1. Analyze physiologic changes in pregnancy that impact outcomes for the pregnant trauma patient.
2. Identify complications in the pregnant patient who experiences trauma.
3. Outline additional monitoring for the pregnant trauma patient.

INTRODUCTION

Trauma during pregnancy is a frightening situation. Most medical professionals who deal with trauma do not have experience managing pregnant patients, and those who deal with pregnant patients rarely have experience with trauma protocols. Trauma courses discuss kinematics at length, and these concepts help us predict tissue and organ damage based on the mechanism of injury. However, all bets are off if the patient is pregnant! Emergency Department personnel are very knowledgeable about trauma assessment and management protocols, but pregnancy modifies the gravid patient's physiology in ways that complicate her assessment and care. This self-study module will combine information from both the obstetrical and the trauma clinical specialties and help the reader understand the factors that impact the care of the pregnant trauma victim.

Trauma is often defined as a surgical disease because victims are so likely to end up in the operating room. Pregnant women are certainly not immune to the devastating consequences of traumatic injury and it is interesting to note that accidents are more common during pregnancy than at any other time in an adult woman's life. Actually, trauma is the leading cause of death in the childbearing population. Most people consider ages 15 to 35 to be the childbearing years, but the reality, based on clinical observations, is that the childbearing years may include anything between 11 and 53 years! Thankfully, most traumatic injury sustained during pregnancy is minor, but health care providers must understand that even minor trauma during pregnancy can be very serious, and serious trauma can be devastating.

Consider the following situation:

A rural EMS squad was dispatched to a motor vehicular accident (MVA) with injuries. On arrival they found that a small car had been hit broadside on the driver's side. Both drivers were dead. The passenger in the car that had been hit was found lying face up in a ditch. She was obviously pregnant and very critically injured. There were deep lacerations on her right arm and she was lying in a pool of blood. She had significant head injuries and her eyes were fixed and dilated. She was very well managed at the scene and air lifted to a regional trauma center. A perimortum cesarean delivery was performed immediately upon her arrival in the ED and a term infant was delivered. The baby was vigorously resuscitated and survived in good condition and without apparent neurologic impairment.

It has been said that obstetrical trauma can precipitate therapeutic paralysis in a healthcare setting. Perhaps that's because we're not sure which is the complication…the trauma or the pregnancy? The answer probably depends on where you work, but combining the words trauma and pregnancy in the same sentence will definitely affect your comfort level, regardless of your clinical setting. It's important to understand that pregnancy is the only normal physiologic state in which all the physiologic parameters are abnormal. The mother and fetus have differing responses to pathologic events. The profound physiologic changes associated with pregnancy are due to hormonal influence, the mechanical changes caused by the expanding uterus, the increased pelvic vascularity, and the marked increase in metabolic demands. Every system is impacted by pregnancy. Changes in the cardiovascular, respiratory, gastrointestinal, and renal system are particularly significant, so pregnancy physiology must be considered in the assessment and evaluation of signs and symptoms, laboratory data, and patterns of injury. There are always two patients involved in any pregnant trauma situation, so an additional critical question must also be answered. "What is the fetal response to maternal injury?" Even minor maternal injuries can be associated with abruption, maternal-fetal hemorrhage, and preterm labor and delivery.

ETIOLOGY OF TRAUMA

Trauma is categorized as blunt, penetrating, or thermal. We are most likely to be dealing with blunt traumatic injuries during pregnancy, and motor vehicular accidents (MVAs), falls and assaults are the most frequently cited causes. Most of the injuries sustained during pregnancy are accidental and the incidence typically increases as gestation progresses. The uterus becomes vulnerable to blunt injury after it begins to rise out of the pelvis at about 16-20 weeks. Fetal injury before this time is unlikely unless direct pelvic trauma is involved. The fatigue and awkwardness associated with late pregnancy makes falls more likely. Anatomic changes and weight gain actually alter the pregnant woman's center of gravity, and relaxin (a hormone secreted by the placenta) relaxes the pelvic ligaments, with the resulting pelvic instability that causes gait changes. Health care providers should also be very aware of domestic violence as a potential cause of trauma. Battering is very frequent in our society and it is being recognized more often during pregnancy. We have understood for some time now that pregnancy is a high risk time in a violent relationship. Incidents typically increase during second and third trimesters. Patients who present frequently (the so-called "frequent flyers") with vague somatic complaints should be very carefully evaluated. Remember that the hospital may well be her only safe haven!

