Anemia of Prematurity - Portal Neonatal

Pathophysiology:
• The umbilical stump represents a unique but universally acquired wound, in which devitalized
tissue provides a medium that supports bacterial growth. Normally, the cord area is colonized
with potential bacterial pathogens during or soon after birth. These bacteria have the
potential to invade the umbilical stump, leading to omphalitis. If this occurs, the infection may
progress beyond the subcutaneous tissues to involve fascial planes (necrotizing fasciitis),
abdominal wall musculature (myonecrosis), and the umbilical and portal veins (phlebitis). The
factors that cause colonization to progress to infection are not well understood.
Frequency: Internationally:
• Overall incidence varies from 0.2-0.7% in industrialized countries. Incidence is higher in
hospitalized preterm infants than in full-term infants. Episodes of omphalitis are reported and
usually are sporadic, but rarely, epidemics occur, eg, due to group A Streptococcus.
Mortality/Morbidity:
• Outcome usually is favorable in infants with omphalitis associated with cellulitis of the
anterior abdominal wall. In a study by Sawin and colleagues, no deaths occurred among 32
infants with omphalitis in the absence of necrotizing fasciitis and myonecrosis. The mortality
rate among all infants with omphalitis, including those who develop complications, is
estimated at 7-15%. The mortality rate is significantly higher (38-87%) after the development
of necrotizing fasciitis or myonecrosis. Suggested risk factors for poor prognosis include male
sex, prematurity or being small for gestational age, and septic delivery (including unplanned
home delivery); however, data are limited and conclusions cannot be drawn regarding the
role of these factors in the mortality rate.
• Sequelae of omphalitis may be associated with significant morbidity and mortality, including
necrotizing fasciitis, myonecrosis, endocarditis, portal vein thrombosis, sepsis, septic
embolization, and death (see Complications).
Sex: No sex predilection has been reported, although male may have a worse prognosis than female
Age:
• In full-term infants, the mean age at onset is 5-9 days.
• In preterm infants, the mean age at onset is 3-5 days.
History:
CLINICAL Section 3 of 10
• A detailed review of the pregnancy, labor, delivery, and the neonatal course is important (see
below). A history of poor feeding or feeding intolerance may be an early indication of
infection. A history of change in mental status, such as irritability, lethargy, and somnolence,
or a history of a decreased level of activity may be an important indicator of systemic
dissemination of the infection.
• Anaerobic bacteria are part of the normal flora of the female genital tract and are commonly
involved in ascending infections of the uterus and in septic complications of pregnancy;
therefore, the higher incidence of omphalitis caused by anaerobes (especially B fragilis) in
infants with adverse perinatal histories, such as premature or prolonged rupture of
membranes and amnionitis, may relate to exposure to maternal infection.
• History of urine or stool discharge from the umbilicus suggests an underlying anatomic
abnormality.