The Child And Abdominal Trauma

Around 8% of injured children will have an injury involving their abdomen and 9% of these end with a fatal result of which 22% will be directly attributable to their abdominal injury (Cooper et al. 1994). Blunt abdominal trauma is seen with much greater frequency than penetrating trauma, however the later is 1.4 times more likely to end in fatality (Cooper et al. 1994). Much progress has been made in the past two decades on the imaging of children with blunt abdominal trauma. This along with a better understanding of the pathophysiology has led to a sharp decline in the laparotomy rate. There are many differences in the assessment and management of abdominal trauma between adults and children, and this will remain the focus of this section. Anatomy Several anatomical factors combine to make the child more vulnerable than an adult to abdominal organ injury. The child’s smaller size, thin abdominal wall, and cartilaginous ribs mean a greater force is transmitted to the abdominal organs. The close proximity of the abdominal organs will also increase the chance of multi-organ injury. Also the more horizontal position of the diaphragm in a child means that the liver and spleen lie lower and more anteriorly and thus more vulnerable to injury. The thin abdominal wall also makes it prudent to assume that all penetrating injuries have entered the peritoneal cavity till proven otherwise. Mechanism of injury Blunt abdominal trauma remains the commonest cause of abdominal injury to the child. In the USA blunt trauma makes up 83% of all paediatric abdominal trauma (Cooper et al. 1994) whereas in Australia it makes up 97%. Motor vehicle accidents are responsible for the majority of blunt abdominal injuries with slightly more occupant injuries (41%) than pedestrian (33%). Falls make up the next highest group (8%) followed by bicycle injuries (7%) (Cooper et al. 1994). Proper use of seat belts with the use of car chairs and booster seats would reduce the injury rate significantly. Lap belt injuries are common in children and characteristically produce the triad of transverse abdominal wall ecchymosis, intestinal injury, and a flexion-distraction fracture to a lumbar vertebra (Chance fracture) (Newman et al. 1990). Handlebar injuries often cause severe organ damage due to the force being applied through a small cross-sectional area. Commonly damaged organs from handle bar injuries include: spleen, liver, pancreas, kidney, and intestine (specifically causing duodenal haematomas and bowel perforations) (Clarnette et al. 1997). Penetrating injuries although less common than blunt are associated with a higher mortality rate. In the USA penetrating injuries are usually the result of a stab or gunshot wounds whereas in Australia most penetrating injuries are minor. Child abuse is unfortunately very common and is the leading cause of trauma death in infants. Abdominal injury from child abuse carries a mortality rate as high as 45% (Cooper et al. 1988). These injuries are often the result of a punch or kick. A neglected infant who is the victim of child abuse can present moribund with rupture of intraabdominal organs. A high index of suspicion with a careful history and detailed examination is mandatory in any child suspected of being abused to prevent repeated assault. The presenting problem is frequently minor e.g. a finger injury, which can distract attention from a more serious abdominal injury. Key points

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Anatomy and mechanism of injury lead to many differences in the assessment and management of abdominal trauma between adults and children.

General plan of management The management of a child with abdominal trauma should follow the basic principals of any trauma resuscitation ie: primary survey with treatment at each stage followed by the secondary survey. Abdominal examination normally comes into the secondary survey but may have to be included in the circulation phase of the primary survey if the child remains hypotensive after fluid resuscitation. The child is physiologically more resilient than an adult to blood loss. The first indication of hypovolaemia in the child is tachycardia, and hypotension may not become manifest until 45% of blood volume is lost. When intraabdominal haemorrhage from blunt trauma is suspected and the child is still unstable after 40-60ml/Kg crystalloid resuscitation, one should give 10ml/Kg of packed red cells, and if still unstable should be taken immediately to theatre for laparotomy (American College of Surgeons, 1997). If the child is stable or becomes stable after resuscitation a non operative approach can be undertaken. This approach followed the realization in the 1970’s that most abdominal organ injuries in children stop bleeding spontaneously, and with time even the most severely damaged organs will usually heal. This approach depends on a surgeon being present and frequently re-examining the child. The child should be able to be immediately taken to theatre if they become unstable or develop signs of peritonitis signifying bowel perforation. Therefore the management of abdominal trauma in children should only be performed in institutions where the child can be fully managed, including laparotomy and after-care. Children will frequently air swallow when involved in trauma. This can lead to gastric distension, which not only impairs respiration but is also quite painful to palpate making abdominal assessment difficult. In these children a gastric tube should be passed, remembering that it should be orogastric in the presence of cranial or facial injuries. A urinary catheter is helpful in the child sustaining major trauma as urine output is a good indicator of haemodynamic status. A catheter should only be passed after one has checked that there are no signs of urethral injury (see renal section). Key points

