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CHAPTER 8 Acid-Base Homeostasis and Oxygenation
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199
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29. Kellum JA. Clinical review: reunification of acid-base disorders.
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30. Khanna A, Kurtzman NA. Metabolic alkalosis. Respir Care.
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31. King TA, Jackson GL, Josey AS, et al. The effect of profound
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33. Kraut JA, Madias NE. Approach to patients with acid-base
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34. Kurtz I, Kraut J, Or nekian V, et al. Acid-base analysis: a critique
of the Stewart and bicarbonate-centered approaches. Am J
Physiol Renal Physiol. 2008;294(5):F1009.
35. Levraut J, Grimaud D. Treatment of metabolic acidosis. Curr
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36. Low JA, Lindsay BG, Derrick EJ. Threshold of metabolic
acidosis associated with newborn complications. Am J Obstet
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37. Malin GL, Morros RK, Khan KS. Strength of association
between umbilical cord pH and perinatal and long term outcomes: systematic review and meta-analysis. BMJ. 2010;340:1.
38. Mokarami P, Wiberg N, Olofsson P. Hidden acidosis: an explanation of acid-base and lactate changes occurring in umbilical
cord blood after delayed sampling. BJOG. 2013;120(8):996.
39. Mokarami P, Wieberg N, Olofsson P. An overlooked aspect on
metabolic acidosis at birth: blood gas analyzers calculate base
deficit differently. Acta Obstet Gynecol Scand. 2012;91(5):574.
40. Olivia PB. Severe alveolar hypoventilation in a patient with
metabolic alkalosis. Am J Med. 1971;52:817.
41. Pomerance J. Interpreting Umbilical Cord Blood Gases; for Clini-
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42. Safar P, Nemoto EM, Severinghaus JW. Pathogenesis of central
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43. Sandberg K, Sjöqvist BA, Hjalmarson O, et al. Lung function in
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44. Shoulders-Odom B. Using an algorithm to interpret arterial
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45. Simmons MA, Adcock EW, Bard H, et al. Hypernatremia
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46. Sirker AA, Rhodes A, Grounds RM, et al. Acid-base physiology:
the “traditional” and the “modern” approaches. Anaesthesia.
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47. Sivieri EM, Bhutani VK. Pulmonary mechanics. In: Sinha SK,
Donn SM, eds. Manual of Neonatal Respiratory Care. Armonk,
NY: Mosby; 2000.
48. Story DA, Morimatsu H, Bellomo R. Strong ions, weak acids
and base excess: a simplified Fencl-Stewart approach to clinical
acid-base disorders. Br J Anaesthesiol. 2004;92(1):54.
49. Swenson ER. Metabolic acidosis. Respir Care. 2001;46(4):342.
50. Sykes GS, Molloy PM. Effect of delays in collection or analysis
on the results of umbilical cord blood measurements. Br J
Obstet Gynaecol. 1984;91(10):989.
51. Valero J, Deasntes D, Perales-Puchalt A, et al. Effect of delayed
umbilical cord clamping on blood gas analysis. Eur J Obstet
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52. Van Gosen L. Organic acidemias: a methylmalonic and propionic focus. J Pediatr Nurs. 2008;23(3):225.
53. Whittier WL, Rutecki GW. Primer on clinical acid-base problem solving. Dis Mon. 2004;50(3):122.
54. Wilson WC. Clinical approach to acid-base analysis: importance
of the anion gap. Anesthesiol Clin North Am. 2001;19(4):907.
55. Wiswell TE, Srinivasan P, Roberton NRC. Aspiration syndromes. In: Greenough A, Milner AD, eds. Neonatal Respiratory
Disorders. London: Arnold; 2003.
56. Woodrow P. Arterial blood gas analysis. Nurs Stand.
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57. Yeh P, Emary K, Impey L. The relationship between umbilical
cord arterial pH and serious adverse neonatal outcome:
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1985;151(6):798.
