Emergencies of pregnancy

W. Scott Gilmore

Introduction

Human pregnancy is generally divided into three 13-week trimesters. While this terminology is useful, it is easier to divide the pregnancy into two halves, each lasting about 20 weeks. The first half is commonly referred to as early pregnancy and the latter as late pregnancy. Each half of pregnancy has its own unique emergencies that the EMS physician should keep in mind.

The most common disorder of early pregnancy is miscarriage. Only 20% of miscarriages occur after the first trimester. Ectopic pregnancy is the most life-threatening emergency of early pregnancy. High suspicion for ectopic pregnancy should always be maintained for females of child-bearing age, and prompt diagnosis and therapy should be reflexive. The most common emergencies of late pregnancy include placenta previa and placental abruption.

Evaluation of the pregnant patient

An EMS physician should rapidly ascertain pertinent information from any pregnant patient. This includes estimated due date or weeks of gestation, last menstrual period, number of previous pregnancies, number and type of deliveries, contraction intervals, membrane rupture, bleeding, and complications with previous pregnancies such as gestational diabetes, preeclampsia, or preterm labor. The EMS physician’s challenge is to identify life threats and initiate treatment in spite of the fact that pregnancy status is often unknown by the patient.

Miscarriage

Miscarriage is the most common complication of early pregnancy. Approximately 15–20% of clinically evident pregnancies are miscarried [1]. Eighty percent of all miscarriages occur before the 12th week of gestation [2]. In most cases, the primary focus for the EMS physician is to provide psychological support to the patient and her family. If the patient has passed tissue it should be transported with the patient to the receiving facility. If the patient is showing signs or having symptoms of hemorrhagic shock, a large-bore intravenous catheter should be inserted for access and the patient appropriately resuscitated with boluses of normal saline.

Ectopic pregnancy

Ectopic pregnancy is the implantation of a fertilized ovum outside the endometrial cavity. It occurs in approximately 1.5–2.0% of pregnancies [3], with some studies reporting the incidence of ectopic pregnancy as high as 2.6% of all pregnancies [4–7]. The reported rise in incidence of ectopic pregnancy is strongly associated with an increased incidence of pelvic inflammatory disease [8].

The clinical use of sensitive pregnancy testing, transvaginal sonography, and diagnostic laparoscopy has had a major effect on the diagnosis of ectopic pregnancy before rupture. Nevertheless, ruptured ectopic pregnancies continue to occur, often because the clinician or the patient did not recognize the early signs and symptoms of the condition, and such pregnancies account for 6% of all maternal deaths and remain the leading cause of first-trimester pregnancy-related death [3]. The most frequent causes of death for women with ectopic pregnancies in the United States are hemorrhage, infection, and anesthetic complications.

The etiology of ectopic pregnancy is multifactorial and as many as 50% of women with ectopic pregnancies have no identifiable risks [9]. Factors that are strongly associated with an increased risk of ectopic pregnancy include damage to the ovarian tubes from pelvic inflammatory disease, previous tubal surgery, or a previous ectopic pregnancy. A history of cigarette smoking, age over 35 years, and many lifetime partners have been identified as minor factors (Table 42.1).

Table 42.1 Relative risk factors for ectopic pregnancy

High	Moderate	Low
Prior ectopic Tubular sterilization Use of intrauterine contraceptive device (IUD) Pelvic inflammatory disease	Chlamydia Infertility Partners >1 Smoking	Age <18 Age >35

The risk of recurrence of ectopic pregnancy is approximately 10% among women with one previous ectopic pregnancy and at least 25% among women with two or more previous ectopic pregnancies [10]. Women in whom the affected fallopian tube has been removed are at increased risk for ectopic pregnancy in the remaining tube.

Ectopic pregnancies that involve implantation outside the fallopian tube account for less than 10% of all ectopic pregnancies. These unusual pregnancies are difficult to diagnose and are associated with high mortality [11]. Abdominal pregnancies occur in 10.9 per 100,000 pregnancies and in 9.2 per 1,000 ectopic pregnancies. The maternal mortality rate has been reported to be 7.7 times higher than that observed in tubal ectopic pregnancies, and 90 times higher than in an intrauterine pregnancy [12].

Heterotopic pregnancy, the co-occurrence of an ectopic pregnancy and intrauterine pregnancy, has increased in incidence and occurs in 0.3–0.8% of the general population and 1–3% of women pregnant as a result of assisted reproduction [13,14].

The patient history (including an assessment for risk factors) and physical examination are the principal tools used to evaluate a patient with possible ectopic pregnancy. In the out-of-hospital setting, any woman of reproductive age with abdominal pain or vaginal bleeding should be considered to have an ectopic pregnancy until proven otherwise.

