[Fetal-pelvic disproportion and X-ray pelvimetry]

X-ray pelvimetry is a method that not only allows exploring the pelvic inlet but also would partially explain the "fetal-pelvic disproportion". The aims of this study are to estimate this capacity to actually explain the aforementioned disproportion, assessing as well its influence on the follow-up of later pregnancies.

A retrospective study was performed in Angers' hospital, France. We went back over 11 years and included 90 nulliparous patients, all of whom had a C-section due to "fetal-pelvic disproportion". We defined a specific sub-group for arrest of labor.

Only 55.5% of the patients had an unfavorable Magnin's index (<23 cm) and 47.8% were, according to it, in the uncertainty - or dystocia - zone. Labor arrest was explained by mechanical obstruction (72% of the patients had pelvic abnormalities) and by dysfunctional patterns (40% due to a posterior position of the occiput, 18% because of hypotonic labor). An important number of elective C-sections (55 cases) was recorded for subsequent pregnancies. Reasons were bound to X-ray pelvimetry (35 cases), the patients' wish (two cases), to maternal pathology (four cases), to a hydramnios (three cases) and to the suspicion of fetal distress (five cases).

The term "fetal-pelvic disproportion" should be carefully used. Some authors used it in case of arrest of labor during two hours, a normal dynamic pattern, sufficient cervical dilation and, for many, an occipoanterior position.