Melaena Flashcards
What is melaena?
Black tarry stools, which usually occur due to an upper GI bleed.
Aside from the characteristic “black tar” appearance, what are other features of malaena?
- Offensive smell
- Difficult to flush away
Why does melaena have it’s characteristic features?
Due to the alteration and degradation of blood by intestinal enzymes.
What are differentials for melaena?
- Peptic ulcer disease
- Variceal bleeds
- Upper GI malignancy
- Gastritis / oesophagitis
- Mallory–Weiss tear
- Meckel’s diverticulum
- Vascular malformations (e.g. Dieulafoy lesion)
What is the most common cause of melaena?
Peptic ulcer disease
When should you suspect peptic ulcer disease as the underlying cause of melaenia?
Patients with:
- Known active peptic ulcer disease
- History of NSAIDs or steroid use
- Previous dyspepsia-like symptoms
- H. pylori positive result
Where does an ulcer classically erode to cause the most extensive bleeding?
Posterior gastric wall into the gastroduodenal artery
However, extensive bleeding can occur with an ulcer at any location.
What are oesophageal varices?
Dilations of the porto-systemic anastomoses in the oesophagus, that occur due to portal hypertension secondary to liver cirrhosis.
What is the most common cause of oesophageal varices?
Alcoholic liver disease
- Therefore significant melena in a patient with a known history of alcohol abuse should be urgently investigated for potential variceal bleeding.
What are other features that exist alongside melaena due to potential ulcerating oesophageal / gastric malignancy?
- Upper GI symptoms
- Weight loss
- Relevant family history
What are key facts to ascertain from a history of melena?
- Colour and texture of the stool
- Jet black, tar-like, and sticky
- Associated symptoms
- Haematemesis
- Abdominal pain
- Hx of dyspepsia, dysphasia or odynophagia
- Past medical history
- inc. smoking & alcohol status & inflammatory bowel disease
- Drug history
- Steroids, NSAIDs, anticoagulants, or iron tablets
What examinations would you carry out on a patient presenting with melaena? & what signs would you be looking for?
- Full abdo exam
Assess for:
- Epigastric tenderness / peritonism
- Hepatomegaly
- Stigmata of liver disease
-
DRE
* To confirm melaena
What investigations would be useful to order for a case of melaena?
- Routine bloods (FBC, U&Es, LFTs, and clotting):
- Any drop in Hb w/ rise in urea:creatinine ratio is indicative of upper GI bleed
- Urea is a by-product of digested Hb & is readily absorbed by the intestine
- LFTs may reveal underlying liver damage as a potential cause
- Group & Save
- For ALL patients with melena
- Those with significant melena (esp. suspected variceal bleed) should have at least 4 units of blood cross-matched
- ABG (look esp at pH, base excess & lactate)
* To assess for signs of tissue hypoperfusion in bleeding / acutely unwell patients - Oesophagogastroduodenoscopy (OGD):
- Definitive investigation
- Forms part of the management in cases of ongoing unstable bleeding
- Colonoscopy / capsular endoscopy may be required to determine the site of bleeding if OGD proves inconclusive
- CT abdo w/ IV contrast (Triple phase)
* To assess any active bleeding, esp if endoscopy is unremarkable or patient is too unwell to undergo invasive investigation.
What is the management of melena?
- A to E approach
* To stabilise any critically unwell patients before considering definitive management steps - OGD (Once the patient is stable or initial resuscitation attempts have proved ineffective)
Range of therapeutic options are available depending on underlying cause
- Blood products transfusion
* To those who are haemodynamically unstable or with a low Hb (<70g/L) - Correction of deranged coagulation as appropriate
May include:
- Reversal agents if the patient is on any anti-coagulants
- FFP +/- platelets in patients with impaired liver function
