Lower gastrointestinal bleeding laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
The essential laboratory workup in the management of lower gastrointestinal bleeding includes a [[complete blood count]], [[Renal function tests|renal function]] | The essential laboratory workup in the management of lower gastrointestinal bleeding includes a [[complete blood count]], [[Renal function tests|renal function]] test, [[liver function tests]], and [[coagulation studies]]. In patients with life-threatening bleeding, although not diagnostic, a [[Blood types|blood type]] and [[Crossmatching|crossmatch]] should be done. | ||
==Laboratory Findings== | ==Laboratory Findings== | ||
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*Other abnormalities, such as [[thrombocytopenia]], may point to a variceal source of bleeding. | *Other abnormalities, such as [[thrombocytopenia]], may point to a variceal source of bleeding. | ||
*The presence of [[uremia]] or a history of [[aspirin]] or [[clopidogrel]] can significantly affect [[platelet]] function without causing [[thrombocytopenia]]. | *The presence of [[uremia]] or a history of [[aspirin]] or [[clopidogrel]] can significantly affect [[platelet]] function without causing [[thrombocytopenia]]. | ||
*[[ | *[[Leukocytosis]] may point to an [[infectious]] or [[inflammatory]] cause. | ||
===[[Renal function tests]]=== | ===[[Renal function tests]]=== | ||
*Abnormal values of [[renal function tests]] | *Abnormal values of [[renal function tests]] may indicate underlying [[kidney disease]]. Chronic kidney disease [[CKD]] is associated with increased risk for gastrointestinal bleeding by disrupting [[platelet]] function. | ||
*The presence of [[uremia]] may suggest bleeding is from an upper gastrointestinal source. | *The presence of [[uremia]] may suggest bleeding is from an upper gastrointestinal source. | ||
*Intravenous contrast for [[Angiogram|angiograms]] must be administered with caution in patients with renal impairment to avoid the risk of [[Contrast induced nephropathy|contrast nephropathy]]. | *Intravenous contrast for [[Angiogram|angiograms]] must be administered with caution in patients with [[renal]] impairment to avoid the risk of [[Contrast induced nephropathy|contrast nephropathy]]. | ||
===[[Liver function tests]]=== | ===[[Liver function tests]]=== | ||
* | *Patients with an underlying [[Liver diseases|liver disease]] are at increased risk of gastrointestinal bleeding. | ||
*[[Bleeding]] will be more difficult to control due to coagulopathy associated with liver dysfunction. Hence [[Liver function tests|LFT's]] are recommended to assess the severity of liver damage. | *[[Bleeding]] will be more difficult to control due to [[coagulopathy]] associated with liver dysfunction. Hence [[Liver function tests|LFT's]] are recommended to assess the severity of liver damage. | ||
*Abnormal liver function without any previous history liver disease may suggest the presence of colorectal varices. | *Abnormal liver function without any previous history of liver disease may suggest the presence of [[colorectal]] [[varices]]. | ||
===Coagulation studies=== | ===Coagulation studies=== | ||
*An elevated [[INR]] may indicate [[Anticoagulation therapy|anticoagulation]] with [[warfarin]] or may be evidence of severe liver dysfunction. | *An elevated [[INR]] may indicate [[Anticoagulation therapy|anticoagulation]] with [[warfarin]] or may be evidence of severe liver dysfunction. | ||
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*Blood type and cross match identifies [[blood groups]] A, B, AB, O and [[Rhesus factor|Rhesus (Rh) factor]]. | *Blood type and cross match identifies [[blood groups]] A, B, AB, O and [[Rhesus factor|Rhesus (Rh) factor]]. | ||
*Blood type and cross match is essential in the management of hemodynamically unstable patients who may need a [[blood transfusion]]. | *Blood type and cross match is essential in the management of hemodynamically unstable patients who may need a [[blood transfusion]]. | ||
===Fecal Occult Blood Testing=== | |||
*Fecal occult blood test ([[FOBT|FOBT's]]) have sufficient sensitivity to detect bleeding that is not visible in the stool. | |||
*Three types of FOBT are currently employed. | |||
**Guaiac-based tests | |||
**Heme-porphyrin tests | |||
**Immuno-chemical tests | |||
{| class="wikitable" | |||
!Types of FOBT | |||
!MOA | |||
!Causes of False-Positive | |||
|- | |||
| | |||
* Guaiac-based tests | |||
** Hemoccult II | |||
** Hemoccult II SENSA | |||
| | |||
* Pseudo-peroxidase activity of [[hemoglobin]] turns the guaiac compound blue in the presence of [[hydrogen peroxide]]. | |||
| | |||
* Red meat consumption (nonhuman [[hemoglobin]]) | |||
* Fruit consumption (cantaloupe, grapefruit, figs) | |||
|- | |||
| | |||
* Heme-porphyrin tests | |||
** HemeSelect | |||
** FECA-EIA | |||
| | |||
*HemoQuant, measures [[hemoglobin]]-derived [[porphyrins]] | |||
*Allowing quantitative measurement of [[hemoglobin]] in stool | |||
| | |||
* Extraintestinal blood loss | |||
** [[Epistaxis]] | |||
** [[Gingival bleeding]] | |||
** [[Tonsillitis]]/[[pharyngitis]] | |||
** [[Hemoptysis]] | |||
|- | |||
| | |||
* Immuno-chemical tests | |||
| | |||
* Detects intact human [[hemoglobin]]. | |||
* Immunochemical [[FOBT|FOBTs]] do not detect digested [[hemoglobin]] | |||
* They are not able to detect bleeding from upper gastrointestinal sources | |||
| | |||
* No false positives | |||
|} | |||
<small> | <small> | ||
<div style="width: 55%;"> | <div style="width: 55%;"> | ||
Latest revision as of 19:38, 29 December 2017
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Lower gastrointestinal bleeding Microchapters |
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Differentiating Lower gastrointestinal bleeding from other Diseases |
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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
The essential laboratory workup in the management of lower gastrointestinal bleeding includes a complete blood count, renal function test, liver function tests, and coagulation studies. In patients with life-threatening bleeding, although not diagnostic, a blood type and crossmatch should be done.
