(Radiographics. 1999;19:S243-S255.)
© RSNA, 1999
Screening Helical CT for Evaluation of Blunt Traumatic Injury in the Pregnant Patient1
Catherine Lowdermilk, MD, 2,
Morris L. Gavant, MD,
Waleed Qaisi, MD,
O. Clark West, MD and
Stanford M. Goldman, MD
1 From the Department of Radiology, University of Tennessee, Memphis College of Medicine, 800 Madison Ave, Memphis, TN 38163 (C.L., M.L.G., W.Q.); Department of Radiology, the Regional Medical Center at Memphis, Elvis Presley Memorial Trauma Center, Tenn (C.L., M.L.G., W.Q.); and the Department of Radiology, University of Texas, Houston (O.C.W., S.M.G.). Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received January 27, 1999; revision requested February 19; final revision received May 28; accepted June 1. Address reprint requests to M.L.G.
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Abstract
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Pregnant patients who sustain severe blunt trauma are infrequently encountered in most practices. However, detection of internal injuries including those to the gravid uterus is essential since maternal disability or fetal loss are physical and psychologic catastrophes that have long-term effects on the mother and her family. Computed tomography (CT) is commonly used to detect blunt traumatic injuries and can play an important role in the screening of the injured pregnant woman. The normal gravid uterus and physiologic changes of pregnancy can confound CT interpretation. Inhomogeneous enhancement of placental cotyledons, hydronephrosis, and enlarged ovarian veins are normal findings. Avascular regions in the placenta indicate infarction or abruption with impending fetal demise. Although CT can demonstrate uterine rupture and retroperitoneal hemorrhage, direct detection of fetal injuries is rare. Fetal demise is more common when maternal injuries include trauma to the uterus. Although screening ultrasonography can depict fetal distress, use of screening CT allows a concurrent evaluation of multiple areas in the pregnant trauma patient including the uterus. CT is a useful diagnostic tool in the triage of the critically injured pregnant woman.
Index Terms: Fetus, injuries, 856.41 • Fetus, death, 856.41 • Pregnancy, 856.41
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INTRODUCTION
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Pregnant patients who sustain severe blunt trauma necessitating radiologic evaluation are infrequently encountered in daily practice. Yet, blunt trauma may complicate up to 7% of pregnancies (1,2), with injuries that threaten the expectant mother and the fetus. Hemodynamic instability caused by undetected visceral or vascular injury to the chest, abdomen, or pelvis may lead to fetal and maternal death despite the absence of direct injury to the uterus. Maternal disability or fetal loss are physical and psychologic catastrophes that have long-term effects on the family. Thus, rapid evaluation and detection of serious internal injuries is essential.
Ultrasonography (US) may be used to evaluate the injured pregnant woman. Elective obstetric US, performed by experienced physicians and sonologists, is an excellent tool for evaluating fetal well-being and placental morphology (3). Emergency focused abdominal US is increasingly used to screen patients suffering blunt trauma. In a hemodynamically unstable patient, the technique is useful for detecting intraperitoneal hemorrhage or fluid, which indicates a visceral injury that may require surgery. However, visceral injuries unaccompanied by intraperitoneal hemorrhage are often missed at US (4). In addition, US is not sufficient for evaluating the chest, mediastinum, aorta, spine, retroperitoneum, bowel, bladder, and bony pelvis (4). Because the gravid uterus distorts the normal peritoneal relationships and contents, even experienced ultrasonographers may have difficulty identifying intraperitoneal fluid and visceral injuries during the short time available to perform the examination. Although US is an important diagnostic tool for the hemodynamically unstable pregnant patient, it may not be reliable enough to prevent delayed morbidity and mortality from a missed injury.
Computed tomography (CT) is the most sensitive, specific, accurate, and cost-efficient diagnostic tool available to evaluate stable, seriously injured, nonpregnant women with blunt abdominal trauma (4). Thus, CT might be considered for evaluating hemodynamically stable pregnant trauma patients because of the technical ease with which it is used to rapidly screen the chest, abdomen, and pelvis for serious injuries. In addition, CT is a familiar examination that is frequently used to evaluate the female pelvis for benign and malignant disease, and it is available around-the-clock in busy emergency departments or trauma centers.
Concerns about long-term morbidity from induced neoplasms and birth defects have led to an aversion to the use of ionizing radiation for elective evaluations of ill pregnant women. However, if the need for such an examination is great—for example, to accurately detect life-threatening injuries to the mother—the low risk of potential injury to a fetus should not impede the performance of radiographic studies (5).
The normal and abnormal CT findings encountered in blunt abdominal trauma to these patients have been infrequently studied or described (most likely due to the reservations about fetal exposure) (6). Our goal is to familiarize radiologists with the CT appearance of the normal and injured uterus in the pregnant patient. In this article, we discuss use of CT in pregnant trauma patients, including indications for and possible risks of the procedure; CT appearances of the normal placenta, fetus, and physiologic changes of pregnancy; and CT findings of the various types of uterine and nonuterine injuries. Our observations and illustrations have been derived from the clinical experience of two trauma centers.
