Whether or not the procedure is performed using ultrasound or CT for guidance, the initial part of the examination is essentially the same. The patient has the procedure explained to them in detail and provides written and informed consent. Ultrasound or CT are used to determine the optimal site of entry for the needle through the skin and this area is cleaned and a local anesthetic is infiltrated into the soft tissue. Typically, ultrasound procedures are fairly short and therefore it is not usually necessary for the patient to receive intravenous sedation, with the examination being performed only under local anesthesia. CT procedures, however, tend to be a little longer in duration and usually the patient does receive intravenous sedation.
Using ultrasound for guidance, the needle is placed into the region of interest and the direct ultrasound visualization and material is then obtained for analysis. If CT is used for guidance, the needle is placed into the lesion in stages with CT scans performed intermittently to ensure that the needle is indeed approaching the region of interest. Specimens are typically of two varieties – a cellular aspirate (known as fine needle aspiration) and a specimen of tissue (also known as a core biopsy). The number of passes necessary to obtain the tissue varies depending on the particular circumstance. At the end of the procedure, the needle is removed from the patients abdomen and the procedure is complete.
What happens after the procedure?
Usually patients will be transferred to an observation area where their vital signs will be assessed from anywhere between 2-4 hours following the examination to ensure there are no complications.
What are the complications?
Complications of percutaneous (through the skin) biopsies very much depend on the area that has been biopsied. For example, livers are highly vascular organs and therefore biopsies of the liver is associated with an increased risk of bleeding compared to a biopsy of a poorly vascularized structure. Aside from bleeding there are other potential complications which should all be minimized significantly with good practice.