Forensic Pathology Chapter 6 - Chest and abdominal injuries

Forensic anatomy

from the forensic aspect, the spleen and most of the liver and stomach are thoracic organs in that they lie largely beneath the costal margin and are vulnerable to both stabbing and blunt injury to the chest

penetrating injuries, especially by knife to the lower lateral wall of the thorax, may enter the peritoneal cavity as well as the plueral spaces, perforating the diaphragm

the stomach, being largely within the rib cage, may often be penetrated

the common stab wounds of the heart may also include diaphragmatic and upper abdominal injuries

Forensic Anatomy - orientation of the heart

the orientation of the heart is often not appreciated after it is removed as an isolate organ, as the tendency is to visualize it as hanging with the apex downwards

in fact, it sits flat on the diaphragm on the lateral edge of the right ventricle, with the inferior vena cava passing immediately downwards into the abdomen

Membrane coverings

pleura - membranes covering the lungs

peritonium - membrane covering the abdominal organs

pericardium - membrane covering the heart

Injuries to the chest wall - rib fractures

fractures of ribs are common, but do not greatly embarass respiration unless:

• they are so numerous that they prevent expansion of the thorax

• broken ends penetrate the pluera and lungs

• plueral and muscular pain limit respiratory effort

Injuries to the chest wall

in any substantial chest injury, broken rib ends may be displaced inwards, the jagged tips ripping the parietal and visceral pluera - this may cause a pneumothorax or a hemothorax from penetration of the lungs, with the formation of a bronchoplueral fistula

in gross chest injuries there may be compound fractures of ribs that allow a pneumothorax to form from external communication with the atmosphere, but this is rare in civil practice, though common in battle casualties

Flail chest

defined as two or more contiguous rib fractures with two or more breaks per rib

it occurs when a portion of the chest wall is destabilized, ususally from severe blunt force trauma

dyspnea and cyanosis may develop and extreme degrees of flail chest are rapidly incompatible with life because of progressive hypoxia

Bronchopleural fistula

abnormal connection between a bronchus and the pleural space

Medical terms

dyspnea - difficulty of breathing

cyanosis - bluish discoloration of skin, concentration of deoxygenated hemoglobin in blood

hypoxia - decrease in oxygen level

Rib fractures

rib fractures are most often seen in the anterior or posterior axillary lines caused by falls onto the side

the upper ribs are less often fractured, except by direct violence from kicking, heavy punching or traffic accidents

CPR

attempts at resuscitation, especially external cardiac massage, now provide a common cause for extensive rib fractures (up to 40%) - make it the task of the pathologist much more difficult when trying to differentiate original trauma from the effects of enthusiastic first aid

in the osteoporosis of senility and some diseases, the ribs may be so fragile as to be breakable by finger pressure - allowance must be made for this fragility in interpreting the cause of the fractures

Fracture healing

fresh fractures will be obvious, both on radiography and at autopsy - within about 2 weeks, callus will form and be visible both on X-ray and by direct postmortem inspection (it is extremely difficult to date the callus)

Callus - the bony healing tissue which forms around the ends of broken bone

it is said by pediatricians and radiologists that anterior rib fractures are rare in infancy other than from child abuse

Sternum fracture

the sternum may be fractured by stomping or other frontal impacts, but far more force is necessary than with ribs - if posterior displacement of a fragment occurs, the underlying heart or great vessles may be severely damaged

the most common location of the fracture is in the sternal manubrium or body

Hemorrhage and infection in the chest

any injury to the chest wall or lung surface that breeches blood vessels and the pleural lining can lead to a hemothorax - intercostal and, less often, mammary arteries can bleed into the pleural cavities, but most massive hemorrhages come from large vessels in the lung or mediastinum

the lung hilum can be torn or penetrated by stab wounds

another obvious source of a hemothorax is the heart itself, though there must also be a defect in the pericardial sac before the blood can reach the chest cavity

Lung hilum

triangular depression on the medial space of each lung that connects the lungs to supporting structures

Mediastinum

space between the lungs

Affects of pleural space

pneumothorax - air in the pleural space

hemothorax - blood in the pleural space

Intrathoracic hemorrhages - stab wound

many intrathoracic hemorrhages may be fatal with virtually no external blood loss - a knife that passes obliquely into the chest through intercostal muscles may puncture a great vessel or heart chamber, allowing a fatal cardiac tamponade or hemothorax

yet the valve-like overlap of the tissues after withdrawal of the blade may seal up the external wound almost completely and prevent significant bleeding, especially as the blood inside the chest is not under any appreciable pressure

