Sono BPP: Improving the Patient Experience with Enhanced diagnostic Accuracy in Antenatal Testing

Posted On: January 12, 2018 By Andrei Rebarber, MD

The introduction of the BPP in antenatal testing has provided an improved prognostic tool for the reassurance of fetal well being.  A reactive NST provides reassurance for fetal well being, however, when abnormal, has a high false positive rate of 45-75%.  FHR is subjective to various dynamic factors including periodic sleep cycles, medications, and antenatal corticosteroids. So using this test alone may lead to inappropriate intervention. Further evaluation is needed to differentiate between the hypoxic and/or academic fetus versus the sleeping or medicated fetus.

As early as 1980, Manning et al defined the BPP as a more comprehensive tool in assessing both acute and chronic well-being, in a 30-minute assessment comprising FHR, fetal movement, fetal tone, fetal respiratory movements and amniotic fluid volume. The long-term goal was to assess the fetus for both acute and chronic signs of hypoxia, and subsequently decrease associated neonatal morbidity and mortality. This antepartum assessment has since been validated in singleton and twin gestations. In an additional randomized study published by Manning et al comparing BPPs to NSTs, BPPs were found to be more predictive of low APGAR score than NSTs. In this study, the BPP scoring included the NST as well.

In 1987, Manning et al assessed the modification of the fetal BPP score by selective use of the NST component and found that in the measurement of gross and corrected perinatal mortality, when the NST was NOT used in the BPP it did not produce any measurable decrease in test accuracy. This study in which the NST was used only with one or more abnormal ultrasound variables supports our clinical protocol at Carnegie Imaging for Women, PLLC. For the past 13 years since Carnegie Imaging’s inception, we have used the SonoBPP (without NST) as a primary screening strategy in at-risk pregnancies with excellent results.

Our group has peer review published the result of our antenatal screening program using the sonoBPP in the setting of advanced maternal age(greater than equal to 35 yo at the time of delivery) and twin gestations, both delineating excellent results.

  • Booker W, et al (JUM 2015) evaluated 539 twin pregnancies scanned at Carnegie Imaging for Women. We noted that the incidence of IUFD per patient was 2/539 (0.4%, 95% CI 0.1% – 1.3%) and the incidence of IUFD per fetus was 2/1078 (0.19%, 95% CI 0.05% – 0.7%) using the sonoBPP approach. The overall positive screen rate was 26/539 (4.8%, 95% CI 3.3% – 7.1%). The false positive screen rate, defined as an abnormal sonoBPP not diagnosing an IUFD or leading to delivery, was 10/539 (1.9%, 95% CI 1.0% – 3.4%). We concluded that in twin pregnancies the use of sonoBPP for routine antenatal surveillance had a lower false positive rate than that reported for the NST, with a very low incidence of IUFD.
  • Fox N, et al (Eur J Obstet Gynecol Reprod Biol 2013) evaluated 4469 patients: 1541 (34.5%) were AMA and 2928 (65.5%) were non-AMA. Using our AMA protocol for surveillance with use of the sonoBPP starting at 36 weeks weekly, the incidence of stillbirth was similar to the non-AMA population (stillbirth ≥ 20 weeks: 3.9 per 1000 vs. 3.4 per 1000, p=0.799; stillbirth ≥ 36 weeks: 1.4 per 1000 vs. 1.1 per 1000, p=0.773). When looking at women age <35, age 35-39, and age ≥ 40, the incidence of stillbirth ≥ 20 weeks and ≥ 36 weeks did not increase across the three groups. Our findings were similar when we excluded all patients with other indications for antepartum surveillance. We concluded that in the AMA patients, antepartum surveillance using the sonoBPP and delivery at 41 weeks appears to reduce the risk of stillbirth to that of the non-AMA population.

Our current recommendations include the use of the sonoBPP (ultrasound components of the BPP with reflex NSTs) to be selectively used in various high-risk clinical settings as listed below:

  • Advanced Maternal Age (weekly starting at 36 weeks)
  • IVF pregnancies (weekly starting at 36 weeks)
  • Postdates pregnancies (weekly starting at 40-41 weeks, optional twice weekly 41-42 weeks)
  • Pregestational/Gestational Diabetes
  • Chronic Hypertension (weekly starting at 32 weeks)
  • Systemic Lupus Erythematous (weekly starting at 32 weeks)
  • Suspected fetal growth restriction (weekly from the time of diagnosis, optional twice weekly as the clinical circumstance dictates)
  • Maternal Hypertensive disorder during pregnancy (weekly starting at the time of diagnosis)
  • Decreased fetal movement
  • Fetal Congenital Anomalies (case by case basis)
  • Cholestasis of pregnancy (weekly starting at the time of diagnosis)
  • Prior placental abruption (weekly starting at 32 weeks)
  • Prior 3rd-trimester fetal demise (weekly starting at 32 weeks, prior to a case by case basis)
  • Obesity (weekly starting at 36 weeks)
  • Abnormal serum markers (unexplained elevated msAFP, low PAPP-A, Low BHCG) (weekly starting at 36 weeks)
  • Thrombophilias (weekly starting at 32-36 weeks based on the clinical circumstance)
  • Polyhydramnios (weekly starting at the time of diagnosis)
  • Multiple gestations (weekly starting at 32 weeks)
  • Other as clinically indicated based on OB/MFM assessment

 

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

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