Lower gastrointestinal bleeding other diagnostic studies
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]
Overview
Nasogastric tube lavage may be helpful in the diagnosis of lower gastrointestinal bleeding. NGT helps in differentiating LGIB from UGIB. Evidence of old (brown colored or ‘coffee grounds’) or fresh blood documents presence of UGIB. Evidence of bilious material rules out bleeding distal to the pylorus.
Other Imaging Findings
Nasogastric lavage
- Nasogastric lavage is only indicated when the diagnosis of UGIB doubtful.[1][2]
- It is rarely used.
- Nasogastric lavage also helps in documenting active or recent UGIB and the need for urgent endoscopy.
- Occasionally used to empty gastric contents in preparation for endoscopy.
Interpretation
- Evidence of brown colored or ‘coffee ground coloured blood documents presence of UGIB.
- Evidence of bilious material rules out bleeding distal to the pylorus.
- Aspiration of any other GI contents is non-diagnostic.
- After the NGT lavage it’s often difficult to determine whether blood in gastric contents is either vomited or from aspiration.
- Slide tests are based on orthotolidine (Hematest reagent tablets and Bili-Labstix) or guaiac (Hemoccult and Gastroccult).
- Rosenthal found orthotolidine-based tests more sensitive than specific; the Hemoccult test’s sensitivity reduced by the acidic environment; and the Gastroccult test be the most accurate[3]. Cuellar documented the following results:
| Finding | Sensitivity | Specificity | Positive predictive value (prevalence of 39%) |
Negative predictive value (prevalence of 39%) |
|---|---|---|---|---|
| Gastroccult | 95% | 82% | 77% | 96% |
| Physician assessment | 79% | 55% | 53% | 20% |
- Holman used simulated gastric specimens and found the Hemoccult test to have significant problems with non-specificy and false-positive results, whereas the Gastroccult test was very accurate[5].
Contraindications
- Avoid gastric lavage in patients with suspected perforated abdominal viscus.
Complicatiions
Complications of the procedure include:
- Bleeding from trauma during tube passage in patients with coagulopathy is a possible complication.
- Other rare complications include
- Pharyngeal and esophageal perforation
- Cardiac arrest
- Ethmoid sinus fracture with brain trauma
- Bronchial intubation.
References
- ↑ Pallin DJ, Saltzman JR (2011). “Is nasogastric tube lavage in patients with acute upper GI bleeding indicated or antiquated?”. Gastrointest. Endosc. 74 (5): 981–4. doi:10.1016/j.gie.2011.07.007. PMID 22032314.
- ↑ Marshall JB (1982). “Management of acute upper gastrointestinal bleeding”. Postgrad Med. 71 (5): 149–54, 157–8. PMID 6978482.
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