PFM.70 Effect of serial scan frequency on antenatal detection of fetal growth restriction

Objective Previous delivery of a small for gestational age (SGA) baby is an accepted indication for increased surveillance in subsequent pregnancies. We sought to quantify the effectiveness of the various serial scan protocols which were in operation in our NHS Region. Method The cohort consisted of 5281 singleton, normally formed pregnancies with a past history of one or more SGA births. Cases were categorised according to the number of serial scans planned at the beginning of pregnancy, with scans done as follow up after first detection of SGA not counted. Birthweight was defined as th customised centile, and antenatal detection was based on one or more ultrasound estimated fetal weights (EFW) recorded as below the 10 th centile. Results The SGA rate in this group was 29.4%. The table shows the respective frequencies of various scan policies and detection rate if the birthweight was SGA. Conclusion Antenatal SGA detection rate is proportional to the number of investigations offered, and increases substantially with scans done at term. Performance of 1 or 2 scans seems no better than doing no scans at all. These findings raise doubt about the utility of routine growth scans proposed for all pregnancies.