Regarding traumatic rupture of the aorta (TRA), which ONE of the following statements is TRUE?
Answer: B: Aortic injuries are usually associated with high kinetic energy injuries. The mechanism of injury is such that as much as 75% of patients have fractures of bones other than the ribs. Traumatic rupture of the aorta begins in the intima and moves outwards into the adventitia, which provides most of the tensile support. The atherosclerosis in the tunica media does not predispose the aorta to traumatic rupture. Approximately two-thirds of the tears start at the isthmus of the aorta where the descending aorta begins just distal to the left subclavian artery and the attachment of the ligamentum arteriosum.
On a supine film the sensitivity of a widened mediastinum is 90%, but its specificity is only 30% to detect traumatic rupture. The sensitivity improves to 95% for aortic injury on an erect film. A chest CT with angiography is the best screening study of choice to diagnose aortic injury. With the use of multi-detector CT (MDCT) in thin-slice rapid scanning and accurate contrast bolus timing, not only aortic injury but other significant thoracic vascular injuries can be detected.
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Regarding diaphragmatic injuries, which ONE of the following statements is CORRECT?
Answer: C: Diaphragmatic injuries are most frequently caused by penetrating trauma to the thoracoabdominal region. A gunshot wound anywhere in the abdomen or chest may put the patient at risk for diaphragmatic injury due to the projectile’s prolonged length of travel within the body. For stab wound, however, the blade has a limited length. Subsequently, wounds below or at the nipple line and above the umbilicus are the only ones that are at risk for causing such damage. The diaphragm normally rises to the level of the fifth rib with expiration and is frequently penetrated by wounds to the anterior chest below the nipple line. Rupture due to blunt trauma is less frequent and occurs in <5% of patients hospitalised with chest trauma. This incidence is somewhat higher (10–15%) in patients with a fractured pelvis. In blunt trauma, diaphragmatic injuries are often associated with other abdominal and pelvic injuries. A high index of suspicion is necessary in such patients.
CXRs pick up diaphragmatic injuries in <25% cases because most of the CXR abnormalities are nonspecific. However, the majority of the patients have at least one abnormality. MDCT has a relatively high sensitivity in diagnosing these injuries. When there remains a high suspicion for diaphragmatic injury, direct visualisation with either thoracoscopy or laparoscopy should be performed. Previously thought to be more common on the left, recent advances in the diagnosis suggest that the incidence of diaphragmatic rupture is similar on both sides.
Except in obvious cases such as penetrating injury to the thoracoabdominal region where diaphragmatic injury can be suspected, there is a risk of delayed diagnosis, especially in blunt abdominal trauma. In these cases, often the diagnosis is made at laparotomy. Most injuries, if undetected, will enlarge with time and delayed rupture and herniation of abdominal structures with accompanying consequences such as obstruction and infarction may occur.
In the assessment of intraabdominal injuries due to blunt trauma, which ONE of the following statements is CORRECT?
Answer: A: Localized tenderness, when present, has a relatively high sensitivity in detecting intraabdominal injury but this sign is not specific. Abdominal girth measurements or general assessment for abdominal distension have no value in identifying intraabdominal bleeding. Abdominal distension is generally due to gas and a large amount of fluid should be present in the peritoneal cavity to cause any measurable increase in abdominal girth. Neither physical examination nor FAST can identify retroperitoneal injury.
A negative FAST scan may be unreliable, especially when the following clinical findings are present:
In these circumstances there could be an intraabdominal injury without producing a haemoperitoneum and an abdominal CT is usually indicated in spite of the FAST being negative.
Regarding splenic injuries due to blunt trauma in children, which ONE of the following statements is TRUE?
Answer: A: Splenic injury is the most common blunt intrabdominal injury in children. As with other solid organ injuries, a feature of splenic injury is slow initial bleeding. Consequently, it may not initially produce haemodynamic instability or signs of peritonism. However, it can cause disastrous haemorrhagic shock due to late sudden rapid bleeding if not detected early. Children tend to be more haemodynamically stable than adults for the same degree of splenic injury. Therefore, children are more likely to be managed conservatively and the vast majority of children recover fully with conservative management. A fatal haemorrhage is more likely to be associated with a liver injury than a splenic injury. Haemodynamically stable liver injuries are often managed conservatively in children.
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Regarding small bowel injury due to blunt abdominal trauma, which ONE of the following statements is TRUE?
Answer: A: Bowel injuries as a whole are fairly uncommon, making up <5% of patients with blunt abdominal trauma. Small bowel injuries specifically are associated with other severe injuries, which accounts for the associated high mortality (~20%) in these patients. Initial symptoms and signs are often subtle and the diagnosis is often difficult, even with the use of contrast-enhanced CT. The detection may become even more difficult if patients are ventilated and sedated due to other major injuries. Small bowel injuries are often associated with some intraabdominal bleeding due to mesenteric injury. This bleeding, combined with peritonitis caused by bacterial contamination, produces features of peritonism. However, this may take 6–8 hours to develop.
On contrast-enhanced CT scan (intravenous and oral contrast) free intraperitoneal gas is present in only 40% cases and extravasation of oral contrast is present in only 5% of cases. These features, when present, are considered to be diagnostic of bowel perforation. Other markers of bowel injury may also be found with CT. Presence of free peritoneal fluid without evidence of solid-organ injury and bowel wall thickening are examples.
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