Self inflicted injuries are also seen during pregnancy. Suicide attempts are more frequent at the time of pregnancy diagnosis and during early third trimester. Approximately 1/3 of those attempting suicide during pregnancy are primiparous (first pregnancy). Risk populations include adolescents, single women, emotionally immature women, and those without adequate support systems.

While blunt trauma is the most common type of injury, other mechanisms also bring pregnant trauma victims into the healthcare system. Penetrating injury, involving gunshot wounds or stabbings to the abdomen, can be devastating at any time during pregnancy. Thermal injuries involving burns or electrical shock can cause maternal injuries that can potentially have critical implications for the fetus.

CONSEQUENCES OF MATERNAL TRAUMA

As we continue with this discussion about trauma during pregnancy, we will first focus on the most common reason for a trauma-related hospital admission, the automobile accident or MVA. Accidents are categorized as major, minor and insignificant. Major MVAs are associated with a high maternal mortality and an even higher fetal mortality. In general, the more severe the maternal trauma, the more likely that a significant fetal insult has occurred. A minor MVA usually leaves us reassured about the maternal condition, but unsure about the fetal condition. Most accidents are insignificant and are usually associated with a good outcome for the mother. However, we must all remember that minor and insignificant accidents can be associated with major fetal injuries and complications. Studies done many years ago by a physician named Rothenberger helped us understand why the fetal status always requires very careful assessment. His research during minor vehicular accidents involved carefully monitored pregnant baboons. The following quote is from his 1979 textbook, Trauma in Pregnancy.

"During a collision the uterus follows the laws of inertia, as does the rest of the woman's body: It continues in the direction the body was going until the body decelerates. The uterus then elongates and flattens itself against the anterior abdominal wall. The amount of deformation of the uterus depends upon the velocity of deceleration and the elasticity of the uterus. Abrupt deceleration may rupture the uterus directly without external penetration, but this is quite unusual. If the uterus remains intact, the elastic recoil of the uterine walls produces a wave-like motion in the amniotic fluid. This causes a reversal of the sequence and the uterus flattens in the opposite plane and becomes shorter. The concomitant rise in uterine pressure may be extreme, with pressures 10 times that observed in labor. The violent motions are more likely to cause a disruption of placental attachments rather than disrupt the uterine wall or crush the fetus. The placenta does not contain elastic tissue, and cannot stretch or contract to adjust to sudden increases or decreases in the area of its' attachment to the uterine wall. Placental tearing or rupture is quite unusual; separation from the uterine wall is much more common".

We now understand that three collisions occur during a crash. The first collision, involving the vehicle is quickly followed by the collision of the occupant and then by the occupant's internal organs. Remember that the fetus is considered an unharnesed passenger! Uterine tissue is rather elastic and has the ability to stretch and conform to changing intrauterine pressures. Unfortunately, the more rigid placental tissue cannot adapt to those same changing contours and pressures. The highest pressures are generated during the deceleration phase and Dr. Rothenberger's research showed us that intrauterine pressures can suddently increase to > 500 mm/sq inch at that time. When we remember that an adequate labor contraction generates intrauterine pressures between 50-70 mm/sq inch, then the pressures generated during deceleration become more impressive. Obviously pressures that high can disrupt placental attachments, so you should now understand that concern about the possibility of placental abruption is warranted.

