When preparing to assess fetal heart tones at 12 weeks of gestation, where should the nurse position the ultrasound stethoscope?

At 12 weeks of gestation, the uterus is located low in the pelvis, typically just above the pubic symphysis. When using an ultrasound stethoscope to assess fetal heart tones, placing it above the symphysis pubis optimally positions the device to detect the heart sounds, as this area is close to where the fetus is situated early in the pregnancy.

As the gestation progresses, the anatomical position of the fetus will change, and the uterus will rise out of the pelvis, altering where heart tones can be best heard. However, at the 12-week mark, the fetus is still small enough and low enough that locating the stethoscope above the symphysis pubis allows for the best chance of detecting fetal heart tones. Other positions, such as over the maternal abdomen, along the maternal spine, or on the left lateral side, would not be as effective for accurately assessing fetal heart tones at this early stage of gestation.