CHAPTER 56 GYNECOLOGIC INJURIES

TRAUMA IN PREGNANCY

Gynecologic trauma includes a large variety of relatively rare and challenging injuries from blunt and penetrating mechanisms. While motor vehicle crashes are the leading cause of major injury in pregnant women, penetrating trauma accounts for almost all injuries to the fallopian tubes, ovaries, and nongravid uterus. Pelvic fractures and straddle injuries often result in trauma to perineum, vagina, and less commonly the cervix and uterus. Injuries to the external genitalia are frequently associated with interpersonal violence and should be treated in that context.

In recent years, trauma has been recognized as the leading cause of death during pregnancy. As unsuspected pregnancy is relatively common in the reproductive years, this possibility must be considered when evaluating female trauma victims. Pregnancy produces significant physiologic and anatomic changes that must be recognized and understood by all health care providers treating pregnant trauma patients (Table 1).

Table 1 Changes in Maternal Physiology during Pregnancy

Change	Consequence
Cardiac output and blood volume increase	Shock after >40% of blood lost
Expansion of plasma volume	Physiologic anemia
Decline in arterial and venous pressure	Vital signs are not reflective of hemodynamic status
Increase of resting pulse
Chest enlargement	Change in anatomic landmarks
Chest enlargement	Caution during thoracic procedures (e.g., thoracostomy)
Diaphragm rise
Substernal angle increase
Decrease in functional residual capacity	Rapid decline in PO₂ during apnea or airway obstruction
Increase in oxygen consumption
Airway closure when supine
Increase in tidal volume and minute ventilation	Fall in PCO₂ and bicarbonates
Decrease in anesthetic requirements	Need for adjustment of sedative doses
Decreased gastric motility	Risk of aspiration
Relaxation of gastroesophageal sphincter

Incidence

According to some authors, nearly 50% of maternal deaths are related to trauma. From 6%–7% of all pregnancies are complicated by trauma, and 0.4% of the patients require hospitalization for treatment of injuries. In 1995, Weiss reported an epidemiologic 1-year study in which all women of childbearing age who required hospitalization for injuries were screened for pregnancy; of 16,722 women, 761 were identified (4.6%) as being pregnant. The actual number of injured pregnant women is underestimated as many of them are unreported, especially with injuries resulting from domestic violence.

Mechanism of Injury

Motor vehicle collisions are the most common causes of injury during pregnancy. As the pregnancy progresses, the shift in the woman’s center of gravity and diminished agility can result in falls and accidental injuries. Other common causes of injury include automobile–pedestrian collisions and firearm injuries. Younger women are at higher risk for injury during pregnancy, with a mean maternal age of 25 years.

Young pregnant women are also at high risk for injuries resulting from battery. It has been reported that 10%–30% of women are abused during pregnancy, and 5% of cases involving abuse result in fetal death. Of injured pregnant patients, 17% experience intentional trauma and 60% suffer repeated episodes of domestic violence. Physical abuse is suspected when the injuries are located proximally and in the midline, rather than distally, and trauma is evident to the neck, breast, face, upper arms, and lateral thighs, as well as with bizarre injuries such as cigarette burns or bites.

Diagnosis

Care is undertaken with attention to both mother and fetus. Uterine blood flow lacks autoregulation and is related directly to maternal blood pressure; consequently, treatment priorities are the same as for the nonpregnant trauma patient, as the best initial treatment for the fetus is the optimal resuscitation of the mother. A thorough physical exam complemented by imaging studies is necessary to identify some of the unique problems that might be present in any pregnant patient, including blunt or penetrating injury to the uterus, placental abruption, amniotic fluid embolism, isoimmunization, or premature rupture of membranes.

As a result of significant changes in maternal physiology (see Table 1), supplemental oxygen should be administered to prevent maternal and fetal hypoxia during transport and in the resuscitation room. Fluid resuscitation should be initiated even in the absence of signs of hypovolemia and shock. To avoid supine hypotension associated with the uterine compression of the inferior vena cava (IVC), patients in the second or third trimester of pregnancy should be transported on a backboard tilted to the left, with special attention to immobilization of the cervical spine. If the patient is kept in a supine position, the right hip should be elevated 4–6 inches, and the uterus should be displaced manually to the left. This maneuver increases cardiac output by 30% and restores circulating blood volume. Although only about 10% of pregnant patients at term develop symptoms of shock in the supine position, fetal distress may be present even in normotensive mothers; therefore, right hip elevation should be maintained at all times including during operative procedures.

Hospital Care

Primary survey includes assessment of airway, breathing, and circulation (ABCs), including volume replacement and hemorrhage control. Secondary survey includes the obstetrical history, physical examination, and evaluation and monitoring of the fetus. The history should include the date of the last menstrual cycle, expected date of delivery, and any problems or complications of the current and previous pregnancies such as preterm labor or placental abruption. Comorbidities such as pregnancy-induced hypertension and diabetes mellitus should also be documented.

The abdominal examination is critically important, as is a determination of uterine size, which provides an approximation of gestational age and fetal maturity. A discrepancy between dates and uterine size suggests uterine hemorrhage or rupture. Uterine rupture is suspected with peritoneal signs, abdominal palpation of fetal parts due to extrauterine location, and inability to palpate the uterine fundus. However, as the uterus enlarges, it displaces the intestines upward and laterally, stretching the peritoneum and making the abdominal physical examination unreliable.

Determination of gestational age is particularly important because this will guide the decision for a premature delivery if indicated. Most institutions will accept a 24–26 week pregnancy as viable, with a probability of survival ranging from 20%–70%. Radiographic estimation of gestational age is bound to an error of 1–2 weeks. Unless the date of the conception is known exactly, gestational age is particularly difficult to determine. A good rule of thumb is to consider patients with a uterus halfway between the umbilicus and the costal margin as having a viable pregnancy (Figure 1). An algorithm for initial maternal and fetal assessment is presented in Figure 2.

Figure 1 Computed tomography scan showing pregnant uterus above the level of umbilicus indicating a viable fetus.

Figure 2 Algorithm for initial maternal and fetal assessment. OB, Obstetrics; US, ultrasound; DPL, diagnostic peritoneal lavage; C-section, cesarean section.

(Adapted from Knudson MM, Rozycki GS, Paquin MM: Reproductive system trauma. In Moore EE, Feliciano DV, Mattox KL, editors: Trauma, 5th ed. New York, McGraw-Hill, 2004, pp. 851–875.)

Physical evaluation of the pregnant patient must be directed to the detection of the following six pregnancy-related acute conditions.

Plain anteroposterior chest x-ray	<0.005 rad
Pelvic x-ray	<0.4 rad
CT scan of head (1-cm cuts)	0.05 rad
CT scan of upper abdomen (20 1-cm cuts)	3.0 rad
CT scan of lower abdomen (10 1-cm cuts)	3.0–9.0 rad