Objectives:
During labor, transperineal sonography is increasingly used to evaluate fetal head
descent. The aim of the present study was to compare the angle of progression assessed
by open magnetic resonance imaging (MRI) versus transperineal ultrasound.
Methods:
31 pregnant women at term (>37 weeks), who were not in labor, underwent a MRI in an
open 1.0 Tesla system. A midsagittal plane of the maternal pelvis was stored. Immediately
after, without changing the supine position, a transperineal ultrasound was performed.
The angle of progression was measured off-line by transperineal ultrasound and MRI.
Results
The angles of progression measured by transperineal ultrasound (mean 79.05°, SD 11.44)
and MRI (mean 80.48°, SD 11.06) correlated significantly (p<0.001). The intraclass
correlation coefficient between the two methods was 0.89 (95% CI: 0.78–0.94).
Conclusion:
The angle of progression measurements obtained by transperineal ultrasound and open
MRI showed very good agreement. This ultrasound technique provides reliable reproducible
information of the fetal head station and it can become a ueful easy bed side tool
to help in the clinical decision making of a trial of instrumental delivery versus
a C-section at full dilatation
