Angle correction can be used to measure peak systolic velocity in the fetal middle cerebral artery.

OBJECTIVE: The objective of the study was to compare Doppler ultrasound measurements of the fetal middle cerebral artery peak systolic velocity (MCA-PSV) obtained at a 0 degrees angle of insonation to assessment at 30 degrees and 30 degrees with angle correction. STUDY
DESIGN: Patients between 14 and 36 weeks' gestation were enrolled (n = 66). MCA-PSV measurements were assessed at 0 degrees , 30 degrees , and 30 degrees with angle correction. The data were analyzed using a mixed model adjusted for gestational age. Pairwise comparisons of mean MCA-PSV measurements were made using the Tukey multiple comparison test.
RESULTS: All measurements were obtained for 50 fetuses (76%). Mean MCA-PSV measurements were statistically different between 0 degrees vs 30 degrees (P = .03 to < .001) but not between 0 degrees vs 30 degrees with angle correction (P = .34-.99) at each of the 5 gestational age groupings.
CONCLUSION: Assessment of the MCA-PSV at 0 degrees and 30 degrees with angle correction provides comparable measurements during the second and third trimester of pregnancy.