Pregnancy Part 2 – HTN – SOGC 2014

Ominous symptoms: RUQ pain, H/A, Visual disturbances


Dx

1) Pre-existing (chronic) hypertension: HTN (>140/90) that develops either pre-pregnancy or at < 20+0 weeks’ gestation

  • Essential HTN ↑ risk of gestational HTN, placenta abruption, IUGR, IUFD
  • Performed during early pregnancy: (if not previously documented): serum creatinine, fasting blood glucose, serum potassium, and U/A, and EKG.
  • With comorbid condition(s): pre-gestational type I or II diabetes mellitus or kidney disease (↑ CV risk)
  • With evidence of preeclampsia = 2) superimposed preeclampsia
    • is defined by the development of one or more of the following at ≥ 20 weeks:
      ● resistant hypertension, or
      ● new or worsening proteinuria, or
      ● one or more adverse conditions,* or
      ● one or more severe complications.*

3) Gestational hypertension

  • hypertension that develops for the first time at ≥ 20+0 weeks’ gestation.

4) Preeclampsia

  • Gestational hypertension with one or more of the following: May arise de novo
    ● new proteinuria, or
    ● one or more adverse conditions,* or
    ● one or more severe complications.*

5) Severe preeclampsia: preeclampsia with >1 complications.


Transient hypertensive effect: Elevated BP may be due to environmental stimuli, e.g., the pain of labour. HTN not confirmed at subsequent measurement
White-coat hypertensive effect: This is defined as BP >140/90 in the office, but consistently normal outside of the office (< 135/85 mmHg)
Masked hypertensive effect: This is defined as BP that is consistently <140/90 in the office, but≥ 135/85 outside of the office


Adverse conditions (↑ severe c/i) and severe complications (warrant delivery) of preeclampsia

CNS:
  • Headache/visual symptoms
  • Eclampsia, PRES ( posterior reversible leukoencephalopathy syndrome), Cortical blindness or retinal detachment, Glasgow coma scale < 13, hemorhagic Stroke (50% of deaths), TIA, or RIND (reversible ischemic neurological deficit (< 48 hr))
CV:
  • Chest pain/dyspnea, Oxygen saturation < 97%
  • Uncontrolled severe hypertension (over a period of 12 h despite use of three antihypertensive agents), Oxygen saturation < 90%, need for ≥ 50% oxygen for > 1 h, intubation (other than for Caesarean section), pulmonary edema, Positive inotropic support, Myocardial ischemia or infarction
Haematological:
  • Elevated WBC / INR / aPTT / ; low platelet
  • Platelet count < 50 × 109, Transfusion of any blood product
Renal:
  • Elevated serum creatinine / uric acid
  • AKI (creatinine > 150 µM with no prior renal disease), New indication for dialysis
Hepatic
  • N/V, RUQ or epigastric pain, Elevated serum AST, ALT, LDH, or bilirubin, Low plasma albumin
  • Hepatic dysfunction (INR > 2 in absence of DIC or warfarin), DIC, Hepatic haematoma or rupture, HELLP syndrome (Tx with FFP infusion / plasma exchange)
Feto-placental:
  • Abnormal FHR, IUGR, Oligohydramnios, Absent or reversed end-diastolic flow by Doppler velocimetry
  • Abruption with evidence of maternal or fetal compromise, Reverse ductus venous A wave, Stillbirth (IUFD)

 Risk factors Gestation HTN
  1. Maternal:
    • primigravida, 1st conception with a new partner, PMHx/FHx of gestational HTN, extremes of maternal age <18 or >35
    • DM, chronic HTN, renal insufficiency, antiphospholipid syndrom
  2. Fetal:
    • IUGR or oligohydramnios, GTN, multiple gestation, fetal hydrops
    • Previous stillbirth or IUFD
Risk factors Preeclampsia
  1. Maternal:
    • Nulliparity, PMHx / FHx of preeclampsia, age >40 or <18, high BMI
    • chronic HTN/renal dz, DM (pregestational or gestational), antiphospholipid syndrome / inherited thrombophilia, vascular / connective tissue dz
  2. Fetal:
    • Hydrops fetalis, unexplained fetal growth restriction, placenta abruption,

