Course Authors

John R. Richards, M.D., F.A.A.E.M.

Dr. Richards is Professor, Department of Emergency Medicine, University of California, Davis Medical Center, Sacramento, California.

Dr. Richards reports no commercial conflict of interest.

Albert Einstein College of Medicine, CCME staff and interMDnet staff have nothing to disclose.

Estimated course time: 1 hour(s).

Albert Einstein College of Medicine – Montefiore Medical Center designates this enduring material activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

In support of improving patient care, this activity has been planned and implemented by Albert Einstein College of Medicine-Montefiore Medical Center and InterMDnet. Albert Einstein College of Medicine – Montefiore Medical Center is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

 

Learning Objectives

Upon completion of this Cyberounds^®, you should be able to:

• Discuss the current role of ultrasonography (FAST) in the triage of blunt trauma patients.

• Discuss the interpretation of abnormal findings on FAST and implications.

• Discuss the therapeutic approaches to managing patients with blunt abdominal injuries and their disposition.

• Discuss the diagnostic options in subgroups such as pregnant, obese, and pediatric patients.

 

Blunt abdominal trauma (BAT) remains a diagnostic challenge to emergency physicians. Despite advances in motor vehicle and occupational safety measures over the past three decades, BAT resulting in intra-abdominal injury (IAI) represents a substantial cause of mortality and morbidity in the United States and worldwide. In this Cyberounds^® review I will discuss the variety of diagnostic imaging options for these patients, trends in utilization of these modalities, and management and disposition of BAT patients presenting to the emergency department. Imaging studies available to emergency physicians include focused abdominal sonography for trauma (FAST), computed tomography (CT), magnetic resonance imaging (MRI) and angiography. The incorporation of FAST into widespread practice has made diagnostic peritoneal lavage (DPL) obsolete in the United States, although it is still mentioned in trauma algorithms and may still be utilized in other countries.(1) Subgroups such as pregnant, obese and pediatric patients pose additional risks and difficulties to the clinician and will be discussed as well.

Case One

A 64-year-old female is brought to your emergency department (ED) after having been struck by a car at five miles per hour. She is complaining of left lateral chest wall pain. Her abdomen is non-tender. A portable chest radiograph shows no hemo- or pneumothorax or rib fractures. Her vital signs and labs are normal. You decide to perform FAST just to be safe, and notice the spleen is difficult to visualize with the probe and appears irregular. The left kidney appears normal, and there is no free fluid in the spleno-renal interface. The remainder of the FAST is negative.

The FAST examination is an important and useful diagnostic and triage tool for emergency physicians, and its role in BAT has evolved over the years.(2) Initially, FAST was proposed for all patients with BAT, but a significant proportion of negative and false positive scans from equivocal findings redefined indications for FAST. Some advocated for serial sonograms to detect enlarging hemoperitoneum over time, but this method has never been followed consistently.(3) Widespread implementation of FAST was also limited to the variability in ultrasound training and experience of emergency physicians, as well as its availability in any given hospital. Today FAST is predominantly utilized in the triage of hemodynamically unstable BAT patients to the operating room. If large amounts of free fluid are seen on FAST and the patient remains hypotensive despite receiving copious isotonic intravenous fluid, the trauma surgeon will most likely proceed to laparotomy. If the free fluid visualized is moderate or minimal and/or the patient becomes hemodynamically stable, then further definitive imaging such as CT is obtained.(4)

With regard to this question, as emergency physicians' FAST skills and experience improve, they may pay greater attention to solid organ appearance while searching for free fluid. The parenchyma of the liver, spleen and kidney are typically homogenous in structure. Theoretically, any disruptions in this structure from trauma may be detected with FAST. Past studies have shown moderate to high grade solid organ injuries can be detected by FAST and confirmed by CT.(5)(6)(7) I recommend all FAST enthusiasts investigate the abdomen not only for free fluid, but also attempt to visualize and comment on the parenchyma of solid organs and surrounding tissue to detect potential hematomas. Lacerations and contusions of the spleen, liver and kidney may be seen as hyper- or hypoechoic areas within the parenchyma. Surrounding hematomas are typically hypoechoic and may be constrained by the capsule. Over time, as the hematoma clots and becomes organized, it may have mixed echogenicity. This provides another dimension to the FAST exam and has been shown to increase its sensitivity in detecting IAI. Future developments to improve the accuracy of FAST include contrast-enhanced ultrasound (CEUS).(8) An intravenous aqueous contrast containing microbubbles is injected prior to FAST to enhance the sonographic appearance of solid organs and detect subtle aberrations of the parenchyma. In recent studies, CEUS approached CT in accuracy of detecting solid organ injuries and picked up additional injuries missed on standard FAST.(9)(10)

