HELLP syndrome

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Evidence last reviewed: 7 Jun 2026

Topic last updated: 23 Jun 2026

HELLP syndrome is considered by many to be a severe form of preeclampsia (sometimes called "atypical preeclampsia"). However, it has a different definition characterized by hemolysis (H), also expressed as microangiopathic hemolytic anemia, elevated liver enzymes (EL), and low platelets (LP).

Usually occurs antepartum, between 27 and 37 weeks' gestation. In 15% to 30% of cases, HELLP syndrome is either initially expressed or progresses postpartum.

HELLP syndrome poses significant diagnostic and therapeutic challenges because only 80% to 85% of affected people present typically with hypertension and proteinuria.

It should therefore be considered in any pregnant woman presenting in the second half of pregnancy or immediately postpartum with significant new-onset epigastric/upper abdominal pain until proven otherwise.

Early detection and aggressive management with a combination of intravenous magnesium sulfate, control of blood pressure to prevent or minimize severe systolic hypertension, replacement of blood products, as needed, and timely delivery of the fetus and placenta seem to be the best and safest ways to arrest disease progression and reduce adverse outcomes. Maternal outcomes are improved considerably with this management approach; perinatal outcome depends predominantly on the gestational age at which delivery occurs.

Although delivery is the only treatment that starts recovery, serious manifestations continue into the immediate postpartum period.

Definition

Although HELLP syndrome is considered by many to be a severe form of preeclampsia, it has a different definition, characterized by hemolysis (H), elevated liver enzymes (EL), and low platelets (LP) in a pregnant or puerperal woman (usually within 7 days of delivery). The diagnosis and management of preeclampsia is not discussed in detail in this topic. See Preeclampsia.

A woman with HELLP syndrome often displays hypertension (defined as blood pressure ≥140/90 mmHg) and proteinuria (80% to 85%), epigastric/right upper quadrant (RUQ) pain (40% to 90%), nausea and/or vomiting (29% to 84%), headache (33% to 61%), and generalized malaise (90%).[1][2][3][4] Some women may present without these signs/symptoms when first evaluated for unexplained thrombocytopenia. The diagnosis of HELLP syndrome should be considered in any pregnant woman presenting in the second half of pregnancy or immediately postpartum with significant new-onset epigastric/RUQ pain until proven otherwise.

Although different classifications have been proposed for HELLP syndrome, the following diagnostic criteria are used: microvascular hemolysis, including characteristic findings (schistocytes, burr cells and polychromasia) on a peripheral blood smear, hematuria, worsening anemia (<8-10 g/dL, depending on the stage of pregnancy and unrelated to blood loss) and/or low serum haptoglobin levels (<25 mg/dL), elevated lactate dehydrogenase (LDH) levels (>600 IU/L), and elevated total serum bilirubin levels (>1.2 mg/dL); elevated liver transaminase levels, including aspartate aminotransferase (AST), and/or alanine aminotransferase (ALT) levels (>70 IU/L or twice the upper limit of normal, not accounted for by alternative diagnoses); and a decreased platelet count (<100x 10⁹/L).[5][6][7]

History and exam

Key diagnostic factors

>20 weeks' gestation
epigastric/right upper quadrant pain and tenderness
nausea/vomiting
hypertension and proteinuria
edema
brisk tendon reflexes

Full details

Other diagnostic factors

generalized malaise
headache
visual disturbances
jaundice
bleeding

Full details

Risk factors

maternal age >35 years
obesity
chronic hypertension
diabetes mellitus
migraine
previous pregnancy with HELLP syndrome or preterm preeclampsia
multiple gestation pregnancy

Full details

Diagnostic tests

1st tests to order

CBC with differential, including platelets
total serum lactate dehydrogenase (LDH) level
liver transaminase levels
bilirubin levels
urinalysis and protein-to-creatinine ratio

