Trowbridge RL, Rutkowski NK, Shojania KG. Does this patient have acute cholecystitis? JAMA. 2003 Jan 1;289(1):80-6.
This Rational Clinical Exam doesn’t in itself look at predictive value of ultrasound in diagnosing cholecystitis, but does cites the following meta-analysis for data on sensitivity and specificity of ultrasound.
Shea JA, et al. Revised estimates of diagnostic test sensitivity and specificity in suspected biliary tract disease. Arch Intern Med. 1994 Nov 28;154(22):2573-81.
Adjusted sensitivity of ultrasound for evaluating acute cholecystitis: 0.88 (0.74 to 1.00). Adjusted specificity: 0.80 (0.62 to 0.98).