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Emergency And Acute Medicine – Uncomplicated Pregnancy
Pregnancy is a normal physiologic state rather than a disease process, yet it imposes significant metabolic and anatomic changes on the mother to support fetal growth and development. In emergency care, all women of reproductive age presenting with abdominal pain are considered pregnant until proven otherwise—even with a history of sterilization. Hormonal changes driven primarily by placental progesterone and estrogen account for most physiologic adaptations. In adolescents, menarche typically occurs between ages 11 and 15. Pregnant adolescents may be unaware of or reluctant to disclose pregnancy; therefore, pregnancy must always be considered. Adolescent pregnancies also carry a higher risk of obstructive labor.
The physiologic changes of pregnancy are largely mediated by placental hormones. Human chorionic gonadotropin (hCG) prevents involution of the corpus luteum and stimulates continued production of estrogen and progesterone. Elevated hCG levels contribute to nausea and vomiting. Progesterone promotes development of decidual cells to nourish the early embryo, decreases uterine contractility to reduce the risk of spontaneous abortion, and helps prepare breast tissue for lactation. Estrogen stimulates enlargement of the uterus and breasts, growth of mammary ducts, enlargement of the external genitalia, and relaxation of pelvic ligaments and joints.
Diagnosis of pregnancy relies on history and physical examination, hormonal assays, and ultrasonography. The most common presenting symptom is amenorrhea in a sexually active woman, often accompanied by nausea, vomiting, breast tenderness, urinary frequency, fatigue, low back pain, constipation, heartburn, pica, weight gain, edema of the lower extremities, and progressive abdominal enlargement. Determining the first day of the last menstrual period (FDLMP) is essential, though up to 40% of women cannot accurately recall it. After 16 weeks’ gestation, fundal height in centimeters from the pubic symphysis approximates gestational age in weeks. Pelvic examination may identify uterine enlargement or abnormal masses.
Pregnancy testing measures the β-subunit of hCG. Urine tests typically detect levels ≥25 mIU/mL but may yield false negatives with dilute urine or high vitamin C intake. Home tests can detect pregnancy 9–12 days after conception but should be confirmed with serum hCG. Serum hCG becomes detectable 8–11 days post-conception and normally doubles approximately every 48 hours until 6–7 weeks’ gestation. hCG may remain detectable for up to 60 days following abortion. Serum progesterone levels help assess viability; levels <5 ng />L suggest a nonviable pregnancy, while levels ≥25 ng/mL are consistent with viability.
Ultrasonography is essential when evaluating abdominal pain, vaginal bleeding, or suspected complications. It confirms intrauterine versus ectopic pregnancy, estimates gestational age, assesses fetal viability, and identifies abnormalities. Transvaginal ultrasound is more sensitive and can detect intrauterine pregnancy at 4–5 weeks, whereas transabdominal ultrasound visualizes the gestational sac at approximately 5.5–6 weeks. Transvaginal ultrasound is contraindicated in cases of premature rupture of membranes or third-trimester bleeding. MRI is considered safe in pregnancy and is often preferred for evaluating appendicitis. Radiation exposure from plain radiography or CT is dose-dependent; efforts should be made to keep fetal exposure below 5,000 mrad. Shielding should be used whenever possible.
In the emergency setting, assume pregnancy until excluded. Prehospital and ED management prioritize maternal stabilization, as optimizing maternal condition improves fetal outcome. Advanced cardiac life support or trauma protocols should be followed when indicated. If gestational age exceeds 24 weeks, the patient should be positioned in the left lateral recumbent position to reduce inferior vena cava compression and improve cardiac output. Oxygen, cardiac monitoring, intravenous access, and fluids should be administered as needed.
Medication use in pregnancy requires careful consideration, especially during the first trimester when organogenesis occurs. Clinicians should review medication safety classifications before prescribing. Acetaminophen is the preferred over-the-counter analgesic, with dosing up to 500 mg every 6 hours (maximum 4 g/day). Short-term use of opioids such as morphine, codeine, oxycodone, hydrocodone, or meperidine may be considered for severe pain. Ondansetron 4 mg IM or IV every 8 hours may be used for nausea, and vitamin B6 (25 mg three times daily) or ginger may also provide relief. Antibiotic selection depends on maternal allergies, gestational age, and likely pathogens. Prenatal vitamins should be encouraged.
Admission is indicated for obstetric complications such as hyperemesis gravidarum with dehydration, complicated urinary tract infection, ectopic or molar pregnancy, septic abortion, preterm labor, premature rupture of membranes, preeclampsia or eclampsia, and severe pregnancy-induced hypertension. Pregnant patients with serious medical conditions warranting admission in nonpregnant patients should also be admitted. Patients without complications may be discharged with instructions for obstetric follow-up by 6–8 weeks’ gestation.
Key principles include assuming pregnancy in all reproductive-age women until ruled out, reviewing medication safety before administration, and minimizing fetal radiation exposure. The primary goal in emergency care is always maternal stabilization to ensure the best possible fetal outcome.
