Radiologic Considerations of the Perinatal Distress Syndrome

During the past decade many articles have appeared in the medical literature describing the causes, symptomatology, and radiologic findings of perinatal distress. Many of these publications include under this terminology any condition responsible for respiratory difficulty in the newborn infant. Consequently, there has developed some degree of confusion regarding the nomenclature of both neonatal and perinatal distress. In the newborn there are many abnormalities, including intracranial lesions, numerous primary pulmonary anomalies, cardiovascular defects, and defects of the diaphragm, which may be responsible for the clinical manifestations of respiratory difficulty. Each of these conditions interferes either mechanically or physiologically with the normal process of respiratory exchange; the cause is usually some anatomical defect which can be recognized by standard clinical, laboratory, or radiographic procedures. Examples include tracheoesophageal fistula, diaphragmatic hernia, congenital heart disease, congenital lobar emphysema, multicystic lung disease, pulmonary agenesis or hypoplasia, intrathoracic masses, and sub-dural hematomas. In addition, in some infants the respiratory distress arises from circumstances which may also affect one or several organs, including the central nervous system, the liver, the adrenal glands, and the alimentary tract. These latter conditions, as well as a select number of primary pulmonary abnormalities which are described below, constitute the perinatal distress syndrome and have the common underlying factor of anoxia and shock (6), occurring in the pre-, intra- or post-partum period. In the perinatal environment a number of obstetrical complications may interfere with the normal circulation across the placenta, resulting in fetal anoxia. It is the purpose of the present paper to discuss the radiologic manifestations of the conditions which in our opinion are the sequelae of hypoxia or anoxia in the perinatal period, i.e., directly prior to delivery, during the birth process, or immediately thereafter: In many instances the obstetrical history will indicate a condition which will be compatible with fetal anoxia. At other times only the effects upon the fetus are evident. Just as there is a common denominator in all of these states, anoxia, there is apparently a common pathogenesis, namely, increased capillary fragility and permeability. Anomalous physiologic responses such as premature respiratory stimulation may also play a role. Neurological influences such as vagal stimulation, with relaxation of the anus, may result in meconium staining of amniotic fluid. The combination of these factors frequently leads to aspiration of amniotic fluid and meconium. The pathologic sequelae of the association of anoxia and increased capillary fragility may be in the form of petechiae or larger hemorrhages.