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preeclampsia

pre-eclampsia and eclampsia

see also Obstetrics

hypertension in pregnancy

risk factors for pregnancy-induced HT:

  • nulliparity (3x) (but HELLP syndrome has a pre-dilection for multigravids)
  • age > 40yrs (3x)
  • African American race (1.5x)
  • FH pregnancy-induced HT (5x)
  • chronic HT (10x)
  • chronic renal disease (20x)
  • antiphospholipid syndrome (10x)
  • diabetes (2x)
  • twin gestation (4x)
  • angiotensinogen gene T235 (HZ 20x, heterozygous 4x)

Classification of hypertension during pregnancy:

chronic HT:

  • HT (BP >= 140/90mmHg) present & observed before pregnancy or is Dx < 20th wk or 1st Dx during pregnancy & persists > 42nd day post-partum

pre-eclampsia/eclampsia:

  • increased BP in pregnancy assoc. with proteinuria &/or generalised oedema
  • NB. it is rare <20wks unless either:
    • multiple pregnancy
    • hydatidiform mole
    • foetal triploidy
    • antiphospholipid syndrome
    • severe renal disease

pre-eclampsia superimosed on chronic HT:

  • as for chronic HT, with BP increase of > 30mmHg systolic, 15mmHg diastolic or 20mmHg MAP with roteinuria &/or generalised oedema

transient HT:

  • elevated BP developing during pregnancy or in 1st 24h post-partum without signs of pre-eclampsia or chronic HT

pre-eclampsia

diagnostic criteria for pre-eclampsia:

  • elevated BP:
    • sustained systolic BP >= 140mmHg or diastolic BP >= 90mmHg measured on 2 occasions >=6h apart
  • AND EITHER:
    • significant proteinuria:
      • > 300mg/24h or >= 1g/ml measured on 2 separate occasions 6h apart (approx. 1+ on dipstick)
    • oedema:
      • generalised oedema or weight gain of at least 5lb in 1wk

diagnostic criteria for severe pre-eclampsia:

  • in addition to above criteria, any 1 of:
    • BP > 160-180mmHg systolic or > 110mmHg diastolic
    • proteinuria > 5g/24h
    • oliguria < 500ml/24h
    • cerebral or visual disturbances (eg. scotomata)
    • pulmonary oedema
    • IUGR or oligohydramnios
    • elevated serum creatinine
    • grand mal seizures (ie. eclampsia)
      • if occur > 20th wk gestation to 7 days post-partum (but reported up to 26th day puerperium)
      • assume all seizures in this period to be eclamptic until proven otherwise
      • up to 30% will not have HT, proteinuria or oedema
      • risk of eclampsia in pre-eclampsia is ~ 1 in 300
      • may be preceded by headache, blurred vision or decreased visual acuity
      • may be focal or generalised
      • usually are a single seizure lasting < 1min responding to IV MgSO4
    • any one feature of HELLP syndrome:
      • Haemolysis as manifest by microscopic features consistent with microangiopathic haemolytic anaemia on blood film (eg. presence of schistocytes)
        • NB. due to depleted intravascular volume, haematocrit may actually rise!!
      • Elevated Liver enzymes (hepatic transaminases) in absence of other causes
      • Low Platelets <100,000/mm3
      • epigastric or RUQ pain

Differential diagnosis of HELPP syndrome:

  • autoimmune thrombocytopenic purpura
  • chronic renal disease
  • pyelonephritis
  • cholecystitis
  • gastroenteritis
  • hepatitis
  • pancreatitis
  • thrombotic thrombocytopenic purpura
  • HUS
  • acute fatty liver of pregnancy

Assessment & management of pre-eclampsia:

general supportive care:

  • monitoring of maternal vital signs, initally every 15-30min
  • place in left lateral recumbent position so that gravid uterus does not produce aortocaval compression
  • ABC's:
    • oxygen if severe PET to maintain SaO2 > 90% (or > 95% if undelivered)
    • if resp. depression intubate & ventilate as indicated
  • IV line & bloods for:
    • FBE, LFT, U&E, Group & hold with Ab screen
  • IV fluid volume loading with 500ml:
    • prior to giving anti-hypertensives
    • prior to epidural Rx
    • if immediate delivery
    • as part of Mx of oliguria
    • NB. routine volume expansion in Rx of severe PET is NOT recommended except under certain circumstances 
      • pros:
        • volume depletion has been demonstrated in these pts
        • correction of this may improve maternal and uteroplacental circulation
        • volume expansion reduces the risk of hypotension during vasodilator Rx
      • cons:
        • risk of pulmonary oedema
        • effects are transient
        • may cause resistance to anti-hypertensives
        • not all pts are volume deplete
  • strict fluid balance record
  • consider CVC line if severe PET
  • clean catch urine for semi-quantitative protein concentration
  • if delivery not imminent, commence 24hr urine collection for protein & creatinine clearance & fluid balance charting

early obstetric consultation

assess fetus:

