Effective August 1, 2021, Northwest Perinatal Center’s Antenatal Surveillance Guidelines 2021 are intended to replace the version we made available in 2014. Similar to prior changes, please use shared decision-making with your current patients when choosing whether to keep their established care plan or to follow these new recommendations.
These updated guidelines reflect updated primary literature and American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal Fetal Medicine (SMFM) publications. We sought to balance evidence, which was limited in some areas, with a focus on patient-centered care—while also considering cost and risk-benefit ratio to the suggested surveillance recommendations.
How do the NWP guidelines align with updated 2021 ACOG recommendations? In Committee Opinion 828 outpatient surveillance guidelines were updated, with ACOG clearly and repeatedly stating that the guidance published “should be construed only as suggestions: should not be construed as mandates or as all encompassing” and “there is a paucity of evidence for the efficacy of antenatal fetal surveillance and for evidence-based recommendations on the timing and frequency of antenatal fetal surveillance.” In the ACOG opinion, the threshold for establishing an increased risk of stillbirth was defined as 0.8/1000, which is the false-negative rate of a BPP (or equivalent to an odds ratio of 2.0). When possible, we compared known stillbirth risks or odds ratios between indications with the goal of creating internal consistency in our recommendations. We chose to use literature to inform our decisions, and when data was lacking, erred on the side of less testing, since testing itself can lead to harm (including time and financial costs plus iatrogenic early delivery based upon false positive testing results).
How was IUGR management updated? First, SMFM recommended recently a transition from the term IUGR to fetal growth restriction (FGR); in our guideline, we choose to include both terms, which can be used interchangeably. The next big change is an updated definition of IUGR/FGR. The SMFM and ACOG Bulletin #227 recommends defining IUGR/FGR when the estimated fetal weight (EFW) OR the abdominal circumference (in isolation) is less than the 10th percentile. This change broadens the definition of IUGR, compared to our prior practice, but is based on updated expert opinion with the goal to minimize stillbirth risk. Risk is greatest for those fetuses with an EFW or AC less than the 3rd percentile or with abnormal umbilical artery Doppler studies. Those fetuses, as well as those diagnosed early (< 32 weeks) may benefit from additional evaluation and surveillance. We have created a new algorithm to assist in the interpretation of updated IUGR/FGR recommendations.
As always, we appreciate participating in the care of your patients and their families. If you have any questions, please call our consult lines: (503) 482-1810 (Eastside) or (503) 416-7565 (Westside). If you would like an updated Perinatal Resources notebook or help accessing our online resources, please email NWP Practice Manager Amber Sandoval.