An access system and guided endovenous (100, 110), comprising: a flexiblealargada part (112) adapted and configured to access the venous vasculature of a patient, wherein the flexible elongate member comprises a catheter a sensor (115, 1415) disposed at a distal end of the elongate flexible member and configured paraproporcionar vivo ultrasound information not based on images of the venous vasculature of the patient a processor (150, 160) comprising an analysis unit patterns (2560, 5250), the procesadorconfigurado for receiving and processing through pattern analysis ultrasonic information in vivo not provided using images of the venous vasculature of the patient provided by the sensor and to provide informationof position relative to the position of the distal end of the flexible elongate member within the patient vasculaturavenosa and an output device (50, 170) adapted to issue the position information from the processor wherein the processor is further configured for processing ultrasonic information in vivo not based enimágenes system the patients vasculature to indicate in the output information the distal delextremo movement of the flexible elongate member in a desired direction or a direction not lavasculatura desired within the patient.Un sistema de acceso y guiado endovenoso (100, 110), que comprende: una pieza flexiblealargada (112) adaptada y configurada para acceder a la vasculatura venosa de un paciente,en el que la pieza flexible alargada comprende un catéter un sensor (115, 1415) dispuesto en un extremo distal de la pieza flexible alargada y configurada paraproporcionar información ultrasónica in vivo no basada en imágenes de la vasculatura venosa del paciente un procesador (150, 160) que comprende una unidad de análisis de patrones (2560, 5250), el procesadorconfigurado para recibir y procesar mediante análisis de patrones la información ultrasónica in vivo no basadaen imágenes de la vasculatura venosa del paciente proporcionada por el sensor y para
