Preeclampsia is a potentially life-threatening disorder that only affects women during pregnancy, starting after 20 weeks gestation or in the first six weeks after birth. If it’s not diagnosed in time, it may lead to serious morbidity and mortality of both mom and baby. The incidence of preeclampsia in the USA is 3 to 4% of pregnancies. Ninety percent of these occur after 34 weeks gestation
There are four major classes of hypertension (high blood pressure) in pregnancy:
1. Chronic hypertension – this is when the patient is known to be hypertensive prior to falling pregnant, or if she develops hypertension in the first 20 weeks of pregnancy.
2. Gestational hypertension – when a pregnant patient is diagnosed with high blood pressure for the first time after 20 weeks gestation and in the absence of other symptoms or signs of preeclampsia.
3. Preeclampsia – this occurs when a pregnant patient develops hypertension for the first time after 20 weeks gestation AND has evidence of end-organ disease. The latter is when certain vital organs are affected by the high blood pressure, such as the kidneys, the liver, the brain or the fetus. It can also present for the first time after the delivery
4. Preeclampsia superimposed upon chronic hypertension – when a pregnant patient is known to be hypertensive prior to 20 weeks gestation, but then develops preeclampsia on top of the hypertension after 20 weeks. To diagnose preeclampsia, the patient needs to be at least 20 weeks pregnant with persistent hypertension (two blood pressure readings of ≥ 140/90 mmHg, four hours apart) and symptoms or signs of end-organ disease, such as kidney disease, liver abnormalities, fetal growth restriction, etc.
The following conditions are associated with an increased risk of developing preeclampsia:
- First pregnancy
- The very young patient (younger than 20 years of age) and the older patient (older than 35 years)
- Patients with gestational diabetes
- A family history of preeclampsia, like a sister or mother
- Chromosomal abnormalities of the fetus
- Multiple gestation (more than one baby)
We believe that preeclampsia develops due to abnormalities of the placental blood vessels, resulting in failure of the placenta to support the growing fetus. These abnormalities develop early on, but only becomes a problem after 20 weeks gestation because then the fetus requires more nutrients, hence the manifestation of preeclampsia. Thanks to modern technology, we can now use ultrasound to assess a patient’s risk of developing preeclampsia. An ultrasound is done at 12-13 weeks gestation and if there’s a high risk for preeclampsia, the patient is started on 150mg Aspirin daily. Aspirin has been shown to significantly decrease the chance of getting preeclampsia in pregnancy. Unfortunately, not all patients have these ultrasound assessments and therefore we still see preeclampsia regularly.
Early diagnosis and correct management of these patients can essentially mean saving a baby and mother’s life. Every pregnant patient with hypertension, regardless if it’s chronic or gestational hypertension, needs to be educated about the warning signs of preeclampsia. These include severe headaches, visual disturbances (like double vision, light flashes or squiggly lines), shortness of breath (especially in the absence of physical exertion) and severe pain in the centre of the abdomen or under the ribs on the right side. An ultrasound can also detect fetal problems. The growth of the baby could be slowing down, the amniotic fluid could be decreasing, or the placental function could be deteriorating. Placental function is assessed by measuring the blood flow through the umbilical cord (called the Doppler test). If there is resistance to the blood flow, it means that the nutrients are struggling to get to the baby. Preeclampsia usually warrants admission to hospital because the blood pressure needs to be properly controlled. Important blood tests also need to be done to exclude or determine the extent of endorgan disease, such as the kidney function, liver enzymes, the haemoglobin and platelet count. The baby also needs to be monitored a few times a day and this is done by a special monitor called a cardio-tocogram (CTG). The CTG machine is connected to the mother’s abdomen by means of two probes. The one probe measures uterine contractions and the other probe monitors the baby’s heart rate. It then prints a tracing that gives important information about the fetal wellbeing. This way we can pick up fetal distress and abnormal uterine activity. Fortunately, there are several medications that can be safely used to control blood pressure. If a patient has mild to moderate preeclampsia and is otherwise stable, the aim is to get that patient to term (≥ 37 weeks). If possible, an induction can be safely planned. The big concern is the patient with severe preeclampsia. This patient has very high blood pressures (160/110mmHg and above), is not responding to medication or has signs of imminent eclampsia.
Eclampsia is when a patient with preeclampsia starts convulsing. So, it is important to constantly screen the patient with preeclampsia for warning signs of eclampsia. Other signs of severe disease are:
• Abnormal kidney function
• Low platelet count (<100)
• Liver abnormalities • Pulmonary oedema (fluid on the lungs)
• Seizures • Severe abdominal pain which could be a sign of an abruption. An abruption placenta is when the placenta detaches from the uterine wall – a life-threatening condition for the baby
Management of preeclampsia The management of preeclampsia depends on the severity of the disease and the gestation of the pregnancy. We know that the best way to treat preeclampsia is by delivering the baby and the placenta. Patients with severe preeclampsia need to deliver as soon as possible. If a pregnancy is not viable (less than 26 weeks) it might be necessary to terminate the pregnancy to save the mom’s life. Magnesium Sulphate is also given intravenously to the mom with severe preeclampsia to prevent seizures. If a patient has mild to moderate preeclampsia, it’s best practice to admit the patient, stabilise the blood pressure and give her steroids. Steroids are given to pregnant mothers (25-34 weeks gestation) to improve fetal lung maturity and is indicated if there’s a chance that the baby might be delivered before 34 weeks. After delivery, the mother still needs to be observed closely because the disease can progress further. Patients who’ve had preeclampsia also need to be advised that their blood pressure needs to be monitored at regular intervals as they are at increased risk of developing cardiovascular disease later in life
By Dr Elmarie Basson
Taken from: Babys and Beyond Volume 6, June 2019 – August 2019