Unexplained Stillbirths and the Role of Amniotic Fluid Infections

Unexplained Stillbirths and the Role of Amniotic Fluid Infections

as a Possible Cause

 

Robert C. Pattinson, University of Pretoria, South Africa, began his talk explaining that antepartum stillbirths constitute approximately 50% of stillbirths in South Africa. In the vast majority of cases the cause of these stillbirths is unknown.

 

Dr. Pattinson explored the role of infection as a cause of antepartum stillbirths. The prevalence of HIV is very high in South Africa (Figure 3.1) and is associated with a high risk of stillbirths. Other major infections causative of stillbirths are syphilis and bacterial infection (i.e Amniotic Fluid Infection Syndrome (AFIS) ).

 

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Vaginosis has been cited as a cause of low birth weight. In a study by Dr. Pattinson’s group (
Figure 3.2), 534 women were studied during pregnancy. Vaginosis was diagnosed in 123 women by a screening (“whiff”) test. Low birth weight was found in 23% of those with vaginosis compared to 15% of those without. The perinatal mortality rate was significantly higher in those with vaginosis.

 

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There is evidence of AFIS in stillbirths (
Figure 3.3). In addition, the presence of 16s ribosomal DNA in gastric aspirates (Figure 3.4) is evidence of bacterial infection of the foetus.

 

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Dr. Pattinson pointed out that asymptomatic bacteriuria represents a risk during pregnancy (Figure 3.5).

 

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It is likely that ascending infection from the vagina can cause choriodecidual disease, with infection of amniotic fluid and funisitis (
Figure 3.6).

 

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There appears to be an association between bacteriuria/chorioamniotis and premature delivery. One means of proving this is through the use of antibiotic therapy (
Figure 3.7). The effects of one such trial are outlined in Figure 3.8.

 

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Dr. Pattinson reviewed the clinical and diagnostic features of AFIS. The gold standard for diagnosis is a positive bacterial culture. An elevated IL6 level is additional evidence. Figure 3.9 describes one study of cases of amniotic fluid infection. Figure 3.10 summarizes the clinical features suggestive of AFIS. 

 

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In addition to diagnosing and treating bacteriuria, urinary tract infection and amniotic fluid infection, prevention should also be considered as an approach to AFIS.  Figure 3.11 shows findings from such prevention trials.

 

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