Diagnostic ultrasound ( PDFDrive )

CHAPTER 8 The Gastrointestinal Tract 299
(Fig. 8.50). Gut wall thickening may be noted if the pneumatosis
is associated with underlying IBD. If gut ischemia is suspected,
careful evaluation of the liver is recommended to look for evidence
of portal venous air.
Mucocele of Appendix
Mucocele of the appendix is relatively uncommon, occurring in
0.25% of 43,000 appendectomy specimens in one series. Many
patients with this condition are asymptomatic. A mass may be
palpated in approximately 50% of cases. Benign and malignant
varieties occur in a ratio of approximately 10 : 1. 91 In the benign
form the appendiceal lumen is obstructed by either inlammatory
scarring or fecaliths. he glandular mucosa in the isolated segment
continues to secrete sterile mucus. he neoplastic variety of
mucocele is associated with primary mucous cystadenoma or
cystadenocarcinoma of the appendix. Although the gross
morphology of the appendix may be similar in the benign and
malignant varieties, the malignant form is oten associated with
pseudomyxoma peritonei if rupture occurs. 92
On sonography, mucoceles typically produce large, hypoechoic,
well-deined RLQ cystic masses with variable internal echogenicity,
wall thickness, and wall calciication (Fig. 8.51). he internal
contents oten show a laminated or whorled appearance. hese
masses are frequently retrocecal and may be mobile.
Gastrointestinal Tract Hematoma
Blunt abdominal trauma, complicated by duodenal hematoma
and rectal trauma, either sexual or iatrogenic ater rectal biopsy,
are the major causes of local hematomas seen on sonography.
Hematoma is usually localized to the submucosa. Larger or more
difuse hematomas may complicate anticoagulation therapy or
bleeding disorders associated with leukemia. If hematomas are
large, difuse gut wall thickening may be seen on sonograms.
FIG. 8.50 Pneumatosis Intestinalis. Sonogram shows three loops
of gut with bright, high-amplitude echoes (arrows) originating within the
gut wall.
Peptic Ulcer
Peptic ulcer, a defect in the epithelium to the depth of the
submucosa, may be seen in either gastric or duodenal locations.
Although rarely visualized, peptic ulcer has a fairly characteristic
sonographic appearance. A gas-illed ulcer crater is seen as a
bright, echogenic focus with ring-down artifact, either in a focal
area of wall thickening or beyond the wall, depending on the
depth of penetration (Fig. 8.52). Edema in the acute phase and
ibrosis in the chronic phase may produce localized wall thickening
and deformity.
A
B
FIG. 8.51 Mucocele of the Appendix. (A) Sonogram and (B) CT scan show a large, mucus-illed appendix as an incidental observation. The
whorled appearance on the sonogram is characteristic. There is a leck of calciication in the wall on the CT scan.