Chronic hypertension in pregnancy: Clinical sciences

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Introduction0:00–0:39

Chronic hypertension in pregnancy is defined as an elevated blood pressure that’s present prior to conception or first identified before 20 weeks of gestation.
This condition requires increased surveillance because of the significant risks to the patient, including stroke, renal insufficiency, superimposed preeclampsia with or without severe features, placental abruption, and postpartum hemorrhage; as well as the risks to a fetus like congenital anomalies, growth restriction, and preterm birth.
Your first step is to perform a CABCDE assessment and conduct a primary obstetric survey. If the patient is unstable, first check for uncontrolled bleeding and control any hemorrhage, as severely elevated blood pressures may cause a placental abruption.

Unstable Patient0:39–1:22

Next, stabilize their airway, breathing, and circulation, and consider intubation when appropriate. Obtain IV access and continuously monitor maternal vital signs, especially blood pressure.
Perform your primary obstetric survey, which includes monitoring the fetal heart rate as well as possibly testing for rupture of amniotic membranes and checking cervical dilation.Alright, let’s talk about stable patients.

Stable Patients1:22–2:42

Start by obtaining a focused history and physical exam, and measure their blood pressure. History might reveal pre-existing hypertension, and your patient may already be taking antihypertensive medications.
As for their blood pressure, measure it on two separate occasions at least 4 hours apart. If both measurements show a systolic blood pressure of 140 mmHg or more, a diastolic blood pressure of 90 mmHg or more, or both, that’s hypertension.
So, if your patient has pre-existing hypertension, or develops newly elevated blood pressures before 20 weeks of gestation, you can diagnose chronic hypertension in pregnancy.
Here’s a clinical pearl! The normal physiologic changes of pregnancy generally cause a patient's blood pressure to decrease in the first half of pregnancy and then rise to preconception levels by about 36 weeks of gestation.
As such, some patients who initially meet criteria for chronic hypertension may not have another elevated blood pressure until later in their pregnancy; however it’s important to continue to treat them for chronic hypertension due to the high risk of adverse pregnancy outcomes.
The treatment varies depending on the phase of obstetric care; let’s start with antepartum patients. First, assess estimated gestational age, or EGA for short.

Antepartum2:42–2:48

EGA < 20 weeks2:48–5:10

If your patient is at less than 20 weeks of gestation, obtain baseline labs, including a CBC to assess for anemia and thrombocytopenia; a CMP to evaluate renal and liver function; a urine protein-to-creatinine ratio to assess for proteinuria; and possibly a 24-hour urine collection to assess total urine protein.Here’s a clinical pearl!
The kidneys are usually the first organ to be affected by chronic hypertension. So, if either the creatinine or the protein-to-creatinine ratio is abnormal, order a 24-hour urine collection to further assess for baseline proteinuria.
This is helpful to either follow a known elevated urine protein throughout pregnancy or to help distinguish new onset proteinuria later on.Additionally, obtain an early pregnancy ultrasound to establish an accurate due date, and plan on obtaining a fetal anatomic survey at 20 weeks of gestation to assess for structural anomalies.
Lastly, get an electrocardiogram. If it’s abnormal or your patient has additional risk factors for cardiomyopathy, such as obesity or a long-standing history of hypertension, consider an echocardiogram as well.
Next, start your patient on daily low-dose aspirin, optimally between 12 to 16 weeks, though it could be beneficial up to 28 weeks, and continue it until delivery to help prevent progression to superimposed preeclampsia.
Additionally, consider starting an antihypertensive medication if your patient has persistently elevated blood pressures of greater than or equal to 140 systolic, 90 diastolic, or both.
Preferred antihypertensives are labetalol or nifedipine; while hydrochlorothiazide is considered a second-line agent. Here’s a high-yield fact!
Make sure your pregnant patient is not taking an ACE inhibitor, an angiotensin 2 receptor blocker, a renin inhibitor, or a mineralocorticoid receptor blocker, as these could result in fetal malformations.Okay, let’s go back to assessing EGA and talk about patients who are at least 20 weeks of gestation.

EGA > 20 weeks: BP consistently <140/905:10–6:02

In this case, your first step is to assess the need for antihypertensive medications. As long as blood pressures are consistently less than 140 systolic and less than 90 diastolic, antihypertensives are not needed.
Remember, these patient’s have already been diagnosed with chronic hypertension but at this time have either normotensive or mildly elevated pressures not requiring medication.
For these patients, obtain routine prenatal labs, and a fetal ultrasound in the third trimester, to ensure there are no complications like fetal growth restriction or oligohydramnios.
Delivery is indicated between 38 to 39 weeks and 6 days of gestation. Alright, let’s talk about patients with EGA of at least 20 weeks who have persistently elevated blood pressures of at least 140 systolic, 90 diastolic, or both.

