Abdominal injuries

Intro:
When forensically evaluating injuries to the abdomen, it is useful to classify contents of the abdomen by their structure and location.  Organs may be solid or hollow.  Solid organs include the liver, kidneys, adrenal glands, spleen, and pancreas. Hollow viscus structures include the large and small intestines, and gall bladder.  The location of the contents can be classified as either intraperitoneal or retroperitoneal. The peritoneum is a smooth, glistening membrane that lines the abdominal wall and continues from the body wall to various organs. Organs that are almost completely enclosed by the peritoneum are connected to the body wall by a mesentery. Examples of this include the small and large intestine.  The mesentery serves to stabilize the location of the organs, and vessels within the mesentery carry the necessary blood supply to the organs.  Some structures close to the back of the abdominal cavity have peritoneum only on the anterior side.  These contents are considered retroperitoneal.  Retroperitoneal structures include the head and neck of the pancreas, 2nd and 3rd portion of the duodenum, adrenal glands, kidneys, bladder, ascending and descending colon, the aorta and the inferior vena cava.  When retroperitoneal contents are injured, symptoms may be delayed.  Conversely, injuries to intraperitoneal contents generally result in immediate or near immediate symptoms.    

Though not covered in further detail in this program, injuries to the kidneys, adrenals, and major blood vessels of the abdomen generally result from violent blunt force trauma to the abdomen.

History, Presentation, Mechanism, and Timing
1. History
Most commonly, children with abusive abdominal trauma present to clinical settings with no history of trauma.  Other typical histories provided in abusive abdominal trauma include short falls off beds, couches or cribs, falls down stairs, or from a caretaker’s arms. Under most circumstances, these the mechanisms described by these histories are not reasonable explanations for a significant abdominal injury.
2. Presenting symptoms
Children with abusive abdominal injuries may present with relatively mild symptoms, like nausea and vomiting, and abdominal pain and distension.  After suffering abusive abdominal injuries, many children are not brought to medical care, or are brought to care late.  On the other hand, a child may be brought to medical care by a non-offending caregiver who may not have knowledge of the mechanism or timing of injury.  Some abdominal injuries may improve or resolve on their own without medical intervention.  This makes diagnosing the nature of the injury and timing the injury very difficult in many circumstances. As with many injuries, the lack of a reliable history makes the time of injury difficult or impossible to determine in most cases. 
3. Mechanism of Injury Significant inflicted injury to the abdomen generally occurs through either direct compression of abdominal contents against a bony structure, or shearing of the blood supply to abdominal contents. Injuries to both solid organs and hollow viscera in the same child are highly specific for inflicted injury and are rarely seen with accidental trauma.  Accidental injuries to the abdomen typically involve falls on to protruding objects, car crashes, or bicycle handle-bar injuries.
4. Timing
The nature and progression of the child’s symptoms reflect the type and severity of the injuries sustained, the amount of time that has elapsed prior to seeking medical care, and the rate of bleeding.  Although delay in presentation or recognition of an abdominal injury is concerning for child abuse, it can be seen in cases of accidental trauma, particularly in preverbal children.  Additionally, minor injuries and injuries to abdominal structures that are retroperitoneal are more difficult to detect and may have a significant delay in symptoms and seeking care.
Some abdominal injuries may present weeks after the initial trauma.  These include pancreatic pseudocysts and bowel wall hematomas.  They are discussed in their respective sections of this program. 

Basic Review of Radiology studies  ^ top
X-ray (Plain radiographs)
  
X-rays of the abdomen may be obtained as an initial study in patients with suspected trauma.  However, most important details of abdominal injury cannot be seen on x-rays.  Some indicators of injury that may be seen on x-ray include free air and bowel edema.

Free air in the abdomen typically indicates that a hollow viscus has been perforated.  However, the absence of free air is not a reliable method to exclude perforation, as up to 85% of small bowel peforations have no pneumoperitoneum.  Other potential sources of free air include a perforated diaphragm, and a penetrating wound that allows air to pass into the abdominal cavity, such as a bullet or knife wound. Bowel edema indicates general inflammation of or injury to the bowel.  It is not specific for trauma.  X-rays of the abdomen often fail to detect free air, even though it is actually present.

