Is local anesthesia safe during pregnancy?

Choice of drugs during pregnancy and breastfeeding

Pregnant patients are not uncommon in dental practice, but the diverse hormonal changes and the complex metabolic processes in mother and child can pose challenges. If surgery is necessary during pregnancy, expectant mothers worry about the health of their child. Dentists therefore often have to answer questions about whether the pain elimination and the medication are safe - an overview.

Even in early pregnancy, the body begins to prepare for the birth: hormones constantly change the cardiovascular system, the organs of the digestive tract and the respiratory tract. They also have an impact on oral health. Due to the increased release of estrogen, the capillaries in the nasopharynx narrow, which is why pregnant women breathe more through the mouth. The flow of saliva decreases and this in turn favors the development of tooth decay. The organs in the abdominal cavity also adapt to hormonal (progesterone) and mechanical influences. These changes, as well as the growing uterus, which displaces the organs, stimulate gagging and can trigger reflux.1 But the most serious changes affect the cardiovascular system.

Cardiovascular system for two

The amount of blood increases during pregnancy and the heart enlarges. It is also pushed upwards by the growing fetus. The stroke volume and pulse increase and the cardiac output increases by around 50 percent during pregnancy.2 Blood pressure drops slightly in the second trimester, and is usually slightly increased shortly before birth.3 These cardiovascular adaptations harbor two risks for the dentist: On the one hand, the so-called orthostasis syndrome can occur due to the vasomotor instability, for example if the treatment chair is lowered or raised too quickly.1 The blood pressure suddenly drops so rapidly that syncope can occur.4 On the other hand, changes in pharmacokinetics are to be expected: Due to the increasing amount of blood, the increased capillary pressure and the higher water content in the body, hydrophilic drugs are distributed and diluted more quickly in the body. In order to achieve the correct plasma concentration, a higher dose is often necessary. It is the other way around with substances that bind to proteins. The binding capacity decreases and so these drugs are usually broken down more slowly.2 This also applies to local anesthetics.

Effect of local anesthetics and vasoconstrictors

Pharmacological tests must not be carried out in pregnant women, which is why a strict risk-benefit analysis must always be carried out with local anesthesia. It is important to choose a means of which as little as possible crosses the placental barrier. Whether an anesthetic gets into the fetal circulation depends mainly on the rate of protein binding: the lower the rate, the faster it crosses the placenta. Since protein binding is also reduced by around 50 percent in fetuses, the increased proportion of unbound active ingredient can more easily lead to intoxication in them. According to a statement by the DGZMK, the local anesthetic with the highest protein binding capacity should therefore be preferred.5 In Germany, articaine with a protein binding of 94 percent and a low distribution coefficient of 17 (low toxicity) is the drug of choice for pregnant women.5,6 Due to the short elimination half-life of around 20 minutes, it is rapidly metabolized compared to other local anesthetics.7 Only about ten percent of the substance is broken down in the liver and five percent excreted renally, the rest is primarily inactivated by plasma and tissue esterases.8,9 This means that only a few articaine molecules can get into the child's circulation from the blood. The fetal blood level is around 25 to 30 percent of the maternal values.10 It can also be used during breastfeeding, as no clinically relevant quantities of the active ingredients are found in breast milk.6,9,11 Pregnant and breastfeeding women do not have to do without analgesia. It is important to completely eliminate pain as possible in order to keep the body's own adrenaline secretion as low as possible. Most local anesthetics contain adrenaline as a vasoconstrictor. Since increased exogenous adrenaline intake - especially in the first trimester - increases the risk of uterine contractions and abortion, the lowest possible addition of epinephrine (e.g. ultracaine® D-S 1: 200,000).5,6 This is especially true for patients who also suffer from cardiovascular problems or gestational diabetes. Norepinephrine and felypressin are contraindicated in pregnant women.5 For short interventions, a local anesthetic is recommended without any vasoconstrictor (Ultracain® D without adrenaline).6,11 Careful aspiration should be a matter of course to avoid intravascular injection.1

Analgesics and antibiotics

Medicines should be avoided altogether during pregnancy, but infections or severe pain can also endanger mother and child. If medication is indicated after an operation, the analgesic and antipyretic paracetamol is still the gold standard during pregnancy and breastfeeding. Ibuprofen can be used in the first and second trimester if there is a strict indication. Acetylsalicylic acid preparations cross the placental barrier very easily, which is why the other two analgesics are preferable. A strict risk-benefit assessment also applies to the treatment of infections. Because most antibiotics reach concentrations similar to those in the mother in the fetus. If antibiosis is indicated, penicillins are recommended.12

Oral Health During Pregnancy

Many people do not know that there is a direct link between pregnancy and oral health. In addition to xerostomia, hypersalivity, erosion and the pyogenic granuloma, periodontal effects in particular can be observed. Almost all pregnant women develop gingivitis, known as pregnancy gingivitis, as early as the first trimester.1,3 The gingiva has estrogen- and progesterone-sensitive receptors, which changes the tissue morphology in the form of increased vascular permeability and increased vascular and fibroblast proliferation. Gingivitis develops from this, and in some cases an epulis forms.13 Changes in the microbial flora of the mouth also favor the growth of anaerobic bacteria and thus plaque. Nausea and vomiting are also common. Those affected should then rinse their mouths well with water and, if necessary, a little baking soda and not brush their teeth directly.14 Only extremely careful oral hygiene can contain the biofilm and periodontal inflammation. The use of dental floss and fluoridated toothpaste as well as cooking with fluoridated table salt should be a matter of course to prevent tooth decay. If non-surgical periodontal therapy is necessary, this should be done in the second trimester. Untreated periodontitis increases the risk of miscarriage by a factor of 7.5.13

Practical tips for caring for pregnant women

In general, the practice team should listen carefully to preventive medical checkups and point out the importance of oral hygiene during pregnancy to women of childbearing age or who are planning to have children. It is advisable to carry out necessary renovations in advance to prevent inflammation. In the first trimester, the fetus is particularly sensitive, which is why only emergency interventions are carried out with the exception of the PZR. X-rays may only be used if they are essential for an accurate diagnosis - with a lead apron, of course, and not in the first trimester. The second trimester is ideal for routine procedures and surgical interventions that cannot be postponed. From the middle of the third trimester onwards, no more complex procedures should be carried out.4 In an emergency, the special precautionary measures for anesthetics, analgesics and antibiosis as well as the patient's position apply. If the fetus is already very heavy, the weight in the supine position can crush the inferior vena cava. This can lead to shortness of breath, sweating, nausea, but also to a sudden drop in blood pressure or bradycardia with syncope. If these symptoms occur, the patient can turn on her left side and place a pillow under her hip to relieve the vein.1–3

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Note: The procedure described in the text is for guidance, but the individual medical history and the treatment decision by the treating doctor are always decisive. The specialist information must be observed.

Author: Isabel Becker

The full literature list is available here.

The pharmaceutical information is available here.

The post is in Implantology Journal published.

Photo: travin_photo - shutterstock.com