Practice scenario: Presence of dark or tarry stools

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Problem representation

A healthy middle-aged man presents with an acute change in the colour and consistency of his stools, accompanied with abdominal tenderness.

Hypothesis generation

Gastrointestinal (GI) bleeding is divided anatomically into upper and lower bleeds. Bleeding below the junction of the duodenum/jejunum (i.e. the ligament of Treitz) is classed as lower GI bleeding and tends to exhibit fresh, bright red blood. This is associated with conditions such as haemorrhoids, fissures and proctitis.

In contrast, upper GI bleeds produce characteristic dark or tarry stools with an offensive smell, referred to as melaena. The colour results from degradation of blood as it travels through the GI tract.

GI bleeds occur with varying severity. The more severe cases signal acute bleeding and life threatening hypovolaemic shock. In such cases, the mortality rate is high, especially in at-risk groups such as the elderly and those with multiple co-morbidities. Almost all cases of melaena require urgent assessment.

GI bleeds can also present as haematemesis or vomiting blood (dark blood or ‘coffee grounds’ suggests a smaller bleed than a large volume of bright red blood, which is suggestive of a rapid and sizeable haemorrhage). This points to more severe bleeding than melaena.

Paul has presented with darker than normal stools, suggesting that if bleeding is happening, the upper GI tract is implicated. You can, for now, discount lower GI conditions and need to consider the following:

Likely diagnosis 

• False melaena
• NSAID-induced bleeding
• Peptic ulcers.

Possible diagnosis

• Gastritis
• Mallory-Weiss tear.

Critical diagnosis

• Acute mesenteric vascular occlusion
• Malignancy or oesophageal varices.

Key points: tarry stools

• Peptic ulcer is the most common cause of upper GI bleeding
• Offensive smell always accompanies true melaena
• Urgent hospital management is almost always needed.

Continued information gathering

Paul’s description of his stools is consistent with melaena, but to rule out any lower GI bleed, you ask if he has noticed any bright red blood when he goes to the toilet. He says he has not, so you can rule out most lower GI bleeds.

Next, you ask him to describe his stomach discomfort in more detail. He says he is a bit uncomfortable and describes it as an ache rather than a true pain, and that the ache is pretty much there all the time. He points to his central abdomen, approximating to his lower sternum. This description is consistent with peptic ulcer, especially given his age.

Ulcers can be precipitated by lifestyle factors. You ask about smoking and alcohol consumption. He tells you that he has never smoked but does admit to drinking more than he knows he should. Alcohol is implicated in ulcer formation, although the evidence is conflicting.

At this point, peptic ulcer is a real possibility as it is the leading cause of melaena. Many people have a history of dyspepsia-like symptoms, so you ask if he has had similar symptoms in the past.
He says this is the first instance. While this does not rule out ulcers as the cause, it also does not help to further support your thinking.

Problem refinement

You want to know more about Paul’s stools since true melaena has an unpleasant smell. He says that he has noticed an unusual odour. This supports the ulcer differential diagnosis and also rules out false melaena.

You want to explore if anything may have contributed to these symptoms, given that Paul has no history of dyspepsia.

You ask further about medicines he might have taken as NSAIDs are known to precipitate such symptoms. He tells you he has been taking ibuprofen for the last seven to 10 days after hurting his knee playing squash.

Ibuprofen therefore seems to be the causative agent for his symptoms.

Red flags

Paul has no symptoms suggesting carcinoma, such as weight loss, dyspepsia or dysphagia. A check for vital signs of heart rate, blood pressure, respiratory rate and temperature should be performed to assess if there are any signs of shock. The findings are:
HR: 75
BP: 118/69
RR: 16
T: 36.7C

These suggest no signs of shock, such as tachycardia and hypotension. Paul’s skin is also not cool or clammy to the touch.

Management

• Self-care options

You tell Paul to stop taking the ibuprofen immediately.

• Prescribing options

None.

Safety netting

You tell Paul that you believe his symptoms are being caused by the anti-inflammatory painkiller and that the dark colour of his stools is due to the presence of blood. This needs to be investigated urgently at the hospital, despite his symptoms not causing him too much discomfort. 

At the hospital, tests can be performed (full blood count, urea and liver function tests) to confirm this and start treatment if necessary.