CORRELATION BETWEEN ULTRASOUND FINDING OF PLACENTA PRAEVIA AT TERM AND SURGICAL DIAGNOSIS AMONGST PREGNANT WOMEN AT THE UNIVERSITY OF BENIN TEACHING HOSPITAL, BENIN CITY

Abstract

Design: A cross-sectional study. Objective: To determine whether ultrasound will make an accurate diagnosis of placenta praevia at term when compared with findings at caesarean section and to assess the influence of the cadre of the sonologist on this correlation. Setting: Departments of Radiology and Obstetrics and Gynaecology in the University of Benin Teaching Hospital, Benin. Sample: The sample was 83 patients who were successfully followed up after an ultrasound scan at term and were delivered by caesarean section. Methods: Patients who had transabdominal ultrasound scan at term carried out at the Department of Radiology were followed up till delivery over a period of 11 months (September, 2005 to July, 2006) in the Department of Obstetrics and Gynaecology. Variables extracted were age, parity, and gestational age at ultrasound diagnosis. Those with praeviae were variously typed sonologically viz type Ia, Ib, IIa, IIb, IIIa, IIIb and IV matched with the cadre of sonologist alongside their years of experience. These were compared respectively with findings at caesarean section. Accuracy was assessed using some major outcome measures such as sensitivity, specificity, positive and
negative predictive values, likelihood or odds ratio and overall accuracy. Results obtained were analyzed using EPIINFO 2004. Results: A total population of 155 consecutive patients who had ultrasound scan at term were recruited. 104 had ultrasound scan without finding of placenta praevia, 43 were diagnosed with placenta praevia and 8 were lost to follow up. 83 patients from the population studied were delivered by caesarean section. These formed the selected sample out of which 39 were compared successfully with a prior ultrasound diagnosis of placenta praevia. The condition was found to be commoner amongst older (30 – 39years) and multiparous ladies. Ultrasound placenta localization at term from this study has a sensitivity of 90.3%, specificity of 78.8%, positive predictive value of 71.8% a negative predictive value of 93.1% and likelihood ratio of 35 : 1. The overall accuracy obtained was 83.13%. The difference in the efficiency of ultrasound diagnosis of placenta praevia at term between consultants and residents was not statistically significant( p value 0.8998 ). Conclusion: Ultrasound placenta localization can reasonably diagnose placenta praevia at term. The influence of the cadre of the sonologist on the accuracy of this diagnosis was not significant.

CORRELATION BETWEEN ULTRASOUND FINDING OF PLACENTA PRAEVIA AT TERM AND SURGICAL DIAGNOSIS AMONGST PREGNANT WOMEN AT THE UNIVERSITY OF BENIN TEACHING HOSPITAL, BENIN CITY