HELLP syndrome is a complication of pregnancy; the acronym stands for hemolysis, elevated liver enzymes, and low platelet count. It usually begins during the last three months of pregnancy or shortly after childbirth. Symptoms may include feeling tired, retaining fluid, headache, nausea, upper right abdominal pain, blurry vision, nosebleeds, and seizures. Complications may include disseminated intravascular coagulation, placental abruption, and kidney failure. The cause is unknown. The condition occurs in association with pre-eclampsia or eclampsia. Other risk factors include previously having the syndrome and a mother older than 25 years. The underlying mechanism may involve abnormal placental development. Diagnosis is generally based on blood tests finding signs of red blood cell breakdown (lactate dehydrogenase greater than 600 U/L), an aspartate transaminase greater than 70 U/L, and platelets less than 100×109/l. If not all the criteria are present, the condition is incomplete. Treatment generally involves delivering the baby as soon as possible. This is particularly true if the pregnancy is beyond 34 weeks of gestation. Medications may be used to decrease blood pressure and blood transfusions may be required. HELLP syndrome occurs in about 0.7% of pregnancies and affects about 15% of women with eclampsia or severe pre-eclampsia. Death of the mother is uncommon (< 1%). Outcomes in the babies are generally related to how premature they are at birth. The syndrome was first named in 1982 by American gynaecologist Louis Weinstein.
Signs and symptoms The first signs of HELLP usually start appearing midway through the third trimester, though the signs can appear in earlier and later stages. It is highly associated with known pre-eclampsia. Risk factors for pre-eclampsia include older age, uncontrolled hypertension, diabetes mellitus, and obesity. Signs and symptoms of HELLP vary in severity and between individuals and are commonly mistaken for normal pregnancy symptoms, especially if they are not severe. HELLP syndrome patients experience general discomfort followed by severe epigastric pain or right upper abdominal quadrant pain, accompanied by nausea, vomiting, backache, anaemia, and hypertension. Some patients may also have a headache and visual issues. These symptoms may also become more severe at night. As the condition progresses and worsens, a spontaneous hematoma occurs following the rupture of the liver capsule, which occurs more frequently in the right lobe. The presence of any combination of these symptoms, subcapsular liver hematoma in particular, warrants an immediate check-up due to the high morbidity and mortality rates of this condition.
Risk factors Elevated body mass index and metabolic disorders, as well as antiphospholipid syndrome, significantly increase the risk of HELLP syndrome in all female patients. Females who have had or are related to a female with previous HELLP syndrome complications tend to be at a higher risk in all their subsequent pregnancies. The risk of HELLP syndrome is not conclusively associated with a specific genetic variation, but likely a combination of genetic variations, such as FAS gene, VEGF gene, glucocorticoid receptor gene and the tol-like receptor gene, increase the risk.
Pathophysiology The pathophysiology remains unclear, and an exact cause is yet to be found. However, it shares a common mechanism, which is endothelial cell injury, with other conditions, such as acute kidney injury and thrombotic thrombocytopenic purpura. Increasing the understanding of HELLP syndrome's pathophysiology will enhance diagnostic accuracy, especially in the early stages. This will lead to advancements in the prevention, management, and treatment of the condition, which will increase the likelihood of maternal and fetal survival and recovery.
Inflammation and coagulation As a result of endothelial cell injury, a cascade of pathological reactions manifests and becomes increasingly severe and even fatal as signs and symptoms progress. Following endothelial injury, vasospasms and platelet activation occur alongside the decreased release of the endothelium-derived relaxing factor and increased release of von Willebrand factor (vWF), leading to general activation of the coagulation cascade and inflammation. Placental components, such as inflammatory cytokines and syncytiotrophoblast particles interact with the maternal immune system and endothelial cells, further promoting coagulation and inflammation. These interactions also elevate leukocyte numbers and interleukin concentrations, as well as increase complement activity.
Low platelet count vWF degradation in HELLP syndrome is inhibited due to decreased levels of degrading proteins, leading to an increased exposure of platelets to vWF. As a result, thrombotic microangiopathies develop and lead to thrombocytopenia.
Blood breakdown As a result of the high number of angiopathies, the erythrocytes fragment as they pass through the blood vessels with damaged endothelium and large fibrin networks, leading to macroangiopathic haemolytic anaemia. As a consequence of hemolysis, lactic acid dehydrogenase (LDH) and hemoglobin are released, with the latter binding to serum bilirubin or haptoglobin.
Liver During the coagulation cascade, fibrin is deposited in the liver and leads to hepatic sinusoidal obstruction and vascular congestion, which increases intrahepatic pressure. Placenta-derived FasL (CD95L), which is toxic to human hepatocytes, leads to hepatocyte apoptosis and necrosis by inducing the expression of TNFα and results in the release of liver enzymes. Hepatic damage is worsened by the disrupted portal and total hepatic blood flow that results as a consequence of the microangiopathies. Collectively, widespread endothelial dysfunction and hepatocellular damage result in global hepatic dysfunction, often leading to liver necrosis, haemorrhages, and capsular rupture.
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