Continuing Education Activity

Small bowel bleeding compromises 5% to 10% of all GI bleeds. The etiology is extensive and poses a diagnostic challenge for physicians. To avoid the high morbidity and mortality associated with this condition, it must be promptly diagnosed and treated. This activity reviews the evaluation and treatment of small bowel bleeding and highlights the interprofessional team's role in evaluating and treating patients with this condition.

Objectives:

• Describe the etiology of small bowel bleeding.
• Outline the typical presentation of a patient with small bowel bleeding.
• Explain the typical imaging findings associated with small bowel bleeding.
• Review the management of a patient with small bowel bleeding.

Introduction

Gastrointestinal bleed is the most common diagnosis for GI-related inpatient admissions. Amongst the GI bleeds, about 50% are due to upper GI tract bleeds, 40% are due to lower GI tract bleeds, and about 5% to 10% are due to lesions in the small bowel.[1] The small bowel is the part of the GI tract between the ligament of Treitz and the ileocecal valve. Small bowel bleeding can be divided into overt or occult.[2]

Patients are considered to have overt bleeding when they have visible bleeding, either melena or hematochezia. The bleeding is considered occult when there is no gross bleeding, but signs and symptoms of anemia, including fatigue, dyspnea, or palpitations, are present. Small bowel bleeding poses a significant diagnostic challenge for gastroenterologists. The clinical significance lies in the fact that most small bowel causes go undetected because the small bowel is long and hard to reach and therefore difficult to evaluate.[3][4]

Etiology

The etiology of small bowel bleeding is extensive, and it varies with the patient's age.[5] Patients with age less than 40 are likely to have Dieulafoy lesion, neoplasm, Meckel diverticulum, or inflammatory bowel disease. In patients older than 40 years, angiodysplasia, Dieulafoy lesion, or NSAID-related ulcers are more likely.[6]

The most common cause of small bowel GI bleed is a vascular lesion. 30-40% of bleeding in the small bowel is caused by abnormal vessels in the small bowel, with angiodysplasia being the most common.[7] The vascular lesions may also be induced by nonsteroidal anti-inflammatory drugs (NSAIDs). The other causes include tumors, aorto-enteric fistula, medications, small intestine ulcers, and non-specific enteritis.[8]

Epidemiology

The prevalence of small bowel lesions has been estimated to be 5 to 10% in patients presenting with GI bleeding.[9] The studies have shown neoplasms to be the most common cause in Asian countries. In contrast, angiectasias were the leading cause in Western countries.[10] The type of lesion causing the bleed is dependent on the age of the patient. Crohn disease and Meckel diverticulum are more likely in the younger population, less than 40 years. Angiectasia and vascular lesions are mostly seen in the older population, greater than 40 years. Neoplasms and Dieulafoy lesions are seen equally among the younger and the older age groups.[11] There is no role of gender, and prevalence is equal in males and females. There is limited data available regarding small bowel findings among different ethnicities.

History and Physical

The patient's initial assessment with small bowel bleeding must include a good clinical history and physical examination. A small bowel bleed can present with varying presentations. It can be overt or occult bleeding. It can be a massive bleed presenting as shock or could be persistent bleeding leading to anemia. A detailed history can help in guiding towards a specific diagnosis.[12][13] It should include the following, 

• Medical history (valvular heart disease, liver cirrhosis, chronic pancreatitis, radiation therapy)
• Surgical history (liver transplantation, abdominal aortic aneurysm repair, bowel resection)
• Medications (NSAIDs, anticoagulants, antiplatelets)
• Family history (Hereditary hemorrhagic telangiectasia, Peutz Jegher syndrome)
• Social history (alcohol intake) 

The physical examination findings can help to narrow down the diagnosis. The findings of telangiectasia in HHT (hereditary hemorrhagic telangiectasia), spider angioma, and caput medusa in portal hypertension, pigmented lips in Peutz Jegher's syndrome can be found on examination.[14] 

The history of chronic pancreatitis can lead to the diagnosis of rare causes like Haemosuccus pancreaticus.[15] Additional causes like a history of worms in the stools should be sought in people, especially in tropical regions.

Evaluation

Small intestinal bleeding is a rare cause of gastrointestinal bleeding. The diagnosis is challenging for the physician and involves much time and financial burden. The initial step in evaluation is endoscopy. However, with the advancement in novel endoscopic and radiological techniques, diagnosis and treatment have evolved. The latest diagnostic modalities including, capsule endoscopy and deep enteroscopy, have made it possible to go farther into the small bowel, helping to visualize and treat the lesions.[13] There is no single diagnostic study with high sensitivity and specificity that could be used, thus making the diagnosis challenging. 

Endoscopy 

Endoscopy is the first diagnostic study. A regular endoscope helps evaluate the esophagus, stomach, and duodenum. It is capable of providing a good view up to the first part of the small bowel. It has the advantage of being diagnostic and therapeutic at the same time. The endoscopist would be able to perform an intervention if any lesion is found.[16]

Imaging Studies

CT enterography involves the use of oral contrast solution. It allows for the detailed inspection of the small bowel lining and looks for any lesions.[17] The CT scan's advantage is finding the bleeding source out of the standard endoscope's reach. The primary limitations are the inability to do any intervention even if an abnormality is seen. Another imaging modality, CT angiography, helps in localizing the lesion and embolizing it. CT angiography's disadvantage is that the lesion should be actively bleeding, and the rate of bleeding should be 0.3 to 0.5 mL/min.[18] The nuclear studies involving the scintigraphy study with tagged RBC scans are more sensitive than CT angiography. It can detect bleeding at a rate of 0.1 mL/min.[19] 

