Answer: 5. Number of gallstones.  1, 2, 3, and 4 (also known as sonographic Murphy’s sign), are principal aspects of determining cholecystitis.

The following images from the patient also obtained to screen for cholecystitis accompanying her gallstone:

Diagnosis: Cholelithiasis without cholecystitis

Ultrasonographic Findings of Cholelithiasis and Cholecystitis

• Determinants of Cholelithiasis: Visualization of hyperechogenic object with shadowing behind it, generally >5mm in size, as in the image question
• Determinants of Cholecystitis:

1. Increased gallbladder wall thickness (> 3mm is significant, make sure that the measurement is perpendicular through the wall)
2. Dilation of common bile duct (>5mm is suspicious, >8mm pathogenic)

Imaging tip: The common bile duct is anterior to the portal vein and deep to the liver – use color Doppler to identify the duct overlaying the portal vein as in the above images

Making the Diagnosis: Imaging Choice

Ultrasound is diagnostic and more sensitive than CT or HIDA scan.

Differential Diagnosis:

• Cholelithiasis
• Gallbladder polyp
• Cholecystitis
• Choledocholithiasis
• Calcified (porcelain) gallbladder
• Carcinoma of gallbladder

Treatment:

• IV fluids, Pain control, NPO (especially if surgery)
• If cholelithiasis, can be discharged with outpatient follow up if tolerated vs admission for non-emergent cholecystectomy for severe pain.
• If acute cholecystitis is present antibiotic treatment (cefazolin, cefuroxime, ceftriaxone) and possible (likely) surgery.
• Expanded antibiotic regimen if infection is severe or if the patient has developed complications such as emphysematous cholecystitis.

References:

1. Noble V, Nelson B.  Manual Of Emergency and Critical Care Ultrasound, 2^nd Ed.  New York: Cambridge Univ Press; 2011. 151-171. Print
2. Ma O, Mateer J, Reardon R, Joing S.  Ma & Mateer’s Emergency Ultrasound.  3^rd Ed.  New York: McGraw-Hill Education. 2014. 247-272.  Print
3. http://radiopaedia.org/articles/acute-cholecystitis