Fetal acoustic stimulation test for early intrapartum fetal monitoring

Abstract

Introduction The fetal acoustic stimulation test (FAST) is a simple cost effective screening test for antenatal fetal monitoring. The aim of the study was to evaluate the FAST as a screening test for early intrapartum fetal well being. Methods An initial non stress test (NST) followed by a FAST using corometric model 146 was carried out in 486 participants in early labour with uncomplicated singleton pregnancies and >32 weeks gestation. A repeat NST was recorded in the participants who had an initial non reactive NST. The results of the NST and FAST were compared with fetal outcome. Maternal perception of fetal movements after FAST, results of NST before and after FAST, and the babies' 5 minute APGAR scores were measured. Results Of the 486 participants 413 (85%) noticed fetal movements after FAST. Initial NST was non reactive in 203 (42%) but 149 (31%) became reactive after FAST. Compared to the NST, FAST had a better sensitivity (97% vs 62%, p<0.001), specificity (100% vs 87%, p=0.017), positive predictive value (100% vs 98%, p=0.024), negative predictive value (79% vs 17%, p<0.001) and accuracy (99%vs 64%, p<0.001) in predicting 5 minute APGAR <7 in the baby. Conclusions FAST is a reliable screening test for assessing fetal well being in early labour. It complements the NST and is better than the NST alone.

Strategies for intrapartum foetal surveillance in low- and middle-income countries: A systematic review

“…Two publications reported on the same study [ 24 , 25 ]. The final 37 included studies consisted of five (13.5%) intervention studies (three randomised controlled trials (RCT)[ 26 – 28 ] and two clustered RCT [ 24 , 25 , 29 ]), and 32 (86.5%) observational studies (23 cohort studies, six cross-sectional studies, and three case-control studies) [ 30 – 60 ]. The studies were conducted in Africa (n = 16), Asia (n = 21) and Europe (n = 1) and were from LICs (n = 6), L-MICs (n = 21) and UMICs (n = 11).…”

“…Studies were on low risk (n = 3) [ 44 , 57 , 60 ], high risk (n = 3) [ 34 , 48 , 56 ], and mixed-risk pregnancies(n = 1) [ 32 ]. Abnormal CTG traces were associated with intrapartum FHR abnormalities (foetal distress) [ 32 , 34 , 44 , 48 , 57 ], meconium-stained liquor [ 32 , 57 ]; low Apgar scores at 5 minutes [ 32 , 44 , 48 , 57 , 60 ], perinatal deaths [ 32 , 44 , 48 ], and admission to neonatal intensive care unit (NICU) [ 32 , 44 , 48 , 57 ]. Test performance of admission CTG varied across studies: PPV of 19% to 88%, while the NPV was between 88.6% to 100% [ 32 , 48 , 56 , 57 , 60 ].…”

“…foetal acoustic stimulation, FAST, n = 2) performed well in predicting foetal distress, perinatal death, Apgar score <7 at 5 minutes, admission to NICU [ 60 , 61 ]. It also improved the test performance of CTG in two studies (PPV: 45.2% to 65.5%, 19% to 73.6%, NPV: 94.2% to 96%, 100% to 100%) [ 56 , 60 ]. Admission amniotic fluid index (aAFI) performed worse than admission CTG (specificity: 64% and 92% respectively, n = 326) [ 35 ].…”

“…The use of CTG required a high level of skills, resources, and costs [ 26 , 31 ]. Combining FHR monitoring with simpler adjunctive tests such as meconium, FAST, FSST, and FPO may provide non-invasive and reliable ways to confirm foetal wellbeing, avoiding unnecessary interventions [ 42 , 45 , 56 , 60 , 61 ].…”

“…The observational studies in this review suggest that admission tests (including CTG, IA or FAST) can predict adverse outcomes in LMICs, and mode of delivery in both low and high-risk pregnancies [ 32 , 34 , 48 , 56 , 57 , 60 , 61 ]. We suggest that admission tests might have a much better use in low resource settings because of: 1) the incidence of intrapartum stillbirths could modify the predictive test results [ 11 ], 2) inadequate risk assessment and stratification during antenatal care, making admission tests a good screening tool to identify high-risk foetuses and 3) a triaging tool for better allocation of resources in settings with heavy workload and scarce (human) resources [ 32 , 34 , 48 , 57 ].…”