HELLP syndrome is a rare, potentially life-threatening pregnancy complication defined by hemolysis, elevated liver enzymes, and low platelet count. While HELLP syndrome is considered to be a variant of preeclampsia, both proteinuria and hypertension are less predictably present in this condition.

HELLP syndrome shares some risk factors with those of preeclampsia, including chronic hypertension, pregestational renal disease, pregestational diabetes, obesity, and family history of preeclampsia spectrum disorders. However, women with HELLP syndrome are more likely to be of advancing maternal age and/or multiparous than those with preeclampsia without end-organ damage. Complications of pregnancy can also increase the risk of preeclamptic spectrum disorders including molar pregnancies and multifetal pregnancies.

While preeclampsia occurs in approximately 4% of pregnancies, HELLP syndrome occurs in 0.5%-0.9%. However, of the pregnancies affected by severe preeclampsia, 10%-20% will eventually develop HELLP syndrome. Over two-thirds of cases of HELLP syndrome develop in the antepartum period, with nearly all other cases developing within 48 hours following delivery, though it may manifest up to 7 days after delivery.

Clinical presentations are variable. Initial presentations may include any combination of abdominal pain and tenderness (right upper quadrant or epigastric), nausea, vomiting, edema, malaise, headache, and/or visual changes. The initial disease process may also be asymptomatic.

Complications of HELLP syndrome include placental abruption, postpartum hemorrhage, disseminated intravascular coagulation (DIC), pulmonary edema, acute renal failure, and hemorrhagic stroke. Rarely, HELLP-related retinopathy can cause temporary or permanent bilateral visual loss, and liver dysfunction can culminate in spontaneous rupture of a subcapsular liver hematoma. Any of these significant complications can result in maternal and/or fetal death.