Pediatric pathology

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PEDIATRIC PATHOLOGY
Department of Pathology
Cornell University Medical College

EPIDEMIOLOGY OF PEDIATRIC DISEASES
There are approximately 16,000 pediatric deaths per year in the U.S. The major causes of childhood death are not homogeneous, but show variation according to age subgroups.
The highest mortality rate is found in children less than one year old. The vast majority of theseoccur in the neonatal period (first 28 days), and most occur in the first seven days. By one year of age, accidents are the major cause of death. Along with homicides and suicides, these traumatic deaths account for approximately 50% of childhood deaths.

PERINATOLOGY AND PERINATAL PATHOLOGY
INTRODUCTION
Neonatal/perinatal medicine deals with problems of the fetus or neonate thatinterfere with transition from intrauterine to extrauterine life.
Perinatal period - the time when the fetus is capable of sustaining extrauterine life (24-25 weeks gestation) to 7 days after birth Neonatal period - the first 28 days after birth. This time is fraught with the highest mortality. Problems in this period, be they congenital or acquired, interfere with the transition toextrauterine life, when the infant takes on many tasks previously performed by the mother.
Approximately 1/2 of the deaths occuring in this period are due either to low birth weight and its associated problems or to birth defects.
CLASSIFICATION OF NEWBORN INFANTS
Gestational Age:
Normal term pregnancy : 40 weeks (280 days)
Preterm (premature): < 36-37 weeks
Thepreterm infant is characterized by small size, immature appearance of the face, thin, reddish skin, paucity of subcutaneous fat (fat storage occurs in the third trimester), scanty hair, hypotonia.
Postterm (postmature): > 41-42 weeks
The posterm infant has abundant hair, nails, thicker skin, wizened appearance, wrinkling (decreased subcutaneous fat due to catabolism of stores)Preterm infants have problems due to immaturity of many organ systems.
Postterm infants are handicapped by placental senescence.
Birth Weight:
The normal weight of a full term infant is >2500 g.
Small for gestational age (SGA): < 10%ile  in weight for the expected duration of pregnancy.
Despite a small size, the SGA infant has an alert, more mature face, hair,flexed posture, and thicker skin. Often the result of factors such as maternal disease, such as high blood pressure, or drug and/or alcohol abuse, autoimmune disorders etc.; with multiple pregnancy; or with intrauterine infection.
Appropriate for gestational age (AGA): 10-90%ile in weight for the expected duration of pregnancy.
Large for gestational age (LGA): > 90%ile  in weight forthe expected duration of pregnancy.
The LGA infant is large and fat ("Campbell's soup" baby). This is most often due to maternal diabetes. These babies are at risk for injury during delivery because of their unusual size.
APGAR Score:
The APGAR score is a rapid means of evaluating an infant's cardiopulmonary and neurologic function at set intervals after birth (routinely at 1and 5 minutes). The infants are given scores of 0-2 on each of 5 characteristics categorized according to the letters of Dr. Apgar's name, and a total score is given.

0
1
2

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Appearance
the baby is blue  indicating cyanosis
pale/grayish
pink /ruddy

Pulse
absent
less than 100
strong

Grimace*
absent
weak response
cough/sneeze

Activity
limp/not crying
in betweenvigorous/crying

Respirations
apneic/not breathing
weak breathing
good respiration

*a grimace, or reflex grimace, is when the baby coughs and/or sneezes while the doctor suctions out the mouth and nose
A good APGAR score is 9 or 10, and most normal babies have scores greater than 7 .  Low APGAR scores (0-3) require immediate attention in the delivery room to avoid the...