SEATBELT USE DURING PREGNANCY

Please note that the pregnant victim, restrained by a seatbelt, does not experience an increased risk of injury to the fetus, uterus, or placenta. Actually, it is statistically much more dangerous for anyone to be unrestrained during an MVA. However, there are misconceptions about seatbelt usage during pregnancy. Several studies have indicated that only slightly over ½ of pregnant women use seat belt restraints, and of those, many do not use them correctly. Discomfort is listed as the major reason for non-use. Some women complain that they cannot fasten the seatbelt late in pregnancy, so they are obviously unaware that seatbelt extensions are available from dealerships. Many older cars are equipped with only the lap belt and this is a serious concern during pregnancy because it allows extreme forward flexion that can be associated with severe fetal injuries. Those potential fetal injuries include fractures of the skull, clavicle, femur, tibia, humerus, pelvis, and fingers. Potential maternal injuries, which are caused by the extremely high pressures associated with recoil, include abruption, rupture of the uterus, bladder, intestines, and diaphragm. The lap belt should never be placed directly over the uterus. Pregnant women should be taught to position the lap belt low and under the uterus. Emergency medical service personnel (EMS) should also be reminded that restraint belts should be placed above and below the uterus. The three point harness is considered safer during pregnancy because it prevents forward flexion and helps to distributes the intrauterine pressures that are generated during deceleration. Again, the lap portion of the belt should be placed low and under the uterus. Breast compression by the upper portion of the belt is not a concern, although seatbelt bruising across the breast will likely be evident if the woman is involved in an accident. Pregnant women should also be reminded to put the seat back as far as possible in an attempt to avoid head and knee injuries. We're beginning to learn more about injuries associated with air bag deployment, especially in children and in "vertically challenged" adults, but there is still little information about air bag deployment during pregnancy.

INJURY PATTERNS

The driver's forceful contact with the steering wheel during an accident is always a concern, but during pregnancy, the potential for additional injuries must also be considered. The maternal bladder becomes an abdominal rather than a pelvic organ during mid-pregnancy, as it rises on the peritoneal wall due to the expanding uterus. The large uterus too is very vulnerable to injury. The fetal head becomes fixed in the maternal pelvis during late pregnancy, so the possibility of fetal skull fracture should also be considered within the so-called "ring of injuries."

One cautionary note here…We now understand that various prostaglandins are released as a result of tissue trauma. Prostaglandins of the E and F series are known to cause uterine contractions, a fact which helps explain why preterm labor can be a consequence of traumatic injury. Abdominal pain and tenderness are significant symptoms and may indicate uterine contractions and possibly labor. Any evidence of vaginal fluid must also be investigated, preferably by an OB provider. A speculum exam rather than digital exam is preferred in these situations.

Abrupt separation of the placenta can occur due to the deceleration forces generated during an accident, especially if the placenta is implanted on the anterior uterine wall. Abruptio placenta usually occurs within 24 to 36 hours following the injury, but it is the wise clinician who understands that delayed abruptions have been noted up to seven days following the traumatic event. Ninety percent of abruptio patients experience obvious bleeding, but the amount of bleeding does NOT correlate to the extent of the abruption. Occult retroplacental losses of up to 2000 ml have been documented, with only minimal associated vaginal bleeding. Sometimes a central placental disruption occurs while the edges of the placenta remain sealed. The patient may experience little or no vaginal bleeding in this situation. Other indications of abruption can include uterine irritability and pain. Pain associated with an abruption can be described as anything from mild cramping to excruitating, and some patients experience no pain whatsoever. The fetus is sometimes referred to as the "miner's canary" because the fetus typically exhibits fetal heart tone indications of decompensation very early in the situation, often before the mother becomes symptomatic. Therefore, any pregnant trauma patient requires obstetrical consultation and careful fetal monitoring by experienced perinatal staff.

Uterine rupture due to blunt trauma is unusual, but there is increased potential if the victim had a previous cesarean delivery. When we consider that the national cesarean section (C/S) rate is approximately 22%, it becomes obvious uterine rupture is also a possible complication. Pay attention if your patient has a horizontal suprapubic or vertical abdominal scar, as that may indicate a previous cesarean delivery. Signs and symptoms of uterine rupture usually involve evidence of extreme pain associated with hemorrhage and shock, and rapid fetal decompensation.

