Melena and hematochezia Flashcards
What is melena?
- = passage of dark-colored to black, tarry stools due to hematin (oxidised haemoglobin)
- Colonic hemorrhage can produce melena if intestines are hypomotile
What are the inflammatory causes of melena?
Esophagitis
Gastroenteritis
Eosinophilic gastritis
Inflammatory bowel disease
List ways that blood could be ingested to cause melena….?
Sinonasal lesions (URT -epistaxis)
Oral/Pharyngeal lesions
Pulmonary Lesions (LRT hemoptysis)
Diet (e.g. Raw)
What are common infectious causes of melena?
Bacterial: Campylobacter, Clostridium, Mycobacterium, Neorickettsia helminthoeca, Salmonella
Fungal/Algal Cryptococcus, Histoplasma, Pythium, Prototheca
Parasitic: Spirocerca, Physaloptera, Ancylostoma, Uncinaria
Viral: Parvovirus
What are the ischemic/traumatic causes of melena?
Hypovolemic shock
Thrombosis/infarction
Intussusception
Volvulus
Foreign Body
Racing sled dogs
What are the drugs that can cause melena?
Corticosteroids
Non-steroidal anti-inflammatory drugs
What are the neoplastic causes of melena?
Adenocarinoma
Gastointestinal stromal tumor
Leiomyoma/leiomyosarcoma
Lymphoma
Mast celltumor
Gastrinoma
What are the metabolic causes of melena?
Hypoadrenocorticism
Uremic kidney disease
Liver disease with portal hypertension or portal systemic shunts
Pancreatitis
Hypereosinophilic syndrome
What bleeding disorders are associated with melena?
Thrombocytopenia
Thrombocytopathia
DIC
Rodenticide intoxication
Specific factor deficiencies
What are the vascular causes of melena?
Vascular ectasia/angiodysplasia
Arteriovenous fistula
What mimics melena?
Activated charcoal
Iron supplements
Diarrheal medications containing bismuth
Large quantities of blueberries
What are the defence mechanisms of the GI mucosa?
- Adherent mucus layer
- Hydrophobic nature of epithelial cells
- Epithelial secretion of bicarbonate
- Rapid repaire of epithelial layer by restitution
- High rate of mucosal blood flow
- Prostaglandins
How would you gather history of a patient with melena?
1st step:
- Let owner use descriptors or show examples of fecal colour and scorecard
- Ask specific questions about diet
- Drug administration
- Potential toxins (rodenticides or corrosive compounds)
2nd step:
Other clinical signs:
- Exercise intolerance
- Stridor
- Coughing
- Dyspnea
- Anorexia
- Regurgitation
- Vomiting or diarrhea
- Epistaxis or hemoptysys
- Hematuria
- Ecchymosis
- Concurrent C-steroids + NSAIDS
What are possible findings on physical exam related to melena that are important to examine?
- Skin, MM, and sclera to check for petechia, ecchymosis, or icterus
- Fundic exam to identify retinal hemorrhages indicating bleeding disorder, hyperviscosity, or systemic hypertension
- Skin, mucocutanous junctions, nail beds for masses (mast cell disease)
- Nares and oral cavity
- Pale MM
- Auscultate lung fields
- Abdomen palpation – pain, organomegaly, or masses
- Digital rectal exam – melena, fecal test, mucosal abnormalities, sublumber lymph node evaluation
What treatments are considered for patients with melena?
Treatment:
- Depends on underlying cause
- Medications to treat GI ulceration increase intraluminal acidity and promote mucosal defence mechanisms
Proton pump inhibitors, synthetic prostaglandin, and sucralfate
What diagnostic tests should be performed for patients with melena?
CBC:
- Anemia: common, mild-severe, +/- regenerative
- Chronic low grade haemorrhage => iron deficiency => microcytic, hypochromic, non-regenerative anaemia
- Thrombocytopaenia:
- Mild=> likely secondary from consumption
- Mod/Severe = >likely primary cause of bleeding
- Leukocytosis: , normal, or & +/- left shift depending on underlying disease
- Eosinophilia: due to hemorrhave, parasiism, sysemic mycosis, MCT, eosinophilic gastritis, or hypereosinophilic syndrome
Biochem:
- BUN
- Hypoproteinemia
- hepatic enzyme activities (liver dz)
- Azoetmia
- Hyponatremia+hyperkalemis => hypoadrenocorticism, or salmonellosis and/or whipworm infections
Urinalysis:
- Differentiates azotemia
- Check or concurrent disease
Prolonged coags:
=> Differentiate rodenticide intoxication or DIC
Fecal flotation:
- Identify parasite ova
Next phase of tests depends on owners finances:
- Direct saline preparation
- Stained cytological smear -> parasites, enterotoxigenic bacteria, and other organisms
- Radiographs thorax & abdomen differentiate between resp and GI source of melena.
T rads: Defined lung pattern is likely with hemoptysis & screen metastatic disease.
Abdo abdnormalities: radiopaque foreign bodies, abnormal organ shape/size, mass effects, and abnormal gas and fluid patterns
- Abdo ultrasound –evaluate foreign bodies, abnormal organ architecture, masses, lymphadenopathy, or intussusception
Advanced: specific serologic testing, fecal culture, CT, rhinosope, bronchoscopy, GI endoscopy, and ex lap.
Define hematochezia
Definition:
Bright red colored stools due to presence of haemoglobin
Hematochezia is mostly colonic but could be small intestinal if intestines are hypermotile.
What are the inflammatory causes of hematochezia?
Inflammatory
Inflammatory bowel disease
Histiocytic ulcerative colitis
Idiopathic colitis
Perianal fistula
Mucocutaneous lupus erythematosus
What are the infectious causes of hematochezia?
Bacterial: Campylobacter, clostridium, mycobacterium, salmonella
Fungal/Algal: Cryptococcus, Histoplasma, Pythium, Prototheca
Parasitic: Ancylostoma, Uncinaria, Trichuris, coccidia, Tritrichomonas, Leishmania, Heterobilharzia Americana, Entamoeba histolytica
Viral: parvovirus
What are the ischemic/traumatic causes of hematochezia?
Hypovolaemic shocl
Thrombosis/infarction
Intussusception
Caecal inversion
Volvulus
Foreign body
Pelvic fracture
Rectoanal stricture
Racing sled dogs
What are the neoplastic causes of hematochezia
Adenocarcinoma
Gastrointestinal stroma tumor
Leiomyoma/Leiomyosarcoma
Lymphoma
Plasmacytoma
Colorectal polyp
What are the vascular causes of hematochezia?
Vascular ectasa/angiodysplasia
Arteriovenous fistula
What are the metabolic causes of hematochezia?
Hypoadrenocorticism
Uremic kidney disease
Liver disease, particularly with portal hypertension or portosystemic shunts
Pancreatitis
What bleeding disorders cause hematochezia?
Thrombocytopenia
Thrombocytopathia
DIC
Rodenticide intoxication
Specific factor deficiencies
What can mimic hematochezia?
Ingestion of red food colouring
Large amounts of Beets
Perineal bite wound or anal sac abscess
What treatment options are available for hematochezia?
Treatment:
Depends on underlying cause
Acute hematochezia:
Broad spectrum anthelmintic
Metronidazole
Bland diet with soluble fiber
What diagnostic options are available for hematochezia?
- Acute hematochezia = blood streaking on surfaces of faeces and no other clinical signs or physical exam abnormalities
faecal flotation and direct saline preparation
- Severe hematochezia (raspberry jam), chronic, +/- other clinical signs should be worked up like melena