Intrathoracic hemorrhages - postmortem coagulation

due to the great variablity of postmortem coagulation and subsequeny lysis, much of the blood found at autopsy may not have been there at the moment of death

it is impossible to quantify this additonal leakage in retrospect, but the ever-present possibilty makes it unwise to be dogmatic about the amount of blood loss prior to death

Lobes of the lungs

right lung - 3 lobes

left lung - 2 lobes

Simple pneumothorax

a leakage through the pleura allows air to enter the pleural cavity, but where the communication rapidly closes - the lung partly collapses, but if death does not supervene the air is soon absorbed

if the communication remains open, then a bronchopleural fistula ensues with air in the pleural cavity but, as it is not under pressure

radiology is then the best means of demonstrating the air in the pleural cavity

Tension pneumothorax

when the leak in the pleura has a valve-like action, the air is sucked into the pleural cavity at each inspiration, but cannot escape on expiration - this pumping action leads to a tension pneumothorax, which causes complete collapse of the lung onto its hilum and a shift of the mediastinum to the opposite side

"Sucking wound"

when an injury of the chest call communicates with the pleural cavity, a "sucking wound" may form with direct passage of air from the exterior

this type is most often seen in military surgery and may be complicated by hemorrhage and infection

Natural disease

natural disease can also cause a pneumothorax, which can lead to sudden death

common causes are a ruptered emphysematous bulla, a tuberculous lesion at the lung periphery, or a tear at the site of a fibrous pleural adhesion

Injuries of the lungs - bruising

bruising of the lungs is common in both open and closed chest injuries

any substantial impact on the chest can contuse the lung surface or deeper parts - this may be beneath the area of impact or countercoup damage on the opposite surface

the outline of ribs may be imprinted in lines of contusion on the pleural surface of the lungs

bruising may be so severe as to form subpleural blood blisters, which may rupture to release blood or air into the pleural cavities

Injuries of the lungs - lacerations

laceration of the lung can occur in blunt injuries and even lobes or parts of a lobe may be detached

the hilum may tear and the pulmonary ligament below the hilum is a frequent site of hemorrhage - vessels in the hilum or those more peripherally, may be ripped, causing severe intrapleural or medistinal hemorrhage

in children, lung injuries can occur without fracturing of the ribs, because of the greater elasticity of the latter and the ability of the chest wall to deform

Injuries of the heart - stab wound

the heart is vulnerable to both penetrating and blunt injuries

a common form of homicide is a stab wound of the chest which penetrates the heart - the entry point may be anywhere over the precordium or adjacent areas if the angulation of the track is sufficient

sometimes the sternum is penetrated by a forceful blow that reached the underlying heart, but most stab wounds enter via the intercostal spaces, or through a rib or costal cartilage

a shallow stab wound may enter the myocardium and not reach the lumen of the ventricle - in such a case there may be little disability unless a coronary vessel is severed, which may either cause death from myocardial insufficiency or cardiac tamponade

Injuries of the heart - "self-sealing"

in the left ventricle, the contraction of the layered thick wall may partly or wholly seal the wound, and bleeding can be slight

it is more comon for persistent bleeding to occur and, if the drainage from the pericardial wound is less than the leakage from the ventricle, eventually a tamponade will develop

these variables make it impossible to calculate how long the victim was able to carry on with their activites, often a matter of dispute at a criminal trial

in general, wounds in the right ventricle are more dangerous than in the left because of the absence of the muscular "self-sealing" effect

Injuries of the heart - blunt injuries

blunt injuries of the heart are seen in civilian practice mainly in traffic accidents, falls from a height, and in stomping assaults, though any heavy impact can cause fatal damage

there are usually multiple rib and sometimes sternal fractures, with or without a flail chest

the cardiac injuries are usually on the front of the organ, especially to the right ventricle, though posterior bruising and laceration can occur if the heart is compressed against the throacic spine, as in stomping assaults and steering wheel impacts

Hemopericardium

bleeding into the pericardial sac may occur from the surface or the cavities of the heart, or from the intrapericardial segments of the roots of the great vessels, particularly the aorta and pulmonary artery

most causes of hemopericardium are from natural disease but it is not an uncommon sequel to injury to the chest

