A variety of anatomic and physiologic changes occur during pregnancy. In most cases, there is minimal impact on the mother's health. However, there is the possibility that EMS providers will be called to assist a pregnant female.1 Managing the pregnant patient can present unique challenges. Always remember that you are caring for two patients-the mother and the unborn fetus.
The following article provides an overview of the physiologic changes associated with pregnancy, assessment and management of the pregnant patient, examples of pregnancy-related complications, as well as assessment and treatment options to consider when helping a gravid female. Having this background may prove to be invaluable when assessing and managing the pregnant patient, and may even assist in reducing maternal morbidity and mortality.
Anatomical and Physiologic Changes
Following is a brief overview of the anatomic and physiologic changes that occur in the pregnant woman. Table I offers a summary of common OB/GYN terminology.
In a normal pregnancy, the placenta develops in the endometrium-the mucous membrane that lines the uterus. It has several functions, including the exchange of respiratory gases, transport of nutrients between mother and fetus, and hormone production. The umbilical cord connecting the placenta to the fetus consists of one umbilical vein and two arteries and is present from the sixth week of pregnancy through delivery. The vein carries oxygenated blood toward the fetus; the arteries return the blood from the fetus to the mother.2,3
While the placenta provides nutrients to the fetus and assists with the removal of wastes, the amniotic sac, which consists of membranes that cover the fetus, provides protection. The amniotic sac fills with amniotic fluid that is designed to protect the fetus and to provide an environment that is optimal for fetal development. A volume of up to one liter of amniotic fluid is maintained by the fetus's excretion of urine, as well as its swallowing of the amniotic fluid.2,3
Fetal Development & Trimesters
Fetal development begins immediately following implantation of a fertilized egg. The normal duration of pregnancy is 40 weeks from the first day of the mother's last menstrual cycle. Table II provides a summary of fetal development time frames.
Pregnancy is often described in trimesters, with each trimester lasting 13 weeks, or three calendar months. The first trimester is comprised of months one through three, or weeks 1–15; the second trimester consists of months four through six, or weeks 16–27; and the third trimester includes months seven through nine and accounts for weeks 28–40. Pregnancy can also be described in halves: The first half includes weeks 1–20, the second half accounts for weeks 20 through delivery.2,3
Oxygen Delivery to Fetus
Delivery of oxygen to the fetus is dependent on the mother's arterial oxygen content and uterine blood flow. To maximize oxygen delivery, uterine blood flow-normally 2% of total cardiac output in a nonpregnant patient-increases to 18% of cardiac output by the third trimester. Any factor that affects arterial oxygen content (e.g., hypotension, vasoconstriction of the placental bed or uterine contractions) or uterine blood flow will also affect fetal oxygenation. Factors that affect the delivery of oxygen to placenta include the oxygen content of uterine blood, maternal hemoglobin and uterine blood flow.2-9
Maternal system changes
Cardiovascular. The cardiovascular system undergoes unique changes during pregnancy. There is an increased blood flow to the uterus from around 60 millimeters per minute to over 600 millimeters per minute. Total maternal blood volume increases by up to 40%. Cardiac output increases by as much as 50% by week 10 and peaks at the end of the second trimester. The maternal heart rate may increase by as many as 15 beats per minute as early as week 12 of pregnancy. During late pregnancy, the mother's normal heart rate may range between 80–100 beats per minute, or 120% of baseline. The mother may also experience a 5–15 mmHg decrease in blood pressure, mostly due to a reduction in vascular resistance, which also changes with pregnancy. The greatest decrease in maternal vascular resistance usually occurs by the 24th week of pregnancy. Factors contributing to this reduction include the dilation of peripheral blood vessels and the presence of placental blood circulation. These changes are necessary to meet the growing uteroplacental needs of the fetus.1-8
It is important to be familiar with these changes because, when the maternal cardiovascular system is stressed (e.g., blood loss, hypoxia), fetal blood flow may be sacrificed. While this response may be beneficial to the mother, fetal compromise, including fetal mortality, may occur. In situations in which maternal circulation is compromised, prompt recognition and aggressive treatment may prove to be lifesaving to both the mother and fetus.1-8
Blood pressure. In most pregnancies, maternal blood pressure is lower than in a nonpregnant state; however, hypertension can occur during pregnancy. If the mother was borderline hypertensive prior to the pregnancy, her blood pressure may become dangerously elevated. Persistent hypertension can have numerous impacts on the pregnancy, including placing the placenta at risk, fetal compromise, and maternal stroke or renal system complications.20,22
Hypertensive disorders occur in up to 10% of pregnancies. The etiology is thought to involve abnormal maternal vasospasm that can result in an increased blood pressure and a variety of other signs and symptoms (see Table III on page 62).2,20,22
