Outcomes following the detection of fetal oedema in early pregnancy
prior to non-invasive prenatal testing: a retrospective cohort study
Abstract
Objective: To investigate the incidence of structural and chromosomal
abnormalities in cases of fetal oedema on early ultrasound prior to
non-invasive prenatal testing (NIPT). Design: Retrospective cohort
study. Setting: Tertiary obstetric ultrasound clinic in Melbourne,
Australia. Population: Women undergoing pre-NIPT ultrasound examination
from January 2013-November 2018 with fetal crown-rump length (CRL) of
28-43 mm. Methods: Cases of reported fetal oedema or increased nuchal
thickness were included. Clinical information was collected from the
clinic’s patient management database. Oedema was subclassified as
isolated nuchal oedema (>2.2 mm) or generalised
oedema/hydrops by two operators blinded to pregnancy outcomes. Main
Outcome Measures: Incidence of chromosomal or structural defects
following the detection of fetal oedema. Results: We identified 104
cases of reported fetal oedema with a CRL between 28-44 mm. Nuchal
oedema and generalised oedema were present in 40 (38.5%) and 64
(61.5%) cases respectively. Outcomes were available in 93 cases
(89.4%). Relevant chromosomal anomalies were identified in 21.5%
(20/93), occurring in 12.1% (4/33) of the nuchal oedema and 26.7%
(16/60) of the generalised oedema/hydrops cases. Structural anomalies
with normal karyotype were found in an additional four (4.3%) cases.
Miscarriage occurred in four (4.3%) cases and termination of pregnancy
in 18 cases (19.4%). Oedema resolved by 11-13+6 weeks in 81.9% and
these cases had less adverse outcomes than those with NT≥3.5 mm (10.9%
vs 76.5%, p<0.001). Conclusions: Fetal oedema in early
pregnancy is associated with a high incidence of structural or
chromosomal abnormalities, and these rates increase with progressive
severity.