Pregnancy Flashcards
Blood pressure in normal pregnancy
DBP ↓ by 7 to 10 mm Hg in early pregnancy, by as much as 20 mm Hg in midpregnancy. DBP returns to baseline by third trimester. Nondippers may indicate risk for preeclampsia.
Blood pressure in normal pregnancy
SBP only ↓ slightly due to concurrent increase in cardiac output (↑30% to 40%) and ↓ in peripheral vascular resistance.
HTN in pregnancy
BP > 140/90 mm Hg
NOTE: Per the US National High BP Education Program, patients with BP ≤ 140/90 mm Hg, but with increased SBP of >30 mm Hg or DBP > 15 mm Hg compared with prepregnancy BP, should be managed as high-risk patients.
HTN in pregnancy
Chronic HTN:
Occurs before 20 weeks of gestation
May be primary or secondary HTN
HTN in pregnancy
Gestational HTN:
Occurs de novo after 20 weeks and normalizes within 3 months postpartum
Gestational HTN may or may not present as preeclampsia/eclampsia.
HTN in pregnancy
Preeclampsia is a severe form of gestational HTN with end organ dysfunction.
The diagnosis of preeclampsia may be made if patient has one or more of the following
Urine protein to creatinine ratio > 0.3 g/g Cr.
SCr > 1.1 mg/dL.
Aspartate aminotransferase > 50 IU/L ± severe epigastric/right upper quadrant pain.
The diagnosis of preeclampsia may be made if patient has one or more of the following
Neurologic symptoms
Thrombocytopenia and hemolysis
Fetal growth restriction
Preeclampsia
NOTE: A fall in uric acid clearance is a key feature of preeclampsia. Serum uric acid levels > 5.5 mg/dL is a strong indicator of preeclampsia, and levels > 7.8 mg/dL is associated with increased maternal morbidity
Preeclampsia
What happens in normal pregnancy:
Vascular endothelial growth factor (VEGF) and the transforming growth factor β-1 (TGFβ1) are required to maintain endothelial health in the kidney and placenta. VEGF and TGFβ1 exert their angiogenic and endothelial health-maintaining effects via binding to their respective receptors, VEGF receptor-1 and TGFβ1 receptor.
Vascular homeostasis is maintained by physiologic levels of VEGF and TGFβ1.
Preeclampsia
What happens in preeclampsia/eclampsia:
There is excessive placental secretion of sFLt1 (soluble fms-like tyrosine kinase 1 which also binds to VEGF) and sEng (soluble endoglin, a truncated form of endoglin that is a cell surface receptor for TGFβ1). sFlt1 and sEng compete with endothelial receptors for VEGF and TGFβ1 for circulating VEGF and TGFβ1 respectively and deplete VEGF and TGFβ1 for endothelial cell surface binding and signaling to maintain healthy vasculature.
Preeclampsia
Cont’d:
This results in endothelial cell dysfunction, decreased prostacyclin and NO production, and release of procoagulant protein.
Additionally, other proangiogenic factors such as placental growth factor (PlGF) and adiponectin are decreased.
Other antiangiogenic factors (e.g., endostatin) are increased.
Preeclampsia
Use of logarithmic transformed sFLT-1/PlGF ratios is being evaluated to predict preeclampsia. Higher ratio → higher risk.
Histopathology: Glomerular tufts are described as “bloodless”; capillary lumina are narrowed due to endothelial cell swelling, referred to as “endotheliosis.” In contrast, capillary loops are wide open in normal glomeruli. Foam cells with lipid vacuoles may also be seen in this condition.
Preeclampsia
Preeclampsia and future risk of cardiovascular disease: Meta-analyses suggest an increased cardiac risk, albeit small absolute risk.
Association may be related to risk factors common to both preeclampsia and cardiovascular disease (e.g., obesity, glucose intolerance, high BP, kidney disease)
Diffuse endothelial injury occurring during preeclampsia leads to increased risk.
Eclampsia
Same pathogenesis as preeclampsia
Thought to be a form of posterior reversible encephalopathy syndrome (PRES)