Can hydronephrosis cause abdominal pain?

Does Hydronephrosis Cause Abdominal Pain?

Yes, hydronephrosis commonly causes abdominal pain, particularly flank pain, which is a key symptom of urinary tract obstruction leading to renal collecting system dilation. 1

Pathophysiology and Presentation

Hydronephrosis is defined as urine-filled aseptic dilation of the renal pelvis and calyces, generally occurring in response to urinary obstruction or reflux. When symptomatic, it presents with:

• Pain characteristics:

  • Typically flank or groin pain
  • Can manifest as generalized abdominal pain, especially in children
  • May be intermittent in nature, particularly with partial obstructions

• Associated symptoms:

  • Nausea and urinary urgency
  • Infection (potential complication)
  • Hematuria (in some cases)

The American College of Radiology notes that hydronephrosis should be considered in patients with abdominal or pelvic pathology because progressive dilation of the upper urinary tract can lead to acute kidney injury and, if not corrected, permanent nephron loss 1.

Clinical Significance

The relationship between hydronephrosis and abdominal pain is clinically important because:

• Symptomatic hydronephrosis requires prompt evaluation to prevent permanent renal damage 1
• In pregnant patients, symptomatic hydronephrosis may lead to preterm labor or maternal/fetal death if left untreated 1
• Approximately 0.2% to 4.7% of pregnant patients experience symptomatic hydronephrosis, with prevalence increasing in advancing trimesters 1

Diagnostic Approach

When evaluating abdominal pain potentially caused by hydronephrosis:

1. Initial imaging:

   • Non-contrast CT scan of the abdomen and pelvis is recommended as first-line for patients with flank pain and microscopic hematuria (sensitivity 98-100%) 2
   • Ultrasound can identify and grade hydronephrosis but is less useful for identifying etiology 1

2. Correlation with clinical findings:

   • Moderate to severe hydronephrosis on imaging in patients with flank pain is highly specific (94.4%) for symptomatic renal stones 1
   • The presence of hydronephrosis reduces the likelihood of alternative diagnoses (OR 0.31; 95% CI, 0.16-0.60) 1

Special Considerations

In Children

Children with hydronephrosis may present with:

• Abdominal or flank pain
• Abdominal mass
• Gastrointestinal discomfort
• Urinary tract infections 3

Intermittent hydronephrosis is a particularly challenging diagnosis in children, as it can cause recurrent abdominal pain that is easily misdiagnosed. All preschool children with recurrent abdominal pain should be evaluated for this condition 4.

Differential Diagnosis

When evaluating right-sided abdominal pain, hydronephrosis can mimic other conditions:

• Acute appendicitis (particularly in children)
• Other causes of acute abdominal pain 5

Management Implications

The degree of hydronephrosis correlates with clinical outcomes:

• All cases with severe hydronephrosis in one study required intervention 1
• Moderate to severe hydronephrosis on ultrasound examination in patients with moderate or high risk of ureteric calculi provides a definitive answer regarding the presence of a stone 1

Pitfalls to Avoid

1. Misdiagnosis: Abdominal pain from hydronephrosis can be misattributed to other conditions, especially in children 4

2. Delayed diagnosis: Intermittent hydronephrosis may show normal imaging between symptomatic episodes, leading to missed diagnosis 4

3. Incomplete evaluation: Even when stones are found as the cause of hydronephrosis, patients over 35 years or with risk factors for malignancy require complete urologic evaluation 2

4. Overlooking infection: If infection is identified with hydronephrosis, appropriate antibiotic therapy is necessary, with consideration of urologic intervention if evidence of obstructive pyelonephritis is present 2

In summary, hydronephrosis is an important cause of abdominal pain that requires prompt evaluation and management to prevent permanent renal damage and other complications.