DIAGNOSTIC IMAGING IN
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9
maging is an important part of the diagnosis
and treatment of medical problems in new-
I
borns. The ability to noninvasively screen
for and diagnose disease, monitor the effects
of therapy, and help define prognosis has made
imaging an essential part of neonatal care. With
refinements in diagnostic equipment and capabilities, the role of imaging has expanded significantly
in recent years. There are many ways to assess any
problem, and the vast potential of the new imaging
modalities makes appropriate imaging a constant
challenge (Table 9.1). New modalities have been
introduced, and advancement in computer technology has added sophistication to established modalities. Nearly 60% of diagnostic imaging involves
modalities that were not even available 30 years ago.
Many excellent reference books and textbooks on neonatal imaging address specific
questions.* This chapter reviews the various
imaging modalities available for diagnosis and
intervention. A short summary of each imaging
modality includes background information and
the risks and benefits of each. For clarity, this
thumbnail description of each modality provides
a concise, tailored discussion of the physics of
image acquisition. Each section addresses the
most common usage of the modality in neonates,
followed by a focused discussion of one or two
aspects of image interpretation.
Because there is often more than one appropriate
way to evaluate any given problem, it is essential to
understand the inherent advantages and limitations
of each modality to decide which might be most
effective. Understanding some of the challenges
associated with diagnostic imaging can lay the
* References 3, 4, 8, 9, 22, 24, 27, 29–32.
THE NEONATE
JASON P. WEINMAN, BRIDGET M. BRONSERT, AND JOHN D. STRAIN
foundation for a focused problem-solving approach
with appropriate collaboration between clinicians
and radiology that will result in the best care for
the patient.
RADIOGRAPHY
Background
The 1896 introduction of the roentgenogram was
met with great enthusiasm, and x-ray examination
quickly became an indispensable clinical diagnostic
tool throughout the world. Until 35 years ago, the
field of radiology was based almost exclusively on
the use of the x-ray.
A beam of ionizing radiation from a source
(x-ray tube) passes through the patient, and
various structures within the body interact to
attenuate the x-ray before it is received on the
other side. The x-rays pass through the patient and
then expose a film, just as light exposes a negative
in black-and-white film photography. The film is
developed, and the resultant image (radiograph) is a
map that corresponds to the transmitted x-ray (that
portion of the x-ray not attenuated by absorption or
scattered as it passes through the patient). Somewhat
analogous to the shadows that result from objects in
the sun, the images from x-ray are a shadow of the
object being radiographed.
Bone attenuates a greater amount of the
x-ray (or allows the penetration of fewer x-rays)
than lung tissue does, resulting in a film on
which the rib is white and the lung is black. In
some ways, this can be compared with the different
shadows cast by the trunk of a tree and by its leaves.
With radiography, the spatial resolution is exquisite,
BLUE type highlights content that is particularly applicable to clinical settings.
201
TABLE
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9.1
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COMPARATIVE ANALYSIS OF IMAGING MODALITIES
IMAGING
MODALITY
X-ray Very low Excellent Fair Low Never Very fast acquisition
Fluoroscopy Low Excellent Fair Moderate Never Evaluates motion in real
Ultrasonography None Good Fair Moderate Never Portable; evaluates motion
Computed
tomography
Magnetic resonance imaging
Nuclear medicine Very low Poor Excellent Moderate to high Sometimes Physiologic imaging
IONIZING
RADIATION
Low Good Good Moderate to high Sometimes Cross-sectional imaging
None Good Excellent High Frequent Multiplanar (i.e., in multiple
SPATIAL
RESOLUTION
CONTRAST
RESOLUTION
COST SEDATION MISCELLANEOUS
eliminates motion
time
real-time
planes) imaging, flowing
blood without contrast
although the contrast resolution is lacking. One can
capture 10 to 20 line pairs per millimeter with film
radiography, although only five different densities
TABLE
9.2
POSITION OF LINES AND TUBES
can be routinely distinguished: air, fat, water
(which includes all solid viscera—liver, spleen,
kidney, pancreas, and heart), bone, and metal.
