Lower gastrointestinal bleeding laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
==Laboratory Findings== | ==Laboratory Findings== | ||
The minimum essential blood work in diagnosing lower gastrointestinal bleeding includes a complete blood count, renal function and liver function tests, and coagulation studies. Although not diagnostic, a blood type and crossmatch should be done in patients who present with life-threatening bleeding. | |||
===Complete blood count=== | |||
*Complete blood count may show a low hemoglobin level or a drop from a previous baseline level. | |||
* | *In acute blood loss, the initial hemoglobin level may be normal but will fall with fluid resuscitation. | ||
* | *Other abnormalities, such as thrombocytopenia, may point to a variceal source of bleeding. | ||
* | *The presence of uremia or a history of aspirin or clopidogrel use should be noted, as both factors can significantly affect platelet function without causing thrombocytopenia. *A raised leukocyte count may point to an infectious or inflammatory cause. | ||
** | ===Renal function tests=== | ||
** | *Abnormal values of renal function tests of may indicate underlying kidney disease, a condition associated with increased risk for gastrointestinal bleeding. | ||
** | *A disproportionately raised urea nitrogen level may suggest bleeding from an upper gastrointestinal source or hemoconcentration. | ||
*Intravenous contrast for angiograms must be administered with caution in patients with renal impairment to avoid the risk of contrast nephropathy. | |||
* | ===Liver function tests=== | ||
*Persons with an underlying liver disease are at increased risk of gastrointestinal bleeding, and bleeding may be more difficult to control due to coagulopathy associated with liver dysfunction. | |||
*Abnormal liver function may suggest the presence of colorectal varices. | |||
===Coagulation studies=== | |||
*An elevated INR may indicate anticoagulation with warfarin or may be evidence of severe liver dysfunction. | |||
*A prolonged aPTT is seen in anticoagulation with heparin. | |||
===Blood type and cross match=== | |||
*Identifies blood groups A, B, AB, O and Rhesus (Rh) factor. | |||
*Essential in the management of hemodynamically unstable patients who may need a blood transfusion. | |||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} |
Revision as of 23:31, 11 December 2017
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]
Overview
Laboratory Findings
The minimum essential blood work in diagnosing lower gastrointestinal bleeding includes a complete blood count, renal function and liver function tests, and coagulation studies. Although not diagnostic, a blood type and crossmatch should be done in patients who present with life-threatening bleeding.
Complete blood count
- Complete blood count may show a low hemoglobin level or a drop from a previous baseline level.
- In acute blood loss, the initial hemoglobin level may be normal but will fall with fluid resuscitation.
- Other abnormalities, such as thrombocytopenia, may point to a variceal source of bleeding.
- The presence of uremia or a history of aspirin or clopidogrel use should be noted, as both factors can significantly affect platelet function without causing thrombocytopenia. *A raised leukocyte count may point to an infectious or inflammatory cause.
Renal function tests
- Abnormal values of renal function tests of may indicate underlying kidney disease, a condition associated with increased risk for gastrointestinal bleeding.
- A disproportionately raised urea nitrogen level may suggest bleeding from an upper gastrointestinal source or hemoconcentration.
- Intravenous contrast for angiograms must be administered with caution in patients with renal impairment to avoid the risk of contrast nephropathy.
Liver function tests
- Persons with an underlying liver disease are at increased risk of gastrointestinal bleeding, and bleeding may be more difficult to control due to coagulopathy associated with liver dysfunction.
- Abnormal liver function may suggest the presence of colorectal varices.
Coagulation studies
- An elevated INR may indicate anticoagulation with warfarin or may be evidence of severe liver dysfunction.
- A prolonged aPTT is seen in anticoagulation with heparin.
Blood type and cross match
- Identifies blood groups A, B, AB, O and Rhesus (Rh) factor.
- Essential in the management of hemodynamically unstable patients who may need a blood transfusion.