Fetal anomalies may be detected by ultrasonography. Emphasis should be placed on visualization of the genitourinary tract; the head (for anencephaly or hydrocephaly), neck (for thickened nuchal translucency), and back (for spina bifida); skeleton; gastrointestinal tract; and heart. Four-chamber and great artery views are required for detection of heart anomalies. Chromosomal anomaly syndromes are often associated with an abnormal “triple test” (low estriols, low maternal serum alpha-fetoprotein levels, and elevated placental chorionic gonadotropin levels). If a fetal abnormality is detected, fetal therapy or delivery with therapy in the neonatal intensive care unit may be lifesaving.
The approach to the birth of an infant requires a detailed history (Table 58-3). Knowing the mother’s risk factors enables the delivery room team to anticipate problems that may occur after birth. The history of a woman’s labor and delivery can reveal events that might lead to complications affecting either the mother or the neonate, even when the pregnancy was previously considered low risk. Anticipating the need to resuscitate a newborn as a result of fetal distress increases the likelihood of successful resuscitation.
The transition from fetal to neonatal physiology occurs at birth. Oxygen transport across the placenta results in a gradient between the maternal and fetal Pao2. Although fetal oxygenated blood has a low Pao2 level compared with that of adults and infants, the fetus is not anaerobic. Fetal oxygen uptake and consumption are similar to neonatal rates, even though the thermal environments and activity levels of fetuses and neonates differ. The oxygen content of fetal blood
Age Race Sexually transmitted infections, hepatitis, AIDS Illicit drugs, cigarettes, ethanol, cocaine Immune status (syphilis, rubella, hepatitis B, HIV, blood group) Occupational exposure
Chronic hypertension Heart disease Diabetes mellitus Thyroid disorders Hematologic/malignancy Collagen-vascular disease (SLE) Genetic history—inborn errors of metabolism, bleeding, jaundice Drug therapy
Current gestational age Method of assessing gestational age
Fetal surveillance (OCT, NST, biophysical profile) Ultrasonography (anomalies, hydrops) Amniotic fluid analysis (L/S ratio) Oligohydramnios-polyhydramnios Vaginal bleeding Preterm labor Premature (prolonged) rupture of membranes (duration) Preeclampsia Urinary tract infection Colonization status (herpes simplex, group B streptococcus) Medications/drugs Acute medical illness/exposure to infectious agents Fetal therapy
Duration of labor Presentation—vertex, breech Vaginal versus cesarean section Spontaneous labor versus augmented or induced with oxytocin (Pitocin) Forceps delivery Presence of meconium-stained fluid Maternal fever/amnionitis Fetal heart rate patterns (distress) Scalp pH Maternal analgesia, anesthesia Nuchal cord Apgar score/methods of resuscitation Gestational age assessment Growth status (AGA, LGA, SGA)
AGA, Average for gestational age; AIDS, acquired immunodeficiency syndrome; LGA, large for gestational age; L/S, lecithin-to-sphingomyelin ratio; NST, nonstress test; OCT, oxytocin challenge test; SGA, small for gestational age; SLE, systemic lupus erythematosus.
is almost equal to the oxygen content in older infants and children because fetal blood has a much higher concentration of hemoglobin.