Which of the following evaluation methods is most sensitive in diagnosing pregnancy early?
Serum pregnancy test
Detection of fetal heart tones by Doppler equipment
Abdominal ultrasound
Bimanual exam to assess uterine size
A Doppler instrument will detect fetal cardiac action usually no sooner than 10 weeks.
A sensitive serum pregnancy test can detect placental HCG levels by 8 to 9 days post-ovulation, and it is therefore the most sensitive modality for detecting and diagnosing pregnancy.