Physical examination and laboratory testing lack sufficient accuracy to distinguish cholecystitis from cholelithiasis. As a result, imaging studies are often required to safely disposition patients presenting with right upper quadrant or epigastric pain. Ultrasound is the initial test of choice in the majority of these cases, and generally relies a combination of findings (anterior gallbladder wall thickening, pericholecystic fluid/wall edema, hydrops, or a sonographic Murphy’s sign) to establish a definitive diagnosis. We suggest that the Stone-In-Neck (SIN) phenomenon, defined as an immobile stone lodged in the neck of the gallbladder, is specific for cholecystitis in the absence of other findings.
We prospectively compared the surgical pathologies of 57 patients diagnosed with either SIN or simple lithiasis to determine the incidence of cholecystitis in each group.
SIN had a specificity of 97% and a positive predictive value of 93% in diagnosing cholecystitis.
Physicians performing right upper quadrant ultrasound should have a high index of suspicion for cholecystitis when the SIN phenomenon is present, and should be aware that this group of patients are at much higher risk for cholecystitis than those with simple lithiasis.