What could be the cause of intermittent right lower quadrant abdominal pain in a 40-year-old male, which started after holding urine for 3 hours, is not severe, and does not affect urination, eating, or drinking?

Differential Diagnosis and Management of Intermittent Right Lower Quadrant Pain Following Urinary Retention

This clinical presentation most likely represents a passed ureteral stone or resolving ureterolithiasis, given the temporal relationship between urinary retention and subsequent intermittent right-sided pain radiating to the back. 1, 2

Most Likely Diagnosis: Urolithiasis (Kidney Stone)

The clinical scenario strongly suggests urolithiasis based on several key features:

• The temporal relationship between holding urine for 3 hours and pain onset is characteristic of stone disease, as urinary stasis can precipitate stone movement and obstruction 3
• Pain radiating from the right lower quadrant to the back is classic for ureteral calculi, which typically causes colicky pain that radiates from flank to groin 1, 2
• Spontaneous resolution followed by intermittent mild pain suggests the stone has either passed or is no longer causing complete obstruction 4
• The absence of dysuria does NOT exclude urolithiasis, as hematuria (not dysuria) is the cardinal urinary symptom, and even hematuria can be absent in 20-80% of cases 4

Critical Next Steps in Evaluation

Obtain urinalysis immediately to look for microscopic hematuria, which significantly increases the probability of stone disease even when gross hematuria is absent. 1

Imaging Algorithm

• Non-contrast CT abdomen/pelvis is the gold standard if diagnosis needs confirmation, with 98-100% sensitivity and specificity for detecting stones of any size, location, or composition 1
• Ultrasound can be used as first-line imaging to avoid radiation, particularly if you want to assess for hydronephrosis or residual stones, though it is less sensitive than CT 5, 4
• Low-dose CT protocols should be considered to minimize radiation exposure if imaging is pursued 1

Alternative Diagnoses to Consider

While urolithiasis is most likely, the differential for right lower quadrant pain includes:

• Right colonic diverticulitis occurs in 8% of patients with right lower quadrant pain and can mimic stone disease 1
• Retrocecal appendicitis can present with predominant flank pain rather than classic McBurney's point tenderness 1
• Ovarian pathology (if female) including cyst, torsion, or ruptured cyst can cause referred right lower quadrant pain 5, 6
• Inflammatory bowel disease (Crohn's with terminal ileitis) can present with right-sided pain 1

Management Recommendations

If stone disease is confirmed and the stone is <5mm, conservative management with observation is appropriate, as these typically pass spontaneously 1

Conservative Management Protocol

• Avoid excessive fluid intake initially, as an obstructed kidney protects itself and forcing diuresis can worsen pain 4
• NSAIDs combined with Tamsulosin (alpha-blocker) facilitate stone passage, especially for distal ureteral stones 4
• Maintain urine output >2 liters per day once acute obstruction is ruled out to prevent recurrence 3

Red Flags Requiring Urgent Intervention

Immediate urology referral or emergency department evaluation is mandatory if any of the following develop: 4

• Fever with leukocytosis (suggests obstructive pyelonephritis/urosepsis)
• Persistent severe pain unresponsive to oral analgesics
• Inability to tolerate oral intake due to nausea/vomiting
• Anuria or significantly decreased urine output
• Known solitary kidney

Critical Pitfalls to Avoid

• Do not assume absence of dysuria or hematuria excludes urolithiasis - pain pattern and radiation are more reliable than urinary symptoms 4
• Do not force excessive hydration in the acute phase if obstruction is suspected, as this can exacerbate pain and potentially cause fornix rupture 4
• Do not miss complications like hydronephrosis or abscess formation, which can progress to kidney failure if untreated 2
• Recognize that pain worsening with external flank pressure suggests infection (pyelonephritis) rather than uncomplicated stone disease, which typically does NOT worsen with external pressure 1

Follow-up Strategy

• Stone analysis is essential if a stone is passed to guide metabolic evaluation and prevention strategies 4
• Metabolic workup should be pursued if stone is confirmed, including assessment for hypercalciuria, hyperoxaluria, hyperuricosuria, and low urinary citrate 4
• Repeat imaging at 4-6 weeks if symptoms persist to ensure complete stone passage and rule out residual calculi 4