Procedures
The ultrasound database was searched for the terms “oedema”, “edema”
and for increased nuchal translucency measurements in the reports of all
pre-NIPT ultrasound examinations. Cases of singleton pregnancy with a
CRL between 28 mm and 44 mm were then selected for analysis. Early fetal
oedema was classified into two groups (see figure 1):
- Nuchal oedema (figure 1B) – increased oedema in the region of fetal
neck > 2.2 mm (95th percentile for
nuchal translucency measurement at 10 weeks of
gestation7).
- Generalised oedema (figure 1C) – generalised subcutaneous oedema or
fetal hydrops (subcutaneous oedema with at least one of pleural
effusion, pericardial effusion or ascites).
De-identified images and videos of cases with fetal oedema were reviewed
and classified independently by two operators with extensive experience
in obstetric ultrasound, both blinded to the outcomes. In case of
discordance, a third operator’s opinion was requested.
Cases of multiple pregnancy, missed miscarriages, CRL below 28 mm or
above 45 mm or nuchal thickness less than 2.2 mm and without other signs
of fetal oedema were excluded. Ultrasound examinations were performed
using Voluson E10 (GE Healthcare Ultrasound, Zipf, Austria) machines,
equipped with a 3D 4-8 MHz probe for transabdominal and a 5-9 MHz probe
for transvaginal examinations.