DISCUSION
Secondary pleural effusion is usually caused by generalized fluid
retention in non-immune hydrops (8). The causes of this pathology
include cardiovascular and idiopathic diseases, genetic, metabolic and
hematological disorders, infections, structural abnormalities and chest
tumors (9). To the best of our knowledge there where only reported three
confirmed SARS-CoV-2 infections during pregnancy complicated by hydrops
fetalis (2-4). In each case, the SARS-CoV-2 infection occurred in a
different trimester of pregnancy and all of them were complicated by
intrauterine fetal death. Two patients were infected before diagnosis
(2,4) and one was in active infection (3). Whereas, a PCR SARS-CoV-2
test was performed on a fetal lung biopsy and was positive (3). An
active infection from the TORCH group was ruled out in these patients.
Cytogenetic analysis revealed a normal karyotype in every case.
Moreover, histologic examination of the placenta or fetal tissues was
performed. Shende et al. reported fibrin deposition around the villi,
where the syncytiotrophoblast was lysed, and extensive leukocyte
infiltration suggesting inflammation (2). A similar picture was obtained
in the studies by Rodrigues et al. and Popescu et al. In both cases a
postmortem examination showed systemic thrombosis with thrombi in the
small and medium vessels. Recent blood clots were identified in fetal
circulation (3,4). In the study by Popescu et al. the pregnant was Rh
negative so, Rh immune globulin was given, as in our case. An attempt
was made to perform a thoracocentesis and insert a percutaneous in utero
thoracoamniotic shunt (4). The limitations of our case are no SARS-CoV-2
tests performed in placenta, amniotic fluid, and fetal tissues. After
birth the rapid antigen test was performed, which was negative.
Therefore only the clinical symptoms and the exclusion of other
possibilities, i.e. TORCH infections, genetic disorders, Rh immunization
and the proliferative process may indicate vertical transmission of the
virus. This case may constitute the basis for further studies, as the
pleural effusion is a serious emergency for a newborn.