Pregnancy detection is done in several ways:

1. By detecting reflections (echoes) from the thickening of the uterine walls
   in those animals where this occurs, which take place very early in the pregnancy cycle.
   
   
2. By detecting the echoes from the interface between amniotic fluid and
   the far side of the intrauterine wall.
   
   
3. By detecting the echoes from the fetus(es).
   When measuring thickness, the user can restrict the maximum screen depth displayed in order to avoid spurious and non-meaningful data beyond the region of interest.
   Once a reading is obtained, one of the HOLD keys can be pressed to keep the reading on the screen until the key is pressed again to release it. The screen is backlit to aid in low visibility environments.

The instrument is a small handheld device powered from 4 disposable size AA cells. It is made from high impact plastic and though not waterproof, it is shielded to conform to all current applicable standards for electronic immunity and emissions. It is designed to withstand adverse environmental conditions, normally associated with animal production.