Hypertensive disorders are more commonly seen in a first pregnancy or in patients with pre-existing hypertension or diabetes. Hypertensive conditions that are associated with pregnancy place the patient at greater risk for developing serious complications such as cerebral hemorrhage, renal failure and pulmonary edema. When assessing the patient who is suspected of experiencing a pregnancy-related hypertensive condition, include focused questions in the patient assessment. Has the patient experienced excessive weight gain? Has she experienced any visual difficulties, headaches, abdominal pain or seizures?2,20,22
Preeclampsia occurs in as many as 10% of pregnancies and is the second most common cause of maternal mortality after 20 weeks. The primary cause remains unclear. Complications include cardiovascular, neurologic, hepatic, uteroplacental and renal system involvement. Risk factors include family history, nulliparity (not having given birth), age greater than 40 years, African-American race, chronic hypertension or renal disease, diabetes or multiple gestations. 2,20,22
Preeclampsia can be classified as mild or severe. In mild preeclampsia, the patient may experience a combination of hypertension, edema or proteinuria (protein in the urine). Severe preeclampsia may include symptoms like headache or visual disturbances (cerebral vasospasm), shortness of breath (pulmonary vasospasm), epigastric or right upper quadrant pain (hepatic compromise).2,20,22
If the patient experiences seizure activity during pregnancy, consider her to be eclamptic. In addition to recognizing the seizure activity, providers should try to determine the exact cause of the seizure. Potential causes include hypoxia, hypoglycemia, sepsis and drug overdose. Prompt recognition and management of the pregnant patient who is experiencing a seizure is critical to reducing the incidence of fetal morbidity and mortality.2,20,22
The decision to treat the pregnant patient who is experiencing a hypertensive episode during pregnancy must be carefully evaluated. Treatment may compromise maternal and/or fetal outcomes and may obscure the worsening of the condition. In cases of severe maternal hypertension (e.g., systolic blood pressure is greater than 160 or diastolic is greater than 110), there is a risk of intracranial hemorrhage and placental abruption. Part of the goal of treatment is to avoid a sudden decrease in blood pressure. This can be difficult to control in the prehospital environment. Extreme caution must be taken.2,20,22
Supine-hypotensive syndrome. Supine hypotensive syndrome results in a reduced blood pressure, occurring most often during the third trimester and in up to 25% of pregnancies. When the patient is in a supine position, the mass and weight of the gravid uterus can compress the inferior vena cava, resulting in a decreased return of blood flow to the heart. As a consequence, there may be a reduction in cardiac output, leading to a decrease in systolic blood pressure by up to 30 mmHg. This may also lead to decreased blood flow to the placenta.2-4,20
Supine hypotensive syndrome can be managed through appropriate patient positioning. This includes having the patient lie on her left side, with a blanket under her left hip. This may help to deflect the uterus off the vena cava, thereby improving venous circulation. Preventing the patient from being in a supine position may also help to alleviate unwanted episodes of hypotension.2-4,20
Respiratory. During pregnancy the maternal respiratory system also undergoes changes. The mother's diaphragm may be elevated as many as 4 cm, and there may be a slight (up to 25%) reduction in functional residual volume. The mother's anteroposterior diameter and transverse diameter of the chest wall increase. This leads to an increased chest wall circumference, which allows the vital capacity to remain essentially unchanged. Tidal volume (volume of inspired air) may increase by as much as 40%. Although pregnancy does not influence lung compliance, chest wall and total respiratory compliance may be reduced when the mother is at term. 1-8
Hormonal. During pregnancy, a number of hormonal changes occur that influence maternal systems. Changes in pregnancy may affect the patient's upper respiratory tract resulting in hyperemia (congestion), mucosal edema (swelling of the mucosal membranes) and hypersecretion production (increased production of secretions). Increased levels of estrogen contribute to tissue edema, capillary congestion and hyperplasia (increased production of cells) of mucous glands.1-8
Gastrointestinal. Gastric motility is reduced during pregnancy and the bowels are moved in a superior (upward) direction. The peritoneum and abdominal walls are stretched and the bladder is displaced. These factors can lead to an increased risk of aspiration, as well as greater risk of injury to the bladder, bowel and upper abdominal contents. Gastrointestinal changes, in combination with the pregnant uterus, can make examination of the abdomen more difficult. This in turn may lead to inaccurate abdominal assessments by providers.1-8
After the 12th week of pregnancy the uterus rises out of the pelvis and does not receive protection from the pelvic bones. As a result, the uterus is more exposed and potentially vulnerable to traumatic injury. The additional blood flow to the uterus that occurs during pregnancy increases the danger of trauma to the uterus.1-8
There are additional symptoms, such as nausea and vomiting. During the first half of pregnancy, more than half of all patients report nausea; almost 50% experience vomiting. Less than one-quarter of all patients will experience nausea and/or vomiting throughout the duration of their pregnancy. Due to the effects of progesterone on bowel motility, constipation may also occur.1-8
In addition to impacting existing organs, pregnancy is also associated with the development of new anatomic structures. The development of the fetus and placenta, and formation of the amniotic sac will influence maternal physiology.
