Pathophysiology and Clinical Characteristics of HELLP Syndrome

Primary Pathophysiologic Mechanism

• Defective arterial placental perfusion and inadequate placental vessel development occur early in the first trimester, leading to placental ischemia and subsequent endothelial dysfunction, according to the American College of Gastroenterology 1

Thrombotic Microangiopathy and Organ Damage

• Hepatic involvement results from fibrin deposition within hepatic sinusoids, causing sinusoidal obstruction and subsequent hepatic ischemia, which can progress to subcapsular hematomas, parenchymal hemorrhage, and potentially hepatic rupture, as reported by the American Association for the Study of Liver Diseases 1

Relationship to Preeclampsia

• HELLP can occur in patients with normal blood pressure, indicating it is not simply severe preeclampsia, with approximately 15% of cases having no hypertension, according to the American Heart Association 1 and the American Society of Hypertension 2