Accumulation of serous fluid in the peritoneal cavity

US findings

Echo-free fluid in peritoneal “spaces”

Pouch of Douglas fills first

Potential spaces in order of filling:

pouch of Douglas

Lateral paravesical recesses

Paracolic gutters

Major flow from pelvis is in the right paracolic gutter

Supine patient would demonstrate fluid around inferior tip of the rt. Liver lobe, superior rt. Flank, and in the pelvic cul-de-sac—then the paracolic gutters, then lateral and anterior to the liver

Abscess is a cavity formed by necrosis within tissue or a confined collection of pus

S & S of FUO, tenderness and swelling at a wound, chills, weakness, malaise, localized pain

Lab findings of leukocytosis

US findings are variable according to stage and location of abscess

Classic sonographic appearance is of an elliptical sonolucent mass with thick and irregular margins

Gas-containing abscess would contain shadows from air reflectors

Lesser sac abscess

Slit-like epiploic foramen usually seals off the lesser sac from generalized abdominal inflammatory processes.  A pancreatic abscess if most likely to appear here

Classified according to the location in the kidney

Renal carbuncle is an abscess that forms in the renal parenchyma

US findings of a fluid collection in the kidney area

US findings of a complex mass in the RLQ

Cysts

Urinoma

Peritoneal metastases

Lymphomas of the omentum and mesentery

Tumors of this area

Cysts 

May have many origins

US findings of uni- or multi-loculated cyst

May contain debris

 Urachal cyst

Incomplete regression of the urachus

US findings of a cystic mass between the umbilicus and the bladder

May be embryonic, traumatic or acquired, neoplastic, infective or degenerative

Encapsulated collection of urine

May occur post trauma, surgery or obstruction

US findings of anechoic/low echo fluid collection that displaces lower pole of kidney supero-medially 

Cellular implantation throughout the peritoneal cavity

Most common primary sources are ovary, stomach and colon

US findings of nodular, sheet-like,irregular configuration of the peritoneal sheath

May be known as peritoneal ‘caking’

Uniformly thick, hypoechoic, band-shaped structure following the convexity of the omental band

US findings of lobulated, confluent, hypoechoic mass surrounding a centrally positioned echogenic area

Sandwich sign

Lymphomas of the Omentum and Mesentery

Usually seen in middle-aged males exposed to asbestos

S & S: abdominal pain, weight loss, ascites

US findings of a large mass with discrete smaller masses scattered throughout the visceral and parietal peritoneum or as matting of the abdominal contents

Abdominal wall masses

Extraperitoneal hematoma

Inflammatory lesion (abscess)

Neoplasm or peritoneal thickening

Hernia 

Inflammatory lesion (abscess)

Acute/chronic blood collections

due to direct trauma, pregnancy, cardiovascular/ degenerative muscle dx, surgical injury,anti-coagulation therapy, steroids or extreme exercise

US findings

asymmetry of rectus sheath

variable appearing lesion

Bladder flap hematoma

Collection of blood between the uterus and lower uterine segment usually seen with cesarean- section or uterine vessel bleeding

Found in prevesicular space due to disruption of interiorepigastic vessels during C-section

Neoplasms include lipomas, desmoid tumors, or metastases

US findings

Desmoid-anechoic/hypoechoic

Lipomas appear echogenic with good-thru transmission

Protrusion of a peritoneal-lined sac through a defect in the abdominal wall

May become medically significant should bowel protrude through vent