CT scan
CT scans are significantly more accurate than X-rays in detecting abdominal injuries.  IV contrast may help visualize injuries to solid organs and blood vessels.   Hollow viscous injuries may be better visualized on CT with oral contrast.  CT scans may detect lacerations or contusions of solid organs.  Lacerations may be graded based on their severity, with a higher number meaning a more severe laceration.  CT scans may also detect free fluid in the abdomen, bowel wall edema, or free air in the abdomen.  Finding free fluid in the abdomen on a CT typically indicates that a large amount of blood is in the abdominal cavity.  This means that some structure within the abdomen has been damaged and is bleeding.  Free air in the abdomen usually indicates that a hollow viscous has perforated.  Bowel edema indicates general inflammation of or injury to the bowel.  It is not specific for trauma.

CT scans do not detect all injuries.  CTs are particularly useful in the detection of solid organ injury, but less reliable for the detection of intestinal and pancreatic injuries in the early postinjury period.

Bruising in Abdominal Injuries  ^ top
Bruising is absent in 80% or more of patients with abusive abdominal trauma.  Bruising is also frequently absent in accidental abdominal injuries.  The lack of close proximity to underlying boney structures allows the soft tissues of the abdominal wall to absorb a significant amount of force without external bruising. When bruises are present, they are usually small and non-patterned.  Additionally, the colors of the bruises cannot be used to date the bruises.

Solid Organ Injuries  ^ top
1. Liver and spleen
Lacerations and contusions to the liver and the spleen typically occur when a child suffers a blunt impact to the abdomen.  These types of injuries usually do not occur from simple falls onto flat surfaces or falls down stairs.  Common mechanisms include inflicted blows or kicks to the abdomen, a fall onto a protruding object, or bicycle accidents where the child is thrust into the handlebars.  Bruising on the skin is frequently absent despite severe abdominal injuries. 
The liver and spleen are intraperitoneal organs.  Significant injuries to the liver and spleen generally cause the child to become symptomatic at the time of the injury or shortly after the injury.  In addition to the injured organ, bleeding from the injury causes the peritoneum to become irritated, exacerbating ill symptoms.  Typical symptoms of a significant abdominal injury include vomiting, abdominal pain, and decreased activity.
Most liver and spleen injuries do not require surgery, as they generally resolve on their own with medical support and monitoring.

Assessment
Children with liver or spleen lacerations or contusions have suffered a significant impact to the abdomen.  At the time of the impact, the child would be in obvious pain.  Blood from the liver or spleen irritates the peritoneum, and continues causing pain and symptoms.  Minor mechanisms, such as a short fall onto a flat surface, are not reasonable explanations.  In situations where a fall is the explanation provided, it is important to clarify if the child’s abdomen impacted any objects during the fall.

2. Pancreas
Trauma to the pancreas typically occurs from violent compression against the lumbar vertebral column.  Common accidental causes of pancreatic injury include car crashes, seat-belt, and bicycle injuries involving compression by the handlebars. Pancreas blood tests, such as amylase and lipase, may not be elevated despite significant trauma to the pancreas.
Traumatic injury to the pancreas may be confused with pancreatitis due to other medical conditions, including infection, drugs, toxins, and multisystem medical conditions. However, trauma is the most common cause of pancreatitis in childhood.   
As much of the pancreas is retroperitoneal, clinical signs of pancreatic injury may be subtle and become apparent several days after the trauma.  Pancreatic injury may be present, but not detected on CT, shortly after the trauma.  As time passes, pancreatic injuries often become more apparent on CT scans.   
Pancreatic pseudocyst
A pancreatic pseudocyst is a sac of pancreatic fluid resulting from trauma to or inflammation of the pancreas.  Children with pseudocysts often have pain, nausea, and vomiting.  Pseudocysts take weeks to develop.  The presence of a pseudocyst indicates previous trauma or inflammation of the pancreas. 