PENETRATING INJURIES

Penetrating traumatic injuries include stabbing and gunshot wounds and surprisingly, statistics show that these injuries are often inflicted by the father of the baby. The maternal organs are fairly well protected by the uterus during late pregnancy, but of course, the uterus remains quite vulnerable. It is interesting to note that women tend to stab overhand, while men are more likely to stab with an underhand motion. The damage inflicted depends in great part on the length of the blade. Overall, only about ½ of all pregnant stabbing victims end up in the OR. Stab wounds are not always explored, and simple uterine lacerations can sometimes be repaired without disturbing the pregnancy. Even fetal knife wounds will heal in utero, although slowly. One case reports a woman who used a kitchen knife to self inflict 7 wounds to the uterus. Four wounds were deep enough to reach the anterior surface of the uterus, but only two of the wounds actually breached the uterine wall. The uterine lacerations were repaired and because the baby was stable, the pregnancy was allowed to continue. At delivery, a few weeks later, it was discovered that the baby had two healed lacerations, one on the back and one on the thigh! Remember that there is always the potential for liver and small bowel involvement with upper abdominal knife wounds. The small intestines become displaced and compartmentalized within the upper abdominal quadrants during late pregnancy, so the potential for sepsis with bowel perforation must be considered with penetrating trauma in this area.

Gunshot wounds are actually more common than knifings and are generally associated with a higher morbidity and mortality than knifings. Ballistic damage will depend upon the type, caliber, and range of the weapon. Gunshot Injury patterns are unpredictable because the damage is not confined to the tract of the bullet. The tissue damage will extend at right angles due to the kinetic energy dissipated by the missile. The uterus can absorb much of the energy and actually protect maternal vital organs. Gunshot wounds are typically explored, so you can expect that your patient will probably be going to the OR.

THERMAL TRAUMA

Thermal injury occurs when skin comes into contact with a heat source that coagulates the skin's protein component. The resulting coagulation and necrosis causes skin, cellular and capillary disruption, leading to additional adjacent skin damage from the decreased blood flow. Burn injuries during pregnancy are fairly uncommon, but when they do occur, it is more likely that they happen in the home and often at dinnertime. The risk to the mother involves the inhalation of noxious fumes, shock, and infection. We should all be aware that the fetus can die at oxygen levels that are compatible with maternal survival. Carbon monoxide binds to both maternal and fetal hemoglobin and lethal CO fetal levels can exist with non-lethal maternal levels. Shock and sepsis are very prominent in the pregnant burn victim and spontaneous labor is also a concern, again due to prostaglandin release from injured tissues. Note that the "Rule of Nines" is used without modification in the pregnant burn victim. Fetal survival is poor in situations involving > 50% burn surface area (BSA), so depending on gestation, delivery may be part of the immediate treatment plan.

It often seems to be an "all or none" phenomenon when a pregnant woman sustains an electrical shock, meaning that there is either an essentially normal outcome, or fetal death. It is important to remember though, that even common household shocks can be associated with fetal compromise. Electrical current will follow a pathway from hand to foot, but the current tends to follow the path of least resistance. The current enters through the skin and then travels deep into tissue to follow blood vessels, nerves, tendons, and bone. The current also disperses through the uterus, so a history of even minor household shock mandates careful monitoring of the fetal condition. The following fetal complications are associated with non-lethal maternal electrical shock; decreased amniotic fluid volume, decreased fetal movement, increased intrauterine growth restriction (IUGR), and increased incidence of stillbirth.

GENERAL MANAGEMENT OF TRAUMA DURING PREGNANCY

The primary exam is no different for the pregnant victim than for the non-pregnant. The ABCs must be followed and life threatening situations managed appropriately. The secondary exam, which involves a head to toe assessment, includes the uterus.

