Evaluation of sacral rhomboid dimensions to predict contracted pelvis: a pilot study of Indian primigravidae.

OBJECTIVE This prospective study aimed to evaluate dimensions of sacral rhomboid (quadrangular area at lower back) as predictors of Contracted pelvis (CP). METHODS In 300 uncomplicated primigravidae after 37 weeks gestation, transverse and vertical diagonal (TD and VD) of sacral rhomboid were recorded. Post- delivery, patients fell into two groups: Normal Deliveries (group 1) and CP (group 2, i.e., LSCS for contracted pelvis, instrumental delivery for Non Progress of Labor (NPOL) or birth mishaps). Analysis was done with SPSS version 10.5 and cross tabulation. RESULTS Rhomboid dimensions were smaller in CP group (P value 0.003 and 0.012. On univariate analysis, 10th percentile cutoff of TD was the most significant risk factor with Odds ratio of 7.5 (95% CI 3.5-16.2). VD and height below 10th percentile had Odds ratio of 2.7 (95% CI 1.2-6.1) and 2.99 (95% CI 1.2-7.3), respectively. Both dimensions of sacral rhomboid below 10th percentile increased risk of CP by 13 times (OR 13, 95% CI 3.5-48.6) and detected 2 out of 3 at risk women. CONCLUSION Smaller dimensions of sacral rhomboid are promising screening parameter for contracted pelvis which can be used in community to pick up high risk primigravidae.