Anechoic Structure

Peritoneal Cavity

Diffuse Changes

Anechoic Structure

Hypoechoic Structure

Hyperechoic Structure

Localized Changes

Wall Structures

Differentiating Intraand Extraluminal

GI Tract Fluid

Cirrhosis of the Liver

Heart Failure

Peritonitis

Hypoalbuminemia

Peritoneal Carcinomatosis

Hemoperitoneum

Ruptured Cyst

Urinoma (Intraperitoneal)

b Small “angle of ascites” between the right hepatic lobe and the inferior pole of the right kidney in concomitant viral peritonitis.

Peritoneal Carcinomatosis

The malignant ascites in peritoneal carcinomatosis may also be anechoic (Fig. 8.17, Fig. 8.18), but internal echoes within the fluid are much more common. In anechoic ascites, the lack of any signs for cirrhosis of the liver or portal hypertension on the one hand and the demonstration of a possible primary tumor or metastases on the other will lead one to suspect the malignant origin. A detailed description of the ultrasound criteria differentiating between benign and malignant ascites is found in the section on “Wall Structures” (pp. 315–316).

Fig. 8.17 Anechoic ascites enveloping the liver in peritoneal carcinomatosis of metastatic gastric cancer. Most often peritoneal carcinomatosis will display echoes within the fluid, but it may also be anechoic.

Fig. 8.18 Anechoic malignant ascites in advanced gastric cancer. The retracted mesentery quite clearly pulls the bowel loops together.

Hypoechoic Structure

Pancreatitis

Cirrhosis of the Liver with Spontaneous Bacterial Peritonitis (SBP) Peritoneal Carcinomatosis

Purulent Peritonitis Tuberculosis Choleperitoneum Hemoperitoneum GI Tract Perforation Chyloperitoneum

Pseudomyxoma Peritonei

Fig. 8.23 Complete septation in the lower abdomen, classic honeycomb pattern in pancreatogenous ascites (necrotizing pancreatitis). Similar images are also seen in tuberculous ascites.

Peritoneal carcinomatosis is characterized by echogenic ascites with fine echoes, irregular margin, septation, retraction of the mesentery, and solid structures on the peritoneum itself (Fig. 8.25, 8.3). Differentiating between benign and malignant ascites resembles putting together a puzzle and will be explained further on (see Table 8.6, Table 8.7, 8.6). The sensitivity of a single ultrasound-guided fine-needle puncture is unacceptably low (50–60%). If there is a definite case for suspected malignancy, repeat cytology is called for (at least three times, or until a sufficient amount of centrifugate is obtained). Peritoneal carcinomatosis can be chameleon-like in its variability; it is detailed further in 8.3.

Fig. 8.25 Echogenic ascites and markedly thickened as well as irregularly delineated peritoneum in peritoneal carcinomatosis due to advanced cancer of the colon.

The ultrasound image of purulent peritonitis is characterized by inhomogeneous hypoechoic structures displaying a varied echo texture and lacking a definite interconnection (Fig. 8.26). During repositioning of the patient, the septation and adhesions will not permit free shifting of the putrid ascites. The clinical symptoms take puncture over any other modality. Ultrasound studies are of limited value in the primary diagnosis and are much more useful in identifying walled-off abscesses. Most often treatment is by surgery.

Fig. 8.26

a Purulent peritonitis. Structured fluid (calipers) enveloping the liver. Clinically: perforated duodenal ulcer.

b Diffuse purulent peritonitis with locular (structured) ascites after a surgical revision of the bile duct.

Bile leakage may be due to a perforated hydropic or empyemic gallbladder as a rare complication of cholecystolithiasis. Localized perforation is much more common than free bile leakage into the abdominal cavity (choleperitoneum). Other causes may be intraoperative lesions to the biliary tree or iatrogenic endoscopic injury. Another quite common complication after external percutaneous transhepatic bile duct drainage (PTCD) for palliation of a stenosing malignancy is dislocation of the drain with subsequent bile leakage.

Initially the leaking bile is anechoic, but after a few hours the characteristic streaks and septa will appear that induce layering and which are pathognomonic (Fig. 8.28). In those few cases with uncertain diagnosis, ultrasound-guided fine-needle puncture will confirm the free in- tra-abdominal bile (gross assessment and bilirubin panel).

Fig. 8.28

a Anechoic intra-abdominal formation with streaks of internal structures in choleperitoneum due to a perforated gallbladder (GB).

b Thin hypoechoic film around the right hepatic lobe due to intra-abdominal collection of bile in biliary leakage after a dislocated PTCD.

Hemoperitoneum

Within a few hours after hemorrhage, the organizing hemoperitoneum will become more and more echogenic, comprising internal echoes, strands of fibrin, and septation. The effusion will become more hyperechoic and inhomogeneous (Fig. 8.29, Fig. 8.30). If there is no increase in volume (bleeding staunched), ultrasonography lends itself quite easily to morphological follow-up. The advancing orga-

Fig. 8.29 Echogenic ascites in the lower abdomen in a female patient with an overdose of phenprocoumon and extensive free bleeding into the peritoneal cavity (hemoperitoneum).

GI Tract Perforation

The cardinal symptom of GI tract perforation is the demonstration of free gas within the peritoneal cavity. However, there may also be fluid leaking from the stomach or bowel. This fluid is permeated by echoes and displays gas inclusion (Fig. 8.31). Demonstration of the actual site leaking gas and liquid is a rare feat. The preferred localization of fluid collections in a perforated upper GI tract is around the stomach and duodenum as well as around both hepatic lobes. In perforation of the more downstream intestinal regions, the free gas tends to accumulate more in the lower abdomen (e. g., diverticulitis).

It should be kept in mind that the combination of free gas and free fluid may be indicative of GI tract perforation.

Fig. 8.31 Demonstration of echogenic fluid and some free gas after upper GI tract perforation (duodenal ulcer).