old guidelines for gestational htn and preeclampsia

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Gestational Hypertension & Preeclampsia: Guidelines

(Based primarily on ACOG criteria as presented in Creasy & Resnik's Maternal-Fetal Medicine and Harrison's Principles of Internal Medicine)

Classification of Hypertensive Disorders of Pregnancy

There are four distinct types:

Chronic hypertension
Preeclampsia and eclampsia
Gestational hypertension
Preeclampsia superimposed on chronic hypertension

1. Gestational Hypertension

Definition: New-onset blood pressure elevations after 20 weeks' gestation in the absence of proteinuria.

Threshold: BP ≥ 140/90 mmHg on two measurements ≥ 4 hours apart
This is a provisional diagnosis - it includes women who will later develop preeclampsia but have not yet shown proteinuria
Must be monitored closely for progression to preeclampsia
If BP does not normalize within 6 weeks postpartum, the diagnosis is revised to chronic hypertension
Gestational hypertension progresses to overt preeclampsia in 10-25% of cases
Severe gestational hypertension carries similar risks for adverse outcomes as preeclampsia, even without proteinuria

"Gestational hypertension with severe features of the disease is best classified as preeclampsia." - Harrison's Principles of Internal Medicine 22E

2. Preeclampsia

Definition: New-onset hypertension after 20 weeks + proteinuria OR end-organ damage markers.

Diagnostic Criteria

Hypertension:

Systolic BP ≥ 140 mmHg OR diastolic BP ≥ 90 mmHg
On two occasions at least 4 hours apart
Note: The old criterion of a rise of 30 mmHg systolic or 15 mmHg diastolic above baseline is no longer used - it was removed because there is no increased risk of adverse outcomes in this group alone

Proteinuria (any one of):

≥ 300 mg protein on 24-hour urine (preferred method)
Protein-to-creatinine ratio ≥ 0.3 (mg/dL)
Dipstick 2+ (only when quantitative methods unavailable - unreliable due to false positives/negatives)

Preeclampsia without proteinuria can be diagnosed when hypertension is accompanied by ANY of:

Thrombocytopenia (platelets < 100,000/µL)
Elevated liver enzymes (transaminases > 2× upper limit of normal)
New-onset renal insufficiency (serum creatinine > 1.1 mg/dL, in absence of other renal disease)
Pulmonary edema
New-onset cerebral or visual disturbances

Severity Classification

ACOG recommends abandoning the term "mild" - preeclampsia always carries significant morbidity/mortality risk.

Feature	Without Severe Features	With Severe Features
BP	≥140/90 mmHg	≥160/110 mmHg (on 2 occasions, ≥4 hrs apart)
Neurologic	None	New-onset headache unresponsive to meds, visual disturbances
Hepatic	None	Persistent RUQ/epigastric pain unresponsive to meds; transaminases > 2× normal
Platelets	Normal	< 100,000/µL
Renal	None	Creatinine > 1.1 mg/dL
Pulmonary	None	Pulmonary edema
Fetal	None	IUGR (in some classifications)

3. Eclampsia

Definition: Generalized (tonic-clonic) seizures in a patient with preeclampsia
In the absence of treatment, ~1 in 100 cases of preeclampsia progress to eclampsia

4. HELLP Syndrome

A special subtype of preeclampsia with severe features:

H - Hemolysis
EL - Elevated liver enzymes
LP - Low platelets

HELLP is a major cause of maternal morbidity and mortality. Additional complications include coagulopathy/DIC, CVA, hepatic capsule rupture, and placental abruption.

Risk Factors for Preeclampsia

Risk Factor	Notes
Nulliparity	Largest population-attributable fraction (~32%)
Prior preeclampsia	Strong predictor
Chronic hypertension	25% will develop superimposed preeclampsia
Diabetes mellitus	~20% overall risk; up to 70% with classes F/R
Chronic renal disease	Significant risk factor
Antiphospholipid syndrome	Strong independent risk factor
SLE	Especially with HTN or lupus nephropathy
Obesity	~3× increased risk
Advanced maternal age	Risk independent of parity
African-American race	More related to disease severity than incidence
Multiple gestation	Increased risk
IVF pregnancy	Increased risk
Family history	First-degree relative with preeclampsia

Pathophysiology (Key Points)

Chronic uteroplacental ischemia - failure of physiologic transformation of spiral arteries
Exaggerated maternal inflammatory response
Imbalance of angiogenic factors: excess sFlt-1 (anti-angiogenic) + decreased PlGF (pro-angiogenic)
- sFlt-1/PlGF ratio ≥ 40 is associated with increased risk of developing severe disease within 2 weeks
Loss of cerebral vascular autoregulation explains neurologic manifestations and stroke risk
Glomerular endotheliosis is the pathognomonic renal lesion (swollen endothelial cells nearly occluding capillary lumen)
Posterior Reversible Encephalopathy Syndrome (PRES) - vasogenic parietooccipital edema seen on CT/MRI in severe disease

Management Principles

Definitive Treatment

Delivery is the only cure. Timing depends on severity and gestational age.

Antihypertensive Therapy

Indication: BP ≥ 160/110 mmHg (severe range) - treat urgently to prevent maternal stroke
Modest BP reduction to prevent stroke while maintaining uteroplacental perfusion
Agents used: labetalol, hydralazine (IV), nifedipine (oral)

Seizure Prophylaxis

Magnesium sulfate is the agent of choice for prevention and treatment of eclamptic seizures

Aspirin Prophylaxis

Low-dose aspirin initiated between 12 and 14 weeks of gestation reduces the risk of preeclampsia in high-risk women

Preeclampsia Without Severe Features

Close outpatient or inpatient surveillance
Delivery typically at ≥ 37 weeks

Preeclampsia With Severe Features

Delivery if ≥ 34 weeks
Corticosteroids for fetal lung maturity if 24-34 weeks
Intensive maternal monitoring regardless of gestational age

Key Differentiator: Chronic Hypertension vs Gestational HTN

Feature	Chronic HTN	Gestational HTN	Preeclampsia
Onset	< 20 weeks (or pre-existing)	≥ 20 weeks	≥ 20 weeks
Proteinuria	Usually absent	Absent	Present OR end-organ damage
Postpartum resolution	Persists > 6 weeks	Resolves < 6 weeks	Resolves postpartum

Sources:

Creasy & Resnik's Maternal-Fetal Medicine: Principles and Practice, Ch. 45 (pp. 1055-1140)
Harrison's Principles of Internal Medicine 22E (2025), Ch. on Medical Disorders of Pregnancy
Goldman-Cecil Medicine, Hypertensive Disorders Unique to Pregnancy

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