Abdominal circumference: a single measurement versus growth rate in the prediction of intrapartum Cesarean section for fetal distress

Objective The fetal abdominal circumference is the most sensitive ultrasoun d biometric measurement for predicting intrauterine growth restriction, whi ch is associated with an increased risk of intrapartum fetal distress. We s ought to evaluate and compare whether a third-trimester ultrasound measurem ent of abdominal circumference made within I week prior to delivery better Predicts operative delivery for fetal distress when compared with the growt h velocity of the abdominal circumference in the third trimester. Methods Retrospective analysis was carried out of prospectively collected u ltrasound data on 117 patients with singleton gestations who had had at lea st two ultrasound assessments performed less than 6 weeks apart in the thir d trimester, with the last ultrasound performed within 1 week prior to deli very. The abdominal circumference value of the last ultrasound prior to del ivery was placed into one of three categories: less than or equal to 5% cen tile, < 5 to less than or equal to 10% centile and > 10% centile for gestat ional age. The growth velocity of the abdominal circumference per week tc,a s placed into one of three categories: > 5 mm/week, 6-10 mm/week and greate r than or equal to 11 mm/week. The chi-squared test was used to compare dif ferences between the incidence of fetal distress between the groups. Results The incidences of Cesarean section for fetal distress in relation t o a single measurement of the abdominal circumference were: less than or eq ual to 5% centile, 8/23 (35%); > 5 to less than or equal to 10% centile, 3/ 12 (2.5%); > 10% centile, 8/81 (10%) (P < 0,05). The incidences of Cesarean section for fetal distress with the three abdominal circumference growth v elocities were: less than or equal to: 5 mm/week, 9/55 (16%); 6-10 mm/week, 4/11 (36%); greater than or equal to 11 mm/week. 8/51 (16%) (P=0,9401). Conclusion A single measure of the fetal abdominal circumference made withi n 1 week prior to delivery is superior to an assessment of growth rate of t he fetal abdomen in the third trimester in discriminating patients who requ ire Cesarean section for fetal distress.