Workup

Abnormal first-trimester uterine artery Doppler waveforms have shown a correlation with aberrant growth. In the first trimester, notching is seen in the majority of all patients with 55% to 63% having bilateral notching, and an additional 18% with unilateral notching (108-110). Therefore, this characteristic pattern is not as helpful. When using an abnormal PI in the first trimester, the sensitivity for IUGR is only 12% (108), while the sensitivity for severe FGR requiring delivery at <34 weeks is only 24% (108,109). Despite its poor performance as a screening tool in the first trimester, using the information to initiate preventative measures may be beneficial. In women with abnormal uterine artery Doppler evaluation, giving lowdose aspirin prior to 16 weeks significantly reduced the incidence of FGR. Similar to data without using uterine artery Doppler, the benefit was not seen after this gestational age (66). This is obviously not clinically effective if one offers low-dose aspirin to women based on risk factors such as hypertension, prior preeclampsia, prior FRG, as discussed above.