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Ultrasound-guided biopsy
Last reviewed: 18.10.2021
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Ultrasound guidance is especially important when performing biopsy of small tumors or aspiration of small fluid accumulations or abscesses, the location of which is difficult to determine by clinical methods. Not every effusion or abscess should be punctured under ultrasound control, but it is important to use echography when puncturing the lesions located next to vital organs. Ultrasound is used to select the shortest distance to the object and the safest trajectory of passing the needle.
Echography is an ideal method for controlling the passage of the needle, since the needle reflects ultrasound and therefore is visualized after the skin has passed. However, only a part of the needle can be visualized. This occurs when the front of the needle passes through the scanning plane and becomes invisible. The bright dot on the screen in the scan plane is not really the tip of the needle. This not only prevents entry into the site necessary for the puncture, but can also damage other tissues.
Warning: only the part of the needle that is in the scanning plane is visualized on the screen . Make sure that you really see the tip of the needle. A significant portion of the needle may be outside the scanning plane.
There are special devices to hold the needle in the scanning plane. When the needle is already in the correct position, the sensor can be removed.
It is much easier to visualize the needle in liquid-containing structures (amniotic sac, against ascites, cyst, abscess cavity, pleural effusion) than in solid formations. The tip of the needle is not always well visualized in a solid structure: it can be seen only when the needle moves and it is very difficult - in a stationary state.
If possible, the fluid should be aspirated from the cyst cavity, however, it is necessary to avoid entering the necrotic center of the tumor. With pleural puncture, you must choose the site with the greatest amount of fluid. After installing the needle, ultrasound is used to observe the process of removing fluid or the contents of the cyst.
It is very important that the puncture biopsy is performed under sterile conditions.