Diagnostic evaluation of fetal death with special reference to intrauterine infections

Abstract

The incidence of intrauterine fetal death (>=28 gestational weeks) is approximately 4/1000 births in Sweden. In order to arrive at a potential cause of death, a number of investigations have been recommended in the diagnostic evaluation of intrauterine fetal death (IUFD). One of the issues in this thesis was to review the causes of stillbirth and to evaluate a certain arsenal of diagnostic procedures in cases of IUFD.

We examined 188 cases of stillbirth occurring in Stockholm in 1998-99 according to an extensive investigational protocol. A presumptive explanation of the stillbirth was established in 91% of the cases. The most common factors associated with intrauterine fetal death could be identified as infections (24%), placental insufficiency/intrauterine growth restriction (22%), placental abruption (19%), intercurrent matemal conditions (12%), congenital malformations (10%), and umbilical cord complications (9%). Based on our studies, placental pathological examination and autopsy, together with some additional tests, are suggested to be included in die routine investigation of stillbirth to arrive at a minimum of unexplained cases of fetal death.

The association between some infectious disorders and fetal morbidity and mortality is well documented This thesis focuses mainly on two agents: Toxoplasma gondii and parvovirus B19. When a primary toxoplasma infection occurs during pregnancy, T gondii may be transmitted from the mother to the fetus. Fetal infection can result in inflammatory lesions in the brain, retina and choroid, which may lead to permanent neurological damage and visual impairment. Disseminated toxoplasma infection may cause fetal death. Many European countries have screening programs for the detection of congenital toxoplasmosis.

Anti-toxoplasma IgG and IgM antibodies were measured in eluates from PKU cards from 40,978 newborns in Stockholm and Skåne in 1997-98. The seroprevalence in pregnant women was 14.0% in Stockholm and 25.7% in Skåne. On comparing the seroprevalence measured between 1969 and 1987 in pregnant women in Stockholm with our data, it was noted that today the majority of seropositive pregnant women have seroconverted before entering the childbearing period. The incidence of primary toxoplasma infection in our study was 0.51/1000 susceptible pregnancies (9 months). The prevalence of congenital toxoplasmosis in live born children was 0.73/ 10000. We conclude that the incidence of toxoplasmosis during pregnancy is low in Sweden and introduction of a screening program cannot be recommended before the effectiveness of treatment has been evaluated. Health education directed at pregnant women may be sufficient in a country with so low an incidence of toxoplasma infection. Matemal primary infection with parvovirus B19 may be transmitted across the placenta. Several reports have shown that parvovirus B19 can cause fetal death in the second trimester, mainly in combination with hydrops fetalis. Some authors have reported that the infection might also be an important cause of stillbirth in late pregnancy in non-hydropic cases.

Placental and/or fetal tissues from 47 cases of IUFD were examined for the presence of parvovirus B19 DNA by the polymerase chain reaction (PCR). We found a significantly higher frequency of parvovirus B19 in fetal death (15%) compared to live-borns (0%). The majority of parvovirus B19 DNA-positive cases did not exhibit hydrops fetalis. We conclude that most cases of late fetal death due to infection with parvovirus B19 are non-hydropic and conventional diagnostic procedures for diagnosing parvovirus B19-associated fetal death can be greatly improved by adding B19 PCR.

INFPREG, an Internet-based database covering infectious disorders and pregnancy was introduced on the Web in 1999. In our evaluation of INFPREG, we sent an anonymous, self-administered questionnaire to all antenatal clinics in Sweden. The questionnaire consisted of sections covering use of computers, Internet access, and use of INFPREG in patient care.

Based on our results, we conclude that the majority of midwives at antenatal clinics in Sweden have access to the Internet and are confident m using an Internet-based knowledge center for infectious disorders in pregnancy. The significance of the Web as a medical information resource in antenatal care is likely to increase.