# Internal Medicine/Gastrointestinal Bleeding
## Introduction and Differentiation of UGIB from LGIB

Gastrointestinal bleeding (GIB) is a clinical condition characterized by bleeding within the digestive tract. It can present in two main forms: overt bleeding and occult bleeding. Overt GIB is characterized by visible signs of bleeding, while occult GIB is not immediately apparent and may manifest through symptoms such as anemia. To differentiate between these two forms of GIB, it's essential to understand their clinical presentations and categorizations based on the site of bleeding.
Overt GIB includes symptoms such as hematemesis (vomiting of blood or "coffee-grounds" material), melena (the passage of black, tarry stool), and hematochezia (the passage of red or maroon blood from the rectum).
Occult GIB may manifest with symptoms of blood loss or anemia, such as lightheadedness, syncope, angina, or dyspnea. It can also be detected through iron-deficiency anemia or a positive fecal occult blood test, typically identified during colorectal cancer screening.
GIB can be further categorized based on the site of bleeding, which includes:
* Upper GIB: This involves bleeding from the upper portion of the digestive tract, which includes the esophagus, stomach, or duodenum.
* Lower GIB: This pertains to bleeding from the lower portion of the digestive tract, specifically the colon.
* Small Intestinal GIB: In some cases, bleeding may occur within the small intestine.
* Obscure GIB: This classification is used when the source of bleeding is unclear, despite extensive evaluation.

## Common Sources of Upper Gastrointestinal Bleeding (UGIB)

Peptic ulcers, particularly gastric and duodenal ulcers, are the most frequent cause of UGIB. They account for approximately 50% of UGIB hospitalizations. These ulcers can have varying features when observed through endoscopy, and these features provide important prognostic information that guides subsequent management decisions.
Patients with bleeding ulcers often benefit from endoscopic therapy, which helps reduce bleeding, shorten hospital stays, lower mortality rates, and decrease overall healthcare costs. High-dose, constant-infusion intravenous proton pump inhibitors (PPIs) have been found effective in reducing further bleeding and mortality in patients with high-risk ulcers, particularly those with active bleeding or non-bleeding visible vessels.
Other common sources of UGIB include Mallory-Weiss tears, esophageal varices, and erosive diseases such as gastritis and duodenitis, often attributed to the use of nonsteroidal anti-inflammatory drugs (NSAIDs).

## Risk Factors and Initial Assessment of GIB

The evaluation of GIB begins with an initial assessment, which includes measuring the patient's heart rate and blood pressure. These vital signs are critical indicators for assessing the severity of the bleeding. Clinically significant bleeding can lead to specific postural changes in heart rate and blood pressure, ultimately resulting in recumbent hypotension.
One essential aspect of GIB evaluation is understanding that hemoglobin levels may not immediately decrease with acute bleeding. This is because extravascular fluid often enters the vascular space to restore volume, causing a delay in the reduction of hemoglobin levels. As a result, patients may present with normal or only minimally decreased hemoglobin levels, even during severe bleeding episodes.
Differentiating UGIB from LGIB is crucial during the assessment phase. This differentiation is primarily based on the clinical presentation and specific symptoms:
* Hematemesis is a clear indicator of UGIB as it involves the vomiting of blood or "coffee-grounds" material.
* Melena indicates that blood has been present in the gastrointestinal (GI) tract for an extended period, usually ranging from 14 hours to several days. The presence of melena is more likely when the bleeding source is in the upper GI tract.
* Hematochezia typically represents a lower GI source of bleeding, although it's important to note that an upper GI lesion may bleed briskly enough to cause blood to transit through the bowel before melena develops.
* In cases where hematochezia is the presenting symptom of UGIB, it is often associated with hemodynamic instability and a rapid drop in hemoglobin levels. This indicates a potentially severe bleeding episode.
Additional clinical signs that may suggest UGIB include hyperactive bowel sounds and an elevated blood urea nitrogen (BUN) level. The elevated BUN level is primarily due to volume depletion and the absorption of blood proteins in the small intestine.

