Premature Closure and Clinical Responsibility Assessment
Yes, attributing these symptoms solely to early acute appendicitis while missing euglycemic diabetic ketoacidosis (euDKA) in a patient on Invokana (canagliflozin) would constitute premature closure, but your immediate initiation of normal saline bolus was the correct initial intervention for both conditions. The clinical picture—5 days of illness, nausea without emesis, low oral intake, metabolic acidosis (pH 7.24, bicarbonate 17, anion gap 15, base excess -9), and SGLT2 inhibitor use—strongly suggests euDKA rather than appendicitis alone. 1
Critical Diagnostic Error: Missing EuDKA
Why This Represents Premature Closure
The metabolic acidosis is severe and unexplained by appendicitis alone: A pH of 7.24 with bicarbonate of 17 mmol/L and anion gap of 15 represents significant metabolic acidosis that requires immediate investigation beyond a surgical diagnosis. 2, 3
Invokana (canagliflozin) is a known cause of euglycemic DKA: SGLT2 inhibitors cause ketoacidosis even with normal or near-normal glucose levels, particularly in settings of reduced oral intake, dehydration, and acute illness—all present in this patient. 1
The clinical timeline doesn't fit typical appendicitis: Five days of progressive symptoms with nausea but no emesis, combined with dizziness and fatigue, suggests a metabolic rather than surgical emergency. 4
Lactate is only mildly elevated (1.3 mmol/L): This argues against severe sepsis or mesenteric ischemia as primary causes, making the anion gap acidosis more likely ketotic in origin. 5, 6
What Should Have Been Done Immediately
Essential Missing Test
Beta-hydroxybutyrate measurement is mandatory: This is the definitive test for ketoacidosis and should have been ordered immediately given the combination of SGLT2 inhibitor use, anion gap metabolic acidosis, and appropriate clinical context. Blood ketone testing is preferred over urine ketone testing for diagnosing ketoacidosis. 4
Urine or blood ketones should be checked in any diabetic patient with nausea, vomiting, or abdominal pain: The American Diabetes Association explicitly recommends ketone testing during acute illness or stress, especially when symptoms like nausea or abdominal pain are present. 4
Correct Diagnostic Approach
Calculate the corrected anion gap: Your anion gap of 15 with albumin of 36 g/L (3.6 g/dL) is actually higher when corrected—for every 1 g/dL decrease in albumin below 4 g/dL, add 2.5 to the anion gap, making the true anion gap approximately 16. 7
Assess the delta-delta ratio: Compare the increase in anion gap (approximately 4-5 above normal of 12) to the decrease in bicarbonate (7 below normal of 24). A ratio near 1:1 suggests pure anion gap acidosis from ketoacidosis. 7
Recognize the "euglycemic" presentation: The absence of hyperglycemia does NOT exclude diabetic ketoacidosis in patients on SGLT2 inhibitors—this is the hallmark of euDKA and a common diagnostic pitfall. 1
Your Clinical Responsibility
What You Did Right
Normal saline bolus was appropriate: Aggressive fluid resuscitation is the cornerstone of treatment for both euDKA and potential sepsis, and you initiated this correctly. 4, 8
The elevated CRP (30.6) and clinical presentation warranted investigation: Your concern about a surgical abdomen was reasonable given the abdominal pain and inflammatory markers. 4
Where Fault May Lie
Failure to consider medication-induced acidosis: Not recognizing Invokana as a cause of the metabolic acidosis represents a knowledge gap, but this is an increasingly recognized complication that all clinicians should be aware of. 1
Not ordering ketone testing: Given the clear indication (diabetic patient with nausea, abdominal pain, and metabolic acidosis), failure to check ketones represents a deviation from standard guidelines. 4
Premature surgical attribution: Attributing all symptoms to appendicitis without explaining the metabolic acidosis represents diagnostic anchoring—a cognitive error where the first diagnosis considered becomes the accepted diagnosis. 4
