HELLP Syndrome Workup

Updated: Jun 16, 2022
  • Author: Huma Khan, MD; Chief Editor: Ronald M Ramus, MD  more...
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Imaging Studies

Although rare, large-vessel vasculopathy could result in hepatic infarction or subcapsular hematomas. If suspected (usually correlated with worsening hepatic function test results), CT scanning or MRI should be obtained. Hepatic ultrasonography may reveal increased echogenicity in irregular, well-demarcated areas of the liver. [22, 2]


Histologic Findings

Hepatic endothelial disruption and subsequent platelet activation, aggregation, and consumption lead to distal ischemia and hepatocyte death, which can be segmental or apparent diffusely throughout the liver. [35] Since HELLP tends to involve smaller terminal arterioles, characteristic histiologic features are periportal or focal parenchymal necrosis with hyaline deposits of fibrinlike material in the sinusoids. [36, 37, 38] If larger-vessel vasculopathy occurs, hepatic infarction or subcapsular hematomas may result, both of which would require imaging studies such as MRI or CT scanning. [39]



Two common classifications used to predict maternal morbidity and mortality were described in and are known as the Mississippi and the Tennessee classifications.

The two methods of classification, while useful, should not be regarded as a hard and fast rule. Partial HELLP syndrome, as per the Tennessee classification, can progress to the complete form. In addition, increased eclampsia and higher perinatal morbidity and mortality have been demonstrated in patients with HELLP syndrome, [40] while those with Mississippi class 3 disease have been shown to exhibit hepatic rupture. [41, 42]

Mississippi classification

The Mississippi classification divides HELLP syndrome into 3 classes based on platelet count, AST or ALT levels, and LDH levels.

Class 1, which has an approximately 13% incidence of bleeding, is associated with the highest maternal morbidity and mortality rates and longest recovery time. Patients in this class have a platelet count less than 50,000/µL, liver dysfunction with AST or ALT levels greater than 70 IU/L, and hemolysis as evidenced by an LDH level greater than 600 IU/L.

Class 2 includes platelet counts from 50,000-100,000/µL with AST, ALT, and LDH levels similar to those in class 1. Class 2 has an 8% incidence of bleeding.

The mild form of HELLP, class 3, has a platelet count from 100,000-150,000/µL, AST and ALT greater than 40 IU/L, and LDH greater than 600 IU/L, with no increased risk of bleeding.

The more severe the class, the longer the recovery time postpartum. [25, 41]

Table 2: Mississippi Classification of HELLP Syndrome (Open Table in a new window)


Class 1 (Severe)

Class 2 (Moderate)

Class 3 (Mild)






≥70 IU/L

≥70 IU/L

≥40 IU/L


≥600 IU/L

≥600 IU/L

≥600 IU/L

Incidence of bleeding



No increased risk


Tennessee classification

The Tennessee classification describes HELLP as either complete or partial.

Complete HELLP is defined as hemolysis with an abnormal peripheral smear finding and an LDH level greater than 600 IU/L or bilirubin level greater than 1.2 mg/dL. Patients with complete HELLP have platelet counts less than 100,000/µL and AST levels over 70 IU/L.

Partial HELLP describes severe preeclampsia plus some features of HELLP. These features are further defined as LP, or low platelet syndrome (slightly thrombocytopenic but no hemolysis or liver dysfunction); EL, or elevated liver enzyme syndrome (mildly elevated liver enzymes but no hemolysis or thrombocytopenia); HEL syndrome (hemolysis, elevated liver enzyme levels, but no thrombocytopenia); and ELLP syndrome (elevated liver enzyme levels and low platelet counts, no hemolysis). [41]

Complete HELLP syndrome is characterized by the following:

  • Platelet count of 100,000/μL or less

  • AST or ALT levels of 70 IU/L or more

  • LDH (or bilirubin) (with hemolysis as evidenced on abnormal peripheral smear) levels of 600 IU/L (≥0.2 mg/dL) or more

Partial HELLP syndrome is characterized by severe preeclampsia plus one of the following:

  • ELLP: Elevated liver enzyme levels, thrombocytopenia, no hemolysis

  • EL: Mildly elevated liver enzyme levels, no thrombocytopenia, no hemolysis

  • LP: Thrombocytopenia, no hemolysis, normal liver enzyme levels

  • HEL: Hemolysis, liver dysfunction, no thrombocytopenia


Laboratory Studies

Laboratory evaluation should include the following:

  • Type and screen

  • Complete blood cell (CBC) count: Thrombocytopenia, anemia with possible reticulocytosis

  • Coagulation studies: Normal prothrombin time, 50% may have prolonged activated partial thromboplastin time

  • Peripheral smear: Schistocytes, helmet cells, and burr cells secondary to microangiopathic hemolytic anemia

  • Serum aspartate aminotransferase/alanine aminotransferase (AST/ALT) levels: Elevated secondary to liver dysfunction

  • Lactate dehydrogenase (LDH) level: Elevated secondary to liver dysfunction or hemolysis

  • Complete metabolic panel (CMP): Elevated blood urea nitrogen (BUN)/creatinine with acute renal failure

  • Bilirubin level: Increased secondary to hemolysis

  • Haptoglobin level: Decreased secondary to hemolysis

  • Fibrinogen levels: Low secondary to increased coagulation

  • D-dimer: Increased due to fibrinolysis/DIC

Laboratory abnormalities apparent in HELLP syndrome and the recovery time postpartum required for normalization of these findings are summarized in Table 1. [24, 2]

Table 1: Laboratory Findings in HELLP Syndrome (Open Table in a new window)

Laboratory Test

Possible Result


Recovery to Baseline (in Number of Hours or Days Postpartum)



24-30 hours


Hemolysis or liver dysfunction

3-5 days


Liver dysfunction

3-5 days




Platelets (CBC)


6-11 days

Hemoglobin/Hematocrit (CBC)








Liver dysfunction



Increased coagulation and secondary fibrinolysis