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Children are more resistant than adults to the effects of blood loss and the signs of hypovolaemia may not be apparent until 45% of blood volume is lost.

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Non-operative management may be possible in children even in severe organ trauma. However the child should be taken to theatre if they become unstable.

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Gastric distension due to swallowed air can present a problem to assessment

Investigations Blood tests Serum amylase measurement is useful as one will see a rise not only in traumatic pancreatitis but also with small bowel injuries. Beware that parotid trauma can also give an elevated serum amylase. Liver enzymes are usually

elevated with hepatic damage (Sahdev et al. 1991, Hennes et al. 1990) and have been shown to be a useful indicator of occult hepatic injury in victims of child abuse (Coant et al. 1992). Urinalysis Microscopic and macroscopic haematuria apart from being an indicator of urinary tract damage are also an indicator of other intraabdominal organ injury especially of the spleen and liver. However this only remains true when there are other positive abdominal signs on examination (Taylor et al. 1988). Plain x-ray A plain abdominal film can be useful in detecting the presence of free gas signifying a bowel perforation. However this investigation is only positive in 25%-46% of perforations and should not be use to rule out the possibility of a visceral injury (Ulman et al. 1996, Ciftci et al. 1998). Other helpful signs on a plain abdominal film are loss of the psoas shadows, retroperitoneal gas (in the presence of a duodenal perforation), and bony injuries including lower rib, vertebral, and pelvic fractures. In the case of penetrating trauma a foreign body may be located. Ultrasound It has been shown in the paediatric trauma setting that free intraabdominal fluid correlates very well with organ injury (Taylor et al. 1995, Akgur et al. 1997). Ultrasound examination has been shown to be very reliable in detecting this free fluid and is being increasingly used as a trauma room screening tool (Patrick et al. 1998, Katz et al. 1996). The FAST (focused abdominal sonography in trauma) examination looks at pockets in the peritoneal cavity where blood will collect in the supine position ie: retrovesical pouch or pouch of Douglas in males and females respectively, Morrison’s pouch, spleno-renal recess and right and left paracolic gutters. The advantage of this examination is that it can be performed in the trauma room, takes less than 3 minutes to perform, does not use ionizing radiation, and is repeatable. The FAST examination technique is fairly easy to learn (Ingeman et al. 1996) and is increasingly being used successfully by non-radiologists in the trauma room. Although this test is sensitive, it does not demonstrate the injured organ, therefore a positive test in a stable child is an indication that the patient requires a CT scan. It is also useful in the multitrauma patient in whom initial resuscitation has not been successful and one is not certain where the bleeding source is. In this situation a FAST examination would rapidly confirm whether the bleeding was intraabdominal or not. CT scan CT scanning with the use of intravenous and oral contrast has become invaluable in the assessment of abdominal trauma (Ruess et al. 1997, Graham and Wong 1996). First reported by Rance and Bear (1980), the examination will usually demonstrate specific organ injuries allowing for effective triage and a more focused plan of management (Neish et al. 1998). The main drawback of this examination is that it must be performed in the radiology department and therefore can only be done when the child is haemodynamically stable. Although CT will pick up many intestinal injuries, some will be missed and a negative examination is no substitute for frequent clinical assessment (Bensard et al. 1996,.Akgur et al. 1997) Diagnostic peritoneal lavage

