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Combination of ultrasound pelvimetry and fetal sonography in predicting cephalopelvic disproportion
1Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Beijing, China.
Objective:
To assess a method of antepartum diagnosis of cephalopelvic disproportion by comparing the diameters of fetal head with those of the maternal midpelvis.
Methods:
Transvaginal ultrasound pelvimetry was performed on 190 healthy primigravidas with cephalic presentation at 28-35 weeks of gestation, and the fetal heads were measured within one week before delivery. The cephalopelvic indices of diameter, circumference and area were calculated and compared.
Results:
The index exhibiting the highest degree of accuracy (77.9%) was the cephalopelvic index of diameter (CID) defined as the difference between the mean diameter of the midpelvis and the fetal biparietal diameter (BPD). Eighty-three percent of the cases with CID less than 15.8 mm needed operative delivery, and 76.2% of the cases with CID more than 15.8 mm underwent vaginal delivery.
Conclusions:
The CID may be used to identify cephalopelvic disproportion before the labor and help obstetricians choose the most appropriate form of delivery in an uncomplicated vertex presentation.