Intrapartum sonography to determine fetal occipital position: interobserver agreement.

OBJECTIVE To investigate the interobserver agreement on the intrapartum ultrasonographic definition of the fetal occipital position. METHODS In 60 singleton pregnancies in labor at term the fetal occipital position was determined by transabdominal ultrasound by two appropriately trained sonographers who were not aware of each other's findings. The Bland-Altman plot was performed and the 95% limits of agreement were calculated. Logistic regression analysis was used to investigate the association between complete agreement in the fetal occipital position between the two observers and maternal and labor characteristics. RESULTS The two observers had complete agreement on the fetal occipital position in 22/60 (36.7%) cases and disagreement by 15 degrees and 30 degrees in 31 (51.7%) and seven (11.6%) cases, respectively. The mean of the differences between the two observers was 0.25 degrees and the 95% limits of agreement were -28.9 degrees (-32.2 degrees to -25.6 degrees) to 29.4 degrees (26.1 degrees to 32.7 degrees). There were no significant associations between complete agreement and maternal and labor characteristics. CONCLUSION The interobserver agreement on sonographically determined fetal occipital position during labor is within 15 degrees in nearly 90% of cases and within 30 degrees in all cases.