Trauma care providers must be aware that vena caval syndrome can seriously impact uterine perfusion in the pregnant victim. The supine position allows the heavy uterus to compress the large maternal vessels that return blood from the lower extremities. Approximately 1//3 of the maternal blood volume can be sequestered in the lower extremities if no one pays attention to the patient's position. Stroke volume can also be profoundly decreased when the pregnant victim is maintained in the supine position. Trauma protocols mandate immobilization during initial assessment and until the cervical spine is cleared, but remember that the entire backboard can be tilted slightly to the left to relieve inferior vena caval syndrome until the pregnant trauma victim can be safely repositioned.

AXIOMS FOR THE CARE OF THE PREGNANT TRAUMA VICTIM

The following axioms provide additional information to assist providers in caring for pregnant trauma victims. Pregnancy physiology impacts every system and a clear understanding of the physiologic changes associated with pregnancy will insure that this victim receives appropriate trauma and obstetrical care.

AXIOM # 1…THE BABY DIES IF THE MOTHER DIES

All immediate resuscitative care must be directed to the mother. Maternal death is the leading cause of fetal death and head injuries and hemorrhagic shock are responsible for the majority of maternal deaths. Fetal death typically occurs by 1 of 5 mechanisms; maternal death, maternal shock, maternal hypoxia, uterine or placental damage, and direct fetal trauma (especially of the engaged fetal head). Prompt and effective maternal resuscitation is the best fetal therapy. A well respected obstetrical lecturer, Dr. Gary Hanks, once remarked that "a fetus surrounded by a dead mother does not do well!" It is appropriate to follow all BLS (Basic Life Support) and ACLS (Advanced Cardiac Life Support) protocols. A slightly higher position on the maternal chest should be considered when performing cardiac compressions because the thoracic cavity is modified in late pregnancy due to elevation of the diaphragm by the gravid uterus.

A perimortum cesarean delivery is truly a crisis in any unit, but it must be considered quickly if maternal survival is unlikely. The uterus is usually entered by a rapid midline incision. There is often little bleeding in the mortibund patient due to minimal perfusion pressures. CPR should be continued throughout the perimortum cesarean procedure. There have been a few instances of maternal improvement following delivery of the baby. This very infrequent event is probably due to the autotransfusion associated with placental delivery. Of course, resources for an aggressive neonatal resuscitation would be necessary in any perimortum cesarean situation.

AXIOM # 2…SYMPTOMS OF ADVANCING SOCK ARE SUBTLE

Maternal physiologic compensatory mechanisms will compromise this victim's responses to hypovolemic shock. Maternal blood volume increases by up to 50% during pregnancy to support uterine perfusion. Uterine blood flow increases from the non-pregnant 50 ml per minute to at least 500 ml per minute. The pregnant woman who experiences significant blood loss has the ability to immediately vasoconstrict uterine arteries and divert blood from her uterus to her central circulating volume. She essentially initiates an autotransfusion to maintain her circulating volume, but at the expense of uteroplacental circulation! Typical signs and symptoms of hypovolemia are often not evident until she has sustained at least a 30% volume loss. This is the patient who will abruptly decompensate. Remember that the gravida's physiologic response to shock is self preservation at the expense of uteroplacental perfusion.

AXIOM # 3…THE GRAVID UTERUS COMPRESSES MAJOR BLOOD VESSELS

Remember too, that vena caval compression can trap up to 30% of her total blood volume in her legs. It is well documented that decreases in central circulating volume initiate physiologic responses that decrease uterine blood flow. Inferior venal caval compression should be avoided if the patient appears pregnant. It only requires a 15 degree left tilt of the backboard using a rolled bath blanket to maintain uterine displacement. The uterus can also be manually displaced during imaging procedures, and during critical situations, such as CPR, that require a supine position. Elevation of the pregnant victim's legs, if appropriate, can also increase blood return from the lower extremities. This technique may be beneficial during CPR. If MAST trousers are necessary, only the leg compartments should be inflated.

