What is Colicky Pain in the Context of Nephrolithiasis
Colicky pain is a characteristic pattern of severe, wave-like pain that comes in intense episodes followed by periods of less severe discomfort, caused by internal obstruction and distension of the urinary collecting system rather than external pressure. 1, 2, 3
Defining Characteristics of Renal Colic
Pain Pattern and Quality:
- The pain is sudden in onset and unilateral, classically radiating from loin to groin 4
- It occurs in waves of severe intensity alternating with periods of reduced discomfort, distinguishing it from constant pain 1, 3
- The pain is independent of body position, unlike musculoskeletal causes 2
- Intensity depends on individual pain threshold and changes in hydrostatic pressure above the obstruction 3
Location-Specific Pain Radiation:
- Renal pelvic or upper ureteric stones cause predominantly flank pain and tenderness 4
- Lower ureteric stones radiate toward the ipsilateral testicle or labia 4
- Right lower quadrant pain during urination suggests a stone in the distal ureter on that side 5
Pathophysiology of the Pain
Mechanism of Pain Generation:
- Pain results from obstruction and distension of the collecting system, not from the stone itself 1
- Increased hydrostatic pressure in the urinary tract above the obstruction triggers the pain 3
- Direct irritation of the renal collecting system and inflammation of surrounding tissues contribute 1
- Prolonged stone impaction activates autoregulatory mechanisms that lower upper tract pressure, which can paradoxically reduce pain intensity 3
Key Distinguishing Feature:
- Nephrolithiasis pain does not worsen with external flank pressure 1
- Pain that significantly worsens with external pressure suggests pyelonephritis, kidney infection, or perinephric abscess instead 1, 2
Associated Symptoms
Common Accompanying Features:
- Nausea or vomiting occurs in approximately 50% of cases 3, 4
- Hematuria (blood in urine) is common but not universal 4
- Irritative lower urinary tract symptoms may be present 4
- Hypotension and fainting can occur in severe cases 3
Warning Signs Requiring Urgent Evaluation:
- Fever >38°C with chills indicates possible pyelonephritis or obstructive pyelonephritis 2
- Systemic infection signs require immediate hospitalization 2, 4
- A febrile patient with renal colic needs immediate hospital admission 4
Clinical Pitfalls to Avoid
- Do not assume absence of hematuria excludes stone disease, as the clinical picture evolves 2
- Do not miss that absence of hydronephrosis does not exclude obstructive nephrolithiasis (negative predictive value only 65%) 6
- Do not delay imaging based on normal urinalysis alone 2
- In young females with recent pregnancy complications, do not miss gynecologic causes that may mimic renal colic 2