Ultrasonic vibration transmittable probe and ultrasonic treatment assembly

An ultrasonic treatment assembly comprising:

• an ultrasonic transducer configured to generate ultrasonic vibration in response to a power supply;
• and
• an ultrasonic vibration transmittable probe coupled to the ultrasonic transducer, the ultrasonic vibration transmittable probe comprising:
• a probe body configured to transmit the ultrasonic vibration generated by the ultrasonic transducer from a proximal end side to a distal end side along a longitudinal axis of the probe body;
• an ultrasonic transducer connector provided on the proximal end side of the probe body and configured to connect the ultrasonic transducer;
• a treatment section provided on the distal end side of the probe body and configured to cut a treatment object with the ultrasonic vibration, the treatment section comprising:
• a first cutting surface orthogonal to or approximately orthogonal to the longitudinal axis;
• a second cutting surface proximal of the first cutting surface and orthogonal to or approximately orthogonal to the longitudinal axis, a first step being provided between the first cutting surface and the second cutting surface;
• and
• a third cutting surface proximal of the second cutting surface and orthogonal to or approximately orthogonal to the longitudinal axis, a second step being provided between the second cutting surface and the third cutting surface;
• and
• an index configured to be recognized in a field of view of an endoscope when seen from the proximal end side to the distal end side, the index being formed by a protruding portion that protrudes from the first cutting surface in a distal direction along the longitudinal axis,
• wherein the index is formed at an outermost edge of the treatment section that defines a largest outer perimeter of the treatment section formed around the longitudinal axis, and
• wherein a portion the first cutting surface has a dimension along a first orthogonal direction that is smaller than a dimension of the second cutting surface along the first orthogonal direction, the first orthogonal direction being orthogonal to the longitudinal axis.