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  • Nathan Riley, MD

Obgyno Wino Podcast Episode 5 - Gestational Hypertension and Preeclampsia (Part 1)

“Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming ‘Wow! What a Ride!’” ― Hunter S. Thompson

2015 Lagrein Riserva from Glassier

PB#202 - Published January 2019

Epidemiology

- preeclampsia complicates 2-8% of pregnancies worldwide

- increasing prevalence over past several decades

- 16% of maternal deaths attributed to hypertensive disorders

- costly: $2.18 bn annually spent on preeclampsia

Diagnosis

- gHTN, preeclampsia → diagnosed >20 wks

- cHTN → diagnosed <20 wks

- preeclampsia: systolic BP ≥140 or diastolic BP ≥90 on two occasions at least 4 hrs apart

AND

Proteinuria (≥300 mg protein on 24 hr urine collection or protein/creatinine ratio ≥0.3 or dipstick reading of 2+)

- Caution: dipstick should only be used if quantitative methods unavailable; high false pos (70% if +1, 7% if +3) and false neg (10%)

- In the absence of proteinuria, diagnosis can be made if thrombocytopenia <100, renal insufficiency (Cr 1.1 mg/dL or doubling of baseline Cr) in absence of other renal disease, impaired liver fxn (elevated liver enzymes to twice normal conc), pulmonary edema, new-onset headache refractory to medication, visual disturbances

Three important points about diagnosis of preeclampsia

- “although often accompanied by new-onset proteinuria, hypertension and other signs or symptoms of preeclampsia may present in some women in the absence of proteinuria”

- “Reliance on maternal symptoms may be occasionally problematic in clinical practice”

- “An astute and circumspect diagnostic approach is required when other corroborating signs and symptoms indicative of severe preeclampsia are missing. Of note, in the setting of a clinical presentation similar to preeclampsia, but at gestational ages earlier than 20 weeks, alternative diagnoses should be considered, including but not limited to thrombotic thrombocytopenic purpura, hemolytic-uremic syndrome, molar pregnancy, renal disease or autoimmune disease.”


gHTN fun facts

- up to 50% of gHTN will eventually develop proteinuria or other end organ dysfunction

- in hypertensive disease: women w/ proteinuria (versus w/out) more likely to progress to severe hypertension and higher likelihood of preterm birth and perinatal mortality; BUT women without proteinuria had higher frequency of thrombocytopenia or liver dysfunction


HELLP

- diagnosis: LDH ≥ 600, AST/ALT ≥ 2x baseline, Plts <100

- normally diagnosed in the 3rd trimester, but 30% of cases first expressed postpartum

- 15% of cases not accompanied by HTN or proteinuria

- main presenting symptoms: RUQ pain and generalized malaise in up to 90% of cases; N/V in 50% of cases


Eclampsia

- any type of seizure activity in absence of other etiology

- consider alternative diagnoses in cases in which seizure activity occurs 48-72 hrs postpartum or when seizures occur during administration of mag sulfate

- incidence of rare: 1.9% of women w/ preeclampsia; 3.2% w/ severe preeclampsia

- the long-held notion that preeclampsia has the natural progression to severe to eclampsia is unfounded and inaccurate

- seizures are dangerous: may lead to severe maternal hypoxia, trauma, and aspiration (PNA)

- residual neurological damage is rare

- 80% of the time is preceded by warning signs: severe occipital or frontal HA, blurred vision, photophobia, AMS

- up to 40% of women with eclampsia will have none of the classic signs of preeclampsia (HTN or proteinuria) before the seizure episode


Conditions associated w/ eclampsia

- PRES (posterior reversible encephalopathy syndrome) - constellation of neuro signs and symptoms such as vision loss, seizure, deficit, headache, and altered sensorium or confusion

- edema and hyperintensities in posterior aspects of brain on MRI

- Reversible cerebral vasoconstriction syndrome - reversible multifocal narrowing of the arteries of the brain resulting in thunderclap headache and occasionally neuro deficits, stroke, or seizure

- increased risk in setting of preeclampsia w/ severe features

- treatment of these conditions include HTN management, anti-leptics, and long-term neurology follow-up


Pathophysiology

- nobody knows!