## Evaluation and Management of UGIB

The evaluation and management of UGIB involve several critical steps and considerations:
Risk Assessment: Risk assessment plays a crucial role in determining the appropriate management strategy. Several factors, including hemodynamic compromise (evidenced by tachycardia or hypotension), increasing age, and the presence of comorbidities, serve as baseline characteristics that can predict the risk of rebleeding and death in patients with UGIB.
Risk Assessment Tools: Various risk assessment tools may be used to identify patients at very low risk of adverse outcomes. These tools can help healthcare providers make informed decisions about patient management. For instance, patients with a low Glasgow-Blatchford score (ranging from 0 to 1, as detailed in Table 48-1) may be candidates for discharge from the emergency room with outpatient management. This approach has been associated with reduced hospital stays and lower costs.
Pre-Endoscopic Medications: Before performing endoscopy, pre-endoscopic medications may be considered. This includes proton pump inhibitor (PPI) infusion, which has been shown to decrease high-risk ulcer stigmata (such as active bleeding) and reduce the need for endoscopic therapy. However, it's important to note that PPI infusion does not necessarily improve clinical outcomes, such as further bleeding, surgery, or mortality. Additionally, the promotility agent erythromycin (administered intravenously at a dose of 250 mg) may be suggested approximately 30-90 minutes before endoscopy. This approach aims to improve visualization during endoscopy, potentially reducing the need for repeat endoscopy and minimizing hospital stays.
Management of Cirrhotic Patients: Patients with cirrhosis who present with UGIB should receive specific interventions, including antibiotics (such as ceftriaxone) and intravenous vasoactive medication (such as octreotide) upon presentation. These interventions are essential for decreasing the risk of bacterial infections, rebleeding, and mortality. Vasoactive medications, in particular, may help improve the control of bleeding during the initial 12 hours after presentation.
Endoscopy: Upper endoscopy is a fundamental diagnostic procedure in the evaluation of UGIB. It should be performed within 24 hours in most patients hospitalized with UGIB, regardless of whether they have clinical features predicting a low or high risk of further bleeding and death. Even in high-risk patients, more urgent endoscopy (performed within 6 hours of gastroenterology consultation) does not necessarily lead to improved clinical outcomes.
Early Endoscopy in Low-Risk Patients: For low-risk patients who are hemodynamically stable and do not have severe comorbidities, early endoscopy can be particularly valuable. It may identify low-risk endoscopic findings, such as clean-based ulcers, erosions, or non-bleeding Mallory-Weiss tears. These findings may allow for the discharge of over 40% of patients, resulting in reduced hospital stays and associated costs.
Management of High-Risk Endoscopic Findings: Patients with high-risk endoscopic findings, such as varices, ulcers with active bleeding, or a visible vessel, benefit from hemostatic therapy during endoscopy. This immediate intervention can help control bleeding and prevent further complications.

## Evaluation and Management of Lower Gastrointestinal Bleeding (LGIB)

The evaluation and management of LGIB are essential components of gastroenterology practice. This section outlines the key steps and considerations in managing LGIB:
Evaluation of Hematochezia with Hemodynamic Instability: In cases where patients present with hematochezia (passage of fresh red or maroon blood from the rectum) and hemodynamic instability (such as low blood pressure or rapid heart rate), the initial evaluation should include upper endoscopy. This procedure aims to rule out an upper gastrointestinal source of bleeding before proceeding to evaluate the lower gastrointestinal tract.
Colonoscopy as the Preferred Procedure: In most patients admitted with LGIB, colonoscopy following oral lavage preparation is the preferred procedure. This approach allows for a comprehensive examination of the colon and is highly effective in identifying the source of bleeding.
Angiography for Massive Bleeding: In cases where LGIB is associated with massive bleeding that cannot be effectively managed with colonoscopy, angiography is recommended as an alternative diagnostic and therapeutic approach. Angiography can detect the site of bleeding by visualizing the extravasation of contrast material into the gut. It also enables treatment with transcatheter arterial embolization if necessary.
Computed Tomography (CT) Angiography: Before proceeding with angiography, CT angiography is often suggested to document evidence of active bleeding and determine its location. This step aids in planning the angiographic intervention.
Sigmoidoscopy for Minor Bleeding in Young Patients: In specific scenarios, such as when patients are under 40 years old and present with minor bleeding, sigmoidoscopy may be considered as an initial diagnostic procedure. This minimally invasive technique can be valuable in identifying the source of bleeding in younger individuals.
Imaging Studies for Unidentified Sources: If colonoscopy does not reveal the source of LGIB, various imaging studies may be employed to further investigate the cause. These may include 99mTc-labeled red cell scans, which allow for repeated imaging over a 24-hour period and can provide insights into the general location of bleeding. However, CT angiography is increasingly favored due to its superior diagnostic capabilities and wider availability. In cases of active LGIB, angiography remains a valuable tool for detecting the site of bleeding and permitting therapeutic intervention through transcatheter arterial embolization.