More recent developments in x-ray technology include computed radiography (CR) and
digital radiography (DR). Although the physics
of x-ray generation is essentially the same, the
receiver has changed. With CR, a phosphorescent plate replaces film, and the latent image is
captured digitally. With DR, the image is directly
captured by a digital detector. The introduction
of these products was driven by the desire to capture, archive, distribute, and display digital images.
Almost all medical imaging is now digital, and a
picture archiving and communication system (PACS)
LINE/TUBE POSITION
Endotracheal tube 1 cm above the level of the carina
Umbilical artery catheter Descending aorta between T8 and T10
Umbilical venous catheter Junction inferior vena cava and right
atrium
Central line Junction superior vena cava and right
atrium
PICC line Junction superior vena cava and right
atrium
Nasogastric tube Antrum of the stomach
PICC, Peripherally inserted central catheter; T8 and T10, thoracic vertebrae 8 and 10.
has become an essential component of any imaging department.
suboptimal line or tube placement, allowing for
repositioning and helping to eliminate compli-
Clinical Utility in the Neonatal
Intensive Care Setting
cations (Table 9.2). Chest radiographs are most
commonly used to evaluate the heart and lungs.
Abdominal imaging allows a limited assessment
Radiography is the simplest and most reliable way to
define tube and line position. Radiopaque markers
are incorporated into most of these devices. From
peripherally inserted central catheters (PICCs)
to endotracheal, thoracostomy, and feeding
tubes, a simple radiograph can quickly identify
of the solid viscera (the liver, spleen, and kidneys), as well as the bowel gas pattern, which
is useful in evaluating a neonate with a feeding
intolerance (Fig. 9.1). The bones of the trunk
and extremities are easily assessed with plain-film
radiology.
CHAPTER 9 Diagnostic Imaging in the Neonate
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203
Focused Discussion: Chest
Radiographs
The most common use of x-ray imaging in the
neonatal unit is for evaluation of the chest to
help define abnormalities that might contribute to respiratory distress. Respiratory distress
in newborns can be divided into three categories:
conditions that are managed medically, those that
are managed surgically, and iatrogenic respiratory
distress.
MEDICALLY MANAGED RESPIRATORY
DISTRESS
Table 9.3 summarizes plain-film diagnosis of
respiratory distress in newborns. The use of this
approach takes advantage of the fact that only
a limited number of changes can be identified
radiographically, and a constellation of findings can
define a specific group of etiologic factors. A sys-
tematic analysis of these various characteristics
helps determine a specific group that has a fairly
limited differential diagnosis (Box 9.1).
FIGURE 9.1 Frontal chest and abdomen show gaseous distention of the
stomach (open arrow) and duodenal bulb (curved arrow), the classic double
bubble seen in duodenal atresia. Incidental note is made of 13 pairs of ribs in
this patient with Down syndrome.
TABLE
9.3
C Congenital
H Hyaline
I Immature
M Meconium
P Neonatal
PLAIN-FILM DIAGNOSIS OF MEDICALLY MANAGED CAUSES OF RESPIRATORY DISTRESS IN THE
NEWBORN (CHIMP DIFFERENTIAL)
GESTATIONAL
AGE
heart
disease
<36 weeks Decreased Diffuse granumembrane
disease*
<26 weeks Normal Decreased Diffuse
lung
≥39 weeks Normal Increased Streaky and
aspiration
pneumonia
HEART SIZE LUNG
VOLUME
Increased Normal or
increased
Normal or
increased
SURGICALLY MANAGED RESPIRATORY
DISTRESS
Respiratory conditions that are managed surgically can be subdivided into three groups: (1)
NATURE OF
INFILTRATE
Increased pulmonary vascularity
or edema
larity with air
bronchograms
granularity
patchy
Either diffuse or
focal
PROGRESSION ANCILLARY
FINDINGS
Stable or
progressive
Progressive over
first 24 hours
Progressive Absent thymus from
Stable Air leak (i.e.,
Abnormal situs,
aortic discordance
No pleural effusions
or body wall edema
stress
pneumothorax)
Pleural effusions and
body wall edema
*Surfactant deficiency disease.