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CLINICAL EXPERIENCE
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The clinical experiences of two regional level one trauma centers from January 1995 to June 1998 were combined for a retrospective nonrandomized, nonblinded study. During this 42-month period, 605 of 27,500 patients treated for traumatic injuries were pregnant or had positive urine pregnancy tests. Of these 605 women, 48 patients (7.9%) underwent CT examination. Twenty-five percent of the 48 patients were in the first trimester of pregnancy; 25%, the second trimester; and 50%, the third trimester. In five patients, unsuspected early pregnancies were first detected at CT. Ninety-two percent of the patients were injured in automobile crashes; 6%, assaults; and 2%, falls.
Most patients underwent screening US of the uterus while the mother was evaluated, and CT was performed afterward. Written consent was not required for diagnostic examinations, medical treatments, or emergency surgeries that the injured patient required after coming to the trauma center for triage and treatment. It was implied that the patient gave her consent for procedures that would rapidly detect or treat her life-threatening injuries. Long-term risks from ionizing radiation were discussed with the patient or family at an appropriate time during the hospitalization.
Seventeen of the 48 patients (35%) had normal findings at CT and uneventful recovery from the trauma. Two women with near-term pregnancies and asymptomatic preexisting or traumatic small placental infarcts or abruptions delivered normal, live neonates. Fifteen women (31%) had nonuterine injuries, and 13 (27%) had both uterine and other maternal injuries (2.3 injuries per patient). One patient in the first trimester of pregnancy who had no other injuries had a spontaneous abortion.
Eleven patients (23%) had abnormal placental enhancement, and one patient had an uterine rupture. Ten of these injuries resulted in fetal death. The placenta could not be seen at CT in another patient with first trimester fetal loss. Traumatic fetal loss was presumed in another patient known to be in her early second trimester because the fetus and placenta were not seen at CT. However, this patient died of a closed head injury soon after the CT study and before her fetal loss could be confirmed.
Five women (10%) died, with three deaths due to brain injuries. The fetal death rate was 33% (11 isolated fetal deaths and five due to maternal death). CT did not demonstrate any internal fetal injuries or anomalies.
In four of the 14 patients (29%) with either abnormal or no placental enhancement, normal fetal heart tones were detected at US. Fetal demise occurred in two of these patients.
No elective abortions were performed because of potential harm from ionizing radiation.
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CT EVALUATION OF PREGNANT TRAUMA PATIENTS
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Indications for CT Examination
Screening CT of the head, spine, face, and torso are indicated in the hemodynamically stable, injured pregnant woman when findings from physical examination; admission radiography of the cervical spine, chest, or pelvis; or abdominal US are abnormal or equivocal. Unconscious, intubated, or intoxicated patients must be presumed to have injuries and require screening helical CT examinations, since the traumatic forces during the accident may be unknown but are presumed to be severe.
Pregnant patients with life-threatening blunt traumatic injuries to the body need external fetal monitoring. Obstetric US should be performed to determine the placental and fetal positions and to detect placental and fetal abnormalities that may indicate whether the fetus can be monitored with serial studies or an early delivery is needed. Normal results from the fetal US examination do not exclude a placental or uterine injury, nor do they exclude nonuterine injuries. Thus, the gravid uterus should be included in the screening helical CT study.
Magnetic resonance imaging is an alternative in the elective evaluation of the pregnant patient because it does not use ionizing radiation. Currently, however, it is contraindicated for the rapid triage of severely injured patients and for the emergency evaluation of complex or multiple injuries because of long examination times, lack of equipment availability, difficulty in access to the patient, and difficulty with monitoring resuscitation efforts during the procedure.
CT Procedures and Risks
At our two trauma centers, CT studies were usually performed with the patient in a supine position. Nasogastric tubes were not removed, and ventilators were not paused. Orally administered contrast material was used in all cases, and cystographic contrast material was frequently given if a bladder catheter was in place. Nonionic contrast media (300 mg of iodine per milliliter, 2 mL/sec) was administered intravenously in all cases. Both conventional and helical techniques with standard peak kilovoltage and milliampere settings were used.
Contrast media may be used during pregnancy if medically needed (manufacturer's recommendation, Mallinckrodt, St Louis, Mo). Small amounts of contrast material may cross the placental barrier. Obvious enhancement of fetal structures is not usually seen at CT. Results from animal studies indicate that contrast media are not mutagenic or teratogenic and do not affect fertility. There have been no controlled studies in humans.
