Diagnostic ultrasound ( PDFDrive )

CHAPTER 14 The Peritoneum 517
M
M
A
B
FIG. 14.28 Non-Hodgkin Lymphoma of the Peritoneum. (A) Transverse ultrasound image and (B) axial CT image of the right lower quadrant
show a mass (M) displacing bowel loops medially. Iniltrated fat (arrows) is seen lateral to the mass as echogenic mass effect on the sonogram.
Most cases of infective peritonitis are bacterial, secondary
to complications of disease processes involving intraabdominal
organs. Common causes include bowel necrosis secondary to
ischemia, perforated appendicitis, perforated diverticulitis,
perforated duodenal ulcer, inlammatory bowel disease, and
postoperative leaks. Culture of the exudate generally reveals a
mixed lora in this setting, with gram-negative bacilli and
anaerobes predominating.
Primary or spontaneous bacterial peritonitis occurs much
less oten, predominantly in association with cirrhosis and
nephrotic syndrome. he clinical indings are oten subtle, and
correct diagnosis requires a high index of suspicion. Spontaneous
bacterial peritonitis should be considered in any cirrhotic patient
with ascites, fever, and an unexplained clinical deterioration.
Culture of the ascitic luid will characteristically reveal a single
organism, usually Escherichia coli.
he sonographic appearance of infective peritonitis varies
but may include particulate ascites (Fig. 14.30A), loculated ascites,
or ascitic luid containing septations (Fig. 14.31), debris, or gas. 57
Difuse thickening of the parietal and visceral peritoneum
(Fig. 14.30B), mesentery, and omentum may also be observed,
and heterogeneous exudate may be seen interposed between
bowel loops.
Peritonitis secondary to viruses, fungi, or parasites is rare
and usually occurs in immunocompromised patients (Fig. 14.32)
or patients on continuous ambulatory peritoneal dialysis. Echinococcal
disease may involve the peritoneum. 58 A hepatic or
splenic cyst may rupture, resulting in difuse seeding of the
peritoneal cavity. Ultrasound may reveal one or more of the
typical appearances of hydatid cysts, including daughter cysts,
the sonographic “water lily” sign, or multiple, closely folded
echogenic membranes within the cyst cavity.
Abscess
Abscesses may occur at the site of a localized perforation or may
result from delayed treatment of peritonitis, in which case they
oten develop in dependent areas of the abdomen and pelvis.
he subphrenic or subhepatic spaces and the pouch of Douglas
are common locations. Ultrasound is oten limited in detecting
intraabdominal abscesses, particularly in postoperative patients.
hese patients are less mobile because of their recent surgery
and frequently have open wounds and dressings, limiting access
for the ultrasound probe. In addition, visibility is oten limited
by extensive bowel gas, a result of paralytic ileus. In this setting,
it may prove extremely diicult to distinguish between a dilated,
aperistaltic, luid-illed or gas-illed bowel loop and an extraluminal
abscess collection.
Recognized features of intraabdominal abscesses include round
or oval luid collections with well-deined and irregular walls.
hey usually contain internal debris and septations (Figs.14.33
and 14.34) and occasionally small pockets of gas that appear as
echogenic foci with ultrasound, oten with posterior reverberation
artifact. he presence of gas within a collection is virtually
diagnostic of infection. 59 Ultrasound-guided or CT-guided
percutaneous drainage is generally the treatment of choice, and
follow-up sonographic examinations are helpful at assessing
response to therapeutic intervention.
Tuberculous Peritonitis
Tuberculosis (TB) is still prevalent in developing countries, with
a recent resurgence in the developed world, particularly among
AIDS patients and immigrant populations. 60 Other groups at
risk include patients with alcoholism and cirrhosis. Of all non-
AIDS patients with TB, extrapulmonary disease occurs in only