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BOX
9.1
Congenital heart disease
Hyaline membrane disease*
Immature lung
Meconium aspiration
Pneumonia
Bronchopulmonary dysplasia represents the chronic lung disease that
* The use of exogenous surfactant modifies the picture of hyaline membrane disease
(idiopathic respiratory distress syndrome [IRDS]) significantly. The irregular distribution
after endotracheal administration causes a much less uniform infiltrate, and the patchy
pattern that results has a look similar to that in meconium aspiration, which might be seen
in a term or postterm infant.
CHIMP DIFFERENTIAL DIAGNOSIS
MODEL
Transient tachypnea of the newborn (resolves over first 24 hours)
Extracardiac shunts
Diffuse atelectasis
Represents anectasis rather than atelectasis
Amniotic fluid aspiration
Diffuse
Birth asphyxia
Focal
Pulmonary hemorrhage
may result from any of the causes of respiratory distress.
those associated with aspiration, such as cleft
palate, laryngeal cleft, or tracheoesophageal fistula
(TEF); (2) those that compromise functional
lung volume, including congenital diaphragmatic
hernia (CDH), congenital lobar emphysema (Fig.
9.2), pulmonary sequestration, and congenital pul-
monary airway malformation (CPAM); and (3)
those associated with tracheal or bronchial
narrowing, such as a double aortic arch and other
vascular rings and slings, congenital tracheal stenosis,
and bronchogenic cyst (Box 9.2).
FIGURE 9.2 Frontal view of the chest shows a hyperaerated lucent left
upper lobe (arrows) associated with mediastinal shift from left to right and is
characteristic of congenital lobar emphysema.
BOX
9.2
1. Associated with aspiration
a. Cleft palate
b. Laryngeal cleft
c. Tracheoesophageal fistula
2. Compromised functional lung volume involvement
a. Congenital diaphragmatic hernia
b. Congenital lobar emphysema
c. Congenital cystic adenomatoid malformation
3. Cause tracheal or bronchial narrowing
a. Double aortic arch
b. Tracheal stenosis
c. Bronchogenic cyst
SURGICALLY MANAGED RESPIRATORY
DISTRESS
IATROGENIC RESPIRATORY DISTRESS
Most iatrogenic respiratory distress results from
either a misplaced catheter or tube or from
barotrauma. An endotracheal tube (ETT) can be
placed too deep and will preferentially ventilate
only a single lung. An ETT may even be placed
inadvertently into the esophagus, resulting in inadequate ventilation (Fig. 9.3), which is further com-
promised by distention of the esophagus and small
bowel, limiting lung expansion.
Air leaks are often the result of barotrauma
(Fig. 9.4). Although barotrauma occurs much less
frequently because of the availability of exogenous
surfactant, high-frequency ventilation, and nitric
oxide therapy, air leaks continue to be a problem that
causes significant concern. Appropriate ventilation
management requires timely and accurate diagnosis.
One goal in the review of a chest x-ray is to
define the location of any extrapulmonary gas.
Abnormal extrapulmonary gas can include any
one or a combination of the following: pulmonary interstitial emphysema, subcutaneous emphysema, pneumomediastinum, pneumothorax,
FIGURE 9.3 Frontal chest film. Although the endotracheal tube projects over
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the midline mediastinum near the thoracic inlet, the dilated esophagus (arrowheads) and distended stomach (arrow) associated with right upper lobe and left
lower lobe atelectasis suggested esophageal intubation, which was diagnosed
in this patient.
CHAPTER 9 Diagnostic Imaging in the Neonate
205
pneumopericardium, pneumocardia, and portal
venous gas.
