Key Clinical Topics in Paediatric Surgery Max Pachl, Michael N de la Hunt, Girish Jawaheer
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Abdominal trauma

 
Learning outcomes
  • To appreciate the significant anatomical and physiological differences between children and adults
  • To learn when to suspect and how to diagnose intra-abdominal injury
  • To develop a pragmatic and tailored approach to imaging and treatment based on the above
 
Overview
Accidental injury is the leading cause of death among 10- to 19-year-olds and is a leading cause of disability. While prevention is the key, appropriate recognition and management of childhood injuries is also paramount.
Compared with adults, children have a compliant ribcage, which allows direct transmission of force to the thoracic and abdominal viscera. The diaphragm is relatively flat and the liver and spleen are comparatively large. In addition, the abdominal musculature is less developed and there is little fat or connective tissue to cushion the organs. The pelvis is shallow, such that the urinary bladder is an intraabdominal organ in young children. The abdominal viscera are therefore poorly protected from blunt or penetrating trauma.
Children have good cardiac function, which is able to compensate well for hypovolaemia. While adults manifest hypotension after a 15% loss of blood volume, children can compensate for up to 40% blood loss. Hypotension in a child is an ominous sign.
Although children have a greater circulating blood volume per unit mass (70–80 mL/kg), the absolute volume is very small compared to an adult. Therefore, loss of a small amount of blood may be critically important. The body surface area to volume ratio is greater in children, allowing rapid heat loss and the onset of hypothermia.
 
Epidemiology and aetiology
More than 75% of trauma cases are caused by road traffic accidents, in which the child may be involved as a pedestrian or as a passenger. Risky sports also cause some of these injuries, especially in the older child or adolescent. The majority of injuries are blunt and in Europe, where use of firearms is controlled, penetrating injury during peacetime is rare. Males are involved two to three times more often than females. Thoracic and abdominal trauma occurs most often before the end of the first decade of life, when children have achieved a degree of autonomy.
 
Clinical features
Signs of abdominal injury are usually apparent on secondary survey, and these include abrasions and contusions on the abdominal wall, abdominal tenderness and distension. Especially in young children, distress leads to aerophagia and gastric distension. Placement of a nasogastric tube and aspiration of gastric content may assist clinical evaluation, especially if consciousness is impaired. The groin, external genitalia and perineum are carefully inspected. The anus is inspected at the time of assessment of the back by logrolling. There is insufficient published evidence to support the use of routine rectal examination in the assessment of paediatric trauma patients.
 
Splenic injury
The spleen is the most frequently injured abdominal organ in children. Injury to the spleen typically results from impact to the left upper abdomen or lower chest, and fractured lower ribs on the left side should raise strong suspicion. Left shoulder tip pain (Kehr's sign) as a result of diaphragmatic irritation by blood is often present.
 
Liver injury
The liver is the second most commonly injured abdominal organ. The right lobe 2is more frequently involved than the left lobe. Right shoulder tip pain (Kehr's sign) is a frequent accompaniment. Elevated transaminases are strongly suggestive of liver injury, as are fractured lower ribs on the right side.
 
Bowel injury
A frequent mechanism of intestinal injury is due to a lap belt or seat belt, usually because of inadequate fit between the child and the restraint. Patterned abrasions due to the restraint are often seen. Lumbar spine fractures, called Chance fractures, are detected in a number of children with lap belt injury. The children most at risk are those who are generally too big for a children's car seat but too small for adult belting systems.
In young children, absence of a plausible mechanism must raise suspicion of child abuse. These injuries often present late. A fall down stairs is not usually associated with bowel injury.
 
Pancreatic and duodenal injury
The classic mechanism causing this injury is the bicycle handlebar injury where the child is impaled in the epigastrium by the handlebar. This can lead to transection of the pancreas where it crosses over the lumbar spine or injury to the duodenum. Vehicular accidents and child abuse are other causes. A patterned abrasion in the epigastrium is common.
 
Renal injury
Microscopic haematuria following abdominal injury is very common and is of no consequence. Frank haematuria resulting from trivial injury may signify underlying renal anomaly, such as pelvi-ureteric junction obstruction or renal tumour.
 
Investigations
Blood is sent for full blood cell count, cross-matching, liver and renal function tests, amylase and lipase as a baseline and as indicators of liver, renal or pancreatic injury, though laboratory studies are seldom useful in the acute phase.
In the haemodynamically unstable child, abdominal ultrasound can be used to differentiate between intraperitoneal and extraperitoneal blood loss. It can also be used as an adjunct to serial abdominal examination when physical examination is not straightforward. Focused assessment with sonography in trauma (FAST) is used in some trauma centres, and its primary goal is to detect free fluid in Morrison's pouch, pelvis, perisplenic region and pericardium.
In the haemodynamically stable child, further abdominal imaging is not required if there is no suspicion of intra-abdominal injury based on the mode of injury and a reliable clinical examination or, even better, on serial abdominal examinations. In all other situations, intravenous contrast-enhanced computed tomography (CT) is the standard of care for the evaluation of the child with abdominal injury. It helps with the diagnosis and grading of solid organ and other associated injuries. CT detects 60–70% of pancreatic injuries. Fluid in the lesser sac is a useful marker. In addition, the radiologist may instil enteral contrast via the nasogastric tube. This may be useful to delineate duodenal injury. Frank haematuria should instigate prompt imaging by CT.
 
