Chapter 91 - The High-Risk Infant

Neonates at risk should be identified as early as possible to decrease neonatal morbidity and mortality (Chapter 87). The term high-risk infant designates an infant who should be under close observation by experienced physicians and nurses. Factors that define infants as being high-risk are listed in Table 91-1. Approximately 9% of all births require special or neonatal intensive care. Usually needed for only a few days, such observation may last from a few hours to several months. Some institutions find it advantageous to provide a special or transitional care nursery for high-risk infants, often within the labor and delivery suite. This facility should be equipped and staffed like a neonatal intensive care area. Examination of the fresh placenta, cord, and membranes may alert the physician to a newborn infant at high risk and may help confirm a diagnosis in a sick infant. Fetal blood loss may be indicated by placental pallor, retroplacental hematoma, and tears in the velamentous cords or chorionic blood vessels supplying the succenturiate lobes. Placental edema and secondary possible immunoglobulin G deficiency in a newborn may be associated with fetofetal transfusion syndrome, hydrops fetalis, congenital nephrosis, or hepatic disease. Amnion nodosum (granules on the amnion) and oligohydramnios are associated with pulmonary hypoplasia and renal agenesis, whereas small whitish nodules on the cord suggest a candidal infection. Short cords and noncoiled cords occur with chromosome abnormalities and omphalocele. True umbilical cord knots are seen in approximately 1% of births and are associated with a long cord, small fetal size, polyhydramnios, monoamniotic twinning, fetal demise, and low Apgar scores. Chorioangiomas are associated with prematurity, abruptio placentae, polyhydramnios, and intrauterine growth restriction (IUGR). Meconium staining suggests in utero stress, and opacity of the fetal surface of the placenta suggests infection. Single umbilical arteries are associated with an increased incidence of congenital renal abnormalities and syndromes. For many infants who are born prematurely, are small for gestational age (SGA), have significant perinatal asphyxia, are breech, or are born with life-threatening congenital anomalies, there are no previously identified risk factors. For any given duration of gestation, the lower the birthweight, the higher the neonatal mortality; for any given birthweight, the shorter the gestational duration, the higher the neonatal mortality (Fig. 91-1). The highest risk of neonatal mortality occurs in infants who weigh <1,000 g at birth and whose gestation was <28 wk. The lowest risk of neonatal mortality occurs in infants with a birthweight of 3,000-4,000 g and a gestational age of 38-42 wk. As birthweight increases from 500 to 3,000 g, a logarithmic Table 91-1 HIGH-RISK INFANTS