Definition of "Pre-eclampsia"
Pre-eclampsia (from Greek "eclampsia" meaning "lightning", previously called pre-eclamptic toxemia, PET) is a disorder of pregnancy. The disorder usually occurs in trimester 3 of pregnancy, and gets worse over time. Rarely, pre-eclampsia may begin postpartum (i.e. after delivery).
Patient information
What is pre-eclampsia, and how does it differ from eclampsia?It's 2 things. High blood pressure. And protein in urine. How does it differ from eclampsia? Eclampsia is one step up. It's where you also get seizure.
What's the difference between high blood pressure+end organ damage, and gestational hypretension then? Isn't that high blood pressure?
Yes, but gestational hypertension doesn't have protein in urine.
Generally, none of the signs of preeclampsia are specific, even convulsions are more likely to have causes other than eclampsia. Thus, the final proof is their regression after delivery:
- Swelling, especially pitting edema, especially in the face, hands and ankles → edema → water follows protein
- Weight gain → edema
- SOB → pulmonary edema
- If severe, warning signs for eclampsia will show:
- Severe headache, that doesn't dissapear with normal painkillers
- Visual disturbances (blurred vision, flashes of light)
- Right hypochondrial, or epigastric pain
- Vomiting
- End organ damage → circulatory effect
- Dizziness
- Epigastric pain → liver damage
- Impaired liver function
- Fetal growth restriction
- Kidney dysfunction
- Other end organ damage
- Eventually, seizure (known as eclampsia)
Patient information
How do I know if I have high blood pressure+end organ damage? What will I experience?Remember that pre-eclampsia without protein in urine is not pre-eclampsia. It's gestational hypertension. So we can expect the results of finding protein in urine. Swelling. Weight gain. Water in the lungs.
I'm concerned +seizure is about to happen. How do I know?
Severe headache. Visual disturbances. Right hypochondrial or epigastric pain. Vomiting.
BOTH:
- Hypertension, where systolic>=140, OR diastolic>=90, at 2 separate times, more than 4 hours apart, in a woman >20 weeks of pregnancy. Where a Pt has essential HTN <20 weeks gestation, it requires an increase in systolic blood pressure >=30mmHg, or an increase of diastolic BP >=15mmHg
- Proteinuria, of >=0.3g in a 24 hour urine sample, or a spot urinary protein to creatinine ratio >=0.3, or a urine dipstick reading of 1+ → kidney damage. Note however, that 10% of Pt's w/ Sx of preeclampsia
- Alternatively, in some jurisdictions, evidence of end organ damage, including:
- Oligouria, elevated creatinine levels → kidney dysfunction
- Impaired LFT's → impaired liver function
- Platelets<100,000/microliter → thrombocytopenia
- Pulmonary edema
- Ankle edema that is pitting
- Cerebral or visual disturbances
Pre-eclampsia is progressive, and the Dx criteria are indicative of severe preeclampsia, including:
- Systolic >=160, or diastolic >=110
- Proteinuria >5g in a 24 hour urine sample
Even if the Dx criteria is not met (i.e. >=140/90), if baseline BP rises 30mmHg systolic, or 15mmHg diastolic, is still important to note.
Patient information
I read on some web sites you don't need protein in urine though, to have high blood pressure+end organ damage?That's correct. The definition depends on where you are in the world. Instead of protein in the urine, some definitions replace that with just any "end organ damage".
- Hx:
- Sx of eclampsia, including hyporeflexia, hypotonia, clonus
- BP → HTN
- HELLP syndrome, is a life-threatening obstetric complication usually considered to be a variant or complication of pre-eclampsia. Both conditions usually occur during the later stages of pregnancy, or sometimes after childbirth. It includes 3 main features:
- Hemolysis → damaged small blood vessels
- Elevated liver enzymes (AST, ALT, LDH) → liver damage
- Low platelets (thrombocytopenia, <100,000/microliter) → blood clot
- Coags → blood clots
- Urine dipstick → proteinuria → kidney damage
- UEC, showing: → kidney damage
- Elevated creatinine
- Spot urine protein/creatinine ratio → proteinuria
- Elevated uric acid → kidney damage
- Growth scan → IUGR
- Pelvic exam → if delivery is indicated
Patient information
What tests will doctors do for high blood pressure+end organ damage?First, to diagnose pre-eclampsia, they'll do a blood pressure test to test for that being high, and analyze your urine to test for protein in there. They're also going to want to test for end organ damage. So test for things that can leak out of a damaged liver (that's your "liver enzymes"
, things that can leak out of a damaged kidney (that's your "proteinuria", things that a damaged kidney cannot clear out (that's your "uric acid" and "creatinine", and things that are used up to clot blood (that's your "platelets".
HELLP. Even the name doesn't sound that great 
. How does it differ from pre-eclampsia? I thought the idea behind pre-eclampsia was that it affected multiple organs, including the liver and blood?
HELLP is a where the liver and blood are affected. And yes, it can result from pre-eclampsia. It is sometimes called a variant because it can occur without high blood pressure and protein in urine. That means it can occur without pre-eclampsia or even gestational hypertension !
