Introduction
Fetal echogenic bowel (FEB) refers to the ultrasound images of the fetal
intestine, which are similar to or stronger than the echo of adjacent
bone. 1 FEB is one of the soft indices of fetal
chromosomal abnormalities. Between 0.2% and 1.8% of fetuses have this
sign in the second trimester of pregnancy based on an ultrasound
examination.2-3 Most fetuses with FEB have a good
outcome, but some fetuses have an underlying pathologic condition,
including chromosomal abnormalities, cystic fibrosis (CF), intrauterine
growth restriction (IUGR), and intrauterine
cytomegalovirus.4 However, The mechanism of FEB is
unclear. Some studies suggest that meconium may be caused by fetal
intestinal mucus, intestinal gas, and ingestion of amniotic
fluid.5-8
The traditional belief has always been that the fetus is sterilein utero .9 With the development of modern
sequencing technology, more and more evidence has shown that the fetus
is colonized in utero . Collado et al.10reported a low abundance microbiome in the amniotic fluid and placenta.
Several research teams have shown that bacteria not only exist in the
fetal environment of healthy term pregnancies, but also constitute the
placental microbiota that participate in normal fetal development and
initiate colonization of the fetal microbiota.11-14 de
Goffau et al.15 concluded that the microbiota is
transferred between the maternal and fetal interface. Martinezka et
al.16 found that there are rich and diverse bacterial
DNA in mouse embryo guts. The bacterial DNA is transferred from the
maternal microbiota to the fetal gut and may be the key stimulating
factor to promote normal development of fetal mucosal immunity. A recent
radioimmunoassay study showed the presence of culturable bacteria in the
fetal gut in the second trimester.17 Such evidence
indicates that colonization of human intestinal flora begins in the
fetal period.
In recent years, a number of studies have shown that several diseases
during the fetal period are related to intestinal flora. Guzzardi et
al.18 found that growth of the fetal heart is
associated with colonization of the intestinal flora in utero .
Zhang et al.19 found that the diversity of the
intestinal flora in newborn piglets with IUGR was decreased. Therefore,
we propose a hypothesis that hyperechogenic bowel may be related to
intestinal flora via mucus and gas. The purpose of this study was to
determine the intestinal flora of neonates using high-throughput
sequencing technology, as well as the relationship between
hyperechogenic bowel and intestinal flora.