Patwadee PiyaromRathachai KaewlaiMahidol UniversityMaharaj Nakhon Ratchasima Hospital2018-11-092018-11-092014-01-01Ultrasound in Medicine and Biology. Vol.40, No.7 (2014), 1483-14891879291X030156292-s2.0-84901982079https://repository.li.mahidol.ac.th/handle/20.500.14594/33387The objective was to describe nature and factors associated with false-negative ultrasound (US) for adult appendicitis. Patients with pathologically proven appendicitis and pre-operative US from January 2011 to May 2013 were included in this retrospective case-control study. They were divided into true-positive and false-negative groups, matched by age and gender. There were 112 patients (40 men, mean age= 40 y, 56 true positives) included. Two factors were found differ significantly: abdominal wall thickness and pain score. Greater abdominal wall thickness (18.6 mm vs. 14.9 mm, p= 0.001) and lower pain score (6.6 vs. 7.5, p= 0.018) were statistically associated with false negativity. The two groups did not differ significantly in terms of weight, height, body mass index, symptom duration, Alvarado score, US examination time, appendix position/size, perforation rate and operator. In conclusion, lower pain score and increased abdominal wall thickness are associated with false negativity in US examinations. © 2014 World Federation for Ultrasound in Medicine & Biology.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyHealth ProfessionsMedicineArticleSCOPUS10.1016/j.ultrasmedbio.2014.02.014