Gallbladder Hydrops and Empyema

Published on 19/07/2015 by admin

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Last modified 19/07/2015

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 Content usually sterile without GB inflammation

• GB empyema: Pus-filled, inflamed, and distended GB secondary to acute cholecystitis with suppurative intraluminal infection

IMAGING

• Hydrops

image CECT: Distended GB filled with low-density contents

– Usually no wall thickening, pericholecystic fluid, or adjacent fat stranding
image US: Distended GB with anechoic and simple contents

– GB wall appears thin or normal
– Negative sonographic Murphy sign
– Gallstones usually (but not always) present
• Empyema

image CECT: Distended GB with intraluminal contents > 15 HU

– Wall thickening with pericholecystic fat stranding and fluid (similar to conventional cholecystitis)
– Advanced cases may show gangrene or perforation
image US: Markedly distended GB with echogenic pus in lumen

– GB wall appears thickened
– Sonographic Murphy sign often positive
– Gallstones usually (but not always) present

PATHOLOGY

• GB hydrops caused by chronic GB outlet obstruction (most commonly due to impacted stone)
• Empyema caused by bacterial infection of bile within inflamed GB, usually in setting of acute cholecystitis

CLINICAL ISSUES

• Hydrops: RUQ pain without fever or signs of infection
• Fever or ↑ WBC with dilated GB concerning for empyema
• Cholecystectomy for GB hydrops if patient is symptomatic
• Urgent cholecystectomy for empyema
image
(Left) Oblique ultrasound shows an enlarged gallbladder in a 5 year old with fever and right upper quadrant pain. The hydropic gallbladder led to the diagnosis of Kawasaki disease, a known predisposing factor for hydrops in children. (Courtesy R.J. Fleck, Jr., MD.)

image
(Right) Axial CECT in a cirrhotic patient with RUQ pain demonstrates that the gallbladder is distended but thin-walled, and a stone is present within the cystic duct image, findings consistent with gallbladder hydrops.
image
(Left) Ultrasound in an elderly patient with sepsis shows a massively dilated and elongated gallbladder with a thick wall image and rounded but mobile internal echogenic sludge.

image
(Right) Coronal NECT in the same patient shows the dilated gallbladder with thickened wall image. Because the patient was considered a poor surgical candidate, she was treated with percutaneous cholecystostomy, which yielded thick bile with a heavy growth of bacteria, consistent with empyema of the gallbladder.

TERMINOLOGY

Synonyms

• Hydrops: Mucocele
• Empyema: Suppurative cholecystitis

Definitions

• Hydrops: Distended gallbladder (GB) secondary to chronic obstruction filled with watery mucoid material

image Content is usually sterile without GB inflammation
• Empyema: Pus-filled, inflamed, and distended GB secondary to acute cholecystitis with suppurative intraluminal infection

IMAGING

General Features

• Best diagnostic clue

image Rounded, distended GB filled with either anechoic watery mucoid content (hydrops) or echogenic pus (empyema)
• Location

image Markedly distended GB can extend downwards into pelvis in most severe cases
• Size

image GB distended > 5 cm transverse diameter
image Size can reach up to 1.5 liters
• Morphology

image Rounded distended GB

Imaging Recommendations

• Best imaging tool

image Ultrasound
• Protocol advice

image Grayscale and color Doppler ultrasound

CT Findings

• Hydrops

image Markedly distended GB filled with low-density contents
image Usually thin wall with minimal inflammatory change

– Typically no evidence of overt wall thickening, pericholecystic fluid, or adjacent fat stranding
• Empyema

image Markedly distended GB with high-density intraluminal contents > 15 HU
image GB wall thickened > 5 mm
image Gallstones usually present, but not always visible on CT
image Pericholecystic fluid and fat stranding
image Advanced cases may demonstrate evidence of wall gangrene or perforation, including areas of diminished wall enhancement, frank defect in GB wall, or pericholecystic fluid collection

MR Findings

• Hydrops

image Distended GB with internal contents demonstrating simple fluid signal (high T2WI and low T1WI)
image No evidence of wall edema or adjacent inflammation
image Gallstones usually present (usually visible as signal voids on all sequences)
• Empyema

image Distended GB with internal contents demonstrating variable signal depending on proportion of bile, pus, and blood
image High signal edema in thickened GB wall on T2WI
image Pericholecystic fluid and fat stranding

Ultrasonographic Findings

• Markedly distended GB in both hydrops and empyema

image GB wall appears thin or normal in hydrops
image GB wall appears thickened (often asymmetric) in empyema
• Sonographic Murphy sign negative in hydrops, but often positive in empyema
• GB contents appear anechoic and simple in hydrops
• Echogenic pus in lumen, similar in echogenicity to sludge, in empyema
• Gallstones often present in both hydrops and empyema, but may also be acalculous
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