Another issue in this case is the decision to perform FAST in a patient with normal level of consciousness, no abdominal tenderness and isolated chest wall pain. Patients with blunt solid organ trauma may not always have significant tenderness on exam, and patients with contusions to the thorax and/or rib fractures are at higher risk for IAI. The liver, spleen and kidneys are partially surrounded by the lower thorax, and the force of a direct blow to the lower chest wall is easily transmitted to these organs. This risk is further increased if the patient's impact occurs at full exhalation. One study group determined that 3% of 301 patients with isolated left lower thoracic contusion from blunt trauma had spleen injuries.(11) With regard to disposition of these patients, the emergency physician should also consider admission for pain control and pulmonary monitoring in elderly patients, as this subgroup tends to have increased risk of pneumonia and pulmonary contusion.(12)

Outcome: A grade III splenic rupture was detected on CT, as well as a small left pneumothorax not visualized on her previous chest radiograph. She was admitted to the Intensive Care Unit (ICU), observed and, ultimately, did not require splenectomy.

Case Two

A 24-year-old male involved in a high-speed motor vehicle crash is brought to the ED and complains only of some mild right flank pain. His vital signs are stable. You perform FAST, which is normal except for a trace amount of free fluid in the pelvis. Your co-worker states he read somewhere it's normal to have a small amount of free fluid in the pelvis.

Trace pelvic free fluid in non-trauma female patients of reproductive age is considered a normal physiological finding by radiologists. This fluid results from progression of the normal menstrual cycle, including ruptured ovarian follicles, ovarian exudation and retrograde menstruation. In the setting of BAT, pelvic free fluid cannot be dismissed as normal. In two studies, the finding of any free fluid in women of reproductive age was associated with a higher incidence of IAI.(13)(14) In males the same is especially true. The emergency physician should assume this represents IAI, pelvis fracture or bladder injury, and obtain definitive CT imaging.

Outcome: CT was obtained and demonstrated a grade II liver laceration that did not require operative intervention.

Case Three

A two-year-old female is brought to the ED still attached to her car seat. She was involved in a rollover motor vehicle crash on the freeway in which she was found hanging upside down for several minutes before paramedics arrived. Palpation of her abdomen reveals no obvious tenderness, but she is crying and squirming during the exam. Of note, there is a harness belt abrasion on her chest and abdomen. She is otherwise acting normally, and vital signs have been stable. A portable chest radiograph and labs are normal.

Trauma is the number one cause of morbidity and mortality in childhood, resulting in approximately 1.5 million injuries, 500,000 hospital admissions and 20,000 deaths per year. The majority of injuries are secondary to blunt-force trauma. After head trauma, BAT is the second most common cause of death in children. Advances in age-appropriate child restraint systems have dramatically reduced serious injury from motor vehicle crashes.(15) Regarding this question, the patient appears uninjured with the exception of a "seat belt sign" on her abdomen. This finding is associated with IAI, specifically bowel perforation, as well as lumbar spine fractures.(16)(17) An emergency physician may be reluctant to obtain CT given the lack of tenderness to palpation on physical examination and potential for radiation exposure in a young child. However, the patient's age, severe mechanism of injury, long period of abdominal compression while hanging upside down, and abdominal abrasion increase the risk of IAI. Admission for observation may seem reasonable to detect possible bowel perforation from signs of peritonitis, but early diagnosis with CT may prevent a prolonged hospital stay and further morbidity.

Despite the radiation concerns, CT remains the most appropriate imaging study for pediatric BAT patients. Most children with solid organ injury are managed non-operatively, as these patients have enhanced vasoconstrictive response to hemorrhage compared to adults. This is not true for children with bowel perforation, as these injuries will require laparotomy. Interestingly, the decision to operate is primarily from clinical and not CT findings. In a study of 1,500 children with BAT who underwent CT, 7% of a subset of those with IAI underwent laparotomy.(18) The decision to operate was based on clinical criteria in 75% and CT findings in 25%. Bowel and mesenteric injuries are probably the most difficult IAI to detect. However, the most accurate imaging modality remains CT in several studies.(19)

Outcome: The patient in this question was diagnosed with jejunal perforation and mesenteric hematoma on CT and underwent surgical repair.

Case Four

A 42-year-old female fell from a two story balcony, and has considerable abdominal and lower back pain. She is brought to your ED and has stable vital signs. She states she is four months pregnant (G1, P0) after months of fertility treatment, and is extremely concerned about fetal exposure to radiation. She has no vaginal bleeding.

The diagnosis and management of pregnant BAT patients is quite different from other patient populations, as fetal outcome becomes an additional important variable. Pregnant patients with BAT are at higher risk of placental abruption and preterm labor.(20) Fortunately, the postnatal outcome of these pregnancies did not appear to differ from non-trauma patients in one large study.(21) The amount of radiation exposure from a single CT examination of the abdomen and pelvis can surpass 100 mGy and increase risk of childhood cancer.(22) If CT is the only option for definitive imaging in a pregnant patient with potential IAI, then informed consent should be obtained if possible before proceeding. Magnetic resonance imaging represents an important alternative to CT in pregnant patients wishing to avoid radiation exposure, as well as those patients with renal failure or allergy to intravenous contrast material. Studies comparing CT to MRI for BAT have been done, and the conclusion is MRI is comparable to CT in the detection of solid organ injury.(23)(24) Another benefit of MRI is that it enables assessment of both spine fractures and spinal cord injury without exposure to radiation. In the current medicolegal climate of the United States, obtaining informed consent for MRI is also a good idea, as long-term prenatal exposure has not been established.

Outcome: MRI was obtained and demonstrated a L2 burst fracture with retropulsion of bone fragments but no spinal cord injury. Her pregnancy was not adversely affected.

Case Five

A 36-year-old male was assaulted with multiple punches and kicks to the abdomen. His vital signs are stable. A CT scan is performed and demonstrates a grade II spleen laceration with active extravasation. His other imaging and lab studies are normal. You call the surgeon on duty and are surprised when told, "You need to call another consultant, but I'll admit him."

Non-operative management for BAT patients has become the standard of care over the past decade, with perhaps the exception of pancreatic and bowel injuries.(25)(26) Angioembolization of splenic, renal, hepatic and pelvic injuries with ongoing hemorrhage has become more commonplace today, hence the consultant's response in this particular question.(27)(28)(29) Multiples studies have confirmed this approach to be safe, with outcomes similar to patients undergoing surgery. Splenic salvage techniques are especially important to mitigate the danger of overwhelming post-splenectomy sepsis.(30)

Case Six

A 50-year-old male weighing 500+ pounds is brought to your ED on two stretchers by four paramedics. He had fallen down six flights of steps injuring his lower back, and now he has developed abdominal pain. His vital signs are stable. Your FAST scan is limited by body habitus and bowel gas. The radiology technician informs you he is too heavy for both the CT and plain radiograph table. His abdominal and back pain is worsening.

Morbid obesity is rampant in the United States, and these patients frequently present to the ED for myriad reasons.(31) When obese patients present for BAT and are "too heavy for the table," the emergency physician must make a decision on how aggressively to pursue CT and/or MRI. If there is high index of suspicion for serious IAI, then all efforts must be made to find an imaging center or hospital that can accommodate this subgroup. This is often a difficult problem requiring multiple phone calls, usually during a busy shift. A recent survey of hospitals, veterinary hospitals and zoos determined only 34% of trauma centers had large-capacity CT.(32) Only two zoos had such capacity and refused to take human patients. There were 16 of 28 veterinary hospitals with large-capacity CT, and only four (14%) would consider imaging humans. Unfortunately, this problem will likely worsen in the future as health care reimbursement continues to decline and the average body mass index of Americans continues to rise. Assuming the patient is stable, maintaining spine injury precautions and admission for observation is not unreasonable if transfer is impossible.

Outcome: After several phone calls and multiple requests, the emergency physician was able to transfer this patient to a private Open MRI facility. The study demonstrated no IAI or spine injury. EMS transportation to and from the private facility was required, and a nurse accompanied the patient. The patient's request to stop at a fast food restaurant during the trip back to the ED was denied.