A 28-year-old multigravida at 28 weeks of gestation is found to have blood pressure 150/95 mmHg on two occasions 4 hours apart, with no proteinuria on urine dipstick. She is asymptomatic. Which investigation is most appropriate to confirm the diagnosis of gestational hypertension and exclude preeclampsia?

Question

Accepted Answer

B. 24-hour urine protein or protein-to-creatinine ratio. ## Distinguishing Gestational Hypertension from Preeclampsia

**Key Point:** Gestational hypertension is elevated BP (≥140/90 mmHg) in pregnancy **without proteinuria or end-organ dysfunction**. Preeclampsia is hypertension **plus** proteinuria (≥0.3 g/24 h or ≥30 mg/mmol creatinine) or end-organ dysfunction.

### Clinical Scenario Analysis

This patient has:
- Elevated BP (150/95 mmHg) on two occasions
- **No proteinuria on dipstick**
- **Asymptomatic**
- **No clinical features of severe preeclampsia**

The diagnosis is **gestational hypertension** (by definition). However, the critical next step is to **exclude subclinical proteinuria** because:

1. Dipstick proteinuria is **insensitive** for mild proteinuria (detects only ≥1+ = ≥30 mg/dL)
2. Preeclampsia may present with **minimal proteinuria** (0.3–1.0 g/24 h) that dipstick misses
3. Quantitative urine protein assessment is the **gold standard** to confirm absence of proteinuria

### Why 24-Hour Urine Protein or Protein-to-Creatinine Ratio?

```mermaid
flowchart TD
  A["Elevated BP in pregnancy"]:::outcome --> B{"Proteinuria on dipstick?"}:::decision
  B -->|"Yes or ≥1+"|C["Preeclampsia suspected"]:::outcome
  B -->|"No"|D{"Quantitative urine protein?"}:::decision
  D -->|"≥0.3 g/24h or ≥30 mg/mmol"|E["Preeclampsia"]:::outcome
  D -->|"<0.3 g/24h"|F["Gestational hypertension"]:::outcome
  C --> G["Assess for end-organ dysfunction"]:::action
  E --> G
  F --> H["Monitor BP, repeat urine protein"]:::action
```

**High-Yield:** In asymptomatic hypertension without dipstick proteinuria, **quantitative urine protein** (24-hour collection or protein-to-creatinine ratio) is the investigation of choice to definitively exclude preeclampsia.

### Why Not the Other Options?

| Investigation | Why Not Appropriate |
|---|---|
| **Serum uric acid** | Elevated uric acid (>5.5 mg/dL) suggests preeclampsia but is **not diagnostic**. It is a secondary marker of endothelial dysfunction. Not used for diagnosis in asymptomatic patients. |
| **LFTs and platelets** | These assess end-organ dysfunction (HELLP syndrome). Not indicated in asymptomatic patient with no proteinuria. |
| **Umbilical artery Doppler** | Fetal assessment tool; does not diagnose maternal hypertensive disorder. |

**Clinical Pearl:** Protein-to-creatinine ratio (PPCR) on a random urine sample is increasingly preferred over 24-hour collection because it is convenient, faster, and equally accurate. PCCR ≥30 mg/mmol (≥0.3 g/g) is abnormal.

Answer

A. Serum uric acid level

Answer

C. Umbilical artery Doppler

Answer

D. Liver function tests and platelet count

Explanation

Distinguishing Gestational Hypertension from Preeclampsia

Clinical Scenario Analysis

Why 24-Hour Urine Protein or Protein-to-Creatinine Ratio?

Why Not the Other Options?

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Investigation	Why Not Appropriate
Serum uric acid	Elevated uric acid (>5.5 mg/dL) suggests preeclampsia but is not diagnostic. It is a secondary marker of endothelial dysfunction. Not used for diagnosis in asymptomatic patients.
LFTs and platelets	These assess end-organ dysfunction (HELLP syndrome). Not indicated in asymptomatic patient with no proteinuria.
Umbilical artery Doppler	Fetal assessment tool; does not diagnose maternal hypertensive disorder.