Comparing bimanual pelvic examination to ultrasound measurement for assessment of gestational age in the first trimester of pregnancy

OBJECTIVE: To compare the accuracy of bimanual pelvic examination to ultrasound in the assessment of gestational age and to evaluate resident and faculty accuracy, and residents' learning to perform pelvic examination. STUDY DESIGN: Prospective, blinded, descriptive, correlational study of clinical bimanual examination versus ultrasound dating pregnancy prior to first-trimester abortion. Women scheduled to undergo abortion received transvaginal ultrasound assessment of gestational age. A resident and faculty physician, blinded to the ultrasound results, each performed a pelvic examination immediately prior to the procedure. The pelvic examination assessments were compared to the ultrasound calculations of gestational age. The absolute value of the difference between the bimanual examination and ultrasound dating were compared using the paired t test. Linear regression was used to evaluate the learning of residents. RESULTS: The pelvic examination agreed with the ultrasound (±2 weeks) in 92% of cases for faculty and 75% for residents. Accuracy of the resident examinations did not change over their two-month rotations. CONCLUSION: If pelvic examination alone is used to assess gestational age in the setting of first-trimester abortion, 8% of patients may experience unnecessary interventions, possibly leading to a greater risk of complications.