Association between external pelvimetry and vertex delivery complications in African women.

OBJECTIVE: To assess association between external pelvimetry and delivery complications in vertex presentation. METHODS: Prospective cohort study of 2,413 pregnant women antenatally measured for height and external pelvimetry in four hospitals of the former Republic of Zaire. OUTCOME MEASURES: Complications during delivery of single fetus weighing 2,000 g or more in vertex presentation. Cut-off values at risk for delivery complications were height and pelvic distances closest to the study population 10th percentile. RESULTS: In univariate analysis, maternal height showed significant relative risk for predicting primary cesarean section for failure to progress: 2.0 (95% CI=1.0-4.1; p=0.050) and vacuum or forceps delivery: 15.7 (95%, CI=6.6-37.5; p<0.001). Selected external pelvic distances showed significant relative risks for predicting the following complications: primary cesarean section for failure to progress, elective repeat cesarean section, vacuum or forceps delivery and spontaneous intrapartum stillbirth. Among pelvic predictors, transverse diagonal (TD) of Michaelis sacral rhomboid area was associated with all of these complications. Intertrochanteric (IT) diameter was associated with three of them. The relative risks ranged from 2.3 (95% CI=1.1-6.3; p=0.030) to 9.6 (95% CI=4.1-22.5; p<0.001) for these strongest predictors. CONCLUSIONS: External pelvic distances help to predict vertex delivery complications in African women. The predicted complications are compatible with the cephalopelvic disproportion concept (CPD). After validation of current results in a separate cohort, measurements of IT and/or TD are recommended to improve antenatal screening of women at risk for CPD in limited resources settings.

Maternal height and external pelvimetry to predict cephalopelvic disproportion in nulliparous African women: a cohort study.

OBJECTIVE: To assess external pelvimetry and maternal height, as predictors of cephalopelvic disproportion. DESIGN: Prospective cohort study. SETTING: Four hospitals in Zaire. POPULATION: Six hundred and five nulliparous women. METHODS: Maternal height and external pelvimetry were assessed during the third trimester antenatal visit. Cut off values for considering women at risk for cephalopelvic disproportion were height < 150 cm and external pelvic distances < 10th centile for the population. Logistic regression analysis, combining height and pelvic measurements, was performed to predict women at risk for cephalopelvic disproportion. MAIN OUTCOME MEASURE: Cephalopelvic disproportion was considered when there was caesarean section for failure to progress, vacuum or forceps delivery or intrapartum stillbirth. RESULTS: Cephalopelvic disproportion was present in 42 women. In univariate analysis, height, intertrochanteric diameter and the transverse diagonal of Michaelis sacral rhomboid area were found to be associated with cephalopelvic disproportion. Logistic regression analysis showed that maternal height < 150 cm and/or transverse diagonal < 9.5 cm were the variables most associated with cephalopelvic disproportion. The adjusted odds ratios were 2 x 2 (95% CI 0.9 to 5.4) and 6.5 (95% CI 3.2 to 13.2), respectively. The positive predictive value and likelihood ratio were 24% and 4.0 (95% CI 2.8 to 5.8), respectively. The addition of transverse diagonal to maternal height increased the sensitivity in predicting cephalopelvic disproportion from 21% to 52%. CONCLUSION: In addition to height, transverse diagonal measurement is able to predict one out of two cases of cephalopelvic disproportion in nulliparous women. After validation in a separate cohort, this simple predictive method may be used in peripheral centres for timely referral of pregnant women at risk for cephalopelvic disproportion.