Complications of Pregnancy
Following are specific examples of medical and traumatic conditions that may occur during pregnancy.
Pregnancy can influence pre-existing disease processes in the mother, and may contribute to the onset of new medical conditions. The diabetic female illustrates this point. Gestational diabetes may develop in the otherwise healthy woman during pregnancy. Patients with pre-existing diabetes may have more difficulty controlling their diabetes following the onset of pregnancy. Gestational diabetes affects as many as 4% of pregnancies in the United States. Disease processes like diabetes can affect both the mother and fetus. The occurrence of hypoglycemia in pregnancy helps to illustrate this point. Maternal hypoglycemia may occur between meals and during sleep as the fetus continues to draw upon the mother's nutrient supply. Once born, the infant may not be free of the complications of such disease processes. In the case of gestational diabetes, infants may be larger, may experience difficulty controlling their body temperature, and may be more likely to experience hypoglycemia.10-13
Vaginal bleeding. Vaginal bleeding warrants careful assessment. Bleeding may result from a variety of conditions, including ectopic pregnancy, threatened miscarriage, spontaneous miscarriage and vaginal trauma (Table IV). The timing and severity of bleeding may also vary. For example, bleeding that occurs later in the pregnancy may be the result of placenta abruption or placenta previa. Causes of less acute vaginal bleeding include cervical lesions, trauma, vaginitis, cervicitis, hemorrhoids or a bloody show at the start of labor.4,14-18
It may not be possible to determine the exact cause of vaginal bleeding in the prehospital environment. When vaginal bleeding is reported, providers should make specific inquiries regarding the episode. Information to obtain includes when the bleeding started, the estimated rate of flow (number of pads used over the period of an hour), any pain associated with the bleeding, and whether or not trauma was involved.14-19
A spontaneous abortion may or may not be associated with vaginal bleeding. It can be defined as the termination of a pregnancy prior to fetal viability and can occur in up to 15% of pregnancies. There are several different classifications of abortions, and the signs and symptoms may vary greatly from patient to patient (Table V). Traditional signs and symptoms include abdominal cramping or pain, vaginal bleeding or discharge.14-19
Embryonic abnormalities account for more than 75% of first-trimester spontaneous abortions. Maternal causes contribute to a majority of second-trimester abortions, including maternal insulin-dependent diabetes mellitus, hypertension, renal disease and infection. Caffeine, alcohol, tobacco and cocaine use have all been cited as potential contributing causes.14-19
Ectopic pregnancy. An ectopic pregnancy (Figure 1) occurs when the fertilized ovum implants outside the uterus, including on the ovaries, abdominal cavity or fallopian tubes. In an ectopic pregnancy, fetal development normally does not exceed 10 weeks. It is a leading cause of pregnancy-related deaths during the first trimester, accounting for 10% of maternal deaths. Teenagers of minority races are reported to have a higher incidence than Caucasian teens. It is more common among women between the ages of 25–34.14-19
Whether suspected or confirmed, an ectopic pregnancy should be considered a medical emergency. If rupture occurs, the mother may hemorrhage into the abdominal or pelvic cavity. In cases of fallopian tube involvement, the pregnancy may erode the wall of the tube, leading to intra-abdominal bleeding without vaginal bleeding. When an ectopic pregnancy does involve vaginal bleeding, the bleeding can be minimal.8,14
Several factors predispose females to experience an ectopic pregnancy. Pelvic inflammatory disease (PID), tubal ligation (a surgical procedure that closes the fallopian tubes and inhibits the egg traveling from the ovary to the uterus), use of fertility pills and the presence of an IUD (intrauterine device) for birth control are all considered risk factors. Patients with an ectopic pregnancy may have a variety of complaints, including abdominal pain, referred shoulder pain or vaginal bleeding. Pregnancy-related symptoms, such as breast tenderness, missed period, intermittent spotting, nausea, vomiting and/or fatigue, may be involved as well.14,20
