What is the diagnosis and treatment for a 17-year-old female patient with epigastric pain, vomiting, negative H. pylori (Helicobacter pylori) test, and ultrasound findings of bilateral mild pelvocaliectasia, cystitis, and minimal ascites?

Clinical Interpretation and Diagnosis

This 17-year-old female most likely has an acute urinary tract infection (cystitis) with secondary upper urinary tract involvement (bilateral pelvocaliectasis), which is causing her epigastric pain and vomiting through referred pain and systemic inflammatory response. The minimal ascites represents reactive fluid from the inflammatory process.

What These Ultrasound Findings Mean

Bilateral Mild Pelvocaliectasis

• This indicates dilation of the renal collecting system (calyces and pelvis) on both sides 1
• In the context of cystitis, this suggests ascending infection or inflammatory changes affecting the upper urinary tract 1
• The bilateral nature suggests a systemic process rather than unilateral obstruction 1

Cystitis

• Represents bladder wall inflammation, typically from bacterial urinary tract infection 1
• This is the primary pathology driving the clinical presentation 2
• Ultrasound findings may include bladder wall thickening and inflammatory changes 1

Minimal Ascites

• Small amount of free fluid in the peritoneal cavity 3
• In this context, likely represents reactive peritoneal fluid from the inflammatory process 3
• Can also occur with systemic inflammatory conditions 3

Why This Occurred

Primary Mechanism

• Ascending urinary tract infection is the most likely cause, with bacteria (typically E. coli) ascending from the urethra to the bladder, causing cystitis 2
• The infection has caused sufficient inflammation to result in bilateral upper tract involvement (pelvocaliectasis) 1
• Young females are at higher risk due to shorter urethral length and anatomical factors 2

Connection to Epigastric Pain and Vomiting

• Referred pain from the urinary tract can manifest as epigastric discomfort, particularly when upper tract involvement is present 1, 4
• Systemic inflammatory response from infection commonly causes nausea and vomiting 2
• The negative H. pylori and absence of typical gastric pathology on ultrasound support an extra-gastrointestinal cause 5, 1

Critical Next Steps Required

Immediate Laboratory Testing

• Urinalysis with microscopy and urine culture must be obtained immediately to confirm infection and guide antibiotic therapy 2
• Complete blood count and C-reactive protein to assess systemic inflammatory response 5
• Serum creatinine and electrolytes to evaluate renal function given bilateral upper tract involvement 2

Urgent Considerations

• Fever, tachycardia, or flank pain would indicate pyelonephritis requiring more aggressive treatment 5, 2
• Blood cultures should be obtained if fever ≥38°C or signs of systemic infection are present 5
• The bilateral pelvocaliectasis requires close monitoring as it may indicate more severe infection 1

Treatment Approach

• Empiric antibiotic therapy should be initiated immediately after obtaining urine culture, typically with fluoroquinolones or cephalosporins for complicated UTI with upper tract involvement 2
• Antiemetics (ondansetron 8 mg) for symptomatic relief of vomiting 2
• Aggressive hydration to maintain urine output and help clear infection 2

Important Differential Diagnoses to Exclude

Life-Threatening Conditions

• Acute pancreatitis must be excluded with serum lipase (≥2x normal) or amylase (≥4x normal), as it can present with epigastric pain and vomiting 2
• Ectopic pregnancy or ovarian torsion should be considered in a 17-year-old female with ascites and abdominal pain 3
• Systemic lupus erythematosus can rarely present with epigastric pain, ascites, and renal involvement in young females 3

Other Considerations

• Peptic ulcer disease is less likely given negative H. pylori and the ultrasound findings pointing to urinary pathology 5, 6
• Functional dyspepsia is excluded by the presence of structural abnormalities (cystitis, pelvocaliectasis, ascites) 5

Common Pitfalls to Avoid

• Do not attribute all epigastric pain to gastrointestinal causes—urinary tract pathology commonly refers pain to the epigastrium 1, 4
• Do not dismiss bilateral pelvocaliectasis as incidental—in the setting of cystitis, this indicates more extensive infection requiring aggressive treatment 1
• Do not delay antibiotic therapy while awaiting culture results if clinical suspicion for complicated UTI is high 2
• The presence of ascites in a young patient with infection warrants investigation for underlying systemic disease if it persists after treatment 3