  • if fetus is pre-viable (< 24wks) then intermittent fetal heart rate recording
  • if fetus viable (> 24wks) then evaluate fetal well being & biophysical assessment:
    • ultrasound:
      • fetal number & biophysical profile (tone, movement, breathing pattens, anatomy, size, gestation, amniotic fluid volume), placental location
    • CTG monitoring:
      • continuous if severe PET ASAP
      • +/- oxytocin challenge test

treat hypertension:

mild HT:

  • strict bed rest, quiet room

severe HT (>160 systolic or > 110 diastolic):

  • expand maternal intravascular volume with crystalloid 500-1000ml, then,
  • urgent IV hydralazine
    • 10mg slow IV boluses every 20min prn (max. 60mg)
    • NB. need to wait 10-20min for response
  • if BP still high, add IV labetalol (not available in Australia as IV) 20mg stat then either:
    • 10-20mg slow IV doubling every 10-2min prn to max. 300mg, or,
    • infusion at 1-2mg/min titrated to response (decrease to 0.5mg/min or less once BP controlled) 
  • NB. nitroprusside can be used for short periods but risks cyanide toxicity
  • NB. GTN can be used but requires arterial line to monitor & risks metHb
  • NB. ACEI's are C/I as may cause fetal anuria or renal failure

seizure prophylaxis:

IV magnesium sulphate therapy:

  • indications:
    • eclampsia
    • severe PET with either:
      • decision to deliver baby has been made
      • hyper-reflexia with clonus
      • fundal vasospasm
      • visual disturbances
      • persistent headache
    • ??? all pts with severe PET:
      • see MJA 16 Feb 1998 Vol.(4) Mg in Rx of pre-eclampsia & eclampsia
  • IV 50% magnesium sulphate:
    • from MAGPIE and Collaborative Eclampsia trials:
      • 4g load over 5min, then 1g/hr (if further seizure, give a further 2-4g IV over 5min)
      • monitor for toxicity looking for:
        • check BP, HR RR every 5min during load dose
        • loss of deep tendon reflexes (usually at 8-10mEq/L)
        • slurred speech, muscle weakness, hypotension
        • decreased resp. rate & cardiac depression (resp. then cardiac arrest usually at 13mEq/L)
        • decreased urine output
      • monitor serum levels (normal range in pregnancy 1.5-2mEq/L, Rx range 4-7mEq/L
        • if mild Mg toxicity, with-hold infusion
        • if severe Mg toxicity:
          • resp. support, O2, monitor ECG, SaO2
          • IV 10% calcium gluconate 10ml at rate`< 5ml/minute
          • consider giving loop diuretic to enhance excretion

Rx of eclamptic seizure:

  • IV MgSO4 as above as well as Mx as for severe PET & deliver baby ASAP
  • if ongoing seizures despite Rx levels of Mg, consider:
    • ensure U&E's, glucose checked
    • CT scan to exclude intracranial pathology
    • seizure Rx as for non-pregnant adults:
      • diazepam (risks fetal resp. depression)
      • phenytoin 20mg/kg IV over 60min

deliver baby:

  • severe PET, deliver ASAP at any gestation
  • mild PET:
    • ASAP if > 37wks (although some may wait if Cx unripe)
    • consider delivery if < 23-34wks (ie. pre-viable)
    • if 34-37wks consider amniocentesis to determine lung maturity

disposition:

if mild PET:

  • if < 37wks, then:
    • admit for bed rest, or,
    • after D/W obstetric team, discharge home for bed rest with close F/U within 7 days & advised to contact hospital if:
      • headaches, scintillating scotomata or other visual changes, abdominal pain, bleeding PV, or decreased fetal movements
  • if > 37wks, then admit for inducement of labor or C.S.

if severe PET then:

  • admit for inducement of labor or C.S. & close monitoring & support as above, or,
  • if stable & delivery not imminent, and pre-term fetus, consider transfer to tertiary obstetric centre with neonatal intensive care prior to delivery
  • NB. C/I to immediate transport (ie. transfer neonate after delivery):
    • severe uncontrolled HT
    • uncontrolled eclamptic seizures
    • severe haemorrhage
    • impending delivery
    • significant fetal compromise

References:

  • Magpie Trial. Lancet 2002; 359:1877-90;
  • Consensus Statement of the Aust. Soc. for the Study of HT in Pregnancy. Aust.NZ J. Obstet.Gynecol. 2000; 40:139-55;
  • Pearlman, Tintinalli: Emergency Care of the Woman 1st Ed. 1998
  • MJA 16 Feb 1998 Vol.(4) Mg in Rx of pre-eclampsia & eclampsia
preeclampsia.txt · Last modified: 2012/10/02 07:59 by gary1