Diagnostic peritoneal lavage (DPL) has greatly declined in popularity in children mainly due to the realization that the majority of solid organ injuries can be managed non-operatively. Disadvantages include that it is a painful test and will cause distress to the conscious child, it can be the cause of intraabdominal trauma, and is non-specific when positive. The fact that fluid and gas are put into the peritoneal cavity makes interpretation of subsequent imaging difficult. The only area that DPL may have a role in children is in the situation where a child must be rushed to theatre for an extraabdominal injury and one wishes to rule out a major abdominal injury. Trauma room ultrasound should make this last indication invalid. Laparoscopy The role and safety of laparoscopy for the diagnosis and treatment of intra-abdominal trauma in children is controversial and a case has yet to be proven. However some preliminary studies have yielded promising results (Hasegawa et al. 1997). Specific organ injury

Spleen The spleen is the most commonly injured intraabdominal organ in the child. The mechanism of injury is usually blunt trauma to the left upper quadrant, flank, or lower chest from a motor vehicle accident or fall. Physical examination will usually elicit tenderness in the left upper quadrant. Unlike adults with a splenic injury, rib fractures are unusual. A plain abdominal film may show the gastric bubble displaced to the right but a CT scan is the investigation of choice. In most instances the spleen will bleed resulting in either free intraabdominal blood or be contained within a subcapsular haematoma. The CT scan often looks dramatic but the key is to observe and act on the cardiovascular parameters which allows over 90% of splenic lacerations to be successfully managed non operatively. Delayed splenic rupture has only been very rarely reported. A vascular contrast blush seen on CT is however associated with arterial bleeding and may be an indication for early laparotomy in children (Cox et al. 1997). In subsequent days with non-operative management the child is often difficult to manage with delayed reestablishment of normal feeding, some persistent abdominal pain, fever, and occasionally a pleural effusion. The main clinical concern is: could there be an associated intraabdominal injury accounting for the persisting symptoms? If there is any doubt then a repeat CT scan is indicated. It has been shown that with selective non-operative management with careful observation the risk of missed associated injuries are minimal (Morse and Garcia 1994). If operation is required efforts are made to preserve the spleen which may include spenorrhaphy, partial splenectomy, or the use of an absorbable knitted bag to enclose the spleen (Aidonopoulos et al. 1995). This is important as it has been shown that splenectomy caries a higher risk of death form overwhelming bacterial sepsis. This risk is highest in the paediatric population. In the situation where splenectomy has to be performed, there has been some success in splenic auto transplantation (Szendroi et al. 1997), although this does not guarantee protection from overwhelming sepsis (Moore et al. 1983), as to preserve splenic function 25% of the spleen has to remain. It is therefore prudent to immunize these children with polyvalent pneumococcal and Haemophilus influenza vaccine. It remains controversial whether children should be on long-term penicillin or have an adequate stock at home to be started as soon as any fever develops.

It is unclear how long one should restrict the physical activity of the child who has sustained splenic trauma. The rate of healing as determined on serial CT scanning seems dependent on the original grade of splenic injury; with grade 1 and 2 injuries healing within 4 months, grade 3 injuries taking up to 6 months and grade 4 injuries taking up to 11 months (Benya et al. 1995). An uncommon sequelae of splenic trauma is the formation of a splenic pseudocyst. Small cysts under 4cm often resolve spontaneously but larger cysts tend not to resolve and run the risk of infection, rupture and haemorrhage. It is for these reasons that an operative approach be taken on large pseudocysts with the aim at splenic preservation. Techniques include enucleation, marsupialization, and partial splenectomy but sometimes these are not possible and splenectomy must be carried out (Teneriello et al. 1997).

Liver In the last two decades the trend with children with liver injuries has also been to attempt non-operative management if possible. This is because in children most hepatic injuries like splenic injuries will stop bleeding spontaneously. Again the principles are of a detailed history working out the forces involved with intensive monitoring. It is important when reviewing the literature on the management of liver trauma to appreciate that the denominator has changed in many papers. With the advent of CT scanning many more minor liver injuries are being picked up. It is in such population groups that operative rates of 7% have been reported. The same basic rules apply for liver injuries as for any intrabdominal haemorrhage, that is if after a half blood volume replacement the child is still haemodynamically unstable then operative intervention is indicated. If one has to operate then same techniques as used in adults such as liver packing, blunt needle suturing and partial hepatectomy are indicated. A rare long-term sequela of hepatic trauma in children is the formation of a hepatic cyst. While most of these are asymptomatic and can be managed conservatively, occasionally can become symptomatic and require surgical intervention (Chuang et al. 1996). Pancreas Pancreatic injuries are uncommon in children. They usually occur as a result of blunt trauma to the upper abdomen where an object has compressed the pancreas between itself and the vertebral column. Common scenarios include injuries occurring from bicycle handlebars, go-cart steering wheels, and punch injuries often unfortunately as a result of child abuse. Pancreatic injuries can present as a solitary finding or as part of multi intra-abdominal organ trauma. If occurring in isolation the presentation is often delayed a few days with the child eventually presenting extremely unwell with established pancreatitis. Trauma is responsible for between 15% - 37% all pancreatitis in children Haddock et al. 1994, Synn et al. 1987, Weizman and Durie, 1988, Yeung et al. 1996, Ziegler et al. 1988). The key to managing these injuries is to determine whether the main pancreatic duct is intact or not. When the duct is intact the management should be non operative, but if transected then distal pancreatectomy is indicated (McGahren et al. 1995). Endoscopic retrograde pancreatography has been shown to be safe in children and clearly defines the main pancreatic duct (McGahren et al. 1995, Richieri et al. 1994). CT scanning has improved the early detection of these injuries but often will not have the resolution to demonstrate the status of the main duct. Serum and urinary amylase will be elevated in pancreatic injury and levels are usually higher than found with isolated small bowel injury. Pseudocysts will complicate acute pancreatitis in children in 10% - 23% of cases, but reaches up to 56% when due to trauma (Haddock et al. 1994, Weizman and Durie, 1988, Yeung et al. 1996, Ziegler et al. 1988). When associated

with trauma up to 60% of pancreatic pseudocysts will require surgical intervention (Yeung et al. 1996). Surgical options for the management of pancreatic pseudocysts in children include percutaneous drainage and open procedures such as cyst-gastrostomy and cyst enterostomy (Poston and Williamson 1990). Endoscopic drainage creating a cyst-gastrostomy with double pigtail catheters has been used successfully in the child with a post-traumatic pancreatic pseudocyst (Kimble et al. 1999). Intestinal These are particularly problematic in children because they can be the result of minor abdominal trauma and early physical examination and investigations may falsely reassure the clinician that there is no intraabdominal injury. The key to management is to suspect the injury and perform serial physical examinations, noting increasing abdominal tenderness, peritonism, tachycardia and fever. The mechanisms of injury that suggest bowel trauma include seat belt injuries (especially lap belt), bicycle handle bar injuries, rapid deceleration, falls onto fences and rocks, and kicks or punches (Newman et al. 1990, Clarnette et al. 1997). Small bowel injuries as a result of child abuse are particularly difficult as they frequently present late with peritonitis and the history of the injury is often hidden or confused. A left lateral decubitus abdominal x-ray is useful if it demonstrates free gas but if absent does not exclude the possibility (Ulman et al. 1996, Ciftci et al. 1998). CT scanning will pick up many intestinal and mesenteric injuries (Ruess et al. 1997, Graham and Wong, 1996) however sometimes the signs are subtle such as focal bowel wall thickening, free peritoneal fluid, and non-progression of the contrast material without demonstrating a leak (Cox and Kuhn, 1996). However the gold standard remains serial physical examinations and if perforated bowel is suspected then laparotomy is indicated (Albanese et al. 1996). Most bowel injuries can be managed with a primary anastomosis, but occasionally a defunctioning ostomy is required (Ciftci et al. 1998). Duodenal haematomas are fairly common following blunt abdominal trauma and present usually with discomfort and bile stained vomiting. Non-operative management, which is quite often prolonged, is usually successful. Penetrating injuries The abdominal wall of a child is very thin. Therefore any object that penetrates through the skin must be assumed to have entered the peritoneal cavity. The non-operative approach that applies to adults is less indicated in children and should only be undertaken by experienced clinicians. All too often a small piece of glass, stick or piece of metal has penetrated the peritoneal cavity and it is a safe policy if these injuries are seen infrequently, to explore the child and fully ascertain the extent of the damage.