AXIOM # 4…PREGNANT WOMEN ARE AT GREAT RISK FOR BLEEDING

Unfortunately maternal blood loss is often underestimated. Providers should probably operate under the assumption that "she is bleeding in the belly until otherwise proven." The pelvic vasculature during pregnancy is massive and retroperitoneal bleeding is likely. Damage to both the liver and spleen can be caused by displaced rib fractures. Splenic rupture is the most common cause of massive intraperitoneal bleeding

Bleeding from fracture sites can also account for extensive hemorrhage. Blood loss due to pelvic fractures is usually estimated at 1000 ml per fracture line. Maternal pelvic fractures are also frequently associated with urinary tract injury since the bladder is elevated and considered an abdominal organ in late pregnancy. Pelvic fractures should also raise suspicions about fetal head injury. Femur fracture can account for 1000 ml, and blood loss associated with tibial shaft, humerus, and rib fractures can also be significant. Vascularity of the head and neck is increased during pregnancy, so maxillofacial injuries can bleed profusely.

AXIOM # 5…RESPIRATORY CHANGES MAKE HER VERY SENSITIVE TO HYPOXIA

Pregnancy related mechanical and chemical changes of the respiratory system allow her to breathe more efficiently and effectively. Her respiratory center is extremely sensitive to even minor changes in carbon dioxide levels and her respiratory rate will quickly reflect any problems. The maintenance of fetal metabolism requires that she take in more oxygen and blow off more carbon dioxide during pregnancy. Since the pregnant woman blows off more carbon dioxide (acid) from the lungs, she compensates by excreting more bicarbonate (base) from the kidneys. These compensatory mechanisms maintain her blood pH between 7.40 and 7.45, but the increased renal excretion of bicarbonate means that she has little ability to buffer the respiratory acids that are accumulated during hypoxic episodes.

Pregnancy hormones are responsible for increased vascularity, edema, and friability of the airway mucosa and bleeding is easily stimulated. Airway placement should be done very gently to avoid trauma to fragile tissues. Airway edema is very common, so intubation seldom requires anything larger than a size 7.0 ET tube. Nasal intubation often initiates excessive bleeding due to the increased vascularity of the upper airways. Be aware too, that the larynx is slightly elevated and more anterior during pregnancy.

AXIOM #6…EVERY PREGNANT VICTIM HAS A FULL STOMACH

Progesterone, the major hormone of pregnancy, causes a decrease in gastric motility. When significant trauma is experienced, gastric motility probably ceases. Relaxation of the esophageal sphincter occurs, again due also to hormonal influence, and the pylorus is obstructed by the enlarged uterus. Therefore, the pregnant trauma victim is at extremely high risk for regurgitation and aspiration. She should always be considered a "full stomach" regardless of when she last ate. Emesis of gastric contents and gastric acid should be anticipated and suction must be immediately available. Intubation should be accomplished utilizing Sellick's maneuver (cricoid pressure) to decrease aspiration potential. Remember that the stomach is positioned more horizontally and is actually separated into two chambers by the dome of the uterus in late pregnancy. If a non-particulate antacid such as Bicitra is administered prior to anesthesia, the patient should be turned so that the medication is mixed through the entire stomach contents.

AXIOM # 7…VOLUME SUPPORT IS MANDATORY

It must be understood that there is little uterine perfusion unless the mother is normovolemic. It is best to resuscitate with volume rather than with drugs and it is actually rather difficult to overload a pregnant victim during her initial care. Her blood volume is normally quite expanded due to the pregnancy, so immediate fluid resuscitation can and should be very aggressive. Continued fluid management however, should be based on careful assessment of her fluid status. We now understand that massive hydration can dilute coagulation factors and hamper the mechanisms of the clotting cascade. Lactated Ringers is an isotonic fluid that closely resembles extracellular fluid , so it is often preferred during trauma situations. Isotonic solutions are good choices for IV replacement because these solutions stay mainly in the vascular spaces and increase circulating volume. Isotonic solutions also have the advantage of being compatible with blood. Dextrose solutions should be avoided in the pregnant victim. If delivery becomes necessary, the glucose that the fetus received in utero could precipitate severe hypoglycemic episodes in the early neonatal period.

