University:
Stanford University
Course:
PEDS 282 | Pregnancy, Birth, and Infancy
Academic year:

2023
Views:

438

Pages:

1
Author:

Pierre BERNARD

Fetal Wellbeing Umbilical Artery Doppler As Placental disease worsens, resistance increase and blood flow is reduced. Normal placental blood flow is low resistance and positive (forward) flow at all stages in cardiac cycle Reduced/Absent forward/Reverse flow in diastole is associated with an increased risk of perinatal death, birth asphyxia, need for preterm birth and necrotizing enterocolitis. Pulsatility index = difference between top & bottom flow rate. Increased PI = increased resistance MCA Doppler anaemia à increased peak systolic flow IUGR à decreased PI because decreased resistance optimises flow & spares brain. Amniotic Fluid Volume Amniotic fluid volume (AFV) can be measured by US using either mean pool diameter (MPD) (range 20-80 mm) or amniotic fluid index (AFI) (sum of four vertical pools of AF measured in the four quadrants of the uterus Oligohydramnios (MPD <20 mm or AFI <3rd centile): can be due to Ruptured membranes, Fetal renal abnormality Fetal illness (e.g. severe IUGR due to UPVD) Polyhydramnios (MPD > 80 mm or AFI > 97 th centile): can be due to Obstruction to fetal swallowing (eg tracheoesophageal atresia) Neurological failure/absence of swallowing (eg anencephalic fetus) Excess urine production (e.g. infant of diabetic mother) Twin-twin transfusion syndrome. Biophysical Testing A chronic insult (especially hypoxia) will à depressed central nervous system à reduced heart rate (FHR) variability, movements, tone, and breathing movements) If severe à depressed renal function (oligohydramnios). The tests used are: Maternally perceived movements - assess how long before 10 movements felt CTG - non-stress FHR recording Biophysical profile (BPS). (most reliable) CTG Baseline between 110-160 bpm baseline variability of 5-15 bpm Normal/Reactive 2 or more accelerations (> 15bpm, lasting > 15sec in 20 mins) No decelerations NB: A Mature Fetus – quiet for 30% time (little oscillation of baseline, no accelerations), active for 70% (wide oscillations & many accelerations) Biophysical Profile FHR pattern (non-stress test or CTG as above) Fetal movements - >3 in 30 mins on US Fetal tone - hand open & close / flex & extend neck Fetal breathing - for > 30 secs in 30 mins Amniotic fluid volume - more than 3cm in 2 planes NB: If four or five of these parameters are present in up to 40 min of recording, then the risk of terminal fetal asphyxia is low