Pregnancy is a normal physiologic state rather than a disease process, yet it imposes significant metabolic and anatomic changes on the mother to support fetal growth and development. In emergency care, all women of reproductive age presenting with abdominal pain are considered pregnant until proven otherwise—even with a history of sterilization. Hormonal changes driven primarily by placental progesterone and estrogen account for most physiologic adaptations. In adolescents, menarche typically occurs between ages 11 and 15. Pregnant adolescents may be unaware of or reluctant to disclose pregnancy; therefore, pregnancy must always be considered. Adolescent pregnancies also carry a higher risk of obstructive labor.
The physiologic changes of pregnancy are largely mediated by placental hormones. Human chorionic gonadotropin (hCG) prevents involution of the corpus luteum and stimulates continued production of estrogen and progesterone. Elevated hCG levels contribute to nausea and vomiting. Progesterone promotes development of decidual cells to nourish the early embryo, decreases uterine contractility to reduce the risk of spontaneous abortion, and helps prepare breast tissue for lactation. Estrogen stimulates enlargement of the uterus and breasts, growth of mammary ducts, enlargement of the external genitalia, and relaxation of pelvic ligaments and joints.
Diagnosis of pregnancy relies on history and physical examination, hormonal assays, and ultrasonography. The most common presenting symptom is amenorrhea in a sexually active woman, often accompanied by nausea, vomiting, breast tenderness, urinary frequency, fatigue, low back pain, constipation, heartburn, pica, weight gain, edema of the lower extremities, and progressive abdominal enlargement. Determining the first day of the last menstrual period (FDLMP) is essential, though up to 40% of women cannot accurately recall it. After 16 weeks’ gestation, fundal height in centimeters from the pubic symphysis approximates gestational age in weeks. Pelvic examination may identify uterine enlargement or abnormal masses.
Pregnancy testing measures the β-subunit of hCG. Urine tests typically detect levels ≥25 mIU/mL but may yield false negatives with dilute urine or high vitamin C intake. Home tests can detect pregnancy 9–12 days after conception but should be confirmed with serum hCG. Serum hCG becomes detectable 8–11 days post-conception and normally doubles approximately every 48 hours until 6–7 weeks’ gestation. hCG may remain detectable for up to 60 days following abortion. Serum progesterone levels help assess viability; levels <5 ng />L suggest a nonviable pregnancy, while levels ≥25 ng/mL are consistent with viability.
Ultrasonography is essential when evaluating abdominal pain, vaginal bleeding, or suspected complications. It confirms intrauterine versus ectopic pregnancy, estimates gestational age, assesses fetal viability, and identifies abnormalities. Transvaginal ultrasound is more sensitive and can detect intrauterine pregnancy at 4–5 weeks, whereas transabdominal ultrasound visualizes the gestational sac at approximately 5.5–6 weeks. Transvaginal ultrasound is contraindicated in cases of premature rupture of membranes or third-trimester bleeding. MRI is considered safe in pregnancy and is often preferred for evaluating appendicitis. Radiation exposure from plain radiography or CT is dose-dependent; efforts should be made to keep fetal exposure below 5,000 mrad. Shielding should be used whenever possible.
In the emergency setting, assume pregnancy until excluded. Prehospital and ED management prioritize maternal stabilization, as optimizing maternal condition improves fetal outcome. Advanced cardiac life support or trauma protocols should be followed when indicated. If gestational age exceeds 24 weeks, the patient should be positioned in the left lateral recumbent position to reduce inferior vena cava compression and improve cardiac output. Oxygen, cardiac monitoring, intravenous access, and fluids should be administered as needed.
Medication use in pregnancy requires careful consideration, especially during the first trimester when organogenesis occurs. Clinicians should review medication safety classifications before prescribing. Acetaminophen is the preferred over-the-counter analgesic, with dosing up to 500 mg every 6 hours (maximum 4 g/day). Short-term use of opioids such as morphine, codeine, oxycodone, hydrocodone, or meperidine may be considered for severe pain. Ondansetron 4 mg IM or IV every 8 hours may be used for nausea, and vitamin B6 (25 mg three times daily) or ginger may also provide relief. Antibiotic selection depends on maternal allergies, gestational age, and likely pathogens. Prenatal vitamins should be encouraged.
Admission is indicated for obstetric complications such as hyperemesis gravidarum with dehydration, complicated urinary tract infection, ectopic or molar pregnancy, septic abortion, preterm labor, premature rupture of membranes, preeclampsia or eclampsia, and severe pregnancy-induced hypertension. Pregnant patients with serious medical conditions warranting admission in nonpregnant patients should also be admitted. Patients without complications may be discharged with instructions for obstetric follow-up by 6–8 weeks’ gestation.
Key principles include assuming pregnancy in all reproductive-age women until ruled out, reviewing medication safety before administration, and minimizing fetal radiation exposure. The primary goal in emergency care is always maternal stabilization to ensure the best possible fetal outcome.
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