Source: NSW Health
- Abnormal development of blood vessels in the placenta (known as placentation) early in the pregnancy, causing hypoperfusion (decreased oxygen supply) to the fetus, causing the placenta to vasoconstrict the mother's circulatory system → HTN
- Prolonged HTN damages the mother's blood vessel's endothelial cells, causing it to become more leaky → edema
- Prolonged HTN damages the mother's blood vessel's endothelial cells, causing it to release inflammatory factors, promoting clotting → clots
- Kidney damage causes protein to leak out → proteinuria
Patient information
Why does high blood pressure+end organ damage occur?The way in which blood vessels are formed supplying the placenta are abnormal. It causes problems supplying oxygen to the fetus. The placenta evidently isn't going to be very happy. It's going to try to increase the pressure - the power, of mom's blood by making the mother's blood vessels narrower. But this causes high blood pressure. High blood pressure in turn damages her blood vessels, making it leaky, causing protein to leak out. As with anything damaged, the blood vessels are going to try and "mend" itself, and therefore forms clots.
That makes sense. When you get things like high blood pressure and clots, it's obviously going to affect just about... every end organ!!
Yes, that's why everything from the brain, eyes, tummy, going to the toilet... is all affected!
Why would you get edema, though? That's puffiness, right?
It's where water accumulates in the skin. The reason why is when protein leaks out of blood vessels, water likes to follow it. Water likes to play follow-the-leader with protein !
- HTN → suspicion for preeclampsia should be maintained, even in the absence of proteinuria
- Obesity
- Previous HTN or pre-eclampsia
- Older age
- Kidney disease
- Diabetes mellitus
- A woman's first pregnancy
- If a woman is carrying twins
Patient information
What makes it more likely you'll have high blood pressure+end organ damage?High blood pressure, because you can easily push into end organ problems. Being overweight. Previously having high blood pressure, or with that, also end organ damage. Old age. Problems with your kidney. High blood sugar. If it's mom's first bub. Or if she's carrying twins.
- Prevention:
- Aspirin, in those at high risk
- Calcium supplementation, in areas with low intake
- Tx of prior hypertension, with medication
- IOL if necessary → delivery of the fetus [and thus the placenta]. When delivery becomes recommended depends on gestational age (>37 weeks), and how severe the pre-eclampsia is (if <37 weeks, and severe) → Placenta is source of factors altering mother's circulatory system, so removing it resolves
- Magnesium sulfate (i.e. an AED), can prevent eclampsia → given in the high risk zone of just before, during, and 24 hours after delivery
- Antihypertensives (e.g. hydralazine, labetalol), can improve the mother's condition before delivery
- NOT found to be useful for either Tx or prevention, include bestrest and salt intake
Patient information
What can my doctor do about pre-eclampsia?They can end up having a seizure, stroke, or cause damage to other end organs, so we want to deliver. That's really all we can do, because we know that it's the placenta that's causing problems. And until that pops up, we're going to have problems. Also, because of the risk of eclampsia, we will give a drug to prevent seizures - it's called magnesium sulfate.
Anything else?
We can't just leave the mother's blood pressure high, so we may also give a drug to bring that down. Something like hydralazine or labetalol is used commonly in pregnancy.
- Mother:
- Placental abruption
- Liver rupture
- DIC (disseminated intravascular coagulation, i.e. clots throughout all vessels in the body)
- Stroke
- HELLP syndrome, which is life threatening complication, considered to be a variant/complication of preeclampsia. It consists of hemolysis, elevated liver enzymes, low platelet count
- If left untreated, it can result in seizures → aka eclampsia, which is more common just before, during, and 24 hours after delivery
- Baby:
Patient information
What are the main concerns with pre-eclampsia?Given that pre-eclampsia occurs because of abnormal blood vessels development in the placenta, we're worried that the placenta may separate from the uterus super early. That's called "placental abruption". The other things we worry about is any and everything that results from end organ failure. We worry particularly about damage to the liver, blood clotting, and seizure.
What happens with the baby?
If there are issues with the placenta, it's unsurprising we're worried about the baby. They may not receive enough nutrients, reducing growth. Also, if placental abruption happens, the baby may need to be delivered early 
.
- Increases risk of poor outcomes for both the mother and baby
- Pre-eclampsia usually occurs after 32 weeks, but if occurs earlier is associated with worse outcomes
- Increased risk of heart disease later in life
- Severe preeclampsia is not a significant risk factor for intrauterine fetal death
- Risk of recurrent pre-eclampsia in next pregnancy
- Most cases are Dx before delivery
- It is routinely screened for during prenatal care
- Pre-eclampsia affects 5% of pregnancies worldwide
- Hypertensive disorders are one of the most common causes of death due to pregnancy, resulting in 29k deaths per annum
- HELLP affects 0.4% of all pregnancies
- 8% of Pt's with preeclampsia will develop HELLP syndrome
- 15% of Pt's with severe preeclampsia will develop HELLP
- Eclampsia (+seizure)
- Gestational HTN (-proteinuria)
- Maternal HTN (category)
- Maternal obesity
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