During the CT examination, the maternal ovaries and fetus are exposed to ionizing radiation. Although a discussion of the teratogenic and mutagenic capabilities of x rays is beyond the scope of this article, the risk of radiation-induced abnormalities is negligible at 5 rad (50 mGy) and increases only at doses above 15 rad (150 mGy), with the greatest risk occurring from exposures at 2–15 weeks gestational age (5). Minimal radiation exposure is the goal of all radiologic examinations, and increasing the scan pitch is the best and easiest method for decreasing radiation doses during helical CT examinations. Our estimated exposure to a fetus during a helical CT study performed with a 5-mm collimated scan was 17.5 mGy at 1:1 pitch, 12.5 mGy at 1.4:1 pitch, and 8.7 mGy at 2:1 pitch (Wilson R, written communication, May 1999).
The clinical benefits of using CT to exclude or detect critical internal injuries outweigh the potential risks. Counseling of the patient or her family with a medical physicist, medical ethicist, or clergy person might be of value to discuss these issues.
CT Appearance of Normal Pregnancy
In our series of 48 pregnant trauma patients, 17 patients had normal findings at CT.
The normal nongravid uterus is fist-sized and homogeneously and moderately enhances. Its T- or arrow-shaped, low-attenuation lumen outlined by a regular, high-attenuation mucosa is commonly seen when the uterus is ante- or retroflexed. Unobstructed menstrual flow may slightly distend the cavity, but the acute-angled shape remains.
The ovarian veins accompany the ureters in the retro- and extraperitoneum to their termination around the broad ligament. The ovarian arteries are usually too small to see. The intraperitoneal inferior mesenteric vessels are immediately anterior to the retroperitoneal left gonadal vessels and should not be confused with these latter vessels, as both sets of vessels course over the left psoas muscle into the lower abdomen.
By 20 weeks gestation, the uterine fundus rises to the level of the umbilicus. The pregnant uterus grows 1 cm per week. Gestational age can be estimated by adding or subtracting the distance in centimeters of the fundus from the umbilicus.
Early intrauterine pregnancy may be suspected when a "bulging," spherically shaped lumen is seen with a slightly enlarged uterus. Prominent endometrial enhancement may occur. Fetal parts are usually not seen at CT until the late first trimester or early second trimester (Figs 1b, 2b).
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Figure 1a. Normal first trimester (10 weeks) pregnancy in a patient who was an unrestrained driver and sustained a closed head injury in an automobile crash. (a) Head CT scan shows diffuse axonal injury with intraparenchymal hematoma and intraventricular hemorrhage (arrow). (b) Pelvic CT scan reveals an enlarged uterus with a "bulging," peripherally enhancing, fluid collection that fills the endometrial cavity (arrow). Fetal parts were not seen. The patient's brain injury led to maternal and fetal death.
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Figure 1b. Normal first trimester (10 weeks) pregnancy in a patient who was an unrestrained driver and sustained a closed head injury in an automobile crash. (a) Head CT scan shows diffuse axonal injury with intraparenchymal hematoma and intraventricular hemorrhage (arrow). (b) Pelvic CT scan reveals an enlarged uterus with a "bulging," peripherally enhancing, fluid collection that fills the endometrial cavity (arrow). Fetal parts were not seen. The patient's brain injury led to maternal and fetal death.
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Figure 2a. Normal first trimester pregnancy in a patient who sustained severe blunt chest trauma in an automobile crash. (a) Chest CT scan shows lung contusions, hemorrhage, and atelectasis, which required endotracheal intubation, and a right pneumothorax, which required chest tube placement. (b) Pelvic CT scan shows a bulging, fluid-filled endometrial cavity (arrow) but no fetal parts. A corpus luteum cyst of pregnancy was seen in the right ovary (arrowhead). The patient had a spontaneous abortion the next day and fully recovered from her chest injuries, which also included a right clavicle and multiple rib fractures.
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Figure 2b. Normal first trimester pregnancy in a patient who sustained severe blunt chest trauma in an automobile crash. (a) Chest CT scan shows lung contusions, hemorrhage, and atelectasis, which required endotracheal intubation, and a right pneumothorax, which required chest tube placement. (b) Pelvic CT scan shows a bulging, fluid-filled endometrial cavity (arrow) but no fetal parts. A corpus luteum cyst of pregnancy was seen in the right ovary (arrowhead). The patient had a spontaneous abortion the next day and fully recovered from her chest injuries, which also included a right clavicle and multiple rib fractures.
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During the early second trimester, the fetus becomes detectable in the amniotic fluid as areas of high attenuation (Fig 3). Portions of the fetal face and skeleton are seen by the end of the second trimester.
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Figures 3, 4. (3) Normal early second trimester (12 weeks) pregnancy in a patient who was in an automobile crash but sustained no internal injuries. On a pelvic CT scan, the fetal parts (arrow) are barely detectable in the endometrial fluid. The hyperattenuation of the fetus should not be confused with active uterine hemorrhage. (4) Normal placental cotyledons of a second trimester (22 weeks) pregnancy in a woman who lost consciousness during an automobile crash but sustained no internal injuries. Abdominal CT scan reveals the normal placental cotyledons, which have central areas of low attenuation (*) and are surrounded by peripheral rings of normally enhancing placenta. Enlarged ovarian veins (o), which are normally seen in later stages of pregnancies, are present. The normal heterogeneously high-attenuation adnexa (arrows) have lifted out of the pelvis with the enlarging uterus. The fetal face and chest (c) are visible.