Abruptio placentae. Abruptio placentae is the premature separation of the placenta from the uterine wall. Separation can be partial or complete, with varying degrees of bleeding. There can be partial separation with no external hemorrhage, partial separation with external hemorrhage, or complete separation with or without external hemorrhage. Separation leads to the reduction and possibly cessation of gas exchange. Predisposing factors include preeclampsia, maternal hypertension, multiparity (giving birth to more than one child), abdominal trauma and a short umbilical cord. In comparison to other obstetric-related complications, there may be minimal vaginal bleeding, as bleeding occurs behind the placenta and may be contained if separation is not complete. If the placenta suddenly separates from the uterine wall, however, hemorrhage may occur quickly.2-4,20
Symptoms of abruptio include constant and severe abdominal pain, reported as tearing in nature. If present, the bleeding may be dark in color. The mother may complain of contractions, loss of fetal movements or abdominal and/or back pain. Fetal complications include hypoxia, hypovolemia and death. Maternal complications can include hypovolemia and disseminated intravascular coagulopathy (DIC).2-4,20
Placenta previa. Placenta previa (Figure 2) occurs when the placenta attaches low in the uterus, sometimes resulting in a partial or complete covering of the internal cervical opening, or os. Previa may be described as complete, partial or marginal. In complete previa, the placenta completely covers the internal opening; in partial previa, there is only partial covering of the opening; in marginal previa, the placenta is next to the internal opening but does not extend over it. Predisposing factors include women over age 35, multiparity and pregnancies in rapid succession. It occurs in five out of 1,000 pregnancies and has a maternal mortality rate of less than 1%. When mortality occurs, it is often the result of uterine bleeding and DIC. 2-4,21
Cases of placenta previa often involve females who are in their third trimester with a history of the condition. Previous uterine trauma, smoking and previous induced abortions may also contribute to previa. Vaginal bleeding may be reported as painless and bright red. It may or may not be associated with contractions, cervical dilatation or placenta separation. A lack of uterine tissue contributes to ineffective control of bleeding. In contrast to placenta abruption, in which vaginal bleeding may or may not present, in previa, bleeding is a hallmark sign. Although previa is often considered to involve painless bleeding, pain may be present if labor is active and cervical dilatation is causing the bleeding.2-4,17 In some cases, placenta previa may not be identified until the third trimester. During this trimester, fetal pressure on the placenta increases and uterine contractions may begin. At the same time, effacement (thinning of the cervix) may occur. When these factors occur concurrently, vaginal bleeding may actually lead to the discovery of previa.2-4,21
It is estimated that 5%–20% of pregnancies are complicated by physical trauma. More than half of the trauma cases encountered during pregnancy are the result of motor vehicle collisions and falls. It is important for EMS providers to suspect the presence of trauma based on the history that is provided, as well as the clues on scene.1,4,5
Major trauma may affect more than 5% of all pregnancies. Maternal death is the leading cause of fetal death; therefore, aggressively caring for the mother is the best way to care for the fetus. Maternal shock, hypoxia, placental abruption and direct fetal injuries can also result in the death of the fetus. Although fetal death can occur in cases of minor or major maternal trauma, more than 50% of fetal mortality cases are associated with significant maternal injury.1,4,5
In cases of trauma, providers must recognize that even though the mother may appear to be fine, internal injuries may exist that are not apparent in the field. If unrecognized or untreated, internal injuries can lead to devastating outcomes, as with placental abruption. As the placenta shears away from the uterine wall, gas exchange is impaired and bleeding occurs. Although it occurs in fewer than 5% of minor accidents and fewer than 50% of major incidents, it causes more than 70% of fetal deaths in those cases in which the mother lives.1,4,5
In trauma, there is potential for loss of circulating volume. Providers must recognize that fetal tolerance to maternal blood loss is impacted by several factors, including maternal sympathetic response, oxygen-carrying capacity of maternal blood and maternal blood pressure. Sympathetic responses, which involve the release of chemicals such as norepinephrine and epinephrine and result in the "fight-or-flight" response, include tachycardia and vasoconstriction. If the mother loses as much as one quarter of her blood volume, sympathetic responses, including tachycardia and peripheral vasoconstriction, may be noted. The mother's ability to compensate for such losses can impact the viability of the fetus.1,4,5
