What the reports actually show

• Kidneys: normal size, cortico‑medullary differentiation preserved, no calculus, no hydronephrosis/hydroureter, no mass
• Urinary bladder: normal wall (3 mm), no calculus/mass, both vesico‑ureteric junctions normal
• Prostate/seminal vesicles: normal
• Liver, gallbladder, pancreas, spleen: normal, no free fluid, no lymphadenopathy

Differential diagnosis (abdominal pain + intermittent hematuria, 18-yr male, normal renal USG)

• Ureteric or renal calculus not visualized due to bowel gas overlying the ureter - still the single most important diagnosis to exclude in a young male with colicky pain and hematuria
• Urinary tract infection / hemorrhagic cystitis - bladder wall thickness was normal but this doesn't exclude cystitis, especially if intermittent
• Nutcracker syndrome (left renal vein compressed between aorta and superior mesenteric artery) - causes left flank pain with hematuria, reported with higher frequency "in the Asian subcontinent" per Medscape/Campbell-Walsh; needs Doppler assessment of the left renal vein, which a routine grey-scale USG will miss
• Loin pain-hematuria syndrome
• Renal/bladder tumor (low probability at 18 but not zero, especially with gross/recurrent hematuria)

• IgA nephropathy (Berger disease) - the classic cause of recurrent gross or microscopic painless hematuria in a young male, often triggered by an intercurrent infection, with entirely normal imaging
• Henoch-Schönlein purpura (IgA vasculitis) - fits well because it classically causes both abdominal pain and hematuria in young patients; look specifically for palpable purpura (buttocks/lower limbs) and joint pain/swelling
• Post-infectious glomerulonephritis
• Thin basement membrane disease / benign familial hematuria
• Sickle cell trait/disease (if relevant ethnic background) - causes papillary necrosis and hematuria

• Renal tuberculosis (endemic in India; causes recurrent hematuria/pyuria, may have a "normal" USG early on)
• Coagulopathy/bleeding disorder
• Exercise-induced or trauma-related transient hematuria
• False hematuria - red/brown urine from foods (beetroot), drugs (rifampin, nitrofurantoin, phenazopyridine), or myoglobinuria - must be excluded first by urine dipstick/microscopy since the report is currently based only on the patient's verbal description, not a confirmed lab finding (Rosen's Emergency Medicine, Box 85.7)
• The gastroenteritis/infective bowel process seen on USG as an incidental, possibly unrelated, cause of the abdominal pain component

Recommended work-up

1. Confirm true hematuria first - urine dipstick + microscopy on a fresh, clean-catch sample. Centrifuge: persistent red sediment = true hematuria; clear sediment with red supernatant = pseudohematuria (food/drug/pigment).
2. Urine microscopy for RBC morphology and casts - dysmorphic RBCs/RBC casts point to a glomerular cause (IgA nephropathy, GN); isomorphic RBCs favor a urological source (stone, infection, tumor).
3. Urine culture to rule out UTI.
4. Plain X-ray KUB - since USG can miss stones obscured by bowel gas, a plain film (or better, non-contrast CT KUB if suspicion is high) should be done before excluding urolithiasis.
5. Renal function tests (urea, creatinine, electrolytes) and blood pressure measurement - hypertension + hematuria suggests glomerular disease.
6. CBC, coagulation profile if bleeding tendency is a concern.
7. Complement C3, ASO titre, serum IgA if a post-infectious or IgA nephropathy picture is suspected clinically (recent sore throat, skin infection).
8. Doppler ultrasound of the left renal vein if flank pain is left-sided and everything else is negative (Nutcracker syndrome).
9. Examine for rash/joint swelling (HSP) and do a full genital/perineal exam.
10. Stool studies / clinical management of the incidental infective enteritis (hydration, antipyretics, antiemetics as needed; antibiotics only if bacterial dysentery is confirmed or clinically indicated).

Management

• Symptomatic care for the gastroenteritis component: oral/IV rehydration, antiemetics, antispasmodics, avoid NSAIDs until a renal cause is excluded (NSAIDs can worsen glomerular bleeding and are nephrotoxic).
• If UTI confirmed: appropriate empirical antibiotics per local sensitivity, adjusted after culture.
• If a stone is found on X-ray/CT: hydration, analgesia (NSAID/opioid as appropriate once renal function is known), alpha-blocker if size favors spontaneous passage; refer to urology for ESWL/ureteroscopy if the stone is large, infected, or obstructing.
• If dysmorphic RBCs/casts, proteinuria, hypertension, or rising creatinine: refer to nephrology - IgA nephropathy and HSP nephritis are managed medically (ACE inhibitors/ARBs for proteinuria, immunosuppression only in progressive disease); renal biopsy may be needed for a definitive diagnosis.
• If purpura/joint pain present: manage as HSP (usually supportive; NSAIDs avoided if renal involvement, short corticosteroid course for severe abdominal pain in some cases).
• If gross hematuria persists despite negative initial work-up, or there are risk factors (smoking, occupational exposure, family history of renal/urothelial cancer): cystoscopy and CT urogram per AUA risk-stratified hematuria pathway.
• Routine follow-up urinalysis in 2-4 weeks to confirm resolution; persistent or recurrent hematuria needs urology/nephrology referral regardless of a "normal" first ultrasound.

Management based on the USG diagnosis (infective enteritis)

1. Supportive care first - most infective enteritis (Campylobacter, viral, mild Salmonella) is self-limiting:
   • Oral rehydration solution; IV fluids if dehydrated or vomiting is significant
   • Antiemetics for nausea/vomiting
   • Antipyretics/analgesics for fever and pain (avoid NSAIDs until a renal cause of hematuria is excluded, since NSAIDs can worsen renal bleeding/ function)
   • Light, easily digestible diet; avoid dairy and fatty foods temporarily
2. Identify the organism before starting antibiotics:
   • Stool microscopy, culture and sensitivity
   • Antibiotics are not routinely needed - Campylobacter enteritis usually resolves without antibiotics; Yersinia responds to co-trimoxazole/chloramphenicol if it persists; Salmonella/typhoid needs antibiotics (e.g., chloramphenicol or a fluoroquinolone/ceftriaxone per local sensitivity) mainly when severe, systemic, or in high-risk patients
   • Give antibiotics empirically only if the patient is toxic, has high fever, bloody diarrhoea, or systemic signs (typhoid pattern) - otherwise treat symptomatically and wait for culture
3. Watch for red-flag/surgical signs: worsening localized tenderness, guarding, rising fever, distension, or signs of perforation/toxic dilatation - these would need surgical reassessment, though the current scan shows no obstruction or perforation.
4. Because the hematuria is unexplained by this scan, run the urinary work-up in parallel rather than assuming it will resolve with enteritis treatment:
   • Urinalysis + microscopy (confirm true hematuria, check RBC morphology/casts)
   • Urine culture
   • Renal function tests, blood pressure
   • Plain X-ray KUB (ultrasound can miss a mid-ureteric stone hidden by bowel gas - which this patient clearly has) or CT KUB if stone strongly suspected
   • Referral to urology (if a stone/structural lesion is found) or nephrology (if urinalysis shows dysmorphic RBCs/casts/proteinuria, suggesting a glomerular cause such as IgA nephropathy)
5. Follow-up: repeat clinical review in a few days; if abdominal pain resolves with enteritis treatment but hematuria persists, that confirms the two symptoms are from separate causes and the urinary work-up above should be pursued to completion.