AXIOM # 8…THE PHYSICAL FINDINGS OF THE ABDOMEN CHANGE

Most maternal organs are mobile and the enlarging uterus displaces everything in its path. The small intestines are compartmentalized in the upper abdomen and very vulnerable to injury. The large bowel is displaced superiorly and posteriorly, so "decreased bowel sounds" is a typical finding. Actually the large bowel is less likely to be injured because it is so well protected by the uterus. The spleen and liver can be distended, compressed, displaced, and possibly even ruptured. Remember that the bladder is elevated into a lower abdominal rather than the normal pelvic position. Peritoneal signs are often diminished because the peritoneum is so tightly stretched across the expanded uterus. Referred pain is common and guarding and rigidity may not be evident despite significant injury. Pain and rebound tenderness however, may actually indicate labor. Consider marking and timing the patient's fundal height on admission. Changing fundal height and contours may indicate abruption with intrauterine bleeding.

AXIOM # 9…HYPERCOAGUALABILITY IS NORMAL

Clotting ability during pregnancy is physiologically enhanced. Some clotting factors increase significantly, which then helps decrease the potential for hemorrhage during placental delivery. Placental abruption causes the release of thromboplastin (factor 3) which can initiate overwhelming retroplacental clotting via the extrinsic pathway. Available clotting factors can be quickly used and then profound bleeding can occur related to an acute depletion coagulopathy. Additionally, we should all be aware that the hypercoaglable state that is normal for pregnancy will increase her risk for thrombus and embolus if her injuries require prolonged bedrest or immobilization.

AXIOM # 10…TRAUMA IS AN EXTREME EMOTIONAL SITUATION

Maternal and family fears focus especially on the possible loss of the baby. Providers should be alert to reassuring fetal signs such as normal heart tones and fetal movement, but always remember that violent fetal movement may precede fetal death. Baseline fetal heart rate should be between 120-160 BPM. Fetal tachycardia is an early sign of compromise. Later signs include decreased variability, periodic decelerations and bradycardia. Continuous electronic fetal heart rate monitoring is mandatory. Intermittent auscultation of fetal heart tones is never appropriate for trauma assessment. However, accurate assessment of fetal monitoring is a critical component of her care and it is best accomplished by experienced perinatal providers. Fetal heart tones should be monitored for a minimum of 4-6 hours. Fetal movement should be indicated by a mark on the fetal monitoring graph and correlated to fetal heart rate. This is properly termed a non-stress test (NST) and when reactive, it is considered a reassuring indicator of fetal condition. A reactive pattern means that the fetal heart rate accelerates appropriately in response to fetal movement. If the patient is cleared for dismissal by both trauma and obstetrical providers, she must be given detailed information concerning daily fetal activity monitoring and the need for on-going medical attention. In general, a very quiet fetus that is not moving normally according to the mother's assessment, needs to be immediately reevaluated.

It should be obvious now that all medical personnel must operate with a very high index of suspicion when the trauma patient is pregnant. However, in order to recognize abnormal assessment findings, we must first recognize normal pregnancy findings. The following chart will help you quickly determine if assessment findings are normal or a reason for concern.