Patient history

The location, nature, and severity of pain with ectopic pregnancy are highly variable. Colicky pain presents mainly in the hypogastric or iliac regions and is most likely due to small-volume intraperitoneal hemorrhage. Localized abdominal or pelvic pain is caused by acute distension of the fallopian tube at the site of implantation. Tubal rupture is typically associated with a longer-lasting, more generalized pain due to hemoperitoneum, but rupture may also be associated with a decrease in or resolution of pain altogether. Pain referred to the shoulder, indicating irritation of the diaphragm from intraperitoneal blood (Kehr’s sign), is a late sign. Vaginal bleeding may be small in volume (spotting) or equivalent to a menstrual period. The passage of tissue does not distinguish failing intrauterine from ectopic pregnancy and may simply represent a cast of endometrial tissue.

Classic signs and symptoms of tubal ectopic pregnancy include abdominal pain, vaginal bleeding, and delay of an expected menses with classic presentation around 6 to 8 weeks of gestation [9]. However, fewer than half of women with ectopic pregnancy have the classically described symptoms of abdominal pain and vaginal bleeding. In fact, these symptoms are more likely to indicate miscarriage [15].

Physical examination

Women with ectopic pregnancy may have pelvic or adnexal tenderness and vaginal bleeding. Hypovolemia, tachycardia, hypotension, diaphoresis, and shock are late signs that may indicate ruptured ectopic pregnancy with intraperitoneal hemorrhage. Although it is less common for women to present with these signs, due to improved diagnostic methods, a woman with hemodynamic instability or peritoneal signs and a positive pregnancy test result or a delay of an expected menses potentially has a ruptured ectopic pregnancy, and should have prompt evaluation by an obstetrician.

Management

For the EMS physician, the key to treating a pregnant patient with early obstetrical complaints is maintaining a high index of suspicion for a possible ectopic pregnancy and recognizing hemodynamic instability secondary to hemorrhagic shock. If the patient is in shock, large-bore intravenous access should be obtained and the patient resuscitated appropriately with crystalloids. In a woman of child-bearing age with abdominal pain and hypotension, the finding of free abdominal fluid on prehospital ultrasound should increase the suspicion of ruptured ectopic pregnancy.

Placental abruption

Placental abruption, defined as the premature separation of the placenta from the uterine wall, complicates approximately 1% of births [16]. Abruption is believed to account for approximately 30% of episodes of bleeding during the second half of pregnancy. It is associated with significant perinatal mortality and morbidity.

Abruption may be “revealed,” in which case blood tracks between the placenta and the endometrium, and escapes through the cervix into the vagina. The less common “concealed” abruption occurs when blood accumulates behind the placenta, with no obvious external bleeding. Finally, abruption may also be classified as total, involving the entire placenta, in which case it typically leads to fetal death, or partial, with only a portion of the placenta detached from the uterine wall.

Placental abruption has a wide spectrum of clinical significance, varying from minor bleeding with few or no consequences to massive abruption with fetal death and severe maternal morbidity. Maternal risks include massive bleeding, disseminated intravascular coagulopathy, and death. The risk to the fetus depends on both the severity of the abruption and the age at which the abruption occurs, whereas the danger to the mother is posed primarily by the severity of the abruption.

The incidence of placental abruption is reported to be between 1% and 3.8% of deliveries [17–22]. The incidence of abruption peaks at 24–26 weeks gestation and drops precipitously with advancing gestation [18,19]. Other risk factors include trauma, thrombophilias, dysfibrinogenemia, hydramnios, advanced maternal age, and intrauterine infections (Table 42.2) [23].

Table 42.2 Risk factors for placental abruption

Source: Oyelese 2006 [18]. Reproduced with permission of Lippincott Williams & Wilkins Inc.

High	Moderate	Low
Cocaine and drug use Chronic hypertension with preeclampsia	Cigarette smoking Multiple gestations Chronic hypertension Preeclampsia Premature rupture of membranes Chorioamnionitis	Maternal age and parity Oligohydramnios Dietary and nutritional deficiencies Carrying a male fetus

Bleeding in early pregnancy carries an increased risk of abruption in later pregnancy [24,25]. Placental abruption is usually the result of shearing forces, may occur without direct abdominal trauma, and is independent of placental location. Approximately 6% of all trauma cases [26] and 20–25% of major trauma cases are associated with placental abruption [27] but placental abruption is difficult to predict based on the severity of trauma [26]. Placental abruption usually manifests within 6–48 hours after trauma but can occur up to 5 days later [26,28,29]. Perhaps the greatest determination of abruption risk, however, is an abruption in a prior pregnancy [30]. When examined, the risk increased 15–20-fold in subsequent pregnancies when an earlier pregnancy was complicated by abruption [31].

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