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J Clin Pathol. 2007 July; 60(7): 846–848.
PMCID: PMC1995792

The importance of placental examination in all fetal biopsy and postmortem examinations

The object of our study is to reflect on our experience and to examine the findings of fetal biopsy specimens and postmortem examinations in cases referred for clinically unexpected fetal death in utero (FDIU). Clinically unexpected FDIU indicates absence of known fetal, maternal or placental risk factors, that may have caused the death.1,2

This is a network‐based cohort study of fetal biopsy specimens and postmortems carried out at Southern Health (which incorporates Monash Medical Centre, Moorabbin, Bentleigh; Monash Medical Centre, Clayton; Dandenong Hospital, Dandenong and Casey Hospital, Berwick, all in Victoria, Australia) from January 2002 to December 2005.

During this period, there were 314 fetal deaths among the 27 085 total births; 181 fetal deaths were unexpectedi—these data include only fetuses of gestational age >20 weeks; unfortunately, the data for fetuses that died at <20 weeks of gestation are not recorded.

A total of 88 cases from 86 pregnancies were referred to as unexpected FDIU. Of these, 78 deaths were of singletons and 10 were of twins (two sets and six single twins). The mean (SD) gestation was 27 (6) (±17 weeks, 2SD), range 14 to 41 weeks (fig 11).). The mean (SD) was 30 (2) weeks for twin pregnancies. The proportion of the sexes was roughly equal with 53% males (47 cases) and 47% females (41 cases). In terms of previous deliveries, 29 were multigravid, 27 were primigravid and 30 were not stated by the clinicians. The mean (SD) maternal age was 30.1 (11) years (fig 22).). Two of the cases (2.3%) were subjected only to external examination.

figure cp41897.f1
Figure 1 Occurrence of fetal death in utero in singleton pregnancies according to gestation in referrals for postmortem examination at Southern Health (2002–5).
figure cp41897.f2
Figure 2 Occurrence of fetal death in utero in singleton pregnancies according to maternal age in referrals for postmortem examination at Southern Health (2002–5).

In our data, 55 cases were of >20 weeks' gestation, so fewer than one‐third of clinically unexpected FDIU had undergone postmortem examination. This reflects, unfortunately, the current declining rate of the hospital autopsy.3,4

In examining the singleton pregnancies, we found 50% of FDIU (39 of 78 cases) to be unexplained. Of these, 35.9% (28 of 78 cases) were classified as “Cause of death not found” or “Only terminal hypoxia” (one fetus was subjected only to external examination and one was severely macerated). In 14.1% (11 of 78 cases), there were positive postmortem findings, but these were not significant; these findings included placental infarction of <10%, loose true knot in cord and positive fetal organ cultures, but absent histological findings.

The most common finding in the whole group was of placental vascular causes (21.8%, 17 cases). These included six cases of abruption and retroplacental haemorrhage, four cases of placental insufficiency (immature and poorly vascularised) and two cases of infarction (involving 40% and 80% of placental volume, respectively). It has been previously shown that infarction of >15% of the placental volume is associated with intrauterine growth retardation or death.5 In three cases, there was a single umbilical artery, and in one case, there was cord prolapse during a breech delivery.

Infections accounted for 14.1%, or 11 cases. There were eight cases of chorioamnionitis, and cultures included maternal flora, Escherichia coli, mixed E coli/Streptococcus viridans, mixed enteric flora and mixed E coli/Staphylococcus aureus. There was one case of isolated funisitis (which cultured mixed maternal flora), two cases of pneumonitis (which cultured a group B Streptococcus and mixed maternal flora), and one of these cases was also associated with chorioamnionitis/villitis.

Fetal pathology was found in 11.5% (nine cases) and these included two cases of thymic involution, and single cases of thymic aplasia, sirenomelia, absent left kidney and spleen, left pelvi‐ureteric junction obstruction with hydronephrosis, membranous ventricular septal defect, prostatic atresia with cystic renal dysplasia, and type 3 congenital cystic adenomatoid malformation with patent foramen ovale.

There was a single (1.3%) case of unexplained FDIU that occurred 2–3 days after the procedure (chorio‐villous sampling).

A chromosomal abnormality was identified in a single (1.3%) case; this was 46XY t(1;7)(q25;q32), and there was associated oligohydramnios and secondary limb contractures.

Intrauterine growth retardation (IUGR) is defined when the weights and measurements are less than the stated gestation and the head circumference is greater than the crown‐rump length. In our series, IUGR was seen in 29.5% (23 of 78 cases). The average delay in intrauterine growth was 3 weeks, with a range between 1 and 6 weeks. Multiple pregnancies were not included, as most show IUGR relative to singleton weights and measurements. Of the 23 cases of IUGR, 52% were unexplained; in the remaining 48%, three cases showed placental abruption, two showed placental insufficiency, two had a single umbilical artery (one of these also had chorioamnionitis), one case had a Group B Streptococcal pneumonitis and one case had sirenomelia (fig 33).).

figure cp41897.f3
Figure 3 Causes of fetal death in utero of singleton pregnancies in referrals for postmortem examination at Southern Health (2002–5). *Placental causes include abruption, insufficiency and infarction.

Discussion

The aetiology of FDIU in most studies is unexplained, and rates from 9% to 59% have been quoted.6,7 Antepartum haemorrhage with or without abruption is the single largest cause (12–17%),6,8 and this accounted for 8% in our study. The single largest cause in our study was chorioamnionitis, which accounted for 11.5% of cases (total of nine cases, one included pneumonitis).

Major anomalies are found in 7–15% of cases,6 this category accounted for 13% in our study.

Maternal age of <20 years and >29 years and increased parity are associated with increased rates.6,9 In our study population, mean (SD) maternal age was 30.1 (11) years, with a range from 19 to 42 years, and FDIU did not show a bimodal distribution. Also, we did not find any significant difference between numbers of primigravid and multigravid mothers.

Footnotes

Competing interests: None declared.

Competing interests: None declared.

References

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