Some advantages
The Rotex Screw Needle Biopsy Instrument offers a safe, simple way of obtaining highly reliable samples. Since material is excised instead of being aspirated, complete cell clusters are obtained rather than single cells. As a result, at least 95% diagnostic accuracy has been obtained using the Rotex Screw Needle Biopsy Instrument for sampling lung tumors (2) and non palpable breast tumors (9). The diameter of the instrument cannula is 0.8, which explains the low incidence of reported complications (2)
The instrument is easy to operate. It occupies a minimum of space under an image intensifier.
Sampling is performed efficiently over a distance of 16 mm, corresponding to the spiral portion of the screw needle. This enhances the possibility of obtaining representative samples. The screw needle and cannula work together as a cutting instrument, and the screw needle stabilize the tissue when the cannula is rotated over it. In this way all tissue components are sampled before they are lifted out. Material from fibrous inflammatory lesions and highly organized tissue such as benign tumors can therefore also be obtained. The material is highly concentrated and is not diluted by tissue fluid and blood as in aspiration biopsy. This facilitates microscopic examination of the material. Rather large flakes of cells and connective tissue can often be obtained. The clumps of tissue which can be sampled from organized tissue may allow treatment of the material with histological techniques.
Material from the screw needle can be inoculated directly on culture media for bacteriological examination.
The dimensions of the instrument have been optimized with regard to minimizing trauma and maximizing stability. This latter factor is of importance in order to enable precision sampling. In this way unnecessary insertion of the cannula in several directions can be avoided.
The screw needle is always in a protected position; i.e., withdrawn into the cannula, when the helical hub is positioned distally in the instrument holder. In this way the risk of tumor seeding to surrounding tissue is reduced to a minimum.
