Abdominal computed tomography prior to trauma laparotomy: a roadmap or detour? A pro-con debate

Summary

The use of abdominal computed tomography (CT) for trauma has grown tremendously in the past several decades, to the point that it is now a regular part of the trauma work-up. Increased utilization of CT has reduced non-therapeutic laparotomy for trauma, which is associated with significant morbidity. Traditionally, findings on physical examination including hemodynamic instability, evisceration, and peritonitis were indicators to proceed with laparotomy without preoperative imaging. However, growing use of and comfort with CT imaging has led to a shift in practice during which patients who meet the traditional indications for emergent laparotomy are proceeding to CT pre-operatively. The use of pre-operative CT for patients meeting criteria for emergency laparotomy was debated at the 42nd Annual Point/CounterPoint Acute Care Surgery Conference in Baltimore, Maryland. The following article summarizes the discussion points along with an overview of supporting evidence.

Introduction

In the USA, the first documented trauma laparotomy was performed by William T. Bull in 1884 at Chambers Street Hospital in New York City on a 22-year-old male with an abdominal gunshot wound. In 1886, he performed another laparotomy for an abdominal gunshot wound in which he repaired multiple bowel injuries. While the procedure was complicated by a partial wound dehiscence, the patient survived the procedure and went on to gain recovery. The case was reported to the New York Surgical Society, and from the 1880s to the 1960s, there was an aggressive rise in operative management of abdominal trauma, which also led to a high rate of nontherapeutic laparotomies.¹

In 1960, Gerald W. Shaftan published “Indications for operation in abdominal trauma,” recommending “selective conservatism” as a method for nonoperative management of abdominal stab wounds.² He proposed peritonitis, hematemesis, proctorrhagia, and positive abdominal paracentesis as indications for trauma laparotomy, with patients not meeting those criteria being closely observed for signs or symptoms requiring operative intervention. The concept was reinforced in 1969 by France C. Nance and Isidore Cohn, who published their findings on 600 patients with abdominal stab wounds. They found that selective management reduced the rate of abdominal explorations from 56% to 28% without an increase in mortality.^{3 4} Around the same time, diagnostic peritoneal lavage was introduced by Haland D. Root in 1965 as a method to evaluate for intra-abdominal hemorrhage secondary to solid organ injury, with up to 98% diagnostic accuracy.⁵

The inception of trauma systems in the USA overlapped with the use of radiographic imaging as a non-invasive diagnostic method in medicine, leading to increased use of radiographic imaging during trauma evaluation. In the 1980s, chest and pelvic radiographs became standard primary adjuncts during trauma evaluation using Advanced Trauma Life Support protocols.⁶ In the 1990s, with the introduction of multidetector technology, computed tomography (CT) became a secondary adjunct, and the Focused Assessment with Sonography for Trauma (FAST) was introduced as a rapid method for diagnostic evaluation of intra-abdominal injury in a hemodynamically unstable patient with blunt abdominal trauma.7,10 Since then, radiography, ultrasonography, CT, and magnetic resonance have been widely used during trauma evaluation and have led to significant increases in diagnostic accuracy. Selective CT imaging is preferred for patients with regional trauma, while whole-body imaging is reserved for severely injured polytrauma patients.^{11 12} Today, the American College of Surgeons Trauma Quality Improvement Program recommends CT as a diagnostic adjunct to evaluate hemodynamically stable patients who may have additional injuries not readily diagnosable by physical examination alone.

Recently, the use of CT imaging as a planning tool to guide operative management has been a topic of debate. Once the decision has been made to proceed with laparotomy for trauma patients with clear indications, how does CT change management?

Abdominal CT is a useful roadmap to trauma surgery (abridged summary)

Dr. Jill Streams, Vanderbilt University Medical Center

Laparotomy for abdominal visceral trauma is the most common procedure we do as trauma surgeons for operative management; however, this has a high associated morbidity and mortality. Over the last three decades, that mortality of 40%–46% is unchanged: we have made no progress despite the fact that we have better trauma systems, markedly advanced prehospital care, improved resuscitation strategies and paradigms, and better damage control techniques.

Most of the early mortality is secondary to hemorrhage, and triaging the patient to the appropriate management location from the trauma bay can be lifesaving. Without appropriate triage, 12% of patients who undergo laparotomy based on physical examination alone receive a non-therapeutic laparotomy, which is associated with an increase in mortality, sepsis, acute kidney injury, ventilator-associated pneumonia, and hospital length of stay. If immediate trauma laparotomy was the answer for everyone, we should have improved mortality by now; it has been three decades and we have not moved the needle.

The practice of obtaining CT scans on hemodynamically unstable patients is controversial; however, studies have shown that CT scanning can be performed safely in hemodynamically abnormal patients and can help select patients for operative versus endovascular management of hemorrhage, with the use of angioembolization decreasing risk of mortality and use of operative management increasing the risk. CT imaging can identify concomitant injuries in polytrauma patients that can ultimately change management.

CT scans can be fast and accurate, leading to faster identification of life-threatening injuries. A study of initially unstable patients with thoracoabdominal trauma found decreased mortality, transfusion, and need for additional procedures when patients were scanned first, rather than doing a laparotomy and then going to CT.¹³ There has not been a single study that shows increased mortality with the preferential use of CT. Once you are in the operating room, CT imaging directs your interventions thoughtfully to the right place. For instance, a preoperative CT scan identifying a grade II kidney injury can prevent unnecessary exploration of the retroperitoneum, and identifying a pancreatic injury preoperatively can help plan for a distal pancreatectomy.

In summary, CT scans do not increase mortality, CT triages the patient to the best post-trauma bay location, and CT triages the retroperitoneum and makes your operation faster.

Abdominal CT is not a useful roadmap to trauma surgery (abridged summary)

Dr. Matthew Vasquez, Naval Medical Center Portsmouth, VA

Surgeons operate. You spend 5–6 years in residency, and then for some, you go through 1–2 years of fellowship to develop clinical acumen to make decisions based on physical exams. We need to trust our physical exam and clinical judgment, instead of relying on a CT scan. When the decision is made to proceed to the operating room (OR) for abdominal trauma, no roadmap is going to change how we’ve been taught to fully explore the abdomen. Unfortunately, the data are lacking regarding using CT as a roadmap in the operating room.

There are many factors that can affect how quickly the CT can be obtained, and that delay can then lead to a delay in definitive care which can negatively affect patient outcomes. A study was done in Boston to evaluate reasons for delay in CT scans. They found 5600 CTs performed on 4300 patients in the emergency room, and the median time to CT was 108 min.¹⁴ Factors that led to delays were behavioral issues, intravenous (IV) access issues, contrast allergy, kidney concerns, and delays in protocols.

So, how good is the data we receive when we obtain an abdominal CT? Studies have shown that CT scans missed injuries almost 40% of the time and overcalled 20% of the injuries, which led to negative ex-laps. Of the missed injuries, hollow viscus injuries were the most commonly missed. Imaging studies are not very good at ruling out injuries. Is a test that only rules out an injury 50% of the time something we should rely on?

So if we decide to wait for a CT scan, what are the implications for the patient? Studies have shown that a delay in getting to the operating room is associated with decreased survival of patients, and in the case of hollow viscus injury, the mortality was due to intra-abdominal sepsis.

Finally, do CT and its findings improve operative time? The answer to this question is difficult to tease out, as there are too many factors to consider when trying to answer this question.

In conclusion, while CT is beneficial in a select set of patients, it does not add any benefit when the decision to perform an operation has been made, and that decision can absolutely be made without a CT scan. Furthermore, flow disruptions can lead to a delay in obtaining a CT scan, and its domino effect can then cause a delay in patient care, which has been shown to create negative outcomes and to increase mortality. During a laparotomy, surgeons are always going to examine the abdomen for all injuries regardless of what the CT shows. Remember to trust your training and your instincts; you do not need a roadmap because you already know where you are going.

Summary of evidence

The term “Golden Hour” was popularized by R. A. Cowley in the 1980s, emphasizing the importance of early diagnosis and intervention in improving survival in critically injured patients. The majority of early mortality in trauma is secondary to hemorrhagic shock, and despite advancements in prehospital care, longer prehospital times and thoracic and abdominal injuries with abbreviated injury scale (AIS) scores >4 are strong independent predictors of patient mortality.¹⁵ A retrospective study of the Pennsylvania trauma registry by Brown et al demonstrated that prolonged scene time is associated with increased odds of mortality, and prehospital interventions partially mediated this association.¹⁶ Another retrospective study by Harvin et al assessing mortality in hypotensive adult trauma patients (systolic blood pressure (SBP) <90) undergoing emergency trauma laparotomy (<90 min from arrival) found that mortality was 46%, with 65% of those being secondary to hemorrhage.¹⁷ Rapid identification and control of hemorrhage are therefore crucial.

While obtaining CT imaging in a hemodynamically unstable trauma patient is controversial, several studies have demonstrated that CT can be obtained safely during resuscitation without increased mortality. A retrospective database review by Ordonez et al of hemodynamically unstable patients with injury severity scale (ISS) >15 showed no difference in mortality between patients who went to CT first compared with patients who underwent surgery or angioembolization first.¹⁸ An international, multicenter, randomized controlled trial by Sierink et al including adult trauma patients with abnormal vital signs who were randomized to immediate total body CT versus standard workup found no difference in mortality in patients who underwent whole-body CT imaging.¹⁹ A retrospective review by White et al of hemodynamically abnormal thoracoabdominal trauma patients found that patients who underwent resuscitation prior to CT (SBP >90) required less blood products and had no difference in length of stay, ventilator time, or mortality.¹³ Interestingly, however, a retrospective study by Nishimura et al of patients with ISS > 15 showed that early CT scanning did not improve mortality or reduce transfusion amounts.²⁰ It is important to note that total body CT scanning is associated with excessive radiation exposure which could increase the risk of radiation-related malignancy and should be used judiciously in selected patients.^{14 21}

One of the principal arguments against obtaining CT for hemodynamically unstable trauma patients is the possible delay in intervention for those patients, especially in less established trauma systems. A retrospective analysis by Dhanik et al of CT studies obtained from an urban tertiary care emergency department showed the median time from CT order to completion is 108 min, with behavioral noncompliance or medical instability being major causes for delay (22.8%).²² Additionally, CT scans have been implicated as the second most common location where significant flow disruptions occur during trauma care.²³ Barbosa et al demonstrated that in patients with hemodynamic instability and a positive FAST, delay in operation was associated with increased early and late in-hospital mortality, with each 10-min delay increasing mortality by 50%.²⁴

Triaging patients to the appropriate location has implications for overall morbidity and survival, and obtaining CT imaging has shown utility in directing patients to the best intervention. A retrospective review of the American Association for the Surgery of Trauma Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery (AAST AORTA) registry by Smith et al showed that mortality rates in patients with resuscitative balloon occlusion of the aorta (REBOA) who went to CT were not significantly different than in patients who went directly to the OR for hemorrhage control, and the patients who underwent CT were more likely to undergo hemorrhage control in interventional radiology than the OR.²⁵ A retrospective review of the NTDB looking at patients with blunt liver trauma found that in patients with AIS >4, angioembolization was associated with significant reduction of odds of mortality when compared with open management.²⁶ Finally, a retrospective single-center study by Murao et al found that early CT was associated with decreased mortality from exsanguination but not overall survival.²⁷ Why is this important? A review of the NTDB from 2007 to 2019 by Atikns et al found that trauma laparotomy is associated with a 12% non-therapeutic laparotomy rate, and patients who underwent negative laparotomy had higher mortality (31.1% vs 20.5%) than those with positive laparotomy.²⁸ Patients who underwent CT imaging prior to laparotomy had a lower rate of negative laparotomy (11.1%) with decreased mortality (22.6%). CT scanning has also shown utility in patients with penetrating thoracoabdominal trauma without clinical indication for immediate laparotomy, reducing the rate of nontherapeutic laparotomy in those patients.²⁹

Once the patient has been triaged to the operating room, the role of CT imaging as a roadmap to laparotomy is controversial. A retrospective study by Vasquez et al evaluating patients with abdominal gunshot wounds concluded that preoperative CT did not alter management for patients with clear indications for operation.³⁰ CT imaging missed injuries in one-third of patients, with small bowel injuries being the most commonly missed. Fakhry et al found a delay in blunt small bowel injury diagnosis that was associated with increased mortality.³¹ While contrast-enhanced CT is sensitive for diagnosing small bowel injuries,³² it is not specific.³³ However, CT may have a role in surgical planning by characterizing retroperitoneal injuries to avoid unnecessary explorations and minimizing non-therapeutic laparotomies.34,36 For example, characterizing injury grade for organs such as the kidneys can reduce the rate of trauma nephrectomies, which are associated with 82% risk of mortality.³⁷

Conclusion

There is an emerging role for the use of CT imaging for preoperative planning in patients with abdominal trauma selected for operative intervention. CT can help triage hemodynamically unstable patients to the best location after arrival to the trauma bay, provide a better evaluation of retroperitoneal trauma, and prioritize injury management for the multiply injured patient. In a well-developed trauma system, CT can be seamlessly incorporated into the evaluation algorithm. However, in less established systems, inefficient CT acquisition times can cause delays in care, which can be associated with increased overall morbidity and mortality. Additionally, while CT can be highly sensitive and specific for diagnosing solid organ injuries, it is less specific for hollow viscus injuries, which can markedly increase morbidity and mortality if missed. Finally, obtaining CT imaging does not change the decision to proceed to the operating room when that decision has been made, and abdominal exploration can be a more definitive method for diagnosing intra-abdominal injuries than CT in critically injured patients.