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Caring for the pregnant patient
By Jessica Berthold
When speaker Anna Kho, MD, asked the audience of hospitalists how many had done a consult on a pregnant patient, nearly every hand in the room shot up. When she asked how many had had training for such consults, however, only a quarter of audience members kept their hands raised.
It’s a discrepancy Dr. Kho aimed to correct during her hour-long talk at the 2009 Society of Hospital Medicine meeting. Given that about 36% of pregnant women will have some sort of medical problem during pregnancy, every hospitalist is likely to encounter a pregnant patient at some point during his or her career, Dr. Kho said.
Dr. Kho: Hospitalists only need to treat hypertension in a pregnant patient when diastolic blood pressure goes above 105 mm Hg.
“Some OB doctors don’t feel comfortable taking care of internal medicine illnesses in pregnant patients, and they will look to us for guidance and recommendations about what to do to ensure the patient has the best care possible,” said Dr. Kho, assistant professor of medicine at Emory University School of Medicine in Atlanta.
Hospitalists need to be versed in the diagnosis and treatment of the most common problems in pregnancy for which they may be consulted, she said. These include hypertension, preeclampsia, asthma, venous thromboembolism (VTE) and diabetes.
“If you’ve never prescribed a Class B medication before in a pregnant patient, you should do a little more research before you prescribe it.”
Think before you prescribe
Some of the physiologic changes that occur in pregnancy include a decrease in systemic vascular resistance, an increase in cardiac output, and an increase in blood volume by about 40%. Other changes are an increase in tidal volume and a decrease in hematocrit. Creatinine clearance also goes up, which is important to remember because medicines that are renally cleared may need to be adjusted in a pregnant patient, Dr. Kho said.
When considering the use of drugs in pregnant patients, hospitalists should be familiar with the FDA’s risk classifications, which categorize medicines into groups from A–D, and X, based on drug risk. A Class A drug is really the only absolutely safe option, as a Class B drug (i.e. “No evidence of risk in humans”) may not have been subjected to human trials, Dr. Kho said.
“If you’ve never prescribed a Class B medication before in a pregnant patient, you should do a little more research before you prescribe it,” Dr. Kho said. “Safety classifications aren’t as helpful as a careful consideration of the risks and benefits of a medication in a given situation.”
Before prescribing a medication in pregnancy, a hospitalist should consider four key things: the severity of the symptoms and illness; whether lifestyle changes can be recommended; what would happen to the fetus and mother if the medicine weren’t given; and whether there is a similar drug that’s safer.
“Also, if you are thinking about prescribing something during the first trimester, take a moment to ask a colleague for an opinion or do a literature search first,” Dr. Kho said. “And lastly, any medicine that has recently come on the market, you should avoid.”
Chronic hypertension is defined by a history of hypertension before pregnancy, a blood pressure of more than 140/90 mm Hg before 20 weeks’ gestation, or hypertension that is diagnosed for the first time during pregnancy and doesn’t normalize postpartum.
Hospitalists only need to treat for the condition when diastolic blood pressure goes above 105 mm Hg. Data from multiple studies have shown that lowering the diastolic blood pressure, if it’s around 95 or 100 mm Hg, doesn’t have an added benefit for the fetus or mom, Dr. Kho said.
“Although there has been no formal recommendation about this, I have also seen people in practice initiate treatment when systolic blood pressure is greater than 160,” Dr. Kho said. “I think this is because we all feel uncomfortable with having a pregnant patient with a blood pressure of 200/100 mm Hg; we feel she could progress and develop complications.”
Methyldopa is the drug of choice for hypertension in pregnancy. The children of many mothers who took this drug are adults now, and there have been no long-term adverse effects, Dr. Kho said. If the drug isn’t available for some reason, labetalol is an “excellent second-best choice,” she added. Hydralazine and other beta-blockers are also fine, although atenolol is associated with a slight risk of intrauterine growth retardation.
Calcium-channel blockers can be used for hypertension, and, as a last resort, one can use diuretics as well as nitroprusside. The latter does increases the risk of the baby developing fetal cyanide toxicity, however. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers should be avoided, as they may lead to renal agenesis and fetal death, Dr. Kho said.
Complicating 5% of pregnancies, preeclampsia is rare before 20 weeks of gestation and is most common after 36 weeks. Risk factors include chronic hypertension, diabetes, renal disease, obesity, first pregnancy, twin gestation, a personal/family history of the condition, or being African-American.
“Patients with preeclampsia will present with high blood pressure, and for that reason you have to keep it in the differential,” Dr. Kho said. “They will also present with complaints of headaches with a frontal and migraine quality, scotomas and scintillations, renal disease, edema in the face and hands, epigastric discomfort and proteinuria.”
Complications associated with preeclampsia include disseminated intravascular coagulation (DIC), eclampsia, cerebral hemorrhage, pulmonary edema, renal failure, placental abruption, and hepatic failure and rupture.
“Because of all of these complications, you want to make sure a hypertensive patient doesn’t have preeclampsia, and check lab work accordingly. So you want to check their complete blood count; their liver function tests to look for hepatic failure or rupture; their chemistry to look for renal failure; a DIC panel; a uric acid, which is often elevated with preeclampsia; and a urinalysis to look for proteinuria,” Dr. Kho said.
The treatment for the hypertensive component of preeclampsia is the same as treatment for chronic hypertension. With preeclampsia, hospitalists should also consider seizure prophylaxis—i.e., magnesium sulfate IV—because preeclamptic patients can go on to develop eclampsia or seizures. The only real cure for preeclampsia is delivery, Dr. Kho said.
Asthma in pregnancy is very common. Safe treatments include inhaled beta-agonists; cromolyn sodium; and inhaled, oral and intravenous steroids. Leukotriene inhibitors should be used only with recalcitrant asthma because there are limited data on their safety, and epinephrine should be avoided because it can introduce uterine contractions. Hospitalists should also try to keep the patient’s oxygen saturation above 95%, to ensure the fetus has adequate oxygen, Dr. Kho said.
If you have a pregnant patient for whom you want to order a chest X-ray—perhaps because she’s spiked a fever or has audible rales—it’s perfectly fine, Dr. Kho said. The rule of thumb for radiologic tests is to keep the total, cumulative amount of radiation exposure during pregnancy below five rads. Nearly all common tests are well below this limit.
The patient should always wear a lead apron to shield the baby and should only be X-rayed in the area needed to make a diagnosis. If the mother needs to have iodine, a single dose is unlikely to be harmful, even though iodine does cross the placenta and is taken up by the fetal thyroid.
“Studies to avoid during pregnancy are the ones with ‘radioactive’ in the title,” said Dr. Kho, to a chorus of laughs. “Don’t order a radioactive iodine uptake (RAIU) and scan, or an I-131 ablation. And even though MRIs are OK in pregnancy, there’s not enough data about their safety in the first trimester. Consider a CT scan instead.”
The use of gadolinium in pregnancy is unknown and therefore not recommended when ordering an MRI, she added.
VTE and diabetes
An increase in blood stasis and coagulation factors puts pregnant women at higher risk of VTE, which is the top cause of nonobstetric maternal death in the U.S., Dr. Kho said. Characterized by unilateral leg edema and pain, VTE occurs at the same rate through all three trimesters, with 90% of deep vein thromboses occurring on the left side. To diagnose, one can safely order an ultrasound, a ventilation/perfusion scan (V/Q) or a pulmonary angiogram.
There are two options for managing VTE: unfractionated heparin and low-molecular-weight heparin. Either option should be used for at least three to six months before delivery; some experts recommend anticoagulation up until the time of delivery. Warfarin should not be used due to extreme teratogenicity; it can result in the fetus having cerebral hemorrhage, a misshapen skull and vertebral stippling.
“In our practice we use unfractionated or low-molecular- weight heparin until the time of delivery as well as six weeks postpartum, because the patient is still at risk of developing worsening VTE postpartum,” Dr. Kho said. “If you do treat until delivery, you want to discontinue heparin or switch to IV heparin at least 24 to 36 hours before delivery. You also want to stop the heparin drip at least six hours before an epidural is placed. Once she delivers, you can resume either form of heparin 12 hours after delivery, then switch to warfarin for six weeks.”
If one is unable to anticoagulate the patient, an inferior vena cava filter can be safely placed in pregnancy, with the indications for placement the same as in a nonpregnant patient, she added.
As for diabetes, the only safe treatment in pregnancy is insulin, Dr. Kho said.
“It’s kind of the old-school insulin, too: NPH, regular, Lispro and Aspart. NPH and regular are preferred, and you can use a combination if you want, like 70/30 or 75/25,” Dr. Kho said. “There’s not enough data on glargine insulin in pregnancy, so you should try to avoid it. Oral hypoglycemics should be avoided because their safety and efficacy haven’t been established, and that comes from consensus recommendations” of several medical groups, Dr. Kho noted.
As a general rule of thumb when treating pregnant patients, hospitalists need to remember that fetal well-being is dependent on maternal well-being, she added.
“I think as internists we feel so worried about what could potentially happen to the fetus that we sometimes forget to take care of the mom. But, really, if the mom has a medical problem that is uncontrolled, then the baby is not going to have a good outcome,” Dr. Kho said. “As long as you try to treat the mom and keep her condition under control, then the baby will have the best shot.”
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From the April 16, 2014 edition
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