Pregnancy leads to several physiological changes that can alter the way the female body responds to injury. In some cases, these changes can mask the normal physiological response to trauma.
A solid understanding of these changes will help trauma nurses make an accurate assessment of the injured mother and provide optimal care to both mother and baby.
1. Increased blood volume can mask symptoms of hemorrhage
During pregnancy, the female body is usually in a hypervolemic state. Total blood volume can increase up to 50%. The increased blood volume improves tolerance to hemorrhage, which can mask signs or symptoms of bleeding. This is especially important when considering sources of internal hemorrhage, such as blood loss resulting from placental rupture or a fractured pelvis.
2. Increased cardiac output increases the “normal” heart rate
Cardiac output increases about 30% during pregnancy, which increases the patient’s heart rate by 15 to 20 beats per minute. As a result, mild tachycardia can be considered a “normal” finding in the pregnant patient.
3. Decreased vascular tone will decrease blood pressure
During pregnancy, the patient’s peripheral vascular tone decreases. This change will decrease both systolic resistance (by about 15 mg Hg) and diastolic resistance (by 15 to 20 mg Hg), resulting in decreased blood pressure.
4. Lying supine can significantly reduce cardiac output
After 20 weeks of gestation, the uterus can compress the vena cava when the pregnant patient is lying on her back. This can decrease cardiac output by up to 30%, resulting in hypotension.
5. Changes in plasma and red cell production can lead to dilutional anemia
During pregnancy, plasma volume increases up to 50%. Red cell production also increases, but to a lesser extent. This imbalance can lead to dilutional anemia. Hematocrit values of 32% to 34% are not uncommon.
6. White blood cell counts are elevated
White blood cells increase dramatically during the second and third trimesters. Pregnant patients may have white blood counts of 15,000 to 20,000, and values can be even higher during labor.
7. Higher fibrinogen levels increase the risk of clotting
During pregnancy, levels of fibrinogen and several other clotting factors rise significantly. This increases the risk of both deep vein thrombosis (DVT) and pulmonary embolism (PE).
8. Breathing adaptions create a state of respiratory alkalosis
As the uterus grows, it compresses the diaphragm. To compensate, the pregnant patient will breathe faster and blow off carbon dioxide, which creates a state of compensated respiratory alkalosis. As a result, arterial blood gas tests may not show acidosis until shock is advanced. In addition, increased oxygen consumption during pregnancy coupled with decreased lung capacity can result in decreased oxygen reserve, making both the uterus and the fetus vulnerable to hypoxia.
9. Abdominal organ displacement increases the risk of organ injury
The enlarging uterus pushes the liver, spleen and bladder upward within the abdominal cavity, which increases the risk of blunt trauma to those organs. In addition, the small bowels and large bowels are pushed backwards, which will tend to lead to diminished bowel sounds.
10. Gastrointestinal changes increase the risk of vomiting and aspiration
Increased progesterone and estrogen levels reduce the motility of the GI tract and can delay emptying times. In addition, the increase in gastric secretions during pregnancy can cause gastric reflux and passive regurgitation. All these changes increase the risk of vomiting and aspiration.
11. Decreased urine concentration can mask hypovolemia
As a result of large circulating volumes and increased renal blood flow, the pregnant woman does not concentrate urine. Consequently, a pregnant patient who is hypovolemic may still produce normal amounts of urine.
12. Pregnancy-induced hypertension can mimic TBI
Pregnancy-induced hypertension may occur at 20 to 24 weeks gestation. Symptoms can include signs of CNS irritability and seizures, which can mimic a traumatic brain injury (TBI). To differentiate between TBI and eclampsia, assess the patient for hypertension, proteinuria, hyperreflexia and peripheral edema.
Learn more about the pregnant trauma patient
This article is based on Obstetrical Trauma, an interactive online course from the Board of Certification for Emergency Nursing (BCEN®). Developed by trauma nursing experts, this CE-eligible course details the most common injuries in pregnant patients, explains pregnancy-specific complications, shows how to adapt the primary and secondary surveys for obstetrical trauma, and reviews life-saving interventions for both mother and fetus. To access Obstetrical Trauma and other courses for trauma nurses, visit BCEN Learn.
Obstetrical Trauma supports the continuing education requirements of the Trauma Certified Registered Nurse (TCRN®) program. The TCRN credential is the only national board certification for trauma nursing, and it spans the body of knowledge for care of the injured patient. More than 6,500 nurses worldwide have earned the TCRN credential. For more information, click here.