Focused Discussion: Skeletal
Dysplasia
Skeletal dysplasias are a group of bone and cartilage
disorders that, although rare individually, overall
occur in approximately 1 in 5000 births. Today over
450 individual skeletal dysplasias are known and
classified by their clinical, radiographic, and genetic
findings. The accurate identification and classification of a patient with skeletal dysplasia can have
important implications for the patient because some
prove fatal in early life. In patients for whom a
complex skeletal dysplasia is suspected, a skeletal survey consisting of anteroposterior (AP) and
lateral views of the skull, AP and lateral views
of the spine, and AP views of the pelvis and
all extremities (with separate AP views of the
hands and feet) should be obtained.
The first step in assessing the radiographs
in a patient with suspected skeletal dysplasia
21
A
FIGURE 9.4 A, Frontal chest film. Surfactant deficiency disease (hyaline membrane disease) in this patient is defined by the diffuse
symmetric granular infiltrates with low lung volumes. This patient required intubation, and the endotracheal tube tip projects in satisfactory
position. B, Follow-up examination in the same patient demonstrates linear lucencies within the right lung resulting from pulmonary interstitial
emphysema. A tension pneumothorax (arrowheads) is identified on the right with mild mediastinal shift from right to left. The lack of atelectasis on the right is the result of the extremely poor lung compliance that accompanies pulmonary interstitial emphysema. The endotracheal
tube tip projects in a satisfactory position, but the nasogastric tube is in the midesophagus.
B
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is to look for disproportion. A disproportionate
appearance of the chest, such as a narrowed, elongated chest, can be an important diagnostic sign
of dysplasia. Other signs include flattening of the
vertebral bodies (platyspondyly), with short-trunk
disproportion, and shortening of the extremities,
such as rhizomelia (root or proximal limb shortening), mesomelia (middle limb), or acromelia (distal
limb). The next step is to evaluate epiphyseal,
metaphyseal, and diaphyseal ossification. Growth
of long bones occurs at the ends, where the midshaft (diaphysis) is contiguous with the distal shaft
(metaphysis) and separated by a radiolucent cartilaginous plate (epiphyseal cartilage or physis) from the
distal end (epiphysis). Ossification centers of the distal femur, proximal tibia, calcaneus, and cuboid are
often present at birth. With these findings in mind,
the patient can often be classified into a group of
skeletal dysplasias. With the help of reference books
on skeletal dysplasias, such as Taybi and Lachman’s
Radiology of Syndromes, Metabolic Disorders and Skeletal
Dysplasias,20 specific findings can lead to a diagnosis.
Achondroplasia is a relatively common dysplasia,
with 2.8 cases per 100,000 births. Achondroplasia
is a disproportionate rhizomelic short-limbed
skeletal dwarfism (i.e., the proximal segment
[humerus] is shorter than the middle [radius and
ulna] and distal [wrist and hand] segments). Patients
with achondroplasia also have a disproportionately
large head, with a decreased size of the skull base
and narrow foramen magnum. The lower lumbar spine demonstrates narrowing of the distance
between the pedicles, which normally widen at the
lower lumbar spine, and kyphosis (posterior angulation) at the thoracolumbar junction. Infants often
suffer from respiratory difficulties due to adenoidal
hypertrophy, narrow nasal passages, and a small thorax. Narrowing of the foramen magnum and cervicomedullary compression can lead to hydrocephalus
and neurologic complications.
Thanatophoric dysplasia is also a disproportionate
rhizomelic short-limbed dwarfism. Although the
radiographic findings are qualitatively similar to
achondroplasia, the severity of the manifestations
helps differentiate the two. Classic findings in newborns with thanatophoric dysplasia include very
short, bowed femurs with metaphyseal flaring (telephone receiver femurs); a narrow thorax; a large head
with small facial bones; and flattened vertebral bodies
with notched endplates. Thanatophoric dysplasia is
frequently suggested on prenatal ultrasonography by
FIGURE 9.5 Anteroposterior film of the chest and abdomen of a patient with
asphyxiating thoracic dystrophy (Jeune syndrome) demonstrates short broad
ribs with a narrow thorax as well as shortened iliac wings with bony spurs. Also
note the malpositioned umbilical venous catheter with its tip in the upper right
atrium (arrow) and umbilical arterial catheter (arrowhead).
shortened femurs and a narrow chest. This dysplasia
has important implications in the neonatal intensive
care unit (NICU) because infants will die within the
first few days of life without respiratory support.
