The symptoms and signs and laboratory findings in congenital infections are listed in Table 22.1.

BACTERIAL INFECTIONS

Bacterial infections in the fetus (Figure 22.1) are more frequently recognized than viral, parasitic, or fungal infections. In most cases acquisition of the organism is believed to be from the maternal genital tract by an ascending route. Premature rupture of membranes or a sudden spontaneous abortion may be the first indication of intrauterine infection.

Other routes of infection are:

1. Hematogenous spread of maternal infection

2. Iatrogenic infections introduced during prenatal procedures such as amniocentesis

3. Direct infection from the maternal peritoneal cavity.

In addition, bacteria can be carried asymptomatically in the male urogenital tractandcan infect the conceptusby the ascending route after sexual intercourse in pregnancy.

Infection may occur by access secondary to rupture of membranes. Once bacteria are in the amniotic sac, they incite maternal leukocyte migration from the intervillous space toward the amniotic cavity (Tables 22.1 and 22.2). The accumulation of neutrophils leads to a loss of translucency of the membranes, which become creamy yellow. Most bacteria infect the membranes diffusely. Inhalation and ingestion of infected amniotic fluid by the fetus (amniotic infection syndrome) can be diagnosed microscopically by sectioning of the fetal lungs and stomach, which will contain neutrophils from the amniotic fluid. Infection of the amniotic fluid can result in intrauterine aspiration pneumonia in the fetus or the development of septicemia particularly if the organism is strongly virulent aswith group B streptococci (Figures 22.2 and 22.3). Oranisms most frequently resulting in chorioamnionitis are shown in Table 22.2.