OVERVIEW
Unexplained gastrointestinal bleeding (OGIB) is recurrent or persistent gastrointestinal bleeding whose cause cannot be clarified by routine gastrointestinal endoscopy (e.g., gastroscopy, colonoscopy) and barium X-ray, or small bowel CT, and it accounts for about 5% of all gastrointestinal bleeding. It manifests as recurrent iron deficiency anemia and a positive fecal occult blood test, or bleeding visible to the naked eye such as black stools, bloody stools, or vomited blood.
Etiology
Unexplained gastrointestinal bleeding tends to occur in the small intestine, and the etiology may be related to inflammation, vascular lesions, parasitic infections, diverticular disease, and tumors, and in some cases may originate from biliary tract bleeding.
Symptoms
OGIB can be categorized as acute bleeding or chronic intermittent bleeding. In the former case, there are different clinical manifestations according to the urgency of bleeding and the amount of blood loss, such as vomiting blood, black stool or blood in the stool, and hemorrhagic shock may occur in severe cases; in the latter case, according to the degree of blood loss, the manifestations are recurrent iron-deficiency anemia and/or positive fecal occult blood test.
Examination
1. History and physical examination
Take a careful history, including current symptoms, past history, medication history and family history. If a patient with OGIB has wasting or obstructive symptoms, this suggests a high likelihood of small bowel disease; elderly patients with renal or connective tissue disease are at higher risk for vascular disease. A detailed and reliable history and physical examination can help reduce the rate of missed diagnosis.
2. Laboratory tests
In patients with chronic intermittent bleeding, laboratory tests may show a decreased red blood cell count and decreased hemoglobin content. Some patients may have a positive fecal occult blood test.
3. Imaging examination
(1) Barium examination of the small intestine: barium contrast has a low diagnostic rate for OGIB and a high false-negative rate. Small bowel barium examination cannot be chosen when there is suspicion of small bowel mass or intestinal stenosis. (2) Endoscopy: ① Conventional endoscopy is the initial examination for patients with OGIB. For those with negative initial examination, the endoscopy can be repeated if necessary due to leakage caused by tiny lesions, hidden location or lack of experience in examination. ② Capsule endoscopy (CE) is the first-line screening technique for small bowel disease and the main method for OGIB diagnosis. This examination cannot be done when there is suspicion of small bowel mass or intestinal stenosis. (3) Double balloon enteroscopy (DBE) is an invasive examination, and CE examination has a complementary role in the diagnosis of OGIB.
(3) CT, MRI examination: it can show the relationship between the lesion and adjacent blood vessels and lymph nodes, which is beneficial for pre-surgical evaluation, and is suitable for patients who cannot tolerate endoscopy or those who cannot be passed by endoscopy.
(4) Angiography: an invasive examination, suitable for patients with active bleeding (bleeding rate ≥0.5ml/min).
(5) Nuclear scanning: only has diagnostic value for active bleeding (bleeding rate ≥0.1ml/min).
(6) Surgery or intraoperative endoscopy: Surgery is the last resort for OGIB and is mainly indicated for those who cannot successfully undergo all of the above tests or for those with heavy bleeding.
Diagnosis
1. History and clinical manifestations
Most patients have a history of small intestinal lesions, parasitic infections, biliary bleeding, and manifestations such as vomiting blood, black stools or blood in the stool. Laboratory tests show recurrent iron-deficiency anemia and/or positive fecal occult blood test.
2. Determination of bleeding site and etiology
①Judge the possible bleeding site according to the patient’s clinical manifestations and repeat the endoscopic examination to avoid missing the diagnosis. If you still can not determine the bleeding site, then CT angiography or nuclear angiography. ② For patients with active bleeding, upper and lower gastrointestinal endoscopy is the first choice, and the bleeding site can be found at the same time to intervene in hemostatic treatment, or 99mTc labeling of their own red blood cells for nuclear scanning to show the site of bleeding, but the cause of bleeding can not be determined. ③ For those who take surgical exploration for acute OGIB, intraoperative endoscopy to find the bleeding site can help surgical localization.
Treatment
Treatment of OGIB includes symptomatic treatment, etiologic treatment and surgical treatment. Among them, etiologic treatment is the main treatment.
1. Symptomatic treatment
According to the patient’s clinical status, bleeding rate and complications, appropriate rehydration and blood transfusion treatment can be given; for patients with unknown lesion sites or diffuse lesions, and for whom endoscopy, surgery or angiographic embolization is not applicable, drug treatment can be considered, including growth inhibiting hormone, erythropoietin and so on.
2. Treatment of etiology
Once the etiology is clear, etiologic treatment can be carried out. Generally speaking, tumors require surgical resection, polyps can be removed endoscopically, and anti-inflammatory treatment is given for inflammation. Various ulcers or vascular lesions bleeding, feasible endoscopic hemostasis or angiographic embolization of the lesion site of the blood vessels to stop bleeding.
3. Surgical treatment
Surgery can be considered for those with large amount of active bleeding, ineffective internal medicine treatment and clear bleeding site.