Exam:) Flashcards
(159 cards)
Demarcate the study field of forensic pathology.
Forensic pathology entails the study of the effects of
1. Trauma.
2. Injury.
3. Unnatural diseases on the human body.
Describe the six (6) circumstances under which deaths are seen as unnatural and state at least one example to illustrate each of the circumstances.
- Deaths due to violence and the consequences of the injuries that result in death (cases of homicide, suicide, or accidents).
- Deaths resulting from external physical factors that impact on the body (when individuals die in a vehicle accident).
- Deaths resulting from the effect of a chemical substance (when individuals die as a result of poisoning).
- When an anaesthetic was administered or the person had a surgical procedure shortly before death (all types of anaesthetic (local or general).
- When a person dies suddenly without pre-existing illness or if the death is unexplained.
- Any death, including deaths that would otherwise be classified as being “natural” where it is suspected that the death was due to an act or neglect to act by any person including medical staff.
Describe the role of forensic pathologists when they attend death scenes.
- Pronounce/confirm the death.
- Determine the manner of death (Natural, Accidental, Homicidal, Suicidal, Undetermined).
- Determine the time of death, also known as the Post Mortem Interval, through studying the post mortem changes (Rigor mortis, Hypostasis, Cooling, Decomposition, Insects which start a life cycle on the body).
- Obtain clues and information at the scene to clarify what occurred at the scene of death.
Provide a detailed explanation of Nysten’s Law.
2 – 4 hours after death: The first signs of RM become visible in smaller muscle groups in the eyelids, facial muscles, neck, and lower jaw.
4 – 12 hours after death: RM develops throughout the body. The order wherein it develops after the smaller muscle groups in the stated order is the wrists and ankles, knees, elbows and hips.
12 - 36 hours after death: The maximum peak of RM is reached within 12 hours and persists (remains constant) in the body for approximately 12 - 36 hours depending on circumstances.
Over the course of the next 12 hours: RM gradually disappears again in the same order it appeared; thus RM disappears in the small muscle groups first. This period is also known as Secondary Relaxation/Flaccidity.
Discuss the guidelines forensic pathologists will follow during their objective search of death scenes.
- Forensic pathologist must make sure all photographs have been taken and sketches made.
- Looking for signs of a struggle is important, for example broken objects, overturned furniture, broken branches.
- If an obvious weapon is present: Note the position of the weapon in relation to the body as this clue may be important to determine whether it was suicide or homicide. Handle weapons with extreme care.
- If no obvious weapon is present at the scene: Homicide should be suspected. The forensic pathologist can also assist in determining the most likely weapon by studying the wound characteristics.
- To assist the investigative process with an opinion about the cause (may appear to be due to a gunshot wound, stab wound, or blunt force trauma to the head) of death and the manner (natural, accidental, suicidal, homicidal, or undetermined) of death.
- The position of the body should be noted and whether the rigor mortis and hypostasis match this position.
- Clothing should be examined with care: Tears, missing buttons, blood stains, and gunshot residue should be observed. Take note of buttons fastened incorrectly/awkwardly. Take note whether wounds were inflicted through clothes or on bared skin.
- The amount of blood at the scene should be noted: The average person has 4.7 – 5.5 litres of blood inside the body. The amount of blood at the scene may indicate that the location where the body is found is a secondary dumping site for the body.
- Preliminary examination of body: Look for self-defence wounds. Paper bags should be placed over the hands for possible biological material under the nails. The body should be transported to the mortuary in a clean white sheet and washed body bag to avoid cross-contamination.
- The forensic pathologist should look for signs of sexual assault, such as removed underwear.
Explain what rigor mortis is and indicate the period of development under normal circumstances including the manner in which it spreads through the body.
Rigor Mortis (RM) is a period of rigidity in the muscles, that follows after the period of flaccidity.
It occurs as a result of the formation of lactic acid in the muscles and causes the body to stiffen and limbs to be locked “in place”.
Under normal circumstances, the period of development, which is also known as the “march of rigor mortis”, is as follows:
(1) 2 – 4 hours after death: The first signs of RM become visible in smaller muscle groups in the eyelids, facial muscