McKesson LUMEON Obstetrical Probe, Optimized for early fetal heart detection and designed as a general purpose obstetrical probe. Not Made With Natural Rubber Latex. For Use With Lumeon Doppler Systems. The Probe is used for ultrasound imaging, also called ultrasound scanning or sonography, this involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. During an obstetrical ultrasound the examiner may evaluate blood flow in the umbilical cord or may, in some cases, assess blood flow in the fetus or placenta.