Comparability of the amniotic fluid index and single deepest pocket measurements in clinical practice

Two ultrasound techniques, the amniotic fluid index (AFI) and the single deepest pocket (SDP), are currently used to detect oligohydramnios, predict variable decelerations, risk of Caesarean delivery for fetal distress, Apgar scores, umbilical cord artery pH, perinatal mortality, and cerebral palsy. Both techniques poorly identify oligohydramnios. Both techniques identify pregnancies at risk for variable decelerations, low Apgar scores, and Caesarean delivery for fetal distress. Only the SDP is predictive of a compromised fetus-umbilical artery pH, as a stand-alone test, has been correlated with perinatal mortality, and as part of the biophysical profile has been linked to cerebral palsy. This brief communication reviews the comparability of these two techniques and which method, if either, is superior in the identification of oligohydramnios, the predictability of these techniques to identify an adverse pregnancy outcome, and the ability to predict cerebral palsy and perinatal mortality.