacuum biopsy (vacuum aspiration biopsy)
As only a very small biopsy sample can be obtained with this method, the doctor often cuts out four to five tissue cylinders. The entire biopsy takes about ten minutes and is often performed under local anesthesia or short anesthesia.
When is a biopsy performed?
Biopsies enable the doctor to make a reliable diagnosis about the disease state of an organ. Taking a tissue sample is particularly important in cases of suspected cancer such as:
- Cervical cancer
- lung cancer
- bowel cancer
- skin cancer
- Cancer of the liver and bile ducts
- Prostate cancer
- Breast cancer
Precancerous lesions can also be detected by biopsy. Inflammatory diseases are another area of application. These include
- Vasculitis (inflammation of the blood vessels)
- Inflammation of the renal corpuscles (glomerulonephritis) – a form of kidney inflammation
- Autoimmune diseases
What is done during a biopsy?
The procedures differ depending on which organ is to be biopsied:
Prostate biopsy
You can read about how a tissue sample is taken from the prostate and when the procedure is necessary in the article Prostate biopsy.
Breast biopsy
Read the article Biopsy: Breast to find out which sampling techniques play a role in breast biopsies and when they are used.
Liver biopsy
You can read about how doctors take tissue samples from the liver and which diseases they can be used to diagnose in the article Liver biopsy.
Kidney biopsy
Under constant ultrasound guidance, the doctor now inserts the puncture needle through the tissue into the kidney and punches a cylinder of tissue out of the organ, which he can retrieve as he withdraws the puncture needle. Finally, the puncture channel is covered with a sterile plaster; suturing is not usually necessary.
Biopsy of the lung
The doctor sometimes obtains a sample of the lung tissue directly via a surgical procedure by opening the chest (thoracotomy).
If lung cancer is suspected, the lungs can be flushed with a saline solution via the bronchoscope. This dissolves superficial tumor cells, which are then aspirated with the fluid. This process is known as bronchial lavage.
If the suspected area of the lung cannot be reached with a bronchoscope, the doctor takes the tissue sample as part of a fine needle biopsy: the doctor defines the area of skin over which the lung is to be biopsied. He then sticks a thin biopsy needle through the skin at this point and guides it carefully into the desired area of the lung under ultrasound guidance. There he aspirates some tissue and then withdraws the needle again.
Bone biopsy
After local anesthesia of the skin over the bone in question, the doctor makes a small incision in the skin and inserts a hollow needle into the bone with pressure. This punches out a bone cylinder, which remains inside the needle and is pulled out with it. After stopping any bleeding, the wound is closed with a sterile plaster or suture.
Biopsy of the sentinel lymph node (sentinel node biopsy)
Removed lymph nodes are examined in the laboratory. If no cancer cells are found, there is a high probability that the tumor has not yet spread and can be removed more gently. However, if the removed sentinel lymph nodes contain cancer cells, all lymph nodes in the tumor drainage area should be removed.
Stereotactic biopsy of the brain
Biopsy of the uterus and cervix
A biopsy of the cervix is indicated if the colposcopy has shown a conspicuously altered surface. The patient is given a local anesthetic for the procedure. The doctor then inserts a small forceps through the vagina up to the cervix and removes a tiny piece of tissue. This is then examined under a microscope.
A biopsy of the uterus follows the same principle.
Placental biopsy
A placental biopsy is the removal of tissue from the placenta from the 15th week of pregnancy onwards – before that it is called a chorionic villus biopsy.
The placental biopsy usually only takes a few minutes and can usually be performed without local anesthesia.
Evaluation of the biopsy
After the tissue has been removed, the sample is examined in a laboratory by a pathologist. First, however, the biopsy specimen is pre-treated to prevent degradation processes. To do this, water is first removed from the tissue sample in alcohol baths. It is then poured into kerosene, cut into wafer-thin slices and stained. This highlights individual structures and allows them to be analyzed under the microscope.
When examining the biopsy, the pathologist pays attention to the following points:
- Presence of tumor cells in the tissue sample
- Degree of dignity (benignity or malignancy of a tumor)
- Type of tumor
- Maturity of the tumor (grading)
What are the risks of a biopsy?
The risks of a biopsy vary depending on the removal procedure. General risks of tissue removal are
- Bleeding and bruising in the area of the sampling site
- Germ colonization and infection of the sampling site
- Wound healing disorders
- Spread of tumor cells and formation of metastases in the removal channel (rare)
- Injury to neighboring tissue structures (such as organs, nerves)
Such risks can be reduced by inserting the biopsy needle under ultrasound guidance, for example, by giving the patient antibiotics as a precaution and by treating the wound created during tissue removal properly (careful wound hygiene).
What do I need to consider after a biopsy?
If the biopsy was carried out as part of a surgical procedure, you will usually have to stay in hospital for follow-up observation. The length of your hospital stay will also depend on the type of biopsy; your doctor will inform you about the follow-up treatment.
In the case of a routine examination, you will receive the result of your biopsy after two to three days, especially if a suspected cancer is to be clarified. However, if examinations in special laboratories are necessary, it may take considerably longer.