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During the second trimester, the normal placental cotyledons develop central areas of low attenuation with surrounding high-attenuation rings of normally enhancing placenta (Fig 4). Prominent eccentric heterogeneous enhancement and dilated vessels may be seen in the myometrium deep to the site of placental implantation. The other portions of the myometrium homogeneously enhance and are frequently higher in attenuation than adjacent bowel and muscle.
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Figures 3, 4. (3) Normal early second trimester (12 weeks) pregnancy in a patient who was in an automobile crash but sustained no internal injuries. On a pelvic CT scan, the fetal parts (arrow) are barely detectable in the endometrial fluid. The hyperattenuation of the fetus should not be confused with active uterine hemorrhage. (4) Normal placental cotyledons of a second trimester (22 weeks) pregnancy in a woman who lost consciousness during an automobile crash but sustained no internal injuries. Abdominal CT scan reveals the normal placental cotyledons, which have central areas of low attenuation (*) and are surrounded by peripheral rings of normally enhancing placenta. Enlarged ovarian veins (o), which are normally seen in later stages of pregnancies, are present. The normal heterogeneously high-attenuation adnexa (arrows) have lifted out of the pelvis with the enlarging uterus. The fetal face and chest (c) are visible.
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By the third trimester, the fetus is easily seen with identifiable portions of the skeleton. The stomach and bladder are filled with fluid. Although the right-left orientation may be confusing, the kidneys, liver, brain, and collapsed lungs are recognizable. A generous strip of subcutaneous fat normally surrounds the fetus in late pregnancy.
During late pregnancy, the placenta has a very high-attenuation, homogeneous enhancement or a regular pattern of heterogeneous enhancing cotyledons. Small avascular areas of asymptomatic infarction or abruption may be incidentally detected during a normal pregnancy (Figs 5, 6). In our series, two patients had preexisting, asymptomatic, small placental infarcts and delivered normal infants.
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Figures 5, 6. Clinically silent partial placental abruption or infarction in late pregnancy. (5) Pelvic CT scan of a woman who was an unrestrained driver in an automobile crash during the 31st week of pregnancy reveals a peripheral area of placental infarction or abruption that does not enhance (arrow). Results of screening fetal US were normal, and the patient's only injury was an ankle fracture. She was discharged home and had a normal delivery at term. L = fetal liver, P = normal placenta. (6) Abdominal CT scan of a woman who was in an automobile crash in her last week of pregnancy shows a 5-cm nonenhancing partial abruption or infarction that involves the peripheral posterior placenta (arrow). Note the normal subcutaneous fat and well-formed tibia and fibula of the leg (L) in the term fetus. In the supine position, the mother's inferior vena cava (i) was compressed and the ovarian veins (o) were enlarged, common findings in the later stages of pregnancy. Results of screening fetal US were normal. The patient was discharged home and had a normal delivery at term.
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Figures 5, 6. Clinically silent partial placental abruption or infarction in late pregnancy. (5) Pelvic CT scan of a woman who was an unrestrained driver in an automobile crash during the 31st week of pregnancy reveals a peripheral area of placental infarction or abruption that does not enhance (arrow). Results of screening fetal US were normal, and the patient's only injury was an ankle fracture. She was discharged home and had a normal delivery at term. L = fetal liver, P = normal placenta. (6) Abdominal CT scan of a woman who was in an automobile crash in her last week of pregnancy shows a 5-cm nonenhancing partial abruption or infarction that involves the peripheral posterior placenta (arrow). Note the normal subcutaneous fat and well-formed tibia and fibula of the leg (L) in the term fetus. In the supine position, the mother's inferior vena cava (i) was compressed and the ovarian veins (o) were enlarged, common findings in the later stages of pregnancy. Results of screening fetal US were normal. The patient was discharged home and had a normal delivery at term.
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The physiologic changes of pregnancy are first seen during the second trimester (Figs 4, 7). Normal physiologic changes occur as the mother's body adjusts to the enlarging uterus and prepares for delivery. These adaptations, which involve the musculoskeletal, gastrointestinal, genitourinary, and vascular systems, may be confused with injury or disease.
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Figure 7. Hydronephrosis of pregnancy in a woman who was injured in an automobile crash during the 37th week of pregnancy but sustained no internal injuries. Abdominal CT scan reveals hydronephrosis (H), which is caused by mechanical compression of the ureter by the gravid uterus. Note the normal subcutaneous fat (arrow) of the thigh in the near-term fetus. Results of screening US of the fetus and other CT studies were normal. Subsequently, the patient had a normal delivery.
