A 28-year-old multiparous woman at 29 weeks gestation is found to have BP 145/92 mmHg on two occasions, proteinuria 4 g/24 h, and platelet count 95,000/μL. Which single feature best distinguishes preeclampsia from HELLP syndrome in this clinical context?

Explanation

## Distinguishing Preeclampsia from HELLP Syndrome ### Core Discriminator: Elevated Transaminases + RUQ Pain **Key Point:** The question asks which **single feature best distinguishes HELLP syndrome from preeclampsia** in a patient who already has hypertension, proteinuria, AND thrombocytopenia (<100,000/μL). Given that thrombocytopenia is already present in the vignette, the feature that most specifically points toward HELLP (rather than severe preeclampsia) is **elevated transaminases with right upper quadrant (RUQ) pain**—the hepatic component of the HELLP triad. ### Why Option A is Correct HELLP syndrome is defined by the triad: **H**emolysis + **E**levated **L**iver enzymes + **L**ow **P**latelets (Sibai, 2004; ACOG Practice Bulletin 202). In this vignette, the patient already satisfies the "L" (Low Platelets = 95,000/μL). The feature that would **distinguish** HELLP from severe preeclampsia with thrombocytopenia is the **hepatic involvement**—elevated AST/ALT (>70 IU/L) and RUQ or epigastric pain due to hepatic capsule distension. This is the discriminating finding not yet established in the stem. ### Comparison Table | Feature | Severe Preeclampsia | HELLP Syndrome | |---|---|---| | **Hypertension & Proteinuria** | Present ✓ | Present ✓ | | **Thrombocytopenia <100K** | May occur | Always present ✓ | | **Elevated transaminases + RUQ pain** | Absent or mild | **Defining hepatic criterion** ✓ | | **Hemolysis (MAHA)** | Absent | Present (part of triad) | ### Why Other Options Are Less Discriminating in This Context - **Option B (Hypertension + Proteinuria):** Already present in both conditions and in this patient—not discriminating. - **Option C (Thrombocytopenia <100,000/μL):** Already documented in the vignette (95,000/μL); present in both severe preeclampsia and HELLP—not the distinguishing feature here. - **Option D (Hemolysis/MAHA):** While hemolysis is part of the HELLP triad, the question asks for the **single best distinguishing feature** in this clinical context. Elevated transaminases + RUQ pain is the **hepatic criterion** that, combined with the already-present thrombocytopenia, most specifically signals HELLP over severe preeclampsia. Hemolysis is also part of HELLP, but the hepatic component (Option A) is the feature not yet accounted for in the stem and is the most clinically actionable discriminator when thrombocytopenia is already established. **High-Yield:** In a patient with preeclampsia + thrombocytopenia, the addition of **elevated liver enzymes and RUQ pain** is the finding that clinches the diagnosis of HELLP syndrome (Sibai BM, *NEJM* 2005; ACOG PB 202). **Clinical Pearl:** RUQ or epigastric pain in a preeclamptic patient with thrombocytopenia should prompt urgent liver function testing. AST >70 IU/L confirms the hepatic criterion of HELLP and mandates expedited delivery planning regardless of gestational age. [cite: ACOG Practice Bulletin 202; Sibai BM. Diagnosis, controversies, and management of the syndrome of hemolysis, elevated liver enzymes, and low platelet count. *Obstet Gynecol* 2004;103:981–991]