The assessment of the pregnant patient is similar to most adult patient assessments, with a few components that are specific to pregnancy. Providers will need to inquire about pregnancy-related symptoms, including breast tenderness, missed menstrual cycle, vaginal bleeding, nausea and vomiting. If pregnancy is suspected, the gestational age of the pregnancy should be assessed.19-20
A quick method of estimating the date of the pregnancy can be achieved by measuring fundal height, which is the distance from the symphysis pubis to the top of the uterine fundus. Each centimeter of fundal height is considered equal to one week of gestation. For example, if the fundal height is determined to be 27 cm, then the gestational age is approximately 27 weeks. If the fundus is felt just above the symphysis pubis, the pregnancy is approximated at 12–16 weeks (see Figure 3).2,3,19,20
When conducting the physical exam or approximating gestation, it is important to recognize that organs may be displaced during pregnancy. Not only can this influence the assessment, it may actually place the organs at greater risk for trauma. After the 12th week of gestation, the uterus rises out of the pelvis and is no longer protected by the pelvis. These changes place the bladder, uterus and fetus at potential risk for abdominal trauma. When assessing the pregnant patient, it is critical to consider the location of the fundus and the potential for blunt or penetrating injury.2,5
The patient interview should include pregnancy-specific components. Questions asked will be influenced in part by what the mother reports. If the patient complains of abdominal pain or cramps, ask when and where did the pain start? Was the onset slow or abrupt? What is the character of the pain, including its duration and location? Does the pain radiate? If so, where? Does anything make the pain less or worse? Has she experienced similar discomforts in the past? What events preceded the cramps/pain? What is the patient's overall state of health? Is she taking any medications, prescribed or over-the-counter? Is there any illegal drug or substance abuse? The provider should also try to determine if the abdominal pain is medical or traumatic in nature.19-20
If the patient reports missing a menstrual cycle or that her period is late, pregnancy should be considered. If she has experienced breast tenderness, increased urination, nausea or increased vomiting, consider the potential for pregnancy. If pregnancy has been confirmed, ask if a sonogram has been conducted. A sonogram can help to identify the age of the fetus, presence of multiple fetuses, abnormal presentations and some birth defects.19-20
If possible, vital signs should be taken with the patient lying on her left side to assist in obtaining more accurate vital signs, as well as promoting circulation. Remember that the blood pressure tends to be lower and heart rate greater during pregnancy.19-20
Unlike managing a single patient, management of the pregnant patient requires that the provider consider both the mother and fetus. Always remember, however, that the best way to treat the fetus is by treating the mother. Table VI provides an overview of the management of several pregnancy-related complications.
Management of the pregnant patient begins with ensuring that the patient's ABCs are intact. If her airway, breathing, and/or circulation are at risk, rapid intervention is indicated. Aggressive airway management and fluid administration may prove to be invaluable in improving patient outcomes. Administer oxygen at a liberal liter flow rate. Carefully evaluate the use of medications, as any medication given to the mother can potentially influence the fetus. The decision to administer medication may be influenced by the mother's health, as the best hope for a healthy fetus is a healthy mother.
Administration of IV fluids will be influenced in part by the patient's chief complaint, symptoms and provider judgment. In cases of suspected hypovolemia, use fluids appropriate for volume replacement, such as lactated Ringer's or normal saline. If fluid boluses are administered, carefully assess the mother for any signs of volume overload prior to and following each bolus.
Trauma cases may involve traditional management techniques including splinting, direct pressure and spinal immobilization. Unfortunately, it may not be optimal to place the patient in a supine position. If hypotension develops, it may be necessary to place the patient on her side while ensuring that the ABCs and immobilization are not compromised. This position may require creative patient packaging.
Knowledge about maternal physiology and fetal development may prove invaluable when assessing and managing the pregnant patient. Key points to remember when caring for a pregnant patient include: The patient can appear well despite having a dangerous injury; hypotension should be managed by placing the patient on her left side; and treating the mother is the best way to treat the fetus.
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