ultrasound diagnosis of fatal anomalies

SACROCOCCYGEAL TERATOMA
germ cell are responsible—this would only explain
ovarian teratomas, if any; 3, teratomas actually
represent a degenerated twin—a theory
that has been popularized in the lay media. If the
latter theory is correct, it would also apply to
brain teratomas, mediastinal and abdominal teratomas,
and sacrococcygeal lesions.
Associated malformations: Obstruction of the
urinary tract may arise secondary to compression
from this type of teratoma. Arteriovenous
anastomosis within the tumor may cause cardiac
insufficiency and development of fetal hydrops.
Malformations of the vertebral column
and neural tube defects are found in 12–18% of
cases. Anal atresia, esophageal atresia, and hydrocephalus
have also been described.
Ultrasound findings: A lesion is seen at the distal
end of the vertebral column, which may appear as
a cystic, partly solid, or purely solid lesion. The lesions
can be very large in size, sometimes even
larger than the fetal torso. The lesion may be located
either externally, outside of the body surface
behind the sacrum or inside the pelvic cavity in
front of the sacrum. Combined forms also exist
involving both locations. Calcifications are often
detected. Tumors lying inside the pelvis may displace
the urinary bladder upwards. Hydramnios
is a common feature. Arteriovenous anastomoses
within the tumor can lead to an increase
in volume load and cardiac failure, and fetal hydrops
may follow.
Fig. 7.26 Fetal sacrococcygeal teratoma, 21+6
weeks.
Fig. 7.27 Fetal sacrococcygeal teratoma. Same
fetus at 24 weeks, with nonimmune hydrops fetalis
(NIHF) due to increased volume and overloading of
the heart. Intrauterine fetal demise.
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