An apparatus includes an elongate body and a sensor. The elongate body has aproximal endand a distal end. The distal end is sized and configured to fit through anaturally occurringorifice of a human body. The sensor is positioned at the distal end of theelongate body. Thesensor includes an electrically conductive coil. The coil extends along alongitudinal axis. Thecoil has a distal terminal winding and a proximal terminal winding. The distalterminalwinding extends along a plane that is obliquely oriented relative to thelongitudinal axis. Theproximal terminal winding extends along a plane that is obliquely orientedrelative to thelongitudinal axis.
