<prompt> IOC for G.E.R.D:24 HR pH monitoringUpper G.I. endoscopyUltrasoundX ray abdomen  <response>: Ans. a 24 HR pH monitoringRef: Harrison 19th ed. 1261-62 24 hour pH monitoring is done for GERD. Components of 24 hour pH monitoring: Percent total time pH 4 Percent upright time pH 4 Percent supine time pH 4 Number of reflux episodes No. of reflux episodes in 5 minutes Longest reflux episode minutesRemember: This method is also used for detection of laryngo-esophageal reflux that causes asthma, laryngospasm. 