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Abstract
Background and Aims Ileus is an important contributor to morbidity after colorectal surgery. Ultrasound may be used to detect early dysfunction by imaging of the stomach and small bowel. The aim of this feasibility study was to identify if gastric ultrasound could detect ileus by demonstrating delayed gastric emptying.
Methods Prospective, non-randomised, observational cohort study, using a curvilinear ultrasound probe. Imaging was performed in the epigastrium, in a parasagittal orientation to obtain a cross-sectional area (CSA) of the gastric antrum. Baseline scanning was performed, followed by ingestion of 200mls of water. Measurements of CSA were performed at 20 and 40 minutes to assess change in volume of the stomach, as well as a single assessment of small bowel peristalsis. Feasibility outcomes were collected including recruitment rates, and adequacy of views.
Imaging position, and view obtained for assessment of Cross sectional area of gastric antrum
ROC plot day 1 CSA at 20 minutes post ingestion of water
Gastric antrum cross sectional area: day1 postop, 20mins
Results 27% of patients had GI dysfunction. On D1, the gastric antrum CSA was significantly larger in the dysfunction group at 20 minutes, 8.3cm2 (4.7) vs. 12.4cm2(4.1), p=0.044 and at 40 minutes 6.0(3.6) vs. 8.0(2.4), p=0.05. The ability of a D1 post op US scan to detect GI dysfunction was best at a cross sectional area of 10cm2, which yields a sensitivity of 71% and a specificity of 76%. The negative predictive value is 89%, with a positive predictive value of 50%.
Conclusions GI dysfunction after major abdominal surgery can be predicted by a day 1 gastric ultrasound after water ingestion. Gastric US is better at predicting those patients who do not have GI dysfunction.