Treatment
Initial management follows the airway, breathing and circulation (ABC) of trauma resuscitation. Large-bore intravenous access is vital. Intraosseous infusion of fluid for resuscitation is life-saving when venous access proves difficult.
 
Splenic injury
Non-operative management without blood transfusion is now the standard of care. In one large series, > 95% of splenic injuries in children were managed in this way. Only 10–12% require blood transfusion, usually due to other injuries. Non-operative management requires significant expertise and is more successful in dedicated paediatric centres. Long-term results demonstrate that missed injuries are rare, as is delayed splenic rupture. Routine follow-up imaging studies are not required.3
Operative management is indicated in the presence of haemodynamic instability and may merit splenectomy. Splenorrhaphy and partial splenectomy are spleen-conserving techniques.
The risk of overwhelming post splenectomy infection is the main reason for spleen conservation. Antibiotic prophylaxis with oral penicillin V and vaccination with polyvalent pneumococcal vaccine are essential in children who lose splenic function.
 
Liver injury
In children, 85–90% of liver injuries can be managed non-operatively, though a greater proportion will require blood transfusion. Other aspects of non-operative management are similar to the management of splenic injury. Bleeding into the biliary tree (haemobilia) and, very rarely, bile in the bloodstream (bilhaemia) are specific long-term complications.
In the presence of major haemorrhage, the vicious cycle of blood loss necessitating transfusion, leading to hypothermia and coagulopathy, is the real killer. Thus, operative management of liver injury is based on the ‘damage control’ philosophy. Tamponade of bleeding with abdominal packs, followed by a planned second look when hypothermia and coagulopathy have been corrected, is preferred over major hepatic resection.
 
Bowel injury
Operative management involves segmental resection with primary anastomosis. Mesenteric lacerations may lead to an ischaemic perforation or stricture. A stricture may present several weeks after the initial injury in the form of intestinal obstruction. Laparoscopy has diagnostic and therapeutic potential that must not be overlooked.
 
Pancreatic and duodenal injury
Pancreatic contusion is managed conservatively along the lines of pancreatitis. Spleen-preserving distal pancreatectomy in cases of ductal transection of the pancreatic body is associated with fewer complications than non-operative management. Treatment of major ductal injury involving the head of the pancreas is more controversial, though most authors support initial non-operative management, followed by drainage of resulting pseudocysts. Alternatively, some authors advocate transductal pancreatic stenting.
Formation of a pancreatic pseudocyst is the most common complication of non-operative management. Small pseudocysts may resolve with time while larger ones (> 5 cm) that persist for > 4–6 weeks require drainage. Internal drainage is standard, in the form of either cyst-gastrostomy or cyst-enterostomy into a Roux-en-Y limb.
Duodenal injury may be in the form of a haematoma or perforation. Haematomas may compromise the duodenal lumen. The majority can be managed non-operatively by nasogastric decompression and parenteral nutrition.
Duodenal perforations are often contained in the retroperitoneum and are difficult to diagnose even by CT. Operative management depends upon the degree of contamination and the extent of injury. Small fresh injuries can be dealt with by primary closure, omental patch and nasogastric drainage. Larger injuries in the presence of significant contamination may necessitate pyloric exclusion and gastrojejunostomy.
 
Renal injury
Renal injuries are managed non-operatively. The chance of renal salvage by urgent operation in cases of complete devascularisation is small as the warm ischaemia time of the kidney is very short.
Injury to the renal collecting system may result in formation of a urinoma. This is managed either by internal stenting (double-J ureteric stent) alone or in conjunction with percutaneous external drainage. Pelvi-ureteric junction obstruction is a long-term complication.
 
Extraperitoneal bleeding
Haemodynamic instability in the scenario of extraperitoneal bleeding, as can be seen secondary to pelvic fracture or renal pedicle injury, warrants the involvement of the interventional radiology team to diagnose the source of the blood loss and for potential embolisation.
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Further reading
  1. Gaines BA, Ford HR. Abdominal and pelvic trauma in children. Crit Care Med 2002; 30:S416–S423.
  1. Hughes G. Children's injuries: a global problem. Emerg Med J 2009; 26:236.
  1. Scaife ER, Rollins MD. Managing radiation risk in the evaluation of the pediatric trauma patient. Semin Pediatr Sur. 2010; 19: 252–256.
  1. Thomas DFM, Duffy PG, Rickwood AMK. Essentials of paediatric urology. London: Informa Healthcare,  2008.
 
Related topics of interest
  • Haematuria ()
  • Head trauma ()
  • Pancreatitis ()
  • Pelvi-ureteric junction obstruction ()
  • Spleen disorders ()
  • Thoracic trauma ()