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Diastasis of rectus abdominal muscles and widening of the sacroiliac joints and pubic symphysis is seen at CT. The enlarging uterus lifts the peritoneal reflections out of the pelvis and displaces the bowel. In addition, the enlarged uterus compresses the ureters and may cause partial ureteral obstruction, leading to hydronephrosis (Fig 7) and hydroureter. Hydronephrosis of pregnancy is normally seen in second and third trimester pregnancies. Frequently, the right collecting system is more severely affected. Hormonal influences encourage ureteral dilatation to proceed silently (Fig 4). Occasionally, a corpus luteal cyst of pregnancy may be seen in an ovary (Fig 2b).
Ovarian vein enlargement occurs as increased blood flow is recruited to accommodate the growing placenta and fetus (Figs 4, 7). The veins can approach the size of the inferior vena cava. In late pregnancy, the inferior vena cava is extrinsically compressed by the large uterus when the patient is supine (Fig 7). Rolling the patient into an oblique position may be more comfortable but may be difficult if extremity or cervical spine injuries are present; in addition, this position further distorts anatomic relationships.
CT Appearance of Maternal Injuries
Most injuries sustained by pregnant women are the result of automobile crashes. The National Highway Traffic Safety Administration recommends that pregnant women continue to use air bags and seat belts (7,8). These restraints must be properly positioned (lap belt under abdomen, shoulder belt across clavicle, seat positioned away from the dash, arms away from air bag deployment area) to be effective. Improper use of these safety devices might make the pregnant patient more susceptible to injury in high-speed crashes since the dilated pyelocaliceal systems, the large ovarian veins, and the laxity of the bony pelvis and ligaments may be more susceptible to blunt forces.
Nonuterine Injuries.—Any body, head, or spinal injury that occurs in the nonpregnant patient can be seen in the pregnant woman. In our series, 15 women had only nonuterine injuries, and another 13 patients had maternal as well as uterine injuries (Table; Figs 1a, 2a, 8a, 8b, 9a, 10a, 11a, 12a, 12b).
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Figure 8a. Severe visceral and skeletal injuries in a woman who was 18 weeks pregnant with twins when she was ejected from her car in an automobile crash. (a) Abdominal CT scan shows a laceration to the posterior liver (arrow), with an adjacent displaced rib fracture and splenic laceration (arrowhead). Intraperitoneal blood was present in the right subphrenic space. (b) Abdominal CT scan reveals a small right renal laceration (arrowhead) and a left renal infarction and laceration (*). Blood was present in the right subhepatic space. She also had severe lung contusions, multiple facial fractures, and a skull fracture. (c) Pelvic CT scan shows a poorly enhancing anterior placenta (arrows). Although results of screening fetal US had been normal, the patient had a spontaneous stillbirth 4 days after admission. A large placental abruption was found at pathologic examination. The patient was treated nonoperatively, and she recovered from her other internal abdominal injuries.
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Figure 8b. Severe visceral and skeletal injuries in a woman who was 18 weeks pregnant with twins when she was ejected from her car in an automobile crash. (a) Abdominal CT scan shows a laceration to the posterior liver (arrow), with an adjacent displaced rib fracture and splenic laceration (arrowhead). Intraperitoneal blood was present in the right subphrenic space. (b) Abdominal CT scan reveals a small right renal laceration (arrowhead) and a left renal infarction and laceration (*). Blood was present in the right subhepatic space. She also had severe lung contusions, multiple facial fractures, and a skull fracture. (c) Pelvic CT scan shows a poorly enhancing anterior placenta (arrows). Although results of screening fetal US had been normal, the patient had a spontaneous stillbirth 4 days after admission. A large placental abruption was found at pathologic examination. The patient was treated nonoperatively, and she recovered from her other internal abdominal injuries.
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Figure 8c. Severe visceral and skeletal injuries in a woman who was 18 weeks pregnant with twins when she was ejected from her car in an automobile crash. (a) Abdominal CT scan shows a laceration to the posterior liver (arrow), with an adjacent displaced rib fracture and splenic laceration (arrowhead). Intraperitoneal blood was present in the right subphrenic space. (b) Abdominal CT scan reveals a small right renal laceration (arrowhead) and a left renal infarction and laceration (*). Blood was present in the right subhepatic space. She also had severe lung contusions, multiple facial fractures, and a skull fracture. (c) Pelvic CT scan shows a poorly enhancing anterior placenta (arrows). Although results of screening fetal US had been normal, the patient had a spontaneous stillbirth 4 days after admission. A large placental abruption was found at pathologic examination. The patient was treated nonoperatively, and she recovered from her other internal abdominal injuries.