Cardiac tamponade

when the damage has been caused by a stab that has perforated the pericardial sac, bleeding can escape into the pleural cavities, mediastinum, or even abdomen if the diaphragm is penetrated

death may occur from sheer blood loss if the hemorrhage can escape from the confines of the pericardium, but another common lethal conditon is cardiac tamponade

blood accumulates in the pericardial sac faster than it can escape

when sufficient blood accumulates, the pressure in the pericardial sac increases and begins to prevent the passive filling of the atria during diastole

Amount of blood buildup to cause death

about 400-500 mL of blood is sufficient to cause death

where trauma to the heart co-exists, it is difficult to apportion the relative contribution to death of the tamponade as opposed to the other injuries

Systole and diastole

cardiac cycle events can be divided into diastole and systole

diastole represents ventricular filling, and systole represents ventricular contraction/ejection

systole and diastole occur in both the right and left heart, though with very different pressures

Injuries to great vessels

the most vulnerable vessel is the aorta, which most commonly suffers injury in deceleration trauma from both road and air accidents, as well as from falls from a height

when the thorax is suddenly decelerated, the heart attempts to continue in the original direction - this causes severe traction on the root of the heart, and a common sequel is complete or partial rupture of the aorta in the descending part of its arch

Aorta rupture

sometimes, there may be multiple parallel intimal tears near the main transection, the so-called "ladder-rung tears"

in deceleration trauma, these incomplete tears, which only affect only the intima and inner media, may be found without major transection; where death is delayed, false aneurysms and dissections may be diagnosed on aortograms

Aorta

the great vessels are often involved in penetrating injuries, notably stab wounds

stabs of the upper part of the chest may pass directly into the arch of the aorta, especially on the right side of the sternum - here even a shallow injury may reach the aorta, even by a short bladed penknife

stabs that are either too high or are directed too laterally to puncture the chambers of the heart may penetrate the ascending aorta or the pulmonary artery

if the wound is below the reflection of the pericardium, a hemopericardium and perhaps a cardaic tamponade may result

Abdominal injuries

as with the thorax, the damage caused by blunt and penetrating trauma of the abdomen depends upon the location of the injury

in addition, the large area of the anterior abdomen occupied by the intestine provides a target for perforation with consequent chemical or infective peritonitis

Abdominal injuries - stab wounds

the liver, and especially the spleen, may bleed extensively causing a hemoperitoneum

the intestine and mesentery are the other major targets, wounds often being multiple, because of the overlapping nature of the coils and their mesentery

the stomach, being partially protected by the rib margin, is less often penetrated from the abdomen, but is not uncommonly involved in chest stabbings that pass downwards through the diaphragm

the kidneys are rarely stabbed except from a thrust in the back

Abdominal injuries - blunt injuries

closed or blunt injury to the abdomen is common from both accidents and assault

impact on the abdomen by a car steering wheel was more common before the widespread use of seatbelts and air bags and still occurs in severe deceleration accidents

the liver, intestine, spleen, and mesentery are most vulnerable

Abdominal injuries - bruising

bruising of the abdominal wall, both of the skin and the underlying muscles, is often seen in abdominal trauma

where subcutaneous bleeding is profuse it may track from the inital area of impact to become more diffuse and may cover a large area of abdominal wall, especially in the lower segment

blood may track down the inguinal canal and appear in the scrotum or labia

Abdominal injuries - intestines and mesentery

the intestine and its mesentery are frequently damaged in abdominal trauma

extensive bruising of the gut and its vascular mesentery may occur, mainly from being crushed against the prominent lumbar veterbrae in the midline

the duodenum and jejunum are particularly vulnerable to transection from being compressed against the spine, especially in children

Anatomy of the small intestine

small intestine comprises the duodenum (25 cm), jejunum (2.5 m), and ileum (3.5 m)

Abdominal injuries - ruptures

rupture of the spleen is a common surgical emergency after trauma but may be first found at autopsy if undiagnosed, or if death occurs from lack of speedy surgical treatment, or if other injuries made recovery impossible

rupture of the liver is also a common lesion following a serious abdominal trauma, such as fall from a height or a crush injury between 2 wagons - it is seen especially in traffic accidents

a more recent cause of liver injury is enthusiastic external caridac massage

Foreigns bodies in the gut

disorders of the mental state may lead to extraordinary numbers of objects being swallowed, which may be present anywhere from mouth to anus, but especially in the stomach

in recent years, the smuggling of narcotics though ports and airports has commonly been accomplished by "body-packing", the drugs being concealed in condoms, which are then either swallowed or less often, inserted into the rectum or vagina