In asphyxiating thoracic dysplasia (Jeune syndrome),
presenting signs include a long, narrow thorax with
short horizontal ribs and respiratory difficulties in
infancy (Fig. 9.5). Shortening of the extremities,
including the hands and feet, with occasional polydactyly (extra digits), also occurs and can present at birth or
later in life. In the pelvis, the iliac wings are shortened
in the craniocaudal direction, with bony spurs projecting from the acetabula. Complications of asphyxiating
thoracic dysplasia in the neonate center on respiratory
distress due to reduced lung volumes/small chest size.
Later in life, respiratory infections become a problem,
and progressive renal disease leading to renal failure
may occur. Patients may also develop hepatic fibrosis,
pancreatic fibrosis, and retinal degeneration.
FLUOROSCOPY
Background
Fluoroscopy employs an x-ray tube similar to
that used for plain-film radiography. The x-ray is
generated in the same manner as in plain radiogra-
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phy, but it is received in most cases by a device that
is similar to a TV camera or VCR. Fluoroscopy
allows real-time evaluation of a patient and can
be performed with or without contrast material. The spatial resolution in fluoroscopy is not as
good as that in plain-film radiography, but it is still
excellent. The contrast resolution is about the same:
air, fat, water, bone, and contrast are the primary
densities that can be separated. Contrast media can
be given orally or per rectum, instilled into the
urinary bladder, or given intravenously. The contrast
attenuates the radiation beam to a variable extent
related to physical properties and thickness of the
attenuator. Most contrast agents are compounds that
use either inert barium or iodine as the attenuator
of the radiation beam. The most important char-
acteristic of fluoroscopic imaging is the ability
to evaluate motion in real time. This is essential
in the evaluation of swallowing function, gastrointestinal (GI) peristalsis, and diaphragmatic
motion.
Clinical Utility in the Neonatal
Intensive Care Setting
CHAPTER 9 Diagnostic Imaging in the Neonate
FIGURE 9.6 A lateral film from the early filling phase of a contrast enema
demonstrates spasm of the distal rectal segment (short arrow) with a transition
zone to dilated colon (long arrow). These findings are characteristic of colonic
Hirschsprung disease.
207
The most common fluoroscopic examinations
requested for neonates include the upper GI
(UGI) series, contrast enema, and voiding cystourethrography. The UGI series (and modifica-
tions of it) is useful in the evaluation of swallowing,
feeding intolerance, vomiting, and abdominal distention with possible bowel obstruction.
A contrast enema should be the initial diag-
nostic study of choice when low bowel obstruction is suggested clinically or on radiographs. A
contrast enema can be diagnostic in many cases of
low bowel obstruction, including distal small bowel
atresia, meconium ileus, and small left colon syndrome. Findings suggestive of Hirschsprung disease
can lead to further evaluation with punch biopsy and
play an important role in surgical planning (Fig. 9.6).
In addition to a diagnostic role, a contrast enema
can be therapeutic in small left colon syndrome
and meconium ileus.
A voiding cystourethrogram is used to evaluate
the urinary bladder and the urethra and to look
for vesicoureteral reflux (Fig. 9.7), which is associ-
ated with urinary tract infection. Vesicoureteral reflux
is a common cause of hydronephrosis, which is now
frequently identified during prenatal ultrasonography.
FIGURE 9.7 Frontal view from a voiding cystourethrogram demonstrates
grade II vesicoureteral reflux on the left (arrow).
UNIT TWO Support of the Neonate208
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Ureteroceles, periureteral diverticula, and posterior
urethral valves all can be associated with hydronephrosis in the neonatal period and demonstrated with
cystourethrography.