- hypotheses: uteroplacental ischemia, immune maladaptation, VLDL toxicity, genetic imprinting, trophoblastic apoptosis or necrosis, exaggerated inflammatory response to deported trophoblasts, or imbalances of angiogenic factors

- or some combo of these


Vascular changes

- hemoconcentration, vasospasm, capillary leak w/ resulting decrease in oncotic pressure

- for these reasons, vigorous fluid therapy is likely to be ineffective (and potentially dangerous)


Hematologic changes

- thrombocytopenia: activation, aggregation, and consumption of platelets

- hemolysis (note: hematocrit may not appear decrease despite hemolysis because of baseline hemoconcentration)


Hepatic changes

- periportal necrosis: AST, ALT both elevated but AST >ALT

- increased bili later secondary to hemolysis

- decrease clotting factors in severe disease


Renal changes

- glomerular endotheliosis

- proteinuria due to increased tubular permeability

- urinary calcium decreases due to increased tubular reabsorption of calcium

- these damages all secondary to vasospasm resulting in contraction of the intravascular space and decreased renal perfusion → oliguria

- serum uric acid increases in pregnancy but to a greater extent in preeclampsia as there’s increased reabsorption and decreased excretion of uric acid in the proximal renal tubules


Fetal consequences

- IUGR, oligomenorrhea, abruption, and tracing issues


Screening methods

- biomarkers like placental growth factor and angiogenic factors AND uterine artery Doppler have been proposed but poor PPV, especially in low risk patients


Prevention

- Vitamin C, E, & D, fish oil, garlic, folic acid, and bed rest → studies haven’t panned out

- Aspirin: decreased risk of development of severe preeclampsia and fetal growth restriction especially if started at <16 wga

- aspirin: start 12-28 wga and continue until delivery if she meets criteria

- metformin is investigational; currently not recommended


Delivery versus expectant management

- must balance risks to mom versus risk to fetus

- risks to waiting: development of severe BPs, eclampsia, HELLP, abruption, fetal growth restriction or IUFD; however, these risks are small and counterbalanced by the increased risks to the fetus (increased rates of admission to the NICU, respiratory complications, neonatal death)

- gHTN or preeclampsia without severe features: deliver by 37.0 wga (in absence of other obstetric indications)

- HYPITAT trial concluded that delivering at 36.0 wga may provide additional benefit to mom without exposing fetus to additional risk

- monitoring: serial ultrasound, antepartum testing, close monitoring of BPs, and weekly lab tests (frequency personalizable to patient)

- serial protein monitoring likely to be of benefit, as it’s not predictive of perinatal outcome

- in patients with gHTN, progression to preeclampsia with severe features usually takes 1-3 wks

- in patients with preeclampsia, progression to preeclampsia with severe features can take only days so close monitoring is critical


Preeclampsia with severe features

- pulmonary edema, MI, stroke, ARDS, coagulopathy, renal failure, and retinal injury all more likely as underlying disease process progresses so delivery at 34.0 wga is recommended

- don’t delay delivery for the administration of steroids in the late preterm period, but delays until 34.0 wga when possible has benefits to fetus (even Cochrane agrees)

- Previously, fetal growth restriction was considered an indication for delivery, but in the setting of otherwise normal fetal parameters (AFI, Dopplers, antenatal fetal testing) expectant management reasonable if mom is healthy (see Box 4)



Inpatient versus outpatient management

- hospitalization appropriate if severe features or for women in whom adherence to frequent monitoring is a concern

- if outpatient: proper fitting BP cuff, strict parameters

- take BP w/ arm at level of heart

- no caffeine or cigarettes prior to checking

- weekly fluid assessment

- fetal growth no more frequently than every 2 weeks

- NST 1-2x weekly

- weekly labs

- weekly BP check in clinic

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