Hypertension during pregnancy is common. Hypertension is defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg. A woman may be hypertensive when entering pregnancy or she can become hypertensive during pregnancy. Pregnancy is divided into three trimesters – first trimester, second trimester, and third trimester. Hypertension during pregnancy can be very serious and can cause problems for both the mother and the child. Therefore a pregnant woman with hypertension is often a high-risk patient.
There are different types of hypertensive disorders in pregnancy. Week 20 of pregnancy which is around the second trimester is an important mark to remember. The reason is that week 20 is the time point used to classify the different hypertensive disorders of pregnancy. Hypertension diagnosed before week 20 of pregnancy is called chronic hypertension. This is hypertension diagnosed before pregnancy or before week 20 of gestation.
It’s important to remember that during pregnancy there is usually a drop in blood pressure, specifically diastolic blood pressure. So if you have an increase in blood pressure or hypertension any time during pregnancy, it is somewhat abnormal. If the pregnant woman has an increase in blood pressure first detected after week 20 of gestation, this can be either preeclampsia or gestational hypertension.
There is a big difference between preeclampsia and gestational hypertension. In preeclampsia, which is a more serious form of hypertension during pregnancy, there is an increase in blood pressure which occurs after 20 weeks of pregnancy. This is accompanied by the presence of protein in the urine or systemic features of preeclampsia. These systemic features include vision problems, liver problems, and even kidney problems.
Gestational hypertension is very similar. There is an increase in blood pressure occurring after 20 weeks of pregnancy but the difference is that in gestational hypertension there are no systemic features associated as we see in preeclampsia.
The signs and symptoms of preeclampsia include:
2. Visual disturbances
3. Right upper quadrant pain which relates to hepatic ischemia (reduced blood flow to the liver).
4. Reduced urine output
5. There can be low abdominal pain which may be a sign of placental abruption (when the placenta separates from the inner wall of the uterus before birth) which is more common in patients with preeclampsia.
On clinical examination, preeclampsia can reveal signs of pulmonary edema, hepatic tenderness from the hepatic ischemia, peripheral edema, and hyperreflexia. The triad of preeclampsia includes hypertension, proteinuria, and edema.
The exact pathophysiology of preeclampsia is unknown. However several factors have been identified in preeclampsia.
1. Vasoconstriction leading to hypertension
2. There is platelet activation with intravascular coagulation
3. Endothelial dysfunction contributes to the edema caused by fluid shifting from the vascular compartment into the interstitial compartment.
For maternal plasma volume contraction, preeclampsia is life-threatening because it can lead to a number of complications. This includes eclampsia which is essentially the new onset of seizures or coma in a pregnant woman with preeclampsia. Maternal plasma volume contraction can also cause pulmonary edema, renal failure, and even stroke.
Preeclampsia not only affects the mother but also can cause fetal complications. These include intrauterine growth problems, placental abruption, and stillbirth.
If a patient with preeclampsia presents with vaginal bleeding, placental abruption must be suspected.
The risk factors for developing preeclampsia include:
1. A history of previous preeclampsia
2. First pregnancy
3. A family history of preeclampsia
4. Pre-existing hypertension
6. Renal disease
8. Some connective tissue diseases such as rheumatoid arthritis and systemic lupus erythematosus
A pregnant woman presenting with hypertension during pregnancy needs to be investigated.
Investigation of hypertension during pregnancy includes:
1. A full blood count
2. Serum electrolytes, urea, and creatinine to check for kidney function
3. Liver function tests to check for liver function
4. Checking the urea: creatinine ratio
5. Urine dipstick test which may reveal proteinuria in preeclampsia
6. It is also important to perform fetal assessments. So doing an ultrasound to check for the fetal anatomy, blood flow, and any signs of growth restriction.
7. Cardiotocogram to check for fetal heart rate
In the management of preeclampsia specifically, it is important to assess the need for delivery.
When is delivery in pregnancy with preeclampsia indicated?
1. When there is progressive maternal organ dysfunction
2. There is an inability to control the blood pressure with other means including medication
3. When the fetal well-being is compromised
At the end of the day, the only way to stop preeclampsia is by delivering the baby.
To manage hypertension during pregnancy, the pregnant woman can be treated with medication including methyldopa, hydralazine, nifedipine, or labetalol.
When the plan is to deliver the baby from the mother, antenatal corticosteroid injections are given. This is in order for fetal lungs to mature. This is done if the fetus is being planned to be delivered before week 34 of pregnancy.
Finally, it is mandatory to assess the mother’s blood pressure postpartum after delivery to be sure that the blood pressure goes back to normal.
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