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NG aspiration and lavage of limited utility in diagnosis of GI bleeding source

Clinical Question:
Is nasogastric aspiration and lavage useful in differentiating an upper from lower source of gastrointestinal bleeding in patients presenting with hematochezia or melena and without hematemesis?

Bottom Line:
Nasogastric aspiration and lavage (NGAL) has a relatively low sensitivity and negative predictive value for accurately ruling out an upper gastrointestinal (GI) bleeding source in patients with melena or hematochezia without hematemesis. A randomized trial is needed to truly determine the clinical usefulness of this test in a real world setting. (LOE = 2a)

Reference:
Palamidessi N, Sinert R, Falzon L, Zehtabchi S. Nasogastric aspiration and lavage in emergency department patients with hematochezia or melena without hematemesis. Acad Emerg Med 2010;17(2):126-132.

Study Design:
Systematic review

Setting:
Emergency department

Synopsis:
These investigators thoroughly searched multiple databases including MEDLINE, EMBASE, the Cochrane Library, national meeting abstracts and online resources, and references from pertinent retrieved articles for studies evaluating the accuracy of NGAL in differentiating an upper from lower source of GI bleeding in adults presenting with melena or hematochezia without hematemesis. Upper GI bleeding refers to a source proximal to the ligament of Treitz. Esophagogastroduodenal endoscopy served as the reference standard for identifying the source of bleeding. Three retrospective observational studies met study selection criteria. The prevalence of an upper GI bleeding source in these patients ranged from 32% to 74%. The overall sensitivity and specificity of NGAL in accurately differentiating an upper from lower GI source was 42% to 84% and 54% to 91%, respectively. The negative predictive value of NGAL ranged from 61% to 78%, corresponding to a false negative diagnosis of upper GI bleeding in 1 in 3 to 4 patients. The positive predictive value of the NGAL ranged from 41% to 93%, corresponding to a false positive diagnosis of an upper GI source of bleeding in from 1 in 10 to nearly half the patients. One of the 3 studies included patients with myocardial ischemia and yielded the highest positive predictive value, which was explained by the higher prevalence of upper GI bleeds due to aspirin use or other anticoagulation therapy in this group. This may affect the overall generalizability of these results. Thus, the authors state that a negative or positive NGAL result should not in most cases change the management of patients with melena or hematochezia without hematemesis. Only 1 study reported the rate of complications (ie, gastric erosions and epistaxis) from NGAL (1.6%).

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