New Concept of Fetal Station Based on the Trapezoidal Plane (T-Station)
The precise reporting of fetal station is important in the decision-making regarding whether instrumental vaginal delivery or cesarean section should be performed. However, accurate evaluation of DeLee’s fetal station is difficult because it is defined on the basis of a hypothetical vertical midline to the spine, and the findings may vary between individuals. Moreover, during delivery, the fetal head descends anteriorly into the pelvis along the pelvic axis and not in the vertical direction.For this reason, we have clinically used this T-station to evaluate fetal head descent on the basis of the trapezoidal plane at the University of Tokyo Hospital since the 1970s. This concept of evaluating fetal head descent along the pelvic axis might be better than the conventional station system proposed by DeLee.
The relationship between the site of the largest fetal head circumference and t-station.The higher site of the largest fetal head circumference in the frontoanterior position (right) is observed at the same t-station, compared with that in the occipitoanterior position (left).
Differences between area and shape of the largest fetal head circumference plane in the occipitoanterior (left) and the frontoanterior position (right).
Actual measurement of t-station by vaginal examination.
Relation between t-station, the site of the largest fetal head circumference plane, the palpable rage of the posterior surface of symphysis, and the space among the fetal head and the sacrum.
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