Immediate Next Steps Required
Urgent Laboratory Testing
Order beta-hydroxybutyrate immediately: Levels >3 mmol/L confirm ketoacidosis. 4
Repeat basic metabolic panel in 2-4 hours: Monitor bicarbonate, anion gap, and potassium closely during fluid resuscitation. 4
Check glucose level: Even if normal, this doesn't exclude euDKA. 1
Treatment Modifications
Continue aggressive IV fluid resuscitation: Target 250-500 mL/hour of normal saline initially, monitoring for fluid overload. 4, 8
Hold Invokana immediately: SGLT2 inhibitors must be discontinued in the setting of ketoacidosis. 1
Prepare for insulin therapy: If ketones are elevated, you'll need to start an insulin infusion (0.05-0.1 units/kg/hour) even with normal glucose, adding dextrose-containing fluids to prevent hypoglycemia. 1
Monitor potassium closely: Insulin therapy will drive potassium intracellularly; maintain serum potassium >3.3 mEq/L before starting insulin. 4
Surgical Consultation Considerations
CT abdomen/pelvis may still be warranted: If ketoacidosis is confirmed but symptoms don't improve with treatment, appendicitis could be a concurrent diagnosis or the precipitating stressor. 4
Communicate the metabolic picture to surgery: If surgical consultation proceeds, ensure they understand the primary metabolic derangement to avoid unnecessary operative intervention. 4
Common Pitfalls in This Scenario
Cognitive Errors to Avoid
Assuming normal glucose excludes DKA: EuDKA is specifically characterized by ketoacidosis with glucose <200 mg/dL (11.1 mmol/L), making it easily missed. 1
Attributing acidosis to sepsis alone: While the CRP is elevated, the lactate of 1.3 mmol/L and WBC of 7.8 argue against severe sepsis as the primary cause of acidosis. 5, 6
Ignoring medication history: SGLT2 inhibitors are increasingly prescribed; always review the medication list when encountering unexplained metabolic acidosis. 1
Delaying ketone testing: Urine ketones can be checked at bedside in minutes; there's no excuse for not performing this test in a diabetic patient with acidosis and abdominal pain. 4
Clinical Red Flags You Missed
Five days of reduced oral intake on an SGLT2 inhibitor: This combination is a setup for euDKA, as reduced carbohydrate intake promotes ketogenesis while the drug continues to cause glycosuria. 1
Nausea without emesis: This pattern is more consistent with metabolic derangement than mechanical obstruction from appendicitis. 4
Dizziness and fatigue: These symptoms reflect the metabolic acidosis and volume depletion, not typical appendicitis presentation. 2
Prognosis and Risk Mitigation
If EuDKA Is Confirmed
Prognosis is generally good with appropriate treatment: Unlike traditional DKA, euDKA typically responds well to insulin and fluid therapy, with most patients recovering fully within 24-48 hours. 1
Hospital stay may be prolonged by 2-3 days: This is consistent with reported cases of euDKA in surgical patients. 1
Documentation Recommendations
Document your clinical reasoning: Explain why appendicitis was considered and what prompted the normal saline bolus—this shows appropriate initial management. 4
Acknowledge the diagnostic evolution: Once ketones return, document that euDKA was subsequently recognized and treated appropriately. 1
Note the medication review: Document when Invokana was identified as a contributing factor and when it was discontinued. 1
Bottom Line on Fault
You would share responsibility for the delayed diagnosis, but the immediate harm is limited by your correct initial intervention with IV fluids. The failure to check ketones in a diabetic patient with unexplained anion gap metabolic acidosis represents a deviation from standard care, but this is a learning opportunity rather than gross negligence. 4 The key is recognizing the error now, ordering the appropriate tests immediately, and adjusting treatment accordingly. EuDKA is an increasingly recognized complication that all clinicians managing diabetic patients on SGLT2 inhibitors must be aware of. 1