Air functions as a useful contrast agent, and
the nasal and oral airway, as well as the trachea
and proximal bronchus, can easily be evaluated
fluoroscopically. Because the diaphragm is imme-
diately adjacent to aerated lungs, diaphragmatic
motion and its relationship to inspiratory effort help
in the evaluation of phrenic nerve injury and diaphragmatic paralysis. Eventration of the diaphragm
also can be evaluated fluoroscopically, but at times, it
can be indistinguishable from diaphragmatic hernia.
Focused Discussion: Upper
Gastrointestinal Series
Indications for performing a UGI fluoroscopic
study include swallowing dysfunction, vomiting,
choking, and apnea. An appropriately performed
UGI series offers a systematic approach to the upper
GI tract. Starting with the patient in a left-side-down
recumbent position, deglutition, transport, aspiration,
and laryngeal penetration all can be grossly assessed,
with more detailed assessment reserved for a modified barium swallow using contrast material with
varying thicknesses. The right-side-down position
better separates the esophagus and the tracheal air
column. However, if this position is used initially
and the evaluation of the esophagus is prolonged, the
stomach may empty, filling the proximal small bowel
and obscuring the location of the ligament of Treitz.
The left-side-down position allows evaluation of
swallowing and the esophagus without concern
that the stomach may empty prematurely.
Esophageal atresia usually is diagnosed clini-
cally; plain-film observation of intraluminal bowel
gas defines the most common form, which is associated with a distal tracheoesophageal fistula. Often,
an enteric tube that coils in the proximal esophageal pouch is the initial radiographic finding
in patients with tracheoesophageal fistula. The
benefit of a proximal pouch study in esophageal
atresia is controversial. There is a small incidence
of fistula from the proximal pouch to the trachea;
this incidence is independent of the presence or
absence of a distal fistula. If the surgical approach to
esophageal atresia repair includes direct visualization
of the proximal pouch (esophagoscopy), the pouch
contrast study is superfluous. If, on the other hand,
esophagoscopy is not routinely performed, there is
some value in evaluating the proximal pouch before
surgery. In the absence of esophageal atresia, the
location of the fistula (H type) is at the thoracic
inlet. This is higher than the fistula that occurs at
the level of the carina in the most common form of
esophageal atresia.
The contour and caliber of the esophagus
are evaluated next. Impressions on the posterior
esophagus are suggestive of vascular rings and are
correlated with side of the aortic arch to determine if further work-up for vascular ring is needed.
Impressions on the anterior esophagus can be
related to pulmonary artery slings. Esophageal contour, mucosal detail, and peristalsis are assessed. The
configuration of the gastroesophageal junction
can indicate gastroesophageal reflux, and rare
hiatal hernias can be diagnosed.
Gastric emptying is evaluated, and gastric
peristalsis is examined. Because the rotation and
fixation of the bowel have important consequences
in the newborn period, definition of the duodenal bulb, C-loop, and position of the ligament of
Treitz is a critical part of a complete examination.
Both the posteroanterior (PA) and lateral views are
essential in localizing the ligament of Treitz. For
proximal bowel rotation and fixation to be considered normal, the duodenal-jejunal junction (fixated
by the ligament of Treitz) must be retroperitoneal
(and therefore posterior), to the left of the spine,
and at the level of the retroperitoneal portion of the
second portion of the duodenum (just distal to the
duodenal bulb).
The rotation of the proximal bowel may be independent of the rotation of the hindgut. Therefore,
if the clinical question is malrotation and possible volvulus, the UGI series is the examination
of choice. The caliber, contour, and fold pattern
of the proximal bowel are evaluated, and the transit time is observed. This simple, systematic, yet
comprehensive approach to the UGI series yields a
tremendous amount of information.
ULTRASONOGRAPHY
Background
One of the most prominent mass-media introductions of ultrasound (US) technology came when Dr.
Robert Ballard located the wreckage of the Titanic
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