A 28-year-old woman from Mumbai presents on day 4 of illness with high fever (39.8°C), severe myalgia, and headache. On examination, she has a petechial rash on the lower limbs and axillae. Laboratory findings: platelet count 45,000/μL, haemoglobin 16 g/dL, haematocrit 48%, AST 320 U/L, ALT 180 U/L. Ultrasound abdomen shows free fluid in the pelvis. She is alert and oriented with normal blood pressure (110/70 mmHg). What is the most likely clinical diagnosis?

Explanation

## Clinical Diagnosis: Dengue Fever with Warning Signs ### Key Diagnostic Framework (WHO 2009 Classification) **Key Point:** The WHO 2009 revised classification (now the standard used in India and globally) categorizes dengue as: 1. **Dengue without warning signs** 2. **Dengue with warning signs** 3. **Severe dengue** The older WHO 1997 DHF grading system (Grades I–IV) has been largely superseded by the 2009 classification in current clinical practice and NEET PG/INI-CET examinations. ### WHO 2009 Warning Signs for Dengue | Warning Sign | Present in This Patient? | |---|---| | Abdominal pain or tenderness | Not stated | | Persistent vomiting | Not stated | | Clinical fluid accumulation (ascites, pleural effusion) | ✅ Free fluid in pelvis | | Mucosal bleeding | ✅ Petechial rash (spontaneous) | | Lethargy / restlessness | Not present | | Liver enlargement >2 cm | Not stated | | Rising haematocrit with rapid decline in platelet count | ✅ Hct 48%, platelets 45,000/μL | **High-Yield:** This patient satisfies multiple warning sign criteria: - **Plasma leakage evidence:** Free fluid in pelvis (ascites) on ultrasound - **Haemorrhagic manifestation:** Spontaneous petechiae on lower limbs and axillae - **Thrombocytopenia:** Platelet count 45,000/μL (≤100,000/μL) - **Elevated haematocrit:** 48% (elevated above normal ~40%) - **Elevated transaminases:** AST 320 U/L, ALT 180 U/L (liver involvement) - **Haemodynamic stability:** BP 110/70 mmHg — no shock ### Why Not Dengue Shock Syndrome (DSS)? DSS requires evidence of circulatory failure: narrow pulse pressure (<20 mmHg) or undetectable blood pressure. This patient has BP 110/70 mmHg (pulse pressure 40 mmHg) — no shock. ### Why Not DHF Grade I or Grade II (1997 criteria)? The 1997 WHO DHF classification requires ALL FOUR criteria to be met simultaneously: 1. Fever 2. Haemorrhagic manifestations 3. Thrombocytopenia (≤100,000/μL) 4. **Evidence of plasma leakage with haematocrit rise ≥20% above baseline** A haematocrit of 48% represents approximately a 20% rise from a normal female baseline (~40%), which is borderline. However, the **current standard** in clinical practice and examinations is the WHO 2009 classification. Under this framework, the correct diagnosis is **Dengue with warning signs**, not DHF Grade II. **Clinical Pearl (Harrison's Principles of Internal Medicine, 21st ed.; Park's Textbook of Preventive and Social Medicine):** The WHO 2009 classification was introduced specifically to improve sensitivity for identifying patients at risk of severe dengue. "Dengue with warning signs" captures patients like this one — alert, normotensive, but with plasma leakage, thrombocytopenia, and spontaneous bleeding — who require close monitoring and IV fluid therapy but do not yet have severe dengue. ### Summary A normotensive, alert patient on day 4 of dengue illness with petechiae, thrombocytopenia, elevated haematocrit, ascites, and elevated transaminases = **Dengue fever with warning signs** (WHO 2009).