Summary
We investigated the accuracy of using symphysis pubis-fundal height measurement and ultrasonically derived estimation of fetal weight for identifying small-for-gestational-age (SGA) and large-for-gestational-age (LGA) fetuses. A retrospective cohort study was performed using computerised records of all non-diabetic women referred for an ultrasound growth scan (US) with clinically suspected SGA or LGA singleton fetuses from 35 weeks’ gestation between October 2008 and March 2009 (n = 185). Birth weight data were also collected for all births over the study period (n = 3200). One-third (34%) of ultrasound estimated fetal weights were inaccurate by >10%. However, an inaccurate ultrasound estimation did not significantly increase the likelihood of spontaneous or induced onset of labour or delivery by caesarean section. Most (79%) growth scans were performed on well-grown fetuses. The majority (80%) of SGA and LGA babies in our cohort were not identified by clinicians during routine antenatal care. From 3,200 live births, there were a total of 59 infants weighing <2,500 g or >5,000 g. Of these, only 12 had been referred for an ultrasound growth scan, indicating that abdominal palpation and fundal height measurement has a 20% sensitivity in detecting SGA or LGA fetuses. Of the 12, four were detected using ultrasound, indicating a 33% detection rate. Although ultrasound has a slightly higher sensitivity, neither clinical examination using fundal height measurements nor 3rd trimester ultrasound examinations are effective at detecting SGA or LGA fetuses.
Acknowledgements
Jill Tinsey, IT Specialist Midwife, Norfolk and Norwich University Hospitals NHS Foundation Trust.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.