Assessment
Injuries to the pancreas occur due to violent impacts to the abdomen.  At the time of the impact, a child will be in obvious pain. Because of its location and lack of blood loss, delay in severe symptoms is possible.  Minor mechanisms, such as short falls onto flat surfaces, or falls down stairs, do not generally result in trauma to the pancreas.  In cases of abusive pancreatic trauma, due to the possible time lapse between the trauma and the occurrence of severe symptoms, a non-offending caregiver may bring a child to medical care and have no knowledge of the mechanism of injury.

Hollow Viscous Injuries (Small and Large Intestine) and Mesentery Injuries  ^ top
Much like lacerations of the spleen and liver, significant impacts are generally required to damage the intestines, but bruising on the skin is rarely seen.  Perforations, hematomas, and mesenteric injuries typically occur from blows to the abdomen, significant falls onto protruding objects, and high velocity events, like car crashes.  In general intestinal injury is more common with inflicted abdominal trauma than with accidental abdominal trauma.

Injuries to the intestine are often difficult to detect. The symptoms of small-bowel perforations may not become apparent for several days, especially if the rupture is retroperitoneal, such as the second and third parts of the duodenum.  Additionally, the neutral pH and low bacterial density of the contents of the small bowel may contribute to the delay in severe symptoms.  Additionally, routine trauma labs and imaging studies, including X-rays and CT scans, often cannot detect intestinal injuries in the early post-injury period.  The injuries may become more evident as time passes.

1. Mesentery
The mesentery is a double layer of peritoneum connecting various components of the abdominal cavity.  The mesentery serves to fix the abdominal contents to the abdominal wall.  It also contains blood vessels that supply abdominal structures.  Injuries to the mesentery can result in a hematoma or free blood in the abdominal cavity.  This loss of blood may lead to shock and death.  The disruption in blood flow can also cause ischemia of the bowel with delayed intestinal perforation or stricture.  These factors can make identifying the exact time of injury difficult in some cases. 

2. Small intestine
The small intestine consists of three segments: the duodenum, the jejunum, and the ileum.  Any segment can injured; however the most common site of injury is the junction of the end of the duodenum and the beginning of the jejunum.  This part of the small intestine is anchored by the ligament of Treitz, and is nearest to the vertebral column.  These anatomical features result in greater vulnerability of the duodenum to both compression and shearing forces.

 a. perforation
Intestinal perforations may result directly from an impact rupturing the wall of the intestine, or from disrupted blood supply via trauma to the mesentery. Disrupted blood flow can cause ischemic injury to the intestine, and subsequent perforation.  In extremely rare circumstances, a medical condition, such as vasculitis, may cause an intestinal perforation.
b. hematoma
An intestinal hematoma occurs when an impact to the abdomen results in bleeding into the wall of the intestine. As the hematoma grows, the intestinal lumen narrows, leading to partial or complete obstruction.  It may take days or weeks for the hematoma to obstruct the intestine.  This may result in delayed symptoms and diagnosis.  Significant intestinal hematomas usually result in vomiting.

Peritonitis  ^ top
Injuries to the abdomen may cause blood, stomach or intestinal contents to leak out and accumulate within the abdomen.  This accumulation can irritate the peritoneum and result in abdominal pain and other symptoms of peritonitis.

Peritonitis is often caused by trauma, but may also be caused by rare medical conditions.  Thus, the finding of peritonitis in a child with no explanation requires a broad evaluation.

Stomach  ^ top
Gastric perforation may occur as a result of a significant blow to the abdomen.  Clinical symptoms are generally immediate, due to the noxious effects of the gastric acid on the peritoneum.

More Information: Testing for Occult Injuries  ^ top
Abdominal injuries in abused children can be difficult to detect.  Children with significant abdominal injuries may, at times, have no outward signs or symptoms of abdominal trauma.  Detecting abdominal trauma is even more difficult in pre-verbal children.  Young children who are suspected victims of abuse should have blood drawn for liver function tests, particularly the AST and ALT tests. If the liver function tests are elevated, the child should have a CT of the abdomen to detect clinically occult injuries.  These injuries may not need medical treatment, as some abdominal injuries resolve without treatment.  However, the identification of such injuries contributes to the medical diagnosis, including the assessment of the mechanism and severity of the injury.