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Three Part Question

In [adult patients] presenting with acute appendicitis does a [serum lactate level] aid [diagnosis]

Clinical Scenario

You call the surgical SHO to refer a patient whom you suspect has acute appendicitis and he asks you what the patient's lactate is? You wonder the significance of a serum lactate in the diagnosis of acute appendicitis.

Search Strategy

Medline and EMBASE search via the NICE evidence interface for the following:
Exp APPENDICITIS AND exp LACTATE exp DIAGNOSIS limit English language and humans

Search Outcome

This yielded 9 papers, of these 8 were excluded due to insufficient quality or relevance,

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Kavakli et al, 2010 Turkey	36 patients confirmed to have appendicitis histopathologically compared with a control of 15 healthy volunteers	Retrospective observational case control study	Lactate was elevated in all 36 cases	Sensitivity – 80% Specificity – 53% PPV – 77% NPV – 57% Lactate useful in conjunction with other laboratory investigations	Very small study group Very small control group Could have included a control group with suspected appendicitis but another diagnosis found The paper does not highlight the threshold value they use for an elevated lactate and when converted to mmol/l the highest value does not reach the value we would consider elevated (4mmol/dl) in the UK

Comment(s)

Although the article reports a significant difference in lactate levels between the confirmed appendicitis group and the control group the actual difference is only 1 mmol/l between the greatest lactate level in the appendicitis group and the lowest lactate level in the control group. In addition the actual level is below the threshold of what we would consider to be elevated in the UK (4mmol/dl) In addition, the authors have reported a very low specificity making it of little use as a diagnostic test for solely acute appendicitis but potentially good use in combination with other laboratory investigations and clinical findings

Clinical Bottom Line

A single lactate level should not be used as a specific diagnostic test for acute appendicitis alone. However it may indicate significant abdominal pathology and can be used in the diagnosis of acute appendicitis when in conjunction with other laboratory diagnostic tests and appropriate clinical findings.

References

1. Kavakli HS, Cevik Y, Becel S et al. Diagnostic value of lactate levels in acute appendicitis. Journal of the Pakistan Medical Association November 2010, vol./is. 60/11;913-915.