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Figures 9, 10. (9) Retroperitoneal hemorrhage and severe closed head injury in a patient who was in her second trimester of pregnancy when she was injured in an automobile crash. (a) Abdominal CT scan shows active retroperitoneal hemorrhage (arrow) at the level of the left renal vein that displaces the left kidney. The blood extends along the left hemidiaphragm. (b) On a pelvic CT scan, placental enhancement is absent (arrowheads), and a focal uterine wall defect is seen (arrow). Because of these findings and those of screening US, which had revealed no fetal heart tones or movement, complete placental abruption with possible uterine injury was suspected. The patient became coagulopathic, and the mother and fetus died. (10) Pelvic fracture in a woman who was an unrestrained driver in an automobile crash during the 22nd week of pregnancy. No fetal heart tones were heard at screening US. (a) Pelvic CT scan shows a right acetabular fracture (arrows). She also had right sacroiliac joint diastasis (not shown). (b) On an abdominal CT scan, only a small part of the placenta enhances (arrow). The patient had a spontaneous stillbirth the next day, and pathologic examination revealed acute placental infarction. She recovered from her skeletal injuries.
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Figures 9, 10. (9) Retroperitoneal hemorrhage and severe closed head injury in a patient who was in her second trimester of pregnancy when she was injured in an automobile crash. (a) Abdominal CT scan shows active retroperitoneal hemorrhage (arrow) at the level of the left renal vein that displaces the left kidney. The blood extends along the left hemidiaphragm. (b) On a pelvic CT scan, placental enhancement is absent (arrowheads), and a focal uterine wall defect is seen (arrow). Because of these findings and those of screening US, which had revealed no fetal heart tones or movement, complete placental abruption with possible uterine injury was suspected. The patient became coagulopathic, and the mother and fetus died. (10) Pelvic fracture in a woman who was an unrestrained driver in an automobile crash during the 22nd week of pregnancy. No fetal heart tones were heard at screening US. (a) Pelvic CT scan shows a right acetabular fracture (arrows). She also had right sacroiliac joint diastasis (not shown). (b) On an abdominal CT scan, only a small part of the placenta enhances (arrow). The patient had a spontaneous stillbirth the next day, and pathologic examination revealed acute placental infarction. She recovered from her skeletal injuries.
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Figures 9, 10. (9) Retroperitoneal hemorrhage and severe closed head injury in a patient who was in her second trimester of pregnancy when she was injured in an automobile crash. (a) Abdominal CT scan shows active retroperitoneal hemorrhage (arrow) at the level of the left renal vein that displaces the left kidney. The blood extends along the left hemidiaphragm. (b) On a pelvic CT scan, placental enhancement is absent (arrowheads), and a focal uterine wall defect is seen (arrow). Because of these findings and those of screening US, which had revealed no fetal heart tones or movement, complete placental abruption with possible uterine injury was suspected. The patient became coagulopathic, and the mother and fetus died. (10) Pelvic fracture in a woman who was an unrestrained driver in an automobile crash during the 22nd week of pregnancy. No fetal heart tones were heard at screening US. (a) Pelvic CT scan shows a right acetabular fracture (arrows). She also had right sacroiliac joint diastasis (not shown). (b) On an abdominal CT scan, only a small part of the placenta enhances (arrow). The patient had a spontaneous stillbirth the next day, and pathologic examination revealed acute placental infarction. She recovered from her skeletal injuries.
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Figures 9, 10. (9) Retroperitoneal hemorrhage and severe closed head injury in a patient who was in her second trimester of pregnancy when she was injured in an automobile crash. (a) Abdominal CT scan shows active retroperitoneal hemorrhage (arrow) at the level of the left renal vein that displaces the left kidney. The blood extends along the left hemidiaphragm. (b) On a pelvic CT scan, placental enhancement is absent (arrowheads), and a focal uterine wall defect is seen (arrow). Because of these findings and those of screening US, which had revealed no fetal heart tones or movement, complete placental abruption with possible uterine injury was suspected. The patient became coagulopathic, and the mother and fetus died. (10) Pelvic fracture in a woman who was an unrestrained driver in an automobile crash during the 22nd week of pregnancy. No fetal heart tones were heard at screening US. (a) Pelvic CT scan shows a right acetabular fracture (arrows). She also had right sacroiliac joint diastasis (not shown). (b) On an abdominal CT scan, only a small part of the placenta enhances (arrow). The patient had a spontaneous stillbirth the next day, and pathologic examination revealed acute placental infarction. She recovered from her skeletal injuries.
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Figure 11a. Renal laceration and skeletal injuries in a woman who was an unrestrained passenger in an automobile crash during the 29th week of pregnancy. No fetal heart tones were heard at screening US. (a) Pelvic CT scan shows an anterior laceration (arrowhead) in the right pelvic kidney, adjacent to the caudally located fetal head. Sacroiliac joint diastasis and pubic symphysis diastasis were also present (latter not shown). (b) On an abdominal CT scan, no placental enhancement (arrow) is seen. The fetal liver (L) is seen in the upper fetal abdomen. No fetal subcutaneous fat was present. Labor was induced the next day, resulting in a stillbirth, and the suspected complete placental abruption was confirmed. The patient recovered from her other skeletal and visceral injuries.
