Diagnostic ultrasound ( PDFDrive )

CHAPTER 14 The Peritoneum 521
10% to 15%; this increases to more than 50% in AIDS patients. 61
he peritoneum is a common site of extrapulmonary involvement,
62 but the chest radiograph will show evidence of pulmonary
TB in only 14% of these patients. herefore a high index of
suspicion, particularly in high-risk groups, and knowledge
of the common sonographic features allow for earlier diagnosis
of this potentially curable disease, thus reducing morbidity and
mortality.
here are no pathognomonic sonographic features for TB
peritonitis but, in the proper clinical setting, a difuse peritoneal
process may strongly suggest the diagnosis. Ascites is frequently
present and may be free or loculated. It may be anechoic or more
frequently particulate and may contain ine, mobile strands
composed of ibrin. hese strands may produce a latticelike
pattern. Irregular and nodular hypoechoic thickening of the
peritoneum, mesentery, and omentum is another feature (Fig.
14.35). 63 Associated lymphadenopathy in the mesentery and
retroperitoneum is a common feature and is more common than
in peritoneal carcinomatosis. 64-66 he nodes may be discrete or
conglomerate because of periadenitis. Caseation may give rise
to a hypoechoic center within the node, although a similar
appearance can be seen with metastatic lymph nodes undergoing
necrosis. Echogenic nodes caused by fat deposition may suggest
the diagnosis of TB. Sonographic assessment of the solid viscera
may show involvement, particularly hypoechoic masses in the
spleen. Ultrasound helps guide diagnostic paracentesis in TB
peritonitis and may also guide ine-needle aspiration of enlarged
nodes. 67 Sonography can also readily document response to
treatment.
Sclerosing Peritonitis
Sclerosing peritonitis is a major complication of continuous
ambulatory peritoneal dialysis and is characterized by the
formation of a connective tissue membrane covering the
peritoneum and eventually encasing and strangulating bowel
loops. 68,69 Patients initially complain of abdominal pain and loss
of ultrailtration. Ultimately, bowel obstruction occurs. Surgery is
oten diicult in these patients, and the prognosis is poor. Early
diagnosis of sclerosing peritonitis may be important in reducing
mortality.
Ultrasound is extremely helpful in the diagnosis. 70 Increased
peristalsis in multiple bowel loops is one of the earliest indings
in sclerosing peritonitis. Ascites, both free and loculated, is
common. With time, the luid becomes more complex with
stranding (Fig. 14.36). Bowel loops become matted together
and are tethered to the posterior abdominal wall by a characteristic
enveloping membrane. his membrane can be seen with ultrasound
as a uniformly echogenic layer measuring 1 to 4 mm in
thickness.
LOCALIZED INFLAMMATORY
PROCESS OF PERITONEAL CAVITY
he CT appearance and signiicance of inlamed peritoneal fat
are familiar to sonographers. If ultrasound is to be successful at
investigating patients with abdominal symptoms, the sonographic
appearance of inlamed fat must become just as familiar.
Inlamed perienteric fat appears as an echogenic “mass efect,”
with ultrasound frequently displacing bowel loops out of the
scanning plane. Compression sonography may greatly enhance
the detection of focally inlamed fat, and gentle palpation with
the transducer over this area will frequently show that it is the
site of the patient’s maximal tenderness. Frequently, an associated
underlying abnormality, such as an abnormal bowel segment,
can be identiied with ultrasound 71 (Fig. 14.37). Appendicitis
and diverticulitis are the most common acute processes giving
rise to focally inlamed fat. Other possibilities include inlammatory
bowel disease, pancreatitis, and complicated acute
cholecystitis. Progression to phlegmon typically shows development
of a hypoechoic region within the echogenic fat without
luid content (Fig. 14.38). If untreated, this may progress to abscess
formation. Color Doppler imaging frequently shows increased
blood low in the area of inlammation. 72
RIGHT-SIDED SEGMENTAL OMENTAL
INFARCTION
Right-sided segmental omental infarction is a rare clinical entity
that usually presents with right-sided abdominal pain and is
oten mistaken for appendicitis. It is important to make the correct
diagnosis because the condition is self-limiting and resolves
spontaneously with supportive measures. Omental infarction
occurs in all age groups and is thought to result from an embryologic
variant in the blood supply to the right inferior portion of
the omentum, leaving it prone to infarction. Precipitating factors
include straining and eating a large meal.
Ultrasound reveals an echogenic, ovoid, or cakelike mass in
the right midabdomen at the site of the patient’s tenderness 73,74
(Fig. 14.39). Careful assessment will reveal no underlying bowel
abnormality. he typical location of right-sided omental infarction
is anterolateral to the hepatic lexure of the colon, and it corresponds
to a circumscribed fatty mass on CT, with areas of
stranding. he mass oten adheres to the parietal peritoneum,
with bowel moving deep to it on respiration.
ENDOMETRIOSIS
Endometriosis is a common condition afecting predominantly
premenopausal women and occurs when functional endometrium
is located outside of the uterus. Patients may be asymptomatic
but frequently present with pelvic pain, dyspareunia, or infertility.
he ovaries and suspensory ligaments of the uterus are
the sites most oten afected, but endometriotic implants can
involve the bowel, urinary bladder, peritoneum, chest, or sot
tissues. 75
Sonographic evaluation is oten normal in patients with
endometriosis. If endometriomas are present, TVS is very
sensitive at detecting and characterizing the masses, oten showing
the typical “chocolate” cysts with uniform, low-level internal
echoes (Fig. 14.40, Video 14.8). here may be associated complex
free luid with stranding. Occasionally, tiny echogenic foci may
be identiied along the pelvic peritoneal surfaces. hese foci are
not speciic for endometriosis and may also be seen with serous
papillary ovarian neoplasms. Clinical correlation is essential,