Laboratory Findings
Laboratory findings in patients presenting with lower gastrointestinal bleeding include:[1][2][3][4][5]
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 can significantly affect platelet function without causing thrombocytopenia.
- Leukocytosis may point to an infectious or inflammatory cause.
Renal function tests
- Abnormal values of renal function tests may indicate underlying kidney disease. Chronic kidney disease CKD is associated with increased risk for gastrointestinal bleeding by disrupting platelet function.
- The presence of uremia may suggest bleeding is from an upper gastrointestinal source.
- Intravenous contrast for angiograms must be administered with caution in patients with renal impairment to avoid the risk of contrast nephropathy.
Liver function tests
- Patients with an underlying liver disease are at increased risk of gastrointestinal bleeding.
- Bleeding will be more difficult to control due to coagulopathy associated with liver dysfunction. Hence LFT's are recommended to assess the severity of liver damage.
- Abnormal liver function without any previous history of liver disease 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
- Blood type and cross match identifies blood groups A, B, AB, O and Rhesus (Rh) factor.
- Blood type and cross match is essential in the management of hemodynamically unstable patients who may need a blood transfusion.
Fecal Occult Blood Testing
- Fecal occult blood test (FOBT's) have sufficient sensitivity to detect bleeding that is not visible in the stool.
- Three types of FOBT are currently employed.
- Guaiac-based tests
- Heme-porphyrin tests
- Immuno-chemical tests
| Types of FOBT | MOA | Causes of False-Positive |
|---|---|---|
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| Blood in stools | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Abdominal pain | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Yes | No | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Fever | Rectal pain | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Yes | No | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| H/O of constipation | H/O of constipation | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Yes | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Yes | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Weightloss | Diverticulosis | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Hemodynamic status | Diverticulitis | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| No | Yes | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Stable | Unstable | Polyps | Colon cancer | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Ischemic colitis | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Stool culture | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Positive | Negative | No | Yes | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Infectious colitis | Inflammatory bowel disease | Weight Loss | Anal fissure External Hemmrhoids | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Yes | No | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Rectal cancer Colon cancer | Angiodysplasia Polyps | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
References
- ↑ Tomizawa M, Shinozaki F, Hasegawa R, Shirai Y, Motoyoshi Y, Sugiyama T, Yamamoto S, Ishige N (2015). "Laboratory test variables useful for distinguishing upper from lower gastrointestinal bleeding". World J. Gastroenterol. 21 (20): 6246–51. doi:10.3748/wjg.v21.i20.6246. PMC 4445101. PMID 26034359.
- ↑ Moss AJ, Tuffaha H, Malik A (2016). "Lower GI bleeding: a review of current management, controversies and advances". Int J Colorectal Dis. 31 (2): 175–88. doi:10.1007/s00384-015-2400-x. PMID 26454431.
- ↑ Kim BS, Li BT, Engel A, Samra JS, Clarke S, Norton ID, Li AE (2014). "Diagnosis of gastrointestinal bleeding: A practical guide for clinicians". World J Gastrointest Pathophysiol. 5 (4): 467–78. doi:10.4291/wjgp.v5.i4.467. PMC 4231512. PMID 25400991.
- ↑ Strate LL, Gralnek IM (2016). "ACG Clinical Guideline: Management of Patients With Acute Lower Gastrointestinal Bleeding". Am. J. Gastroenterol. 111 (4): 459–74. doi:10.1038/ajg.2016.41. PMC 5099081. PMID 26925883.
- ↑ Beck DE, Margolin DA, Whitlow CB, Hammond KL (2007). "Evaluation and management of gastrointestinal bleeding". Ochsner J. 7 (3): 107–13. PMC 3096402. PMID 21603524.