What is the best course of action for a patient with a history of kidney stones, presenting with excruciating low back and side pain after lifting a heavy object, who has been treated with Fentanyl (Fentanyl), Toradol (Ketorolac) and Flexeril (Cyclobenzaprine) in the emergency department (ED) and has no urinary or bowel symptoms, normal blood pressure, and no fever or chills?

Management of Suspected Renal Colic with History of Kidney Stones

This patient should not have been discharged without urinalysis and imaging to confirm the diagnosis, and Flexeril (cyclobenzaprine) is inappropriate for renal colic—the patient requires NSAIDs for continued pain management and urgent imaging within 7 days with urology follow-up if a stone is confirmed. 1

Critical Diagnostic Gaps in This Case

Missing Essential Workup

• Urinalysis was not performed, which is a significant omission since over 80% of patients with acute renal colic test positive for hematuria, and its absence should prompt consideration of alternative diagnoses 1
• No imaging was obtained to confirm stone presence, size, or location—this is essential for determining appropriate management and follow-up 1
• The clinical presentation (severe unilateral flank pain radiating to the side after lifting, history of kidney stones, pain unrelieved by position changes, severe nausea) strongly suggests renal colic, but the diagnosis must be confirmed 1

Why This Matters for Morbidity and Mortality

• Without imaging, you cannot identify patients who need urgent intervention (stones >5mm, complete obstruction, or signs of infection) 1
• The patient's history of kidney stones increases recurrence risk, but current stone characteristics determine treatment urgency 1
• Alternative dangerous diagnoses (ruptured abdominal aortic aneurysm, though less likely given age and presentation) cannot be definitively excluded without imaging 1

Immediate Management Errors to Correct

Inappropriate Medication Choice

• Flexeril (cyclobenzaprine) has no role in renal colic management—it is a muscle relaxant that does not address the pathophysiology of ureteral spasm or inflammation 1
• The patient received appropriate acute treatment with Toradol (ketorolac) in the ED, which is first-line therapy for renal colic 1, 2
• NSAIDs should be continued at home, not replaced with a muscle relaxant 1

Pain Management Algorithm Going Forward

• First-line: Continue NSAIDs (diclofenac 75mg IM/PO, ibuprofen, or ketorolac) as they reduce inflammation and lower pressure in the urinary collecting system 1, 2
• NSAIDs are superior to opioids for renal colic, reducing the need for additional analgesia 1
• Use the lowest effective dose for the shortest duration (ketorolac maximum 5 days total) 3
• Second-line: Opioids only if NSAIDs contraindicated or inadequate—if needed, use agents other than pethidine (such as hydromorphone, pentazocine, or tramadol) combined with an antiemetic 1

Required Follow-Up Actions

Urgent Imaging and Urology Referral

• Patient needs non-contrast CT or ultrasound within 7 days to identify stone size, location, and degree of obstruction 1
• If stone is confirmed and >5mm or causing persistent symptoms, urology appointment should be scheduled within 1 week 1
• For stones >5mm in the distal ureter, medical expulsive therapy with alpha-blockers (tamsulosin) should be offered 1

Pain Monitoring Protocol

• Patient should be contacted by telephone 1 hour after initial assessment to ensure pain control 1
• Patients failing to respond to analgesia within 1 hour should be readmitted immediately 1
• Abrupt recurrence of severe pain warrants immediate hospital admission 1

Red Flags Requiring Immediate Hospital Admission

• Fever or signs of systemic infection (sepsis in obstructed kidney requires urgent decompression via nephrostomy or ureteral stent) 1
• Anuria or signs of complete obstruction 1
• Shock or hemodynamic instability 1
• Uncontrolled pain despite adequate analgesia 1

Correct Outpatient Management Plan

Medication Regimen

• Prescribe oral NSAID (diclofenac 50mg TID or ibuprofen 600-800mg TID) for up to 5 days total (including ED doses) 1, 3, 2
• Add proton pump inhibitor if NSAID course >3 days or patient has GI risk factors 1
• Consider alpha-blocker (tamsulosin 0.4mg daily) if stone >5mm confirmed on imaging—this is medical expulsive therapy 1
• Provide limited supply of oral/rectal analgesics for breakthrough pain, though guidelines express concern about drug misuse 1

Patient Instructions

• Drink large amounts of fluids 1
• Strain all urine through tea strainer or gauze to catch any passed stone for analysis 1
• Contact physician immediately if pain worsens, fever develops, unable to urinate, or new concerning symptoms appear 1
• Return to ED if pain not controlled within 1 hour of taking prescribed analgesics 1

Common Pitfalls in This Case

Why Muscle Relaxants Don't Work for Renal Colic

• Renal colic pain is caused by ureteral smooth muscle spasm and inflammation from stone passage, not skeletal muscle strain 4, 2
• The "lifting injury" history is a red herring—the timing (pain worsening throughout day, radiating to flank) and character (constant, unable to find comfortable position, severe nausea) are classic for stone disease, not musculoskeletal injury 1
• NSAIDs work by inhibiting prostaglandin synthesis, reducing ureteral contractility and inflammation—this is the appropriate mechanism for renal colic 4, 2

Opioid Considerations Given Fentanyl Use

• Patient received 75mcg fentanyl en route, which is appropriate for severe renal colic 5, 6
• Avoid prescribing opioids for outpatient management given the opioid epidemic and kidney stones being an important source of initial opioid exposure 7
• If opioids are absolutely necessary for breakthrough pain, fentanyl is the safest choice if patient has any renal impairment (though not indicated here), as it has hepatic metabolism with no active metabolites 5, 6
• Never prescribe morphine, codeine, or meperidine for renal colic, especially if any concern for renal function 5, 6

Documentation and Risk Management

• The discharge without urinalysis or imaging represents a diagnostic gap that could miss serious pathology 1
• If stone causes complete obstruction or infection develops, delayed diagnosis increases morbidity 1
• Document clearly why imaging was deferred (if it was) and ensure explicit plan for obtaining it within 7 days 1