## Evaluation and Management of Small-Intestinal or Obscure GIB

Small-intestinal bleeding or obscure GIB presents a unique diagnostic challenge due to the difficulty in identifying the source of bleeding within the small intestine. This section outlines the evaluation and management strategies for such cases:
Initial Evaluation: In patients with massive bleeding suspected to originate from the small intestine, current guidelines suggest angiography as the initial diagnostic test. If the patient's clinical status allows, CT angiography or 99mTc-labeled red cell scans may be considered before angiography to document evidence of active bleeding and its location.
Second-Look Endoscopy: For patients in whom the initial evaluation does not reveal the source of bleeding, repeat upper and lower endoscopy may be considered as the next diagnostic step. This approach, including second-look procedures, can identify a source of bleeding in up to approximately 25% of cases.
Push Enteroscopy: A push enteroscopy may be substituted for a repeat standard upper endoscopy when second-look procedures are needed. Typically performed using a pediatric colonoscope, this procedure allows for the inspection of the entire duodenum and proximal jejunum.
Video Capsule Endoscopy: If second-look procedures and initial evaluations do not yield a diagnosis, video capsule endoscopy is commonly employed. This minimally invasive technique involves swallowing a small capsule equipped with a camera that captures images as it passes through the digestive tract. Video capsule endoscopy offers a high yield in detecting "clinically significant findings" compared to other diagnostic methods. However, it should be noted that this technique does not allow for full visualization of the small intestine, tissue sampling, or the application of therapy.
CT Enterography: In cases where there are suspicions of small bowel narrowing (e.g., due to a stricture, prior surgery or radiation, or Crohn's disease), CT enterography may be used as the initial diagnostic test. It is considered for patients with negative video capsule endoscopy results and suspected small-intestinal GIB. CT enterography offers higher sensitivity for detecting small-intestinal masses.
Management Following Capsule Endoscopy: When capsule endoscopy results are positive and reveal the source of bleeding, management is determined based on the identified finding. However, if capsule endoscopy results are negative and patients remain clinically stable, they may be observed and treated with iron therapy if iron deficiency anemia is present. For patients with ongoing bleeding requiring transfusions, further diagnostic testing is required.
Second Capsule Endoscopy: In cases where the initial capsule endoscopy is negative but clinical signs persist, a second capsule endoscopy may be considered. This approach has been reported to identify a source of bleeding in approximately 50% of cases.
"Deep" Enteroscopy: Double-balloon, single-balloon, or spiral enteroscopy, collectively known as "deep" enteroscopy, is often the next diagnostic test after capsule endoscopy. This technique allows the endoscopist to examine, obtain tissue specimens from, and provide therapeutic interventions to a significant portion or the entirety of the small intestine.
Additional Imaging Techniques: In the evaluation of obscure GIB, other imaging techniques may also be utilized, including 99mTc-labeled red blood cell scintigraphy, angiography, and 99mTc-pertechnetate scintigraphy, particularly in young patients with suspected Meckel's diverticulum.
Intraoperative Endoscopy: In cases where all diagnostic tests are unrevealing, intraoperative endoscopy may be indicated. This approach is reserved for patients with severe, recurrent, or persistent bleeding that necessitates repeated transfusions.

## Positive Fecal Occult Blood Test

The use of fecal occult blood testing, which is primarily recommended for colorectal cancer screening, typically beginning at age 45-50 years in average-risk adults. A positive fecal occult blood test requires further evaluation through colonoscopy. However, if the evaluation of the colon through colonoscopy is negative, additional workup is generally not recommended unless patients exhibit iron-deficiency anemia or gastrointestinal symptoms.
This comprehensive breakdown provides detailed information on the evaluation and management of gastrointestinal bleeding, including upper gastrointestinal bleeding (UGIB), lower gastrointestinal bleeding (LGIB), small-intestinal bleeding, and obscure GIB, along with relevant risk assessments and diagnostic procedures for each condition.