Diagnostic ultrasound ( PDFDrive )

CHAPTER 53 The Pediatric Gastrointestinal Tract 1841
FIG. 53.13 Lactobezoar. Longitudinal ultrasound of the stomach.
Note large illing defect caused by the lactobezoar in an otherwise
luid-illed stomach (arrow). The child had had nothing by mouth for 6
hours.
FIG. 53.15 Normal Duodenum. The third portion of the duodenum
(arrow) is visible between the aorta and superior mesenteric vessels.
vessels (Fig. 53.15). In addition, gradual compression of the
abdomen with the transducer during scanning oten encourages
the gas to move to other areas, allowing previously obscured
small bowel loops to be examined. he mucosa, submucosa, and
muscular layers can be delineated, 28 especially in those loops
that contain luid (Fig. 53.16).
FIG. 53.14 Trichobezar. Echogenic arc is caused by air trapped
within the mass of hair ibers (arrow).
DUODENUM AND SMALL BOWEL
Normal Anatomy and Technique
Normally, intestinal gas prevents complete visualization of the
duodenum and small bowel with ultrasound. However, if
the stomach is illed with luid, it is oten possible to identify
the duodenal bulb, descending duodenum, and third portion of
duodenum located between the aorta and the superior mesenteric
Congenital Duodenal Obstruction
Sonography can readily identify an obstructed, luid-illed,
distended duodenum, and frequently the level of obstruction
can be determined. Complete duodenal obstruction in the
newborn is oten readily apparent on radiographs, and ultrasound
generally provides little additional useful information. However,
in patients in whom the stomach and duodenum are illed with
luid rather than air, ultrasound can be quite useful.
Proximal duodenal obstruction resulting in the classic doublebubble
sign occurs with duodenal atresia, with or without
associated annular pancreas (Fig. 53.17). Plain radiograph indings
usually are diagnostic, showing two air-illed bubbles representing
the dilated stomach and proximal duodenum. Similar indings
can be seen with severe duodenal stenosis and duodenal
diaphragms or webs. Usually, sonography is not needed to
identify obstructions in this portion of the duodenum. However,
when duodenal atresia is associated with esophageal atresia, air
cannot reach the stomach and duodenum, making radiographic
diagnosis more diicult. Sonography is diagnostic in such infants
by demonstrating the grossly distended, luid-illed duodenal
bulb, stomach, and distal esophagus. 40,41
Sonography has been used for diagnosis of intestinal malrotation
with midgut volvulus in an infant with bilious vomiting,
although the luoroscopic upper GI series remains the reference
standard. If an ultrasound is performed in a patient with volvulus,