Digital auscultation of the uterine artery: a measure of uteroplacental perfusion

Biosensor for Detecting Fetal Growth Restriction in a Low-Resource Setting

One strategy for improving detection of fetal growth restriction (FGR) is developing biosensors identifying placental dysfunction as a leading pathogenesis for FGR. The aim of this pilot study was to investigate the performance of a biosensor specified to detect placental dysfunction by means of maternal arterial turbulence acoustics in a low-resource setting. A cohort of 147 singleton pregnant women were prospectively followed with double-blinded biosensor tests, sonographic estimation of fetal weight (EFW) and Doppler flow at 26–28, 32–34 and 37–39 weeks of pregnancy. Full term live births with recorded birth weights (BWs) and without major congenital malformations were included. Outcomes were defined as (A) a solitary biometric measure (BW < 3rd centile) and as (B) a biometric measure and contributory functional measure (BW < 10th centile and antenatally detected umbilical artery pulsatility index > 95th centile). Data from 118 women and 262 antenatal examinations were included. Mean length of pregnancy was 40 weeks (SD ± 8 days), mean BW was 3008 g (SD ± 410 g). Outcome (A) was identified in seven (6%) pregnancies, whereas outcome (B) was identified in one (0.8%) pregnancy. The biosensor tested positive in five (4%) pregnancies. The predictive performance for outcome (A) was sensitivity = 0.29, specificity = 0.97, p = 0.02, positive predictive value (PPV) was 0.40 and negative predictive value (NPV) was 0.96. The predictive performance was higher for outcome (B) with sensitivity = 1.00, specificity = 0.97, p = 0.04, PPV = 0.20 and NPV = 1.00. Conclusively, these pilot-study results show future potential for biosensors as screening modality for FGR in a low-resource setting.

Association between maternal vascular murmur and the small-for-gestational-age fetus with abnormal umbilical artery Doppler flow

OBJECTIVE

To investigate the association between maternal vascular murmurs (MVMs) and fetal growth restriction (defined as small-for-gestational-age [SGA] fetus) and abnormal Doppler pulsatility index (PI) of the uterine and/or umbilical arteries.

METHODS

A cross-sectional study of women aged 18 years or older with a singleton pregnancy at 28-34 weeks was conducted at Regional Hospital Viborg, Denmark, between May 1 and August 1, 2013. Ultrasound fetal biometry was performed and the Doppler PI of the umbilical and uterine arteries was determined. An estimated fetal weight (EFW) at or below the 10th percentile was defined as SGA. Microphone recordings from the lower abdomen were divided into heart valve sounds and MVMs.

RESULTS

The final analysis included 63 participants, with 25 classified as SGA and 38 as non-SGA. The mean pregnancy duration was 32.4 ± 1.4 weeks. In total, 17 participants had MVMs. There was a clear association between MVMs and a composite of SGA and an abnormal PI of the uterine and/or the umbilical artery (P<0.001), but not between MVMs and SGA only (P=0.154).

CONCLUSION

Maternal vascular murmurs are significantly associated with fetal growth restriction, but not with SGA per se.

Separation and characterization of maternal cardiac and vascular sounds in the third trimester of pregnancy

OBJECTIVE

To characterize the vascular sounds of the uteroplacental blood flow obtained by microphones.

METHODS

The present retrospective study took place in an anechoic chamber facility at Aalborg University, Aalborg, Denmark, in 2012, and included pregnant participants aged 18-40 years with a singleton pregnancy at 32-36 weeks and a parity of 0-2. Abdominal Doppler ultrasonography was performed bilaterally on the uterine arteries. Subsequently, in the same positions, sound recordings were performed with microphones. The derived raw sound signal was separated into two frequency ranges, and characterized accordingly.

RESULTS

The mean pregnancy length among 25 participants was 33.6 ± 2.0 weeks. The pulsatility index of the uterine artery was 0.67 ± 0.24. All 50 recordings displayed the first and second maternal heart sounds (frequency 25-100 Hz), and in 17 of 50 recordings, maternal vascular murmurs (frequency 200-800 Hz) were present. The average pulse wave velocity between the maternal aortic valve and the uterine artery was estimated to be 6.6 ± 1.5 m/s.

CONCLUSION

Maternal vascular murmurs in the frequency range of 200-800 Hz were identified as a possible marker of abnormal uteroplacental blood flow, and provide a means to measure the arterial pulse wave velocity.