To study the efficacy of using maternal height, foot length, external pelvic measurements, sacral rhomboid dimensions as predictors of contracted pelvis (CP) in a cohort of our population and proposed to include estimated fetal weight as an additional parameter as a predictor of cephalopelvic disproportion.
Methods: In 1000 uncomplicated primigravida after 37 weeks gestation, transverse and vertical diagonal (TD and VD) of the sacral rhomboid, intertrochanteric diameter, biacromial diameter, foot length in centimeters, height in centimeters and weight in kilograms and birth weight of the baby in kilograms were recorded. Postdelivery, patients fell into two groups: Group-1: control (no CP) - women having uncomplicated vertex vaginal delivery, Group-2: cases (CP) - this group will include women with pelvic disproportion having: Caesarean section for disproportion detected on pelvic assessment or for non-descent/non rotation of the fetal head, Vacuum or forceps delivery for prolonged second stage, Vaginal delivery complicated by obstruction, birth trauma or unexplained intrapartum asphyxia. These two groups will be compared for their outcome. Data was analyzed using t-test, Pearson's-Chi square, Fishers exact test and multivariant logistic regression.
Cephalopelvic disproportion was present in 123 women. In univariate analysis, maternal height, foot length, intertrochanteric diameter and biacromial diameter were found to be associated with cephalopelvic disproportion, Rhomboid dimensions were smaller in CP group (TD of rhomboid P value < 0.001, VD of rhomboid P value 0.001). For transverse diagonal, when the 10th
percentile (<9.5 cm) was taken as cut off, 219 women were identified to be at risk and 55 (25%) actually had CP. Odds ratio indicated that transverse diagonal < 9.5 cm alone increased the risk by 3.5 times (95% CI 2.33– 5.31 ). Mean vertical diagonal of sacral rhomboid (VD) was also 0.95 cm less in group 2 which also was statistically significant (p = 0.001). Both dimensions of sacral rhomboid below 10th
percentile increased CP by 10 times (OR 10.9, 95% CI 5.62-21.35).
Conclusion: Clinical external parameters Viz: most significant to predict the contracted pelvis were Maternal Height, Foot Length, ITD, BAD, TD and VD. Smaller dimensions of sacral rhomboid are promising screening parameter for contracted pelvis which can be used in community to pick up high risk primigravida women.