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Figure 11b. Renal laceration and skeletal injuries in a woman who was an unrestrained passenger in an automobile crash during the 29th week of pregnancy. No fetal heart tones were heard at screening US. (a) Pelvic CT scan shows an anterior laceration (arrowhead) in the right pelvic kidney, adjacent to the caudally located fetal head. Sacroiliac joint diastasis and pubic symphysis diastasis were also present (latter not shown). (b) On an abdominal CT scan, no placental enhancement (arrow) is seen. The fetal liver (L) is seen in the upper fetal abdomen. No fetal subcutaneous fat was present. Labor was induced the next day, resulting in a stillbirth, and the suspected complete placental abruption was confirmed. The patient recovered from her other skeletal and visceral injuries.
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Figure 12a. Severe visceral injuries in a woman who was a restrained driver in an automobile crash during the 26th week of pregnancy. Oligohydramnios, absent fetal movement, and cardiac decelerations were found at screening fetal US. (a) Abdominal CT scan shows a grade III splenic laceration (arrow) that was successfully nonoperatively managed. (b) Abdominal CT scan reveals a retroperitoneal hematoma with focal areas of active extravasation (white arrow) from an ovarian vein injury. There was a peripheral low-attenuation placental abruption (black arrow). Oligohydramnios was not appreciated at CT. High-attenuation hemorrhage or concentrated proteinaceous amniotic fluid surrounds the fetus. (c) Abdominal CT scan obtained at a lower level shows multiple areas of nonenhancing placenta (arrowheads). The patient had a spontaneous abortion the next day. She remained hemodynamically stable and recovered from her other internal injuries.
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Figure 12b. Severe visceral injuries in a woman who was a restrained driver in an automobile crash during the 26th week of pregnancy. Oligohydramnios, absent fetal movement, and cardiac decelerations were found at screening fetal US. (a) Abdominal CT scan shows a grade III splenic laceration (arrow) that was successfully nonoperatively managed. (b) Abdominal CT scan reveals a retroperitoneal hematoma with focal areas of active extravasation (white arrow) from an ovarian vein injury. There was a peripheral low-attenuation placental abruption (black arrow). Oligohydramnios was not appreciated at CT. High-attenuation hemorrhage or concentrated proteinaceous amniotic fluid surrounds the fetus. (c) Abdominal CT scan obtained at a lower level shows multiple areas of nonenhancing placenta (arrowheads). The patient had a spontaneous abortion the next day. She remained hemodynamically stable and recovered from her other internal injuries.
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Figure 12c. Severe visceral injuries in a woman who was a restrained driver in an automobile crash during the 26th week of pregnancy. Oligohydramnios, absent fetal movement, and cardiac decelerations were found at screening fetal US. (a) Abdominal CT scan shows a grade III splenic laceration (arrow) that was successfully nonoperatively managed. (b) Abdominal CT scan reveals a retroperitoneal hematoma with focal areas of active extravasation (white arrow) from an ovarian vein injury. There was a peripheral low-attenuation placental abruption (black arrow). Oligohydramnios was not appreciated at CT. High-attenuation hemorrhage or concentrated proteinaceous amniotic fluid surrounds the fetus. (c) Abdominal CT scan obtained at a lower level shows multiple areas of nonenhancing placenta (arrowheads). The patient had a spontaneous abortion the next day. She remained hemodynamically stable and recovered from her other internal injuries.
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Uterine Injuries.—The most common uterine injury is a placental infarction or abruption. This injury was either detected or presumed from the CT appearances in 14 patients. CT usually shows placental infarction as a single avascular area of varying size that extends from the placental base to the placental surface (Figs 8c, 9b, 10b, 11b, 12c).
High attenuation in the nonplacenta portion of the uterus indicates contusion, tear, or partial uterine disruption (Fig 9b). Loss of amniotic fluid into the maternal peritoneum or free fetal parts in the maternal abdomen indicate an obstetric catastrophe (Fig 13b, 13c). It may be difficult to determine if intraabdominal fluid is amniotic fluid or hemorrhage from a maternal visceral injury.
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Figure 13a. Isolated pubic ramus fracture in a woman who was a restrained passenger in an automobile crash during the 36th week of pregnancy. Fetal heart tones and motion were absent at screening US. (a) Pelvic CT scan shows an isolated fracture to the right superior pubic ramus (arrow), which was the only maternal injury. (b) Pelvic CT scan demonstrates the fetal head, which lies in the maternal pelvis anterior to the collapsed enhancing uterus (U). Amniotic fluid fills the peritoneal cavity. (c) Abdominal CT scan shows the fetus (F) floating in the upper abdomen anterior to the maternal pancreas. No surrounding uterus was seen. Intraperitoneal amniotic fluid fills the paracolic gutters and subphrenic and subhepatic spaces. Subcutaneous fat surrounds the near-term fetus. A complete posterior fundal uterine rupture was found at surgery, and the extruded fetus was dead. The patient recovered from her skeletal injury.
