Diagnostic ultrasound ( PDFDrive )

1262 PART IV Obstetric and Fetal Sonography
Poor Prognostic Factors in Congenital
Diaphragmatic Hernia
Right-sided or bilateral hernia
Early gestational age at diagnosis
Small lung size (measured by lung-to-head ratio or
volumetry)
Associated abnormalities (structural or chromosomal)
Hydrops
Polyhydramnios
Degree of mediastinal shift
Intrauterine growth restriction
Liver in chest
Predictors of Decreased Survival in
Congenital Diaphragmatic Hernia
Ultrasound LHR < 1
Ultrasound o/e LHR < 25%
Three-dimensional ultrasound TFLV < 35%
Low o/e pulmonary artery ratios
MRI o/e TFLV < 25%
MRI PPLV < 15%
MRI LiTR > 20%
LHR, Lung-to-head ratio; LiTR, liver to fetal thoracic volume ratio;
MRI, magnetic resonance imaging; o/e, observed-to-expected; PPLV,
percent predicted lung volume; TFLV, total fetal lung volume.
Prenatal pulmonary artery measurements at the hila at the
With the use of ultrasound and MRI various measurements level of the four-chamber view have been performed. 211-214
have been taken to estimate the severity of lung hypoplasia and Measuring the main right and let pulmonary artery and comparing
with normals via an observed-to-expected ratio shows a
probable outcome of the fetus. By ultrasound, the lung-to-head
circumference ratio (LHR) has been used as a predictor of reduction in values in fetuses with CDH and pulmonary hypoplasia.
Doppler wave forms have been useful in deining the
outcome for let-sided CDH. To obtain this ratio the right lung
is measured at the level of the four-chamber view and that number most severe CDH cases. Increased pulmonary artery pulsatility
is divided by the head circumference to standardize for gestational index (>1) and peak early diastolic reversed low in the main
age. Metkus et al. irst described the LHR, noting those with an pulmonary artery (>3.5) relect high resistance in pulmonary
LHR less than 0.6 did not survive. 31 Laudy et al. found that an vascular bed with preferential low through the ductus arteriosus
LHR less than 1 had 100% mortality whereas an LHR greater and are correlated with poor lung growth. 215,216
than 1.4 predicted a 100% survival. 200 he LHR appears to be Other tests utilized in CDH include a hyperoxygenation test
most reliable between 24 and 34 weeks’ gestation. 201
for pulmonary vascular reactivity at 31 to 36 weeks’ gestation,
hree techniques to calculate the LHR using ultrasound have in which reactivity (20% reduction in pulmonary artery pretest
been described:
pulsatility index) suggests a good outcome, 217,218 and assessment
1. At the four-chamber heart, the largest transverse dimension of fractional moving blood volume because a decrease in this
of the right lung is drawn parallel to the sternum and the fraction is correlated with decreased lung growth and an increased
largest anteroposterior measurement is obtained at a perpendicular
angle. hese are multiplied and then divided by the Patients with fetuses with CDH generally undergo extensive
intrapulmonary artery impedance in CDH. 219-223
head circumference in millimeters.
prenatal imaging and counseling. Follow-up ultrasound examinations
should be performed to assess fetal well-being, amniotic
2. At the four-chamber heart, the maximum transverse measurement
is multiplied by the longest perpendicular anteroposterior
measurement. hese are multiplied, and then the could result in hemodynamic changes.
luid levels, lung volume, and changes in mediastinal shit that
total is divided by the head circumference in millimeters.
3. At the four-chamber heart, the outline of the right lung is Other Hernias and Eventration
traced in millimeters and then divided by the head circumference.
hernia. 224,225 Mediastinal shit is variable, but typically the heart
In bilateral hernias the falciform ligament is drawn into the
he tracing method has been shown to be the most accurate is displaced anteriorly and superiorly. Features of both right- and
in predicting survival in some centers. 202 Generally an LHR less let-sided CDH are present.
than 1 suggests a poor outcome, with a survival rate of 45%. 203,204 Pericardial hernias result from failure of the retrosternal
he variability of LHR’s prognostic value is due to diferences portion of the septum transversum to close the communication
in methodology and dependence on gestational age resulting in between the pericardial and peritoneal cavities. 226 he liver may
a controversial association with mortality. 204,205
herniate into the pericardial sac. 171,225 Pericardial efusion results
To improve outcome assessment, another ultrasound measure, from mass efect on the heart and obstruction of venous return
the observed-to-expected lung-to-head ratio (o/e LHR) has or from mechanical irritation of membranes. 227 Because the
been used. his ratio appears to have a better predictive value diferential diagnosis of a pericardial mass includes pericardial
compared with LHR. 206-209 A ratio of less than 25% is associated tumors such as teratoma, it is important to recognize the liver
with lower survival rates. 207,210
as part of the hernial sac contents by identifying the hepatic
hree-dimensional ultrasound has been utilized in patients vessels in the mass. 219,228
with CDH to assess lung volume. An o/e TFLV less than 35% In diaphragmatic eventration the intact diaphragm is displaced
cephalad at the weakened muscular portion, without
shown to predict survival. However, in up to 45% of cases, the
measures are suboptimal with sonographic measurements typically communication between the abdominal and thoracic cavities 229
25% lower than MRI values. 206 (Fig. 36.15). Diaphragmatic eventration is associated with a lower