EGA > 20 weeks: BP persistently elevate6:02–10:26

These patients require assessment for superimposed preeclampsia by checking labs, such as a CBC, CMP, urine protein-to-creatinine ratio, and possibly a 24-hour urine protein to check for proteinuria, which is defined as a urine protein-to-creatinine ratio greater than or equal to 0.3, or a 24-hour urine collection with at least 300 mg of protein.
If they do not have proteinuria or their urine protein is at their baseline, they meet criteria for chronic hypertension requiring medication.
In addition to starting antihypertensive medications, monitor their blood pressure and perform serial labs including a CBC, CMP, and urine protein-to-creatinine ratio to assess for superimposed preeclampsia with and without severe features.
Also, initiate antenatal fetal surveillance with nonstress tests and amniotic fluid volume checks, as well as serial fetal growth scans every 3 to 4 weeks.
If maternal and fetal status remain stable, delivery can be performed between 37 and 39 weeks and 6 days of gestation. On the flip side, if patients with persistently elevated blood pressures have new or worsening proteinuria, then superimposed preeclampsia is diagnosed.
Before moving on to management, first assess for severe features. These include blood pressures of at least 160 systolic, 110 diastolic, or both, on two occasions at least 4 hours apart; laboratory abnormalities like thrombocytopenia with a platelet count of less than 100,000; renal insufficiency with a creatinine greater than 1.1; elevated liver function tests greater than two times the upper limit of normal; and signs or symptoms such as pulmonary edema; new onset headache that does not improve with medication; visual symptoms like spots or blurry vision; and severe, persistent epigastric or right upper quadrant pain.
If no severe features are present, your diagnosis remains superimposed preeclampsia. Treatment includes close outpatient monitoring, antihypertensives, antenatal fetal surveillance, and serial fetal growth scans.
You should also monitor for any signs or symptoms of severe features. Plan delivery at 37 weeks unless superimposed preeclampsia is diagnosed after 37 weeks, in which case delivery is indicated at that time.
On the other hand, if at least one severe feature is present, your patient has superimposed preeclampsia with severe features.
These patients require close monitoring and are admitted for the rest of their pregnancy for maternal and fetal monitoring.
Immediately control severe-range blood pressure with IV labetalol, IV hydralazine, or immediate release PO nifedipine, and start magnesium sulfate for seizure prevention.
If your patient is less than 34 weeks of gestation and both maternal and fetal status are reassuring, you can consider expectant management.
Order daily labs and monitor fetal status with daily nonstress tests, periodic amniotic fluid volume checks, and serial growth scans.
Magnesium sulfate can be discontinued after 24 to 48 hours if delivery is not imminent. Finally, if preterm, give corticosteroids to promote fetal lung maturity.
Expectant management can continue until 34 weeks, at which point you’ll deliver your patient. If your patient is greater than 34 weeks, delivery is indicated at that time.
Alright, let's move on to intrapartum and postpartum management. With intrapartum management, monitor these patients closely, as their clinical status can worsen during the stress of labor.

Intrapartum management10:26–11:15

If they’re not taking antihypertensives, consider intermittent fetal monitoring; but otherwise, continuous fetal monitoring is recommended.
Obtain and trend labs to monitor for worsening disease. Control severe-range blood pressures with antihypertensives; and titrate maintenance antihypertensives if blood pressure is greater than or equal to 140 systolic, 90 diastolic, or both; and administer magnesium sulfate to those with superimposed preeclampsia with severe features.
Vaginal delivery is appropriate unless contraindications exist. Okay, let’s end with postpartum management!

Postpartum management11:15–11:45

If your patient was on antihypertensive medication during the pregnancy or while intrapartum, continue it postpartum. If they were on magnesium sulfate while intrapartum, continue that as well for 24 hours.
Upon discharge, advise them to return for a short interval blood pressure check within 7 to 10 days, and counsel them to return if they develop any signs or symptoms of preeclampsia with severe features.
Alright, as a quick recap… Patients with chronic hypertension should start daily low-dose aspirin for preeclampsia prevention, and possibly antihypertensives.

Review11:45–13:00

Patients who are at least 20 weeks and don’t need antihypertensives require routine prenatal labs and a third trimester fetal ultrasound; while those who need antihypertensives require evaluation for superimposed preeclampsia, serial labs, and antenatal fetal surveillance.
Patients with superimposed preeclampsia without severe features need close outpatient monitoring, antihypertensives, and antenatal fetal surveillance; while those with severe features require inpatient maternal and fetal monitoring, control of severe-range blood pressures, and magnesium sulfate.
Intrapartum management involves close monitoring, controlling severe-range blood pressures, and magnesium sulfate in cases of superimposed preeclampsia with severe features.
Finally, in the postpartum period, continue intrapartum medications, obtain a short-interval BP check after discharge, and advise them to be aware of signs or symptoms
Chronic hypertension in pregnancy: Video, Causes | Osmosis