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Figure 13b. Isolated pubic ramus fracture in a woman who was a restrained passenger in an automobile crash during the 36th week of pregnancy. Fetal heart tones and motion were absent at screening US. (a) Pelvic CT scan shows an isolated fracture to the right superior pubic ramus (arrow), which was the only maternal injury. (b) Pelvic CT scan demonstrates the fetal head, which lies in the maternal pelvis anterior to the collapsed enhancing uterus (U). Amniotic fluid fills the peritoneal cavity. (c) Abdominal CT scan shows the fetus (F) floating in the upper abdomen anterior to the maternal pancreas. No surrounding uterus was seen. Intraperitoneal amniotic fluid fills the paracolic gutters and subphrenic and subhepatic spaces. Subcutaneous fat surrounds the near-term fetus. A complete posterior fundal uterine rupture was found at surgery, and the extruded fetus was dead. The patient recovered from her skeletal injury.
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Figure 13c. Isolated pubic ramus fracture in a woman who was a restrained passenger in an automobile crash during the 36th week of pregnancy. Fetal heart tones and motion were absent at screening US. (a) Pelvic CT scan shows an isolated fracture to the right superior pubic ramus (arrow), which was the only maternal injury. (b) Pelvic CT scan demonstrates the fetal head, which lies in the maternal pelvis anterior to the collapsed enhancing uterus (U). Amniotic fluid fills the peritoneal cavity. (c) Abdominal CT scan shows the fetus (F) floating in the upper abdomen anterior to the maternal pancreas. No surrounding uterus was seen. Intraperitoneal amniotic fluid fills the paracolic gutters and subphrenic and subhepatic spaces. Subcutaneous fat surrounds the near-term fetus. A complete posterior fundal uterine rupture was found at surgery, and the extruded fetus was dead. The patient recovered from her skeletal injury.
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Direct detection of fetal injuries is rare. Fetal death is usually caused by placental injury (11 fetal losses in our series) or maternal hypotension with compromised uterine blood flow (five fetal deaths). Hemorrhage in the amniotic cavity may occur, presumably from placental or fetal injury.
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CONCLUSIONS
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Blunt trauma suffered during pregnancy can cause unique injuries that must be detected quickly to save mother and child. The normal physiologic changes occurring during pregnancy may complicate, confuse, or aggravate the diagnosis and treatment of other maternal injuries.
Maternal death is usually caused by head injuries that also occur in the nonpregnant injured woman. The mortality rate (10%) in our series was similar to that observed in nonpregnant women (9).
Placental abruption or devascularization was the most common cause of fetal death. The fetal loss in our patients was 33% (10). Fetal demise is more likely to occur when multiple maternal injuries accompany injuries to the gravid uterus.
US indicates fetal distress after maternal injury, but it may not reveal acute placental infarcts and abruption. This missed diagnosis can result in an unanticipated, posttraumatic spontaneous abortion (3). CT can demonstrate devascularized areas of the placenta as well as multiple areas in the injured mother. The presence of placental abnormalities on CT scans, despite normal results at screening US, may predict impending fetal loss after blunt uterine injury.
CT is useful in the early radiologic evaluation of the pregnant patient with life-threatening blunt trauma. It can be used to direct triage and guide early clinical management toward the treatment of the most critical internal injuries so that both mother and child survive.
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Footnotes
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2 Current address: Department of Radiology, St Mary's Hospital, St Louis, Mo. 
See the commentary by Kenney.
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References
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Kissinger DP, Rozycki GS, Morris JA, Jr, et al. Trauma in pregnancy: predicting pregnancy outcome. Arch Surg 1991; 126:1079-1086.[Abstract]
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Esposito TJ. Trauma during pregnancy. Emerg Med Clin North Am 1994; 12:167-199.[Medline]
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Roszler MH. Blunt abdominal trauma: computed tomography, ultrasound, or diagnostic peritoneal lavage—when and by whom?. Emerg Radiol 1998; 5:403-409.
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National Conference on Medical Indications for Air Bag Disconnection at the Ronald Reagan Institute of Emergency Medicine. ; Department of Emergency Medicine and National Crash Analysis Center, The George Washington University Medical Center, Washington, DC, July 16–18, 1997..
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Esposito TJ, Gens DR, Smith LG, Scorpio R, Buchman T. Trauma during pregnancy: a review of 79 cases. Arch Surg 1991; 126:1073-1078.[Abstract]
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Shah KH, Simons RK, Holbrook T, Fortlage D, Winchell RJ, Hoyt DB. Trauma in pregnancy: maternal and fetal outcomes. J Trauma 1998; 45:83-86.[Medline]
Related Article
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Invited Commentary
- Philip J. Kenney
RadioGraphics 1999 19: 256-258.
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Abstract
INTRODUCTION
