[Villitis of unknown etiology in placentas of pregnancies with hypertensive disorders and of small-for-gestational-age infants].

BACKGROUND

The objectives of this study are to analyze the frequency and the histopathological features of the villitis of unknown etiology (VUE) in placentas of pregnancies with hypertensive disorders and of small-for-gestational-age infants (SGA).

METHODS

Two hundred and thirteen placentas from pregnancies without clinical or laboratorial evidence of infection were studied. These cases were subdivided according to: a) maternal condition in: non-complicated pregnancy (NCP)- 151 cases, pregnancy-induced hypertension (PIH)- 37 and sustained chronic hypertension (SCH)- 25 and b) newborn weight in: small for gestational age (SGA)- 38 cases and adequate for gestational age (AGA)- 175. Of these placentas, 81 belong to the random sample, which was used to determine the frequency of VUE in the population studied. Eight blocks were taken from placental parenchyma and the histological sections were stained with hematoxylin and eosin. Frequency tables of categorical data were analyzed using the chi- square test and Fisher test; statistical significance was considered for p< 0.05.

RESULTS

The frequency of VUE in the placentas was 30.8% in the random sample, 39% in NCP, 29.7% in PIH, 32% in SCH, 34.2% in SGA infants and 37.1% in AGA infants. Placentas of pregnancies with hypertensive disorders were more affected by villitis with parenchymatous component (PIH - 27.0%, SCH - 28.0%). This lesion was also the predominant villitis in the placentas of the SGA infants (31.5%). In contrast, in placentas of NCP and AGA infants, the principal kind of villitis was basal, not associated to a parenchymatous component (16.5% and 14.8% respectively). In the majority of the cases the villitis was mild.

CONCLUSION

In the population studied, the frequency of VUE is high (around 30%). The lesion occurs in a similar frequency in placentas from NCP, PIH, SCH, SGA and AGA infants, but basal villitis not associated to a parenchymatous component affects mainly the placentas of NCP and AGA infants. It is possible that this kind of villitis could be an expression of an antigenic stimulation diverse from villitis with a parenchymatous component.