A lariat-based dilatation device for hysteroscopy: an in vitro study.

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Hysteroscopy is regarded as the golden standard for the therapeutic and diagnostic methods of many uterine diseases. Carbon dioxide, normal saline and pharmaceuticals are generally used to dilate the uterus to obtain enough operating space and clear vision during the surgery. However, these methods often cause various syndromes. In this study, we designed a novel mechanical dilator and operating system. The dilator contains a structure with a diameter of 9 mm in its initial status to pass through the narrow cervix after initial cervical dilation by cervical dilator and then its diameter can be expanded up to 60 mm in the working status to achieve a favorable operating space. The operating system is composed of an endoscope and the surgical instrument driving tube. The endoscope was motioned by pre-bent hyperelastic wires and the surgical instrument was driven by a pre-bent driving tube. To obtain the parameters for successful expansion and operation, the relationships between the tension, the diameter of the dilator and the visual and operating space of the operating system were analyzed in detail. On the basis of the obtained parameters, the surgical experiment was performed and the experimental results demonstrated the ability of this dilator to expand and the ability of the operator to operate in small spaces for hysteroscopy. According to the achieved results, the dilator could support the inner wall of the simulated organ to act like a cage, so that the space in the cage was large enough. The operating system can thrust into the intracavity of the simulated uterus through the channel (with a diameter of 6 mm) of the dilator to search for and excise the raised polyp. It can be concluded that the proposed dilator and operating system can be efficiently applied in organ expansion and operation in hysteroscopy.