Level of fetal head above brim: comparison of three transabdominal methods of estimation, and interobserver agreement

This study compared three intra-partum transabdominal methods of estimating the level of the fetal head above the brim, and determined interobserver agreement in fifths estimation of the fetal head. The researcher examined 508 women in term labour and estimated level of head in fifths by the Crichton method, in fifths by the Notelowitz finger-breadth method, and by symphysis-to-sinciput measurement (SSM). The attending clinicians also made their estimates, using the methods of their choice. Two-fifths of head or less was considered engaged. When two-fifths was palpable by the Crichton method, the Notelowitz method gave a mean of 2.40 fifths. The researcher and clinicians agreed on the level of head in 42.9% of examinations. Interobserver agreement was poor (kappa = 0.22). In conclusion, the Crichton method overestimates head descent in comparison with the Notelowitz method. SSM was easy to perform but requires validation. The fifths method of determining level of head appears inexact and poorly reproducible.