Diagnostic ultrasound ( PDFDrive )

1264 PART IV Obstetric and Fetal Sonography
TABLE 36.5 Sample Studies of
Predictors of Survival in Left-Sided
Congenital Diaphragmatic Hernia
Imaging Findings
Sign/
Value
Outcome
(% Survival)
Liver position 208 Liver up 45%
Liver down 93%
LHR ratio 208 <1 35%
>1 75%
o/e LHR 210 <25% poor
o/e TLV MRI 184,207 <25% poor (13%)
LHR, Lung to head ratio; o/e, observed to expected; TLV, total lung
volume.
Morbidity and Mortality
Mortality varies widely depending on gestational age at diagnosis,
side of the hernia (right-sided hernias have poorer survival than
let-sided hernias, 195 and bilateral hernias have worse prognosis
than do unilateral hernias), associated abnormalities, hernia size,
liver position, 183 presence of hydrops, degree of mediastinal shit,
polyhydramnios, and size of the residual lung. 31 Table 36.5
provides examples of using imaging indings to predict prognosis
(survival predictors).
Mortality from CDH can be high because of termination of
pregnancy and in utero demise (secondary to associated abnormalities
and hydrops). Ater birth, CDH results in high rates of
morbidity and mortality because of pulmonary hypoplasia,
pulmonary hypertension, and iatrogenic trauma to the airways
from mechanical ventilation. Pulmonary hypertension in newborns
in association with CDH is thought to be caused by the
wall thickening of the small pulmonary arteries. Severity of
pulmonary hypoplasia and pulmonary hypertension is related
to the volume and timing of herniation of abdominal viscera
into the hemithorax. 233,234 In a 2000 meta-analysis 234 of studies
from 1975 to 1998, of 676 prenatally diagnosed fetuses, 142
(21%) were terminated, 36 (5%) died in utero, 333 (49%) died
postnatally, and only 165 (24%) survived. More recent studies
show improved survival rates. In a 1999-2001 trial, survival of
fetuses (without in utero intervention) with an LHR of less than
1.4 and liver in the chest (i.e., fetuses presumed to have poor
survival rates) was 77%. 235 Impro`ved overall survival rates in
recent years have been attributed to alterations in clinical care
for CDH, including minimization of iatrogenic lung injury by
gentle ventilation and nutritional support. 232,236-238 Outcome is
improved if delivery is at a center with health care professionals
experienced in caring for infants with CDH.
In Utero Therapy
Options for treatment of CDH focus on lung development. Small
hernias with a large amount of visualized lung or hernias
diagnosed late in pregnancy can be delivered at a tertiary care
center where NICU services (including ECMO) are available.
EXIT to ECMO has been ofered in some centers but has not
demonstrated signiicant survival beneit. 197
Fetal surgery can be performed at specialized centers for
fetuses least likely to survive with conventional postnatal therapies.
180 Surgery is performed to aid in lung growth and typically
is not directed at repair of the diaphragmatic defect, because open
fetal surgery is associated with premature rupture of membranes
and premature labor. In addition, repair of CDH is associated
with intraoperative death caused by kinking of the umbilical vein
and ductus venosus as the liver is reduced into the abdomen. 239
Current in utero therapy is aimed at fetal endoscopic tracheal
occlusion (FETO), by balloon or clips, which stimulates lung
growth. 240-242 he procedure is performed under combined spinal
and epidural anesthesia and fetal analgesia. A 1.2-mm endoscope
within a 3.0-mm sheath is introduced into the trachea to place
a detachable balloon between the carina and vocal cords. 243 FETO
has improved prognosis of severe CDH, with its efect dependent
on the preexisting lung size. Other treatment options, such as
combining FETO with other modalities (e.g., surfactant, corticosteroids),
are being investigated. 244,245
New nonsurgical prenatal options are being evaluated, including
pharmacologic treatments and stem cell–based strategies,
and could be promising in treating pulmonary hypertension and
hypoplasia.
CONCLUSION
When an abnormality of the fetal thorax is visualized, it is
important to have a thorough approach to the fetal evaluation.
he echogenicity of the lesion, whether it is cystic or solid, location
and appearance of the heart, size of normal-appearing lung,
evidence of hydrops, and associated abnormalities are important
at initial diagnosis. Follow-up to assess interval change in appearance
and development of hydrops is important for prognosis.
he speciic diagnosis is important in determining potential in
utero therapy, guiding the appropriate mode of delivery, and
explaining to the parents the types of postnatal therapy that may
be needed.
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