Capsule Endoscopy

Capsule endoscopy is used when the endoscopy studies have failed to find any bleeding source. The camera is attached to a device that is about the size of a pill. It helps visualize the entire GI tract as it takes images until it is finally eliminated in the stool.[20] 

The capsule study is generally safe. It has the advantage of visualizing the entire GI tract and localize the bleeding source. The disadvantages include the inability to take biopsies and do any intervention. In patients with prior history of abdominal surgeries, the capsule can rarely get stuck inside the GI tract. It may require surgery if the capsule gets stuck. Despite these limitations, capsule endoscopy is the second line if the standard endoscope fails to diagnose any bleeding source.[21] 

Push Enteroscopy

Push enteroscopy or double-balloon enteroscopy is a new advancement to standard endoscopes. They have been used when the lesion is farther down in the small bowel and not seen with the standard endoscopes. It uses two balloons, which can help the scope be pushed farther into the small bowel.[22] It is possible to see the lesions, as far as the ileum, depending upon the performer's expertise. The advantage is the ability to treat, take biopsies and mark the area with the tattoo. Studies have shown that the enteroscope has identified the bleeding source in about 74% of patients and treated about 60% to 70%.[23] 

Intraoperative Enteroscopy

Surgery may be required in cases when no diagnosis could be found. Intraoperative enteroscopy is done under general anesthesia by a team comprising of gastroenterologists and surgeons. The scope is advanced through the incision in the small bowel. The advantage is that it allows to treat the cause of bleeding, AVMs, or to remove masses or polyps. It has been shown to treat about 70% of the patients effectively.[24]

Treatment / Management

The management options for small bowel bleeding involve conservative, radiological, pharmacologic, endoscopic, and surgical methods. The choice depends upon the indications, availability, and expertise.[25] The occult bleeding is treated usually in the outpatient setting. It involves endoscopic and imaging studies to localize the lesion and treating it appropriately. The overt bleeding is usually an emergency and warrants inpatient admission. It requires fluid resuscitation, localization of the lesion with angiography and scintigraphy. Enteroscopy could be used for therapeutic management once the lesion has been identified. 

The pharmacological therapies are used when the lesions are extensive and cannot be treated with invasive therapies. The different pharmacological options include hormonal therapies (estrogen and progesterone) and octreotide.[26] Octreotide is effective in various studies. These drugs act via multiple mechanisms involving decreased splanchnic blood flow, improved platelet aggregation, and angiogenesis inhibition.[27] Thalidomide, a VEGF inhibitor, acts by inhibiting angiogenesis. It has been used for refractory and recurrent blood loss secondary to angiodysplasia.[28] Studies have shown that the patients who took this drug had decreased requirement of blood transfusions.

The endoscopic and interventional radiographic techniques are used for treating vascular lesions. The choice of the appropriate therapy depends upon the availability and expertise. The options include electrocoagulation, laser photocoagulation, argon plasma coagulation (APC), injection sclerotherapy, hemoclip placement, endoscopic band ligation, and/or a combination of these.[29][30] Endoscopic hemostatic methods are used in cases of ectopic varices. Interventional radiological techniques using embolization are done when the endoscopic treatment is not successful.[31] Surgery is the last resort and is done in patients with recurrent bleeding and failed endoscopic treatments.

Differential Diagnosis

• Inflammatory bowel disease 
• Meckel's diverticulum
• GI stromal cell tumor 
• Polypoid lesions
• Dieulafoy lesions 
• Angioectasia 
• NSAID ulcers 
• Haemobilia
• Haemosuccus pancreaticus 
• Aorto-enteric fistula

Prognosis

There are limited studies regarding the prognosis after a small bowel bleed. The in-hospital mortality is low, < 5%. Most of the complications occur in patients with comorbid conditions.[32] Death usually occurs due to the worsening of underlying co-morbidities. Increasing age has been shown to increase mortality.[33] The mortality rate was higher in men than women. The negative prognostic factors involve hypovolemia, transfusion requirement, and underlying coagulopathies. Long-term follow-up studies are limited for small bowel bleeding.[34]

Complications

• Heart failure 
• Respiratory distress
• Myocardial infarction
• Infection
• Shock
• Death

Deterrence and Patient Education

Patients should be educated about the manifestations of GI bleed. They should be made aware of various presentations such as melena, signs of anemia such as fatigue, palpitations, and dyspnea. Counseling should be provided to limit the use of nonsteroidal anti-inflammatory drugs and to quit smoking and alcohol.[35] When concerned about any changes in bowel habits or having any overt or occult GI bleed, they should follow up with the local physician. The patients should be educated about the concerning scenarios, such as hypotension or confusion. They should be made aware of the need for emergent management in these conditions. 

Enhancing Healthcare Team Outcomes

Patients usually present to the primary physician with anemia-like symptoms and to the emergency with hematochezia. The management usually involves an interprofessional approach involving surgeons, gastroenterologists, radiologists, and intensivists, supported by nursing staff with training in gastrointestinal disorders.[36] Depending upon the presentation, they might need ICU monitoring. Some patients may require fluid resuscitation and blood transfusions. Multiple imaging studies might be required before the diagnosis is made.[37] Coordinating all these activities with an interprofessional team approach will drive better patient outcomes. [Level 5]

CT enterography and CT angiography are useful in localizing the lesion. Endoscopic management involving EGD and push enteroscopy are helpful diagnostic and therapeutic modalities. Surgery is usually the last resort, and some refractory patients may need it for diagnosis and treatment.[38] The outcomes depend upon the patient's age, underlying co-morbidities, hemodynamic stability, and the need for emergent surgery.