Full details

Tests to consider

peripheral blood smear
haptoglobin level
uric acid level
fibrinogen level
prothrombin time (PT)/PTT
serum glucose level
serum creatinine and electrolyte levels
antithrombin level
LDH-to-aspartate aminotransferase (AST) ratio
maternal upper abdominal ultrasound, CT, or MRI
fetal ultrasound

Full details

Treatment algorithm

INITIAL

suspected/presumed HELLP syndrome

ACUTE

confirmed HELLP syndrome

Contributors

Authors

Judette Louis, MD, MPH

James Ingram Professor and Chair

Department of Obstetrics and Gynecology

Morsani College of Medicine

University of South Florida

Tampa, FL

Disclosures

JML has received research funding from Roche Diagnostics for preeclampsia research and Janssen Pharmaceuticals for consultative work.

Acknowledgements

We would like to gratefully acknowledge the late Dr James N. Martin Jr (Professor Emeritus of Obstetrics, Gynecology, and Maternal-Fetal Medicine at the University of Mississippi Medical Center) for his previous contribution to this topic. Dr Judette Louis would also ike to gratefully acknowledge Dr Marium G. Holland and Dr Alex C. Vidaeff, the previous contributors to this topic.

Disclosures

MGH declares that she has no competing interests. ACV is an author of a number of references cited in this topic.

Peer reviewers

Jerome Yankowitz, MD

Professor and Director

Division of Maternal-Fetal Medicine

Department of Obstetrics and Gynecology

University of Iowa Hospitals and Clinics

Iowa City, IA

Disclosures

JY declares that he has no competing interests.

Deirdre Murphy, MD, MRCOG

Professor of Obstetrics

Trinity College

University of Dublin

Consultant Obstetrician

Coombe Women and Infants University Hospital

Dublin

Ireland

Disclosures

DM declares that she has no competing interests.

Peer reviewer acknowledgements

BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.

Disclosures

Peer reviewer affiliations and disclosures pertain to the time of the review.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Martin JN Jr, Rinehart BK, May WL, et al. The spectrum of severe preeclampsia: comparative analysis by HELLP (hemolysis, elevated liver enzyme levels, and low platelet count) syndrome classification. Am J Obstet Gynecol. 1999 Jun;180(6 Pt 1):1373-84. Abstract

American College of Obstetricians and Gynecologists. ACOG practice bulletin no. 222: gestational hypertension and preeclampsia. Jun 2020 [internet publication].Full text

Martin JN Jr, Blake PG, Perry KG Jr, et al. The natural history of HELLP syndrome: patterns of disease progression and regression. Am J Obstet Gynecol. 1991 Jun;164(6 Pt 1):1500-9; discussion 1509-13. Abstract

Sibai BM. Diagnosis and management of gestational hypertension and preeclampsia. Obstet Gynecol. 2003 Jul;102(1):181-92. Abstract

Martin JN Jr, Brewer JM, Wallace K, et al. Hellp syndrome and composite major maternal morbidity: importance of Mississippi classification system. J Matern Fetal Neonatal Med. 2013 Aug;26(12):1201-6. Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Acute fatty liver of pregnancy (AFLP)
- Thrombotic thrombocytopenic purpura (TTP)
- Atypical hemolytic uremic syndrome (aHUS)
More Differentials
Guidelines
- Hypertensive disorders of pregnancy: diagnosis, prediction, prevention, and management
- ACOG practice bulletin no. 222: gestational hypertension and preeclampsia
More Guidelines
Patient information
Preeclampsia: what is it?
Preeclampsia: questions to ask your doctor
More Patient information
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HELLP syndrome

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

suspected/presumed HELLP syndrome

confirmed HELLP syndrome

Contributors

Authors

Judette Louis, MD, MPH

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Jerome Yankowitz, MD

Disclosures

Deirdre Murphy, MD, MRCOG

Disclosures

Peer reviewer acknowledgements

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Patient information

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice