Stab Wounds.: Knives are not the sole implements used in stabbings. Ice picks, pens, coat hangers, screwdrivers, and broken bottles, to name a few, have been used by assailants. Stab wounds of the abdomen occur most commonly in the upper quadrants, the left more commonly than the right. They are multiple in 20% of cases and involve the chest in up to 10% of cases. Most stab wounds do not cause an intraperitoneal injury, and the incidence varies with the direction of entry into the peritoneal cavity. Anterior stab wounds penetrate the peritoneum in approximately 70% of cases but inflict a visceral injury in only half of these.⁴ Left lower chest wounds are associated with a 17% incidence of intraperitoneal damage in addition to the expected high rate of thoracic and diaphragmatic injuries. Right lower chest wounds have a much lower incidence of 0% to 4%.¹² Abdominal entries from the flank and back have reported incidences of up to 44% and 15%, respectively.^13,14 The organ injured cannot be well predicted by the site of entry in the abdominal wall. The liver and spleen are the viscera most commonly damaged in cases of back and flank wounds.

Gunshot Wounds—Ballistics.: The science of ballistics is complex, but a few basic principles are helpful in understanding the pathophysiologic processes of these injuries. The magnitude of the injury is proportional to the amount of kinetic energy imparted by the bullet to the victim, according to the following equation:

where E is the kinetic energy (in foot-pounds), m is the mass of the bullet, v is the velocity of the bullet (in ft/s), and g is gravitational acceleration (in ft/s). In other words, the degree of injury depends on the mass of the bullet and the square of its velocity.¹⁵ Additional factors that affect injury created by a missile include the resistance and viscoelastic properties of the tissue through which it passes, as well as the stability of the missile in this medium. Missile velocities are categorized as low (slower than 1100 ft/s), medium (1100-2000 ft/s), and high (faster than 2000-2500 ft/s); the impact velocity is the most important determinant of wounding capability. The impact velocity depends on the distance between the firearm and the victim, the muzzle velocity, and various characteristics of the missile. At medium and high velocities, the missile has an explosive effect and creates a temporary passage in the tissue along its course. The size of this passage is directly proportional to the specific gravity of the penetrated tissue. This sudden formation of a tract displaces nearby organs and vascular structures, and bone and viscera may be fractured or torn without being directly struck by the missile. Several cases of an intraperitoneal injury caused by a bullet that remained extraperitoneal throughout its entire course have been reported.¹⁶ Solid viscera, such as the liver and spleen, are more vulnerable to this effect.

High-Velocity Missiles.: Wounds from high-velocity missiles involve additional problems. First, external contaminants tend to be dragged into the wound. Second, the closure of the tract immediately after the bullet’s passage may lead to an underestimation of tissue damage. Finally, high-velocity bullets can fragment internally. In fact, a missile at any velocity can fragment after contact with bone and cause additional multiple trajectories and injuries. Civilian wounds have usually resulted from low-velocity handguns, but unfortunately a trend toward more destructive weapons, such as the .38 and .357, may be occurring.

Shotgun Wounds.: The shotgun was designed to strike a small, fast-moving target at close range. Because of the ballistic shape of the individual pellets, a rapid falloff in velocity occurs, making this weapon ineffective in producing severe wounds at long distances. An initial muzzle velocity of 1300 ft/s drops to 950 ft/s within 20 yards, a decrease of 25%. At close range (<15 yards), however, the shotgun is extremely lethal.

The kinetic energy imparted to the victim depends on the pellet’s size, the number of striking pellets, the type and amount of powder, and the barrel choke (constriction). The most important variable is the distance between the shotgun and the victim. At a distance of 10 yards, 19% of the pellets cluster in a 9-inch diameter circle if fired from a full choke (maximum constriction) barrel. At a distance of 20 yards, the circle is approximately double that diameter. Because the kinetic energy is proportional to the square of the velocity, a 25% loss of velocity at 20 yards results in a significant decrease in the damage produced by the blast.

Shotgun wounds have been previously classified in three groups according to the range and pattern of distribution. More recently, classification has been according to the pattern of injury on the victim. Based on distance from the weapon to the victim, type I wounds involve a long range (>7 yards) and a penetration of subcutaneous tissue and deep fascia only. Type II wounds occur at a distance of 3 to 7 yards and may create a large number of perforated structures. Type III wounds occur at point-blank range (<3 yards) and involve a massive destruction of tissue. When categorized by pattern, type I wounds produce a spread greater than 25 cm in diameter; type II, 10 to 25 cm in diameter; and type III, less than 10 cm in diameter.¹⁷ The tissue damage is proportional to the specific gravity and inversely proportional to the elastic properties of the affected organ. Thus the liver is more vulnerable than the lungs to this injury. Close-range shotgun wounds, in addition to the shot, force external contaminants (e.g., clothing and parts of the shell wadding) into the wounds. Type III wounds carry a substantial mortality risk.

Seatbelt Injuries.: Unrestrained front and rear seat passengers are at unequivocally greater risk of intra-abdominal injury than their restrained counterparts.¹⁸ The three-point shoulder-lap belt is the most effective restraining system and is associated with the lowest incidence of abdominal injuries, compared with older systems. However, abdominal injuries are still ascribed to combined shoulder-lap and lap-belt systems. The shoulder belt component can lead to right-sided and left-sided rib fractures for the driver and front seat passenger, respectively, with potential for injury to underlying abdominal viscera. Improper underarm usage of the shoulder belt increases compressive forces to the upper abdomen, particularly in the event of a front-end crash.

Injuries resulting from solitary lap belts are most often to the abdomen. This is true of nearly half the injuries caused by lap belts. The pathogenesis is usually the compression of bowel between the belt and the vertebral column. Occasionally, an acute, short, closed-loop obstruction occurs along with perforation secondary to the sudden generation of high intraluminal pressures. The resultant injury is primarily a contusion or perforation of the intestines or a tear of the mesentery.

Clinically, two symptom patterns emerge. Approximately one fourth of these patients develop evidence of a hemoperitoneum secondary to mesenteric lacerations. In the remainder, the intestinal injury most commonly involves the jejunum, and the initial signs and symptoms are often absent or considered insignificant. Subsequent delays in diagnosis of up to 8 weeks have rarely been reported. The “seatbelt sign,” contusion or abrasion across the lower abdomen, is found in less than one third of patients with abdominal injuries caused by lap belts. Its presence, however, is highly correlated with intraperitoneal pathologic lesions.¹⁹ Rupture of the diaphragm can also occur. Rare cases of acute abdominal aortic dissection with incomplete or complete occlusion have also been described, and injuries to the lumbar spine are not uncommon.²⁰

Iatrogenic Injuries.: Although well intentioned, diagnostic and therapeutic efforts in patient care are not risk-free. Abdominal injuries may be sequelae of various medical procedures and in certain instances not only are extremely difficult to recognize but may contribute to or cause pronounced morbidity or death. Numerous procedures may cause an iatrogenic injury.

Artificial ventilation can lead to gastric distention, particularly in children. Besides compromising ventilation and increasing the risk of vomiting and aspiration, a significant distention may lead to an esophageal or gastric laceration and perforation. These may occur with bag-mask ventilations, an inadvertent esophageal intubation with a nasotracheal or endotracheal tube, or the mistaken connection of the nasogastric tube to oxygen rather than suction. Esophageal, gastroesophageal junction, and gastric lacerations are evidenced by bloody emesis or nasogastric return. If a gastric perforation occurs and positive-pressure breathing is maintained, a tension pneumoperitoneum or abdominal compartment syndrome may ensue with inferior vena cava compression and decreased cardiac output. External cardiac compressions have produced splenic, hepatic, and gastric injuries. Manual thrusts to clear an airway obstruction, as taught in basic life support courses, and the Heimlich maneuver have caused rib fractures with lacerations and the rupture of abdominal viscera. In cases of a cardiac arrest, these injuries may be occult but life-threatening. If hypotension occurs after cardiopulmonary resuscitation, an abdominal injury and hemorrhage are considered along with cardiogenic shock.²¹

Tube thoracostomy has resulted in injury to the liver and spleen. These injuries may result from an unrecognized elevation of the diaphragm on the side of the thoracostomy or the placement of the tube too low in the chest, with resulting intra-abdominal penetration. Peritoneal lavage, paracentesis, and peritoneal dialysis have caused a series of complications, especially vascular penetration and bowel perforation. Signs of blood loss from a hemoperitoneum in the former case and peritonitis in the latter will evolve.

A liver biopsy can lead to a hemoperitoneum or hemobilia. Endoscopic procedures of the bowel may cause a hollow viscus perforation and peritonitis, particularly when a biopsy is performed, although they can result from rapid retraction of the endoscope without biopsy, as well.²² Peritoneoscopy has been reported to cause small bowel perforations and iliac vessel lacerations. Barium enemas have an extremely low incidence of perforation but can be another cause of unexplained peritonitis and pneumoperitoneum.

Pediatrics.: Congenital anomalies and intra-abdominal neoplasms may be first discovered after a history of blunt trauma. Coagulopathies (e.g., hemophilia) can contribute to the pathologic condition and complicate therapy after apparent minor trauma to the abdomen.

A child’s abdomen has poorly developed musculature and a relatively smaller anteroposterior diameter. These factors increase the vulnerability of abdominal contents to compression between a blunt anterior force and the solid posterior vertebrae. The rib cage is extremely compliant in children and less prone to fractures but nonetheless provides only partial protection against splenic and hepatic injuries. Finally, the bladder is less protected by the pelvis in children, exposing it to greater risk of injury.

The liver, spleen, and kidney are the organs most commonly damaged by blunt mechanism of all varieties, and the incidence of injury for each of these three solid viscera is roughly the same. Gastrointestinal tract perforation is not uncommon with blunt trauma, and these injuries may be isolated. In cases of nonaccidental trauma, those injuries seen most commonly are duodenal and small bowel hematomas and perforations, pancreatic contusions, lacerations and pseudocysts, lacerations and rupture of the liver and spleen, and lacerations of mesenteric vessels.

Stab Wounds.: It is helpful to obtain information regarding the mode of injury from the patient, paramedic, or witnesses. The number of stabs inflicted, type and size of the instrument, posture of the victim relative to the direction of assault, estimated blood loss at the scene, time of injury, and response to fluids should be sought. However, a significant proportion of victims of stab wounds are found under the influence of alcohol or another drug. This state can make obtaining an accurate history a futile effort and further compromises the validity of symptoms and signs.

Gunshot Wounds.: As initial stabilization measures are instituted in the emergency department, the emergency physician can elicit certain facts that can contribute greatly to the evaluation of the patient. These include the weapon used, its distance from the victim when shot, the position of the victim in relationship to the weapon when fired, the suspected number of shots, the blood loss at the scene, the amount and type of field fluids administered, and the vital signs during the prehospital course.

Stab Wounds.: Serial physical examinations performed by the same observer are gaining acceptance in certain centers where these have been found useful, particularly with patients who are alert, communicative, and neurologically intact. The presence of intoxicants does not necessarily preclude reliance on examination but may undermine its value.³⁰ In other series, patients with impressive physical findings after penetrating trauma to the abdomen have undergone exploratory laparotomy, with negative results in 14 to 28% of cases.³¹ Moreover, up to one third of patients with significant intra-abdominal injuries have no suggestive physical signs, particularly when a retroperitoneal injury has occurred.³² Therefore serial clinical evaluations typically involve physical examinations to include trending of vital signs, laboratory testing including serial hemoglobin measurement, and repeated focused assessment with sonography in trauma (FAST) examinations.

Gunshot Wounds.: As with blunt or other modes of penetrating trauma, there is dispute regarding the value of the physical examination of patients with abdominal GSWs. In various series, 20% of patients with a documented intraperitoneal injury had no peritoneal signs before exploration.³² Moreover, objective physical findings suggestive of intra-abdominal damage have been misleading and falsely positive in 15% of patients in whom laparotomy revealed no injury. Other authors contend that selective management can be undertaken safely when physical examination is the fundamental evaluative measure.³⁰

Hematocrit.: The hematocrit reflects baseline value, extent of and time from hemorrhage, exogenous fluid administration, and endogenous plasma refill. The last of these is a physiologic compensatory shift of extracellular fluid into the intravascular space, the intent of which is to restore the original blood volume. Based on a study of volunteers sustaining a 10 to 20% blood loss, this restoration proceeds at a rate of only 40 to 90 mL/hr for the first 10 hours and requires 30 to 40 hours for completion.³⁴ However, patients evidencing hemorrhagic shock with a blood loss of at least 40% demonstrate much faster plasma refill rates, estimated as high as 1500 mL in the first 90 minutes after injury, with significant decreases in hematocrit within this period. Although the hematocrit is an easily acquired measure, it is often a conundrum when viewed in isolation, and serial determinations are more helpful.

White Blood Cell Count.: The white blood cell (WBC) count has little discriminatory value in cases of abdominal trauma, particularly its acute phase.³³ The WBC count may be normal or may show a modest leukocytosis (12,000 to 20,000/mm³ with or without left shift), which can occur in the setting of multisystem trauma as a result of stress-induced demargination in the absence of any intra-abdominal process, or as a result of tissue injury, acute hemorrhage, or peritoneal irritation.

Pancreatic Enzymes.: Neither serum amylase nor lipase is useful in the evaluation of acute abdominal trauma. Normal levels do not exclude a major pancreatic injury, and elevated values may be caused by any of an assortment of reasons in addition to an injured pancreas. The use of serum amylase isoenzymes has not appreciably improved accuracy. Nontraumatic causes of hyperamylasemia include several diseases and the use of alcohol, opioids, and various other drugs. Amylase or lipase may also be elevated with pancreatic ischemia produced by the systemic hypotension that often accompanies trauma. Clearly, these enzymes are neither highly specific nor sensitive for pancreatic injuries. Elevated or rising levels may indicate damage but in themselves are not conclusive.³⁵ In these cases, clinical correlation and further investigation are indicated.

Base Deficit.: Metabolic acidosis in the setting of trauma can suggest the presence of hemorrhagic shock. This can be witnessed chemically as a decreased serum bicarbonate level, increased base deficit, or elevated serum lactate level. Although normal values do not exclude abdominal injury, substantive abnormalities, such as a base deficit greater than or equal to 6, may be predictive. These findings should be considered in clinical context, because the resolution of the laboratory findings will lag behind the clinical improvement of the patient.

Liver Function Tests.: Elevated serum transaminases can result from hepatic trauma but do not distinguish minor contusions from severe injury.³⁶ Alternatively, these may be symptomatic of alcohol-induced liver damage. Elevated liver transaminase levels may be useful for screening pediatric patients for intentional trauma (see Chapter 38). They may also play a role in pediatric patients in combination with a FAST examination as a screening tool to decrease the use of CT scanning, although serial physical examination is still required.³⁷

Toxicology Analysis.: Screens for ethanol and drugs are often used in trauma centers. Their utility in the management of abdominal trauma, per se, has not been established, particularly in patients with normal mental status.³⁸ Positive study findings may prompt the emergency physician to interdict and the patient to decrease the recidivistic use of ethanol or drugs, and physician intervention during this “teaching moment” has been shown to be effective.

Advantages.: In most situations, CT scanning has supplanted DPL because of its higher predictive ability for operative lesions and because it is noninvasive. CT scanning can define the injured organ and the extent of the injury. It is most accurate for solid visceral lesions and accurately discerns the presence, source, and approximate quantity of intraperitoneal hemorrhage (Fig. 46-3). It can demonstrate active bleeding from the liver or spleen and can be used to determine whether therapeutic angiographic embolization is indicated.⁴⁰ CT scanning also evaluates the retroperitoneum (Fig. 46-4), an area not sampled by DPL, as well as the vertebral column, and can be readily extended above or below the abdomen to visualize the thorax or pelvis.⁴¹ CT scanning also provides definitive evaluation for most possible injuries to the urinary tract, including renal artery injury.⁴² It can also detect other vascular hemorrhage and obviate the need for angiography in some patients.⁴³ CT scanning is particularly helpful in guiding nonoperative management of solid organ damage.^44,45 This includes as-needed follow-up studies of convalescing patients with these injuries. It has also proven effective when incorporated in delayed fashion for patients with decreasing hematocrit, increasing base deficit, or subtle examination changes. By minimizing the incidence of nontherapeutic laparotomies for self-limited injury to the liver or spleen, it decreases morbidity and cost attendant to this operation.⁴⁶ Increasingly, trauma centers are using CT with intravenous contrast only, as it has been shown that little additional information is provided by the addition of oral contrast, which delays scanning and may pose an aspiration risk for the patient.^47,48

Disadvantages.: Disadvantages of CT scanning include relative insensitivity for injury of the pancreas, diaphragm, small bowel, and mesentery, although detection of these injuries is improving47,48 (Fig. 46-5). The last two are particularly worrisome because isolated coincidental hollow viscus injury in patients with blunt trauma, although uncommon, is not rare, and increased morbidity and death can ensue if diagnosis is missed or the condition goes undetected for a prolonged period. Findings on CT scans, including the suspected quantity of hemoperitoneum or the presence of isolated free fluid, are not able to forecast well the need for operative intervention.⁴⁹ Complications can result from intravenous contrast administration or uncommonly from contrast material administered orally. Moreover, oral contrast delivery to opacify bowel is infrequently useful and typically omitted.^47,50 Finally, patients must be temporarily removed from the resuscitation area for the study to be accomplished, which can put the patient at risk in the case of rapid clinical deterioration. However, CT scanning remains the cornerstone of diagnosis. In cases with equivocal CT scan results, such as more than physiologic fluid, or a worrisome history and physical examination findings, serial examinations or further diagnostic testing should be strongly considered, including DPL, particularly to evaluate for missed hollow viscus injury (Table 46-1).

Radiation Risk.: Increasingly, there is concern regarding the negative long-term effects from exposure to ionizing radiation resulting from medical imaging. Over 62 million CT scans are performed per year in the United States, including over 4 million in children,⁵¹ and the number of scans performed per patient after trauma is increasing.⁵² Based on data from survivors of the atomic bombs dropped on Japan and average radiation exposure from various types of CT scans, it has been estimated that 0.4% of all cancers in the United States have been caused by exposure to medical radiation, and that number may be increasing to 1 to 2%. Children are especially at risk, and even a single CT scan may increase the lifetime risk of cancer.⁵¹ Although direct evidence of increased cancer risk from CT scans has not yet been demonstrated, several methods are becoming available to reduce radiation exposure. Some groups have attempted to define decision rules to help avoid unnecessary CT scans in very low-risk patients, though their role in clinical practice has yet to be defined.^37,53,54 For very low-risk, hemodynamically stable patients, special consideration should be given to patients with large numbers of negative CT scans in the past, and observation may be preferable to repeat radiation exposure. Adjustment of scanning techniques for children and body habitus on an institutional level through use of “as low as reasonably achievable” (ALARA) principles, developed in conjunction with the department of radiology, can decrease excessive radiation exposure if CT scanning is clinically indicated. If a patient is to be transferred to another facility, attempts should be made to convey hard copy or digital images to the accepting facility, as CT scans are not infrequently repeated at the receiving hospital.⁵⁵ These repeat CT scans are unlikely to change management without a concurrent change in clinical picture.⁵⁶ A balance between minimizing radiation exposure and simultaneously minimizing the number of missed injuries is a challenge for the emergency physician evaluating a patient with abdominal trauma.

Technique.: The technique for CT scanning is reasonably standardized, but certain conventions are debated. The studies should begin in the low chest and be taken through the pelvis. If chest scanning is also required, a single continuous scan is obtained from the root of the neck to the floor of the pelvis. “Quick look” but less thorough studies are problematic and should be avoided; preliminary reads from the CT control room do not have the added accuracy of reconstituted scans and may therefore miss subtle injuries, such as intimal tears of the thoracic aorta. Most centers perform enhanced (intravenous contrast) and nonenhanced scans because the latter alone may not demonstrate intraparenchymal hematomas well. Other practitioners believe that the noncontrast portion contributes little other than time to the procedure. In patients who undergo chest and abdominopelvic CTs, reconstituted images can be obtained of the thoracolumbar spine, sparing the need for additional studies and associated ionizing radiation. Except in certain unusual circumstances, single scans through the areas of interest with intravenous contrast only are recommended.

Advantages.: Ultrasonography carries a host of advantages. It is a portable instrument that can be brought to the bedside in the trauma resuscitation area. Studies of the pericardial, intraperitoneal, and thoracic spaces can be accomplished in less than 5 minutes. FAST ultrasound has a sensitivity in detecting as little as 100 mL and, more typically, 500 mL of intraperitoneal fluid that ranges from 60 to 95% in most recent studies, and specificity for hemoperitoneum is excellent.⁶² Therefore when time is precious in the patient in critical condition, the FAST can provide a rapid answer to the key question in the decision matrix, which is whether hemoperitoneum is present. Unlike DPL, the FAST can evaluate intrathoracic structures, is noninvasive, and can be performed serially and by multiple technicians. Unlike CT scanning, it is not a potential radiation hazard and does not require administration of contrast agents. Accuracy correlates with length of training and experience, but expertise can be readily achieved in emergency medicine and surgical training programs.⁶³ Serially performed FAST increases its diagnostic accuracy for organ injury in patients with BAT.^64,65 Furthermore, E-FAST adds thoracic windows to detect the presence of pneumothorax in patients who have sustained penetrating abdominal trauma (PAT) or BAT. These additional views detect pneumothorax with a sensitivity of almost 60% and a specificity of up to 99% when compared with CT, but more important, the E-FAST is three times as sensitive as a portable supine chest x-ray examination done in the trauma bay, which has a sensitivity of only 20%.⁶⁶ Overall, ultrasonography can serve as an accurate, rapid, and less expensive diagnostic screening tool than DPL or CT.^67–69

Disadvantages.: The FAST study does not image solid parenchymal damage, the retroperitoneum, or diaphragmatic defects well. It is technically compromised by the uncooperative, agitated patient, as well as by obesity, substantial bowel gas, and subcutaneous air. Indeterminate studies require follow-up attempts or alternative diagnostic tests.⁶⁵ It is less sensitive and more operator dependent than DPL in revealing hemoperitoneum and cannot distinguish blood from ascites or uroperitoneum. For unclear reasons, ultrasound has a high (31%) false-negative rate in detecting hemoperitoneum in the presence of pelvic fracture.⁷⁰ The FAST study, like DPL, will not detect the presence of solid parenchymal damage if free intraperitoneal blood is absent, as in subcapsular splenic injury.^70,71 Finally, ultrasonography is poor at recognizing bowel injury in which hemorrhage tends to be inconsequential, and failure to diagnose hollow viscus perforation in a timely manner can have catastrophic results.⁷² Because of these limitations, reliance on a single negative FAST examination performed within minutes of the injury is ill-advised. Serial FAST examinations may help to determine progressive hemorrhage, however.

Advantages.: In cases of blunt trauma, DPL’s primary remaining use is in the triage of the patient who is hemodynamically unstable and has multiple injuries with an equivocal FAST examination or in the patient in whom FAST cannot be obtained owing to the absence of equipment or competent personnel.⁷³ In such complex scenarios, DPL can promptly reveal or exclude the presence of intraperitoneal hemorrhage and can serve as an indication for laparotomy. Rarely, DPL is used to discern potentially serious bowel perforations in patients who are poor candidates for serial clinical observations (e.g., coma) and for which other diagnostic methods can be unreliable.⁷⁴

Disadvantages.: The morbidity associated with DPL occurs at a low rate and can be categorized as local or systemic infection, intraperitoneal injury, and technical failure. Wound complications, including hematoma and infection, occurred in 0.3% of cases in two large reviews.⁷⁵ Technical failure can result in an inaccurate study and difficulty with fluid collection. In addition, DPL is exquisitely sensitive for hemoperitoneum and in a hemodynamically stable patient can lead to unnecessary laparotomy. False-negative interpretations can result from the failure to recover lavage fluid.

Results.: In cases of blunt trauma, the aspiration of 10 mL or more of blood has a positive predictive value of greater than 90% for intraperitoneal injury, predictably solid visceral or vascular, and is responsible for approximately 80% of true positive DPL findings in blunt trauma.⁷⁵ The red blood cell (RBC) count of the lavage fluid is the next most widely used and accurate parameter (Table 46-2). In cases of blunt trauma, an RBC count exceeding 100,000/mm³ is considered positive and generally specific for injury. However, while sensitive to the presence of injury, it may detect self-limited pathology for which laparotomy is unnecessary.

There is a well-known association between false-positive peritoneal lavage in the setting of retroperitoneal hematoma and pelvic fracture.⁷⁶ CT scanning is the standard method by which pelvic fracture with possible retroperitoneal or intraperitoneal hemorrhage is evaluated.⁷⁷

With anterior abdominal stab wounds, aspiration of 10 mL of gross blood or the return of lavage fluid with an RBC count greater than 100,000/mm³ carries a sensitivity exceeding 90% (see Table 46-2).⁷⁸ It is recommended that patients with equivocal RBC counts be carefully observed for 12 to 24 hours.⁷⁹ Most injuries associated with RBC counts less than 100,000/mm³ are to hollow viscera, and clinical manifestations of these should develop within this observation period. With lower chest stab wounds, a positive RBC count of 5000 to 10,000/mm³ should be considered to be evidence of diaphragmatic injury. Because of the more serious nature and greater likelihood of an injury with abdominal GSWs, RBC counts of 5000/mm³ are advocated as the cutoff, as these will signal peritoneal penetration, if not injury.⁷⁵ However, laparoscopy has supplanted DPL for the purpose of identifying or excluding diaphragmatic injury in lower chest penetrating trauma.

Thoracotomy.: Thoracotomy and subsequent cross-clamping of the descending aorta have been used to stabilize patients with thoracoabdominal injuries and profound hypovolemic shock. However, it is rarely lifesaving in the emergency department (see Chapter 45).

In a patient with massive abdominal injuries and hypotension secondary to a hemoperitoneum, the primary purpose of aortic cross-clamping is to shunt available blood into the coronary and cerebral circulation during resuscitation. Second, it is helpful in providing proximal bleeding control of certain vascular and parenchymal injuries, although continued bleeding can occur via collateral flow, until direct clamping, packing, or repair is achieved. Third, it can allow direct atrial access for rapid fluid administration. Finally, it has been advocated as a prophylactic measure in the operating room before laparotomy is performed for a massive hemoperitoneum. In certain instances, abdominal decompression, particularly in the face of a vascular injury, may result in worsening shock and death.

Antibiotics.: An intestinal perforation and spillage can occur after blunt or, more commonly, penetrating trauma to the abdomen. Anaerobes and coliforms are the predominant organisms found. Antibiotics given prophylactically have been demonstrated to be effective in decreasing the incidence of intra-abdominal sepsis and should be given as soon as such an injury is suspected. A single preoperative dose of a broad-spectrum antibiotic or combination of antibiotics that covers both aerobic and anaerobic organisms, such as piperacillin-tazobactam 3.375 g intravenously, is recommended.⁸⁸

Anterior Abdomen.: In approaching the management of stab wounds to the anterior abdomen, the clinician is faced with three fundamental tasks. The first and most important is to determine whether clinical indications exist for laparotomy. The presence of one or more of these indications, particularly in the context of an unstable patient, sets the course to exigent operation. If none is found, however, the clinician may address the second issue of whether the peritoneal cavity has been violated. If it can be definitively demonstrated that it has not, no further diagnostic evaluation is required, and the patient can be discharged after appropriate wound care. If the cavity has been violated, or if it cannot be determined that the cavity has not been violated, the third question is pursued: does injury exist and, if so, is laparotomy required? One general approach to abdominal stab wounds founded on these three queries is summarized in Figure 46-9. This algorithm is largely based on clinical indicators of injury, LWE, CT, and other radiologic modalities. In centers without such resources, diagnostic peritoneal aspiration and lavage may still have a limited role. Other strategies rely more heavily on other techniques, such as serial abdominal examinations or laparoscopy.^91–94

Thoracoabdominal.: Even a single stab wound to the low chest can violate the mediastinum, thoracic cavity, diaphragm, peritoneal cavity, and retroperitoneum. The risk of diaphragmatic penetration from a left thoracoabdominal stab wound has been measured at 17%.¹² When all thoracoabdominal wounds are considered, the risk of occult injury is 7%.¹⁰⁵ Ultrasonography can be extremely useful by permitting quick assessment for hemopericardium and hemoperitoneum in the marginally stable patient, if thoracotomy or laparotomy is not already clinically indicated.⁷⁵ LWE of slash-type wounds may obviate the need for further evaluation. However, the depth of investigation cannot be taken beyond the anterior rib margin to maximize safety and accuracy. Further assessment for intraperitoneal and diaphragmatic injury can be made by DPL. The RBC criterion is lowered to 5000 to 10,000/mm³ to optimize sensitivity for isolated diaphragmatic injury.¹⁰⁴ Laparoscopy or thoracoscopy can visualize and potentially be used to repair the diaphragm and other organs. Newer multidetector CT scanning and MRI show promise in excluding diaphragmatic injury. CT has a sensitivity of 94% and specificity of almost 96% for detecting diaphragmatic injury. However, equivocal scans should be followed up with more definitive management, such as DPL, exploratory laparotomy, or laparoscopy.¹³ A very conservative approach to the left lower chest stab wound, in particular, is mandatory exploration. This approach avoids any opportunity for missed diaphragmatic rents and their delayed consequences but results in an exceptionally high incidence of nontherapeutic operation. Rapid slice helical CT and MRI may provide a solution to this vexing concern, but data are limited to date.

Flank and Back.: The incidence of retroperitoneal injuries after stab wounds to the flank and back is greater than with injury to the anterior wall. However, risk of intraperitoneal organ injury is significant, ranging from 15 to 40%.¹⁴ Again, LWE can be a useful first step. However, the paraspinal muscles are quite thick, rendering the procedure more difficult. Triple-contrast CT scan is becoming the preferred method of evaluation in hemodynamically stable patients and coupled with observation may safely allow nonoperative management of these patients.^32,97

Implement in Situ.: It is routinely advised that foreign bodies in situ of the torso be removed under operating conditions. This is considered safest in the event that the implement is intravascular or in a highly vascularized organ. Plain films are generally all that is required. A CT scan may be indicated in stable patients if plain films suggest impalement of major vascular structures. Angiography may also be necessary. For pregnant patients or those with severe comorbid illness in whom unnecessary laparotomy is preferably avoided, a CT scan may be able to discern the depth of entry and extent of injury, though the risk of radiation to the fetus must be weighed against the risk of operative intervention. In these cases the foreign body may be removed safely outside of the operating room.

Thoracoabdominal.: Patients with GSWs to the low chest have intraperitoneal injuries reported in 45% of cases. Clinical indications for laparotomy are unchanged. DPL is particularly helpful in these cases to discern diaphragm injury, and the RBC threshold of 5000 to 10,000/mm³ produces excellent sensitivity, but a combination of CT scanning and serial examinations is more commonly used.

Flank and Back.: In the past, operative exploration was generally recommended because of the increased likelihood of a serious injury and the greater fallibility of both the physical examination and DPL in cases of retroperitoneal injuries. However, as multidetector CT scanners have evolved, an intravenous contrast CT scan to delineate retroperitoneal pathologic lesions is typically the initial diagnostic test of choice in a stable patient.95,102 As with stab wounds, laparoscopy or observation alone can be attempted in selected circumstances.¹⁰⁶

Shotgun Wounds.: Type I injuries can be effectively managed by reserving laparotomy for patients with clear peritoneal signs or progressive abdominal tenderness. Certain authors advocate an expectant approach to type II injuries, stating that small punctures of the bowel cause no wound eversion and no peritoneal leakage and will spontaneously close.¹⁰⁷ A more prudent approach is to perform laparotomy in cases of these penetrating wounds, especially if there are signs of peritonitis. Reconstruction of abdominal wall defects may be required. Type III injuries are commonly associated with multiple organ injuries, shock, and pronounced tissue destruction, requiring hemostasis and extensive débridement.

Determining Hemoperitoneum:

Demonstrating Organ Injury That Requires Laparotomy.: Indications for the respective studies will vary with clinical need and with the experience, resources, and attitudes of individual institutions.

Clinical Indications for Laparotomy.: The decision to perform immediate laparotomy after injury from a blunt mechanism is rarely determined solely by clinical parameters. Potential indications are any of the following (Table 46-5):

Establishing the need for urgent laparotomy on clinical grounds is particularly problematic in the patient with multiple blunt injuries. Numerous extra-abdominal potential sources of hypotension exist. In addition, there is often coincident head injury or intoxication to further impair the reliability of examination. A nontherapeutic laparotomy may imperil the patient, not so much because of the potential morbidity of the procedure but rather because more vital diagnostic and therapeutic steps are delayed. When confusion exists, corroborative diagnostic tests are strongly preferred.

Hemodynamically Unstable Patients.: In the patient with multiple blunt injuries who is threatened by shock, three cavities are immediately targeted. Chest and pelvic radiographs seek blood loss in the thoracic and retroperitoneal spaces, respectively. FAST or peritoneal aspiration is undertaken to reveal or exclude the presence of blood in the peritoneal cavity. Hemoperitoneum in a clinically unstable patient necessitates laparotomy.

Hemodynamically Stable Patients.: In patients who are hemodynamically stable, CT scanning is the widely preferred diagnostic modality because of its ability to specify organ pathology, semiquantitate hemoperitoneum, and study nonabdominal body regions. Its potential drawbacks in certain clinical circumstances must be understood, however. Ultrasonography, DPL, and, very uncommonly, laparoscopy can be used in a complementary or primary mode.

Pediatrics.: Children are prone to aerophagia, and decompressive nasogastric tubes are particularly important to help prevent compromised lung function and aid in the abdominal examination. Care is taken in fluid resuscitation and drug administration, with attention being paid to the patient’s size and with surface area or body weight used as a guide. Because of their size and relatively larger surface area, children are more susceptible to hypothermia resulting from the administration of unwarmed fluids and blood products. The use of overhead heat lamps, blood warmers, and prewarmed intravenous fluids helps obviate this condition.

Children with major injuries may cause fear and anxiety in even the most experienced emergency physician or surgeon. It is imperative to maintain careful vigilance and overcome any tendency to avoid indicated procedures.

For physiologic reasons, the expectant management of blunt hepatic or splenic injury has better success in the child than in the adult patient.117–119 If stability exists, nonoperative management can ensue if capable personnel and resources are present.¹²⁰ CT scanning is the primary diagnostic agent in both the initial and the convalescent periods to define and grade solid organ injury. As for adults, this modality is insensitive for the discovery of hollow viscus and, to a lesser degree, pancreatic pathologic conditions.⁷¹

FAST has been found to be useful for the detection of free fluid and can be used in triage to send the unstable child with visualized hemoperitoneum for laparotomy.¹²¹ However, FAST appears to have less sensitivity when compared with the adult experience. DPL, specifically peritoneal aspiration, can also uncover hemoperitoneum in the initial management of the critically, multiply injured child. Reliance on cell count alone has prompted significant nontherapeutic laparotomy rates.

In the course of expectant treatment, the child should undergo laparotomy if instability develops, transfusion requirements are excessive, peritoneal signs are unequivocal, or observation is not feasible because of associated injuries or lack of institutional resources. Closed head injury need not preclude nonoperative management of known solid parenchymal injury, but the risk associated with undiscovered and coincident hollow viscus perforation is greatly increased. The diagnostic approach to penetrating trauma in children is the same as that in adults.

Transfer.: Trauma patients in rural settings may require a stabilizing damage control laparotomy by a general surgeon before being transferred to a trauma center for definitive care.