Abstract: We identified 10 studies (545 participants and 560 tube insertions) which met our inclusion criteria. No study was assigned low risk of bias or low concern in every QUADAS-2 domain. We judged only three (30%) studies to have low risk of bias in the participant selection domain because they performed ultrasound after they confirmed correct position by other methods. Few data (43 participants) were available for misplacement detection (specificity) due to the low incidence of misplacement. We did not perform a meta-analysis because of considerable heterogeneity of the index test such as the difference of echo window, the combination of ultrasound with other confirmation methods (e.g. saline flush visualization by ultrasound) and ultrasound during the insertion of the tube. For all settings, sensitivity estimates for individual studies ranged from 0.50 to 1.00 and specificity estimates from 0.17 to 1.00. For settings where X-ray was not readily available and participants underwent gastric tube insertion for drainage (four studies, 305 participants), sensitivity estimates of ultrasound in combination with other confirmatory tests ranged from 0.86 to 0.98 and specificity estimates of 1.00 with wide confidence intervals. For the studies using ultrasound alone (four studies, 314 participants), sensitivity estimates ranged from 0.91 to 0.98 and specificity estimates from 0.67 to 1.00. Of 10 studies that assessed the diagnostic accuracy of gastric tube placement, few studies had a low risk of bias. Based on limited evidence, ultrasound does not have sufficient accuracy as a single test to confirm gastric tube placement. However, in settings where X-ray is not readily available, ultrasound may be useful to detect misplaced gastric tubes. Larger studies are needed to determine the possibility of adverse events when ultrasound is used to confirm tube placement.

Plain-language summary: Studies included in this review are current to March 2016. We included 10 studies involving 545 participants for evaluation of the diagnostic accuracy of ultrasound for confirmation of gastric tube placement. Most studies showed good performance for correct placement of the tube. However, few data were available for incorrect placement of the tube and the possible complications of a misplaced tube. Among the included studies, only 43 participants had a misplaced tube. None of the studies reported complications during ultrasound use. Three methods of ultrasound were reported: neck approach, upper abdominal (tummy) approach and a combination of both. No included studies indicated that ultrasound had sufficient accuracy as a single test for the confirmation of gastric tube placement for feeding. In contrast, ultrasound combined with other tests (e.g. saline flush visualization (pushing salt solution through the tube and seeing it inside the stomach by ultrasound)) might be useful for the confirmation of tubes used for gastric drainage. Generally, the studies were of low or unclear methodological quality. We considered only three (30%) of the 10 included studies to be representative of patients in practice because they performed ultrasound after they confirmed correct position by other methods. The studies reported a variety of results for incorrect tube placement. Larger studies are needed to investigate whether ultrasound could replace X-rays for confirming gastric tube placement, as well as whether ultrasound could decrease severe complications, such as pneumonia, from a misplaced tube.