ASSESSMENT	PREGNANCY FINDINGS
Vital signs	Temperature is not affected by pregnancy. Expect a 20-30% ↑ in pulse rate. 80-90 BPM is typical. A slight in ↑ in respiratory rate is expected A mild ↓ in B/P is typical, especially during 2nd trimester when progesterone levels are high.
Oxygenation	Normal pulse oximetry readings should be expected. Arterial blood gases typically reflect a compensated respiratory alkalosis.   PH is usually 7.4 to 7.45. PCO2 will be ↓ to 27-31 mm Hg   PO2 is usually ↑ to 104-108 mm Hg.   HCO3 levels will be slightly ↓ with results ranging between 18-22 mEq/L.
Neurologic	Any seizure activity should be considered eclampsia until otherwise proven. Check for hypertension, proteinuria, and edema when attempting to differentiate neurologic injury from eclampsia. Remember, the eclamptic seizure could have been the reason for the accident. Unequal pupils, sudden changes in level of consciousness (LOC), and unequal strength point more strongly to neurologic injury.
Cardiac	Systolic murmurs are common due to ↑ blood volume and altered flow through cardiac valves. Left axis deviation on 12 lead EKG is typical due to elevation of the diaphragm. Pulmonary artery monitoring will indicate high cardiac output, ranging from 6-8 L/min, and lowered SVR (1200 dynes is typical). Pregnancy is a time of high output and low resistance. All other pressure readings will be within expected norms
Labs	Hemoglobin (Hg) is typically about 11.5 gms with hematocrit (Ht) of approximately triple the Hg This is due to pregnancy related physiologic hemodilution. A significantly lowered Ht indicates excessive hemodilution, probably as a result of excessive fluid resuscitation. An ↑ Ht may indicate the hemoconcentration that is a pathologic finding in preeclampsia. Hypercoagulability is the norm, so a fibrinogen of < 250 mg/dl is suspiciously low. Decreasing platelets (< 100,000) may indicate an active clotting process and of course, increased fibrin split products (FSPs) indicate active fibrinolysis in response to active clotting (DIC). Renal function is much enhanced during pregnancy, so BUN and creatinine should be on the low side of normal. Increasing serum levels of nitrogenous wastes should raise the suspicion of renal damage or acute glomerulonephritis, possibly as a result of hypovolemic shock. High renal labs may also indicate renal compromise associated with preeclampsia. Liver function studies do not normally change significantly during pregnancy, so elevations may indicate direct organ injury or HELLP Syndrome. This variation on severe preeclampsia is characterized by elevated liver enzymes and and low platelets. Be aware that alkaline phosphatase is usually ↑ during pregnancy since it is produced by the placenta.

Special Note...Significant fetal bleeding is fairly common when the mother experiences severe trauma and sometimes the fetal blood loss can be life threatening. Fetal blood loss can initiate maternal isoimmunization in the Rh negative mother. The Kleihauer-Betke is a laboratory test that identifies fetal red blood cells in a maternal blood smear. Results are usually available within about 45 minutes and indicate the volume of the fetal bleed. Results may be reported as a percentage or as a raw number. Total fetal blood volume is estimated using the formula 80 ml per kg. Using this method, a 3 kg infant would be expected to have a blood volume of about 240 ml. An Rh negative mother who sustains a significant fetal bleed will require prophylactic Rhogam.

IMAGING STUDIES

The International Commission of Radiologic Protection estimates that the fetus absorbs approximately 30% of the maternal dose of ionizing radiation during imaging procedures. The maximum fetal exposure should be limited to < 10 rads, as excessive exposure has been linked to congenital malformations, intrauterine growth restriction (IUGR), and fetal death. It goes without saying that the maternal abdomen should be shielded to the extent possible. Most experts agree that all imaging studies can be completed within the 10 rad limit for fetal exposure, so all necessary imaging studies for trauma assessment can be safely obtained.

It is common to depend on ultrasound technology for information about the fetal condition and the integrity of the placenta. Unfortunately, a retroplacental clot associated with abruption can look very much like placental tissue. Ultrasound is reported to have only a 40% sensitivity for abruption accuracy. It is far better to base clinical decisions about fetal and placental condition on fetal monitoring indicators and patient symptoms.

MEDICATIONS

Narcotics and anesthetics can be appropriately used during pregnancy. Antibiotics are often necessary, but use should be limited to the penicillins, penicillin substitutes, aminoglycosides, and cephalosporins. Sulfa products cause dissociation of fetal bilirubin from albumin and tetracyclines are known to cause yellowish discoloration of the fetal teeth. Tetanus toxoid should be administered as indicated.

Legal Potential Remember that the "twin towers" of defense are documentation and communication

Decision tree…provides general guidance for the management of the pregnant trauma victim



It is probably necessary at this point to remind you that most trauma during pregnancy is minor in nature. However, two patients are at risk in these situations, and the one you can't see will likely cause you the most anxiety. Competent management of the gravid trauma victim requires an solid understanding of the physiologic changes that occur during pregnancy. Knowledge of trauma protocols plus knowledge of pregnancy physiology will insure that these patients receive optimal care.

Selected References