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PE20.1-9 | Genito-Urinary System — PBL Case

CLINICAL SETTING

Paediatric emergency department of a district hospital in Tamil Nadu. It is a humid July afternoon. A 4-year-old boy, Arjun, is brought by his anxious parents. For the past 5 days he has had watery diarrhoea that turned bloody 3 days ago. Over the past 18 hours he has become pale, increasingly lethargic, and has barely urinated. His mother noticed his face looks puffy. He has no fever today. The family lives in a semi-rural area; they obtained drinking water from a community tank. No other family member is unwell.

Trigger 1: Trigger 1 — Arrival and Initial Assessment

On examination: weight 16 kg, temperature 37.4°C, HR 128/min, BP 125/80 mmHg (95th centile for age 115/73 mmHg), SpO₂ 97% on room air. Arjun is pale, listless, and has periorbital puffiness. Abdomen is soft with mild diffuse tenderness; no palpable masses. Capillary refill 3 seconds. No rash. Urine dipstick: blood 3+, protein 2+, leucocyte esterase negative. The nurse notes his last documented urine output was >10 hours ago.

DISCUSSION POINTS

  • What is your immediate prioritised problem list for Arjun based on the history and initial examination?
  • Describe the clinical triad that is forming. What single unifying diagnosis fits bloody diarrhoea, pallor, oliguria, hypertension, and periorbital oedema in a 4-year-old?
  • Why is the leucocyte esterase negative relevant? What does this suggest about the cause of the haematuria and proteinuria?
  • What investigations would you order in the first 30 minutes and why — prioritise them.
Click to reveal Trigger 2: Trigger 2 — Laboratory Results (discuss previous trigger first!)

Trigger 2: Trigger 2 — Laboratory Results

Results are back 45 minutes later: - FBC: Hb 6.8 g/dL, WBC 12,000/µL, platelets 42,000/µL - Blood film: fragmented RBCs (schistocytes), polychromasia - Serum creatinine: 4.2 mg/dL; BUN: 58 mg/dL - Serum potassium: 6.2 mEq/L; sodium: 132 mEq/L; HCO₃⁻: 13 mEq/L - Stool culture: pending; stool microscopy shows RBCs; sorbitol-MacConkey agar ordered - PT/INR: normal; fibrinogen: normal - Urine microscopy: 30 RBCs/HPF (dysmorphic), no casts, no WBCs - Renal ultrasound: mildly enlarged, echogenic kidneys bilaterally; no stones, no obstruction

DISCUSSION POINTS

  • Confirm the diagnosis using the classical triad. Which three laboratory findings in this trigger define this diagnosis?
  • The registrar suggests starting oral ciprofloxacin for the bloody diarrhoea. You disagree strongly — why? What is the mechanism by which antibiotics worsen the outcome in this condition?
  • Interpret the metabolic picture (K⁺ 6.2 mEq/L, HCO₃⁻ 13, creatinine 4.2). Which of these is the most immediately life-threatening and what is your management?
  • The platelet count is 42,000/µL — should you transfuse platelets? Why or why not?
Click to reveal Trigger 3: Trigger 3 — Day 3: Ongoing Oliguria and a New Finding (discuss previous trigger first!)

Trigger 3: Trigger 3 — Day 3: Ongoing Oliguria and a New Finding

Day 3: Arjun has received strict fluid management (insensible losses + hourly urine output replacement). Urine output remains <0.5 mL/kg/hour despite fluid optimisation. Serum creatinine has risen to 6.1 mg/dL. Serum potassium is now 6.8 mEq/L despite salbutamol nebulisation and sodium bicarbonate infusion. Weight has increased by 1.2 kg (fluid overload). Blood pressure is 140/90 mmHg. ECG shows peaked T waves. Meanwhile, an abdominal X-ray (KUB) obtained to check for ileus shows no calcifications. Haematocrit: 17%. The junior doctor also notes that the abdominal X-ray shows a faint soft-tissue density in the right flank — he wants to palpate this further to characterise it.

DISCUSSION POINTS

  • What are the indications for dialysis in this child? List the specific criteria met and decide: does Arjun need dialysis now?
  • The peaked T waves on ECG in the context of hyperkalaemia 6.8 mEq/L indicate an emergency — list the stepwise management of severe hyperkalaemia in a 16 kg child with weight-based doses.
  • The junior doctor wants to palpate the right flank soft-tissue density. How would you counsel him — what is the risk, and what is the correct next step to characterise this finding (hint: consider all diagnoses that cause a renal mass in a 4-year-old)?
  • How does HUS cause AKI at the pathophysiological level — what happens to the glomerular capillaries?
Click to reveal Trigger 4: Trigger 4 — Resolution, Renal Mass Characterisation, and Discharge Planning (discuss previous trigger first!)

Trigger 4: Trigger 4 — Resolution, Renal Mass Characterisation, and Discharge Planning

Arjun is started on peritoneal dialysis. Over the next 10 days, urine output gradually recovers. By day 14, creatinine normalises to 0.6 mg/dL; haematocrit rises to 31% without further transfusion. CT abdomen (performed when Arjun was stable on day 8) shows a well-defined 3 cm intrarenal mass in the right kidney — consistent with nephroblastoma (Wilms tumour). The treating team explains the findings to the family. The stool culture confirmed EHEC O157:H7. At discharge (day 15), BP is 118/78 mmHg, creatinine 0.6 mg/dL, urine protein trace, haematocrit 34%. He is referred to a paediatric oncology centre.

DISCUSSION POINTS

  • What is the NWTS staging system for Wilms tumour? What investigations would be done to stage Arjun's tumour, and what is the standard treatment protocol?
  • The family asks: 'Did the HUS damage his kidney permanently?' How would you counsel them regarding long-term renal outcomes after HUS in children?
  • Design a follow-up plan for Arjun covering: (a) renal function monitoring post-HUS, (b) BP surveillance, (c) ongoing Wilms tumour management, and (d) the family members who should be screened.
  • Summarise the epidemiological significance: what water-safety and food-safety messages would you give this family and the community health worker to prevent future EHEC outbreaks?

Group Task Assignments

Group 1: Collaborative Task

Group 2: Collaborative Task

Group 3: Collaborative Task

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [PE20.1] What are the common organisms causing UTI in children, and what is the imaging protocol for a first febrile UTI?
  2. [PE20.2] What is the pathogenesis of APSGN, what is the expected C3 trajectory, and when should a renal biopsy be performed?
  3. [PE20.3] How is nephrotic syndrome diagnosed, what are its immediate life-threatening complications, and what is the ISKDC first-line treatment protocol?
  4. [PE20.4] How do you differentiate glomerular from non-glomerular haematuria clinically and on urine microscopy?
  5. [PE20.5] What is the KDIGO definition of AKI, what is the pathogenesis of HUS-associated AKI, and why are antibiotics contraindicated in EHEC-HUS?
  6. [PE20.6] What are the complications of CKD in children (anaemia, bone disease, growth failure, hypertension, acidosis) and how is each managed?
  7. [PE20.7] What are the NWTS staging criteria for Wilms tumour, why is palpation contraindicated, and how does it differ from neuroblastoma?
  8. [PE20.8] How do you systematically interpret urine microscopy findings (RBC casts, WBC casts, granular casts, dysmorphic RBCs) to localise the segment of the urinary tract involved?
  9. [PE20.9] What are the key findings on a plain KUB X-ray in a child with urinary tract pathology, and what is the radio-opacity of different stone types?