Diagnostic ultrasound ( PDFDrive )

1426 PART IV Obstetric and Fetal Sonography
A
B
FIG. 41.21 Neck Teratoma. (A) Sagittal ultrasound with face up; mass (arrows) elevates chin. (B) Three-dimensional ultrasound shows the
relation of the mass with the face.
by congenital chylothorax, a primary lymphatic abnormality.
Accumulation of luid in the pleural space may lead to pulmonary
hypoplasia, compression of the heart, and obstruction
of venous return, with subsequent development of hydrops
and compression of the esophagus leading to polyhydramnios.
Untreated, the perinatal mortality is 22% to 53%. 81-85 Associated
malformations (≈25% of cases) and aneuploidy (≈7%) worsen the
outcome. 84-87
In the absence of hydrops, fetuses with isolated hydrothorax
have such a good prognosis that invasive prenatal treatment is
not indicated. 82,88 However, when hydrops develops, the outcome
without intervention is very poor. In a large review, perinatal
mortality in the hydropic group was 69% despite prenatal
interventions in a number of cases. 84
An echogenic lung mass is usually a congenital pulmonary
airway malformation (CPAM), including the previously termed
“congenital cystic adenomatoid malformation”; a bronchopulmonary
sequestration (BPS); congenital lobar emphysema; or,
in rare cases, congenital high airway obstruction syndrome.
Most cases of CPAM, regardless of their size, regress spontaneously
at least partially during the third trimester, and only a minority
of fetuses become hydropic. Focal lung masses can lead to
ipsilateral pleural efusion (Fig. 41.22; see also Fig. 41.7), mediastinal
shit, and, ultimately, hydrops. However, the hydrops may
not be caused only by the mediastinal shit but also by high-output
cardiac failure because of shunting that may occur in an anomalous
systemic artery and venous drainage through pulmonary
or systemic veins. 89
In a report of 67 cases of lung masses, only 7% developed
hydrops. 90 Of 134 fetuses with CPAM referred to two fetal surgical
centers in the United States, 101 were followed expectantly, and
all 25 hydropic fetuses died, whereas all 76 nonhydropic fetuses
survived, 91 suggesting that fetal surgery might be considered for
hydropic cases. In the absence of hydrops, and provided there
are no other anomalies, survival in these cases is virtually 100%. 92,93
When a fetus with CPAM develops hydrops, the prognosis is
poor, and antenatal intervention is oten advisable. Intervention
may be in the form of decompression by cyst aspiration (see
Fig. 41.22), shunt, or open fetal surgery. A 2006 meta-analysis
showed that shunting of CPAMs improved survival in fetuses
with hydrops, as opposed to no efect on survival in fetuses
with chest masses without hydrops. 94 Antenatal predictors of
progression to hydrops include a combination of microcystic
and macrocystic components and a large volume ratio of the
mass to the normal lung (>1.6). 95 For fetuses with no dominant
cyst and CPAM volume ratio less than 1.6, 97% did not
progress to hydrops, whereas in the group with volume ratio
greater than 1.6, 75% progressed to hydrops. 95 he success with
open fetal surgery in cases of CPAM is variable, 29% to 62%.
Antenatal aspiration of a macrocystic CCAM at times may be
an efective treatment, 95 but frequently it is inefective because
of rapid reaccumulation of the cyst luid. In cases with rapid
reaccumulation of luid, thoracoamniotic shunting may be a better
approach. 96 Survival ater shunting is correlated to gestational
age at birth, percent reduction in lesion size, and resolution of
hydrops. 97 Maternal administration of steroids also may be
helpful. 98
Although nonimmune hydrops fetalis rarely occurs in BPS
cases, it is associated with a high rate of perinatal mortality and
severe respiratory insuiciency in the neonate. 99,100 However,
neonates with BPS and hydrops can survive. 101 Diferent strategies
of in utero treatment have been proposed, such as thoracoamniotic
shunting of pleural efusion, 102-105 thoracentesis and intravascular
furosemide and digoxin, 106 alcohol ablation of the vascular pedicle
with placement of a shunt, 107 ablation of the abnormal systemic
artery from the aorta, 108,109 and open fetal surgery. 99
In CHAOS the mechanism of hydrops is secondary to cardiac
and great vessel compression by the enlarged fetal lungs. 110
Chest Drainage Procedures. Aneuploidy is present in about
6% of cases of chylothorax and should be excluded. 111 Isolated