Hx:
  • Hepatic: Epigastric or RUQ pain, severe N/V,
  • CNS: visual disturbances – blurring / scotoma, presence / severity of H/A, tremulousness, irritability, somnolence
  • Hematologic: bleeding
  • Renal: u/o & color
  • Non-dependent edema – hands & face
  • Fetal movement
O/E:
  • Body weight & non-dependent edema
  • CNA: hyperreflexia, visual field
  • Hematology: petechiae
  • Fetal heart tracing – NST
Ix:
  • U/S for growth & biophysical profile, umbilical artery doppler flow studies (part of antenatal fetal surveillance)
  • Hb, plt, blood film, PTT, INR, fibrinogen, d-dimer
  • ALT, AST, LDH, bilirubin, uric acid, creatinine
  • U/A – (proteinuria) 24 hr urine for total protein and creatine clearance
  • Definitive testing for proteinuria (by urinary protein:creatinine ratio or 24-hour urine collection) if suspicious of  preeclampsia, including:
    • ≥ 1+ dipstick proteinuria
    • in women with hypertension and rising BP
    • in women with normal BP, but S/Sx suggestive of preeclampsia.

Tx HTN:

Low Risk Pt (based on risk factors):

  • Dietary salt restriction during pregnancy (I-D), calorie restriction during pregnancy for overweight women (I-D), low-dose acetylsalicylic acid (I-E), vitamins C and E (based on current evidence) (I-E), and thiazide diuretics (I-E) are not recommended.
  • For preeclampsia prevention among low-risk women with low dietary calcium intake (<600 mg/d), oral calcium supplementation of at least 1g/d is recommended
  • smoking cessation for prevention of low birthweight and preterm birth.
  • periconceptual use of a folate-containing multivitamin for prevention of neural tube defects(I-A), and
  • exercise for maintenance of fitness(I-A), abstention from alcohol for prevention of fetal alcohol effects (II-2E),

Increased Risk pt:

  • For preeclampsia prevention, low-dose Aspirin® (75-100 mg/d) is recommended until delivery (starts before GA 16wk)
  • Initial antihypertensive therapy for severe hypertension >160/110 or non-severe HTN (140-159/90-109):
    • Labetalol 100-300mg po bid/tid
    • Nifedipine 30-50mg po daily
    • a-methyldopa 250-500mg po tid/qid (no ACEi, propanolol, diuretics – teratogens)
  • If no deterioration, can be followed till 37wk then decide to induce shortly after
  • Consider corticosteroids for all women with precelampsia before 34 wk GA
  • MgSO4 – 1st line for eclampsia & eclampsia prophylaxis in severe preeclampsia

Tx Preeclampsia:

  • If severe, stabilize and deliver, increase maternal monitoring, hourly in/out, urine dip Q12h, hourly neurological vitals, increase fetal monitoring (FHR)
  • Lower BP – decrease stroke risk
    • Hydralazine 5-10mg IV bolus over 5min Q15-30min prn
    • Labetalol 20-50mg IV q10min
  • Sz prevention
    • MgSO4, PP Rx – risk of seizure highest in first 24hr pp – continue MgSO4 for 12-24 hr after delivery
  • Vitals Q1h, consider HELLP  (Hemolysis, Elevated Liver enz, Low Platelets) in toxic pt
  • Most return to a normal BP in 2 wk
MgSO4 toxicity
  • Flushing, hyporeflexia, somnolence, respiratory and cardiac depression, weakness
  • increase risk with CCB use or renal dz
  • Tx: stop MgSO4, Calcium gluconate 10% in 10ml IV

References:
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Posted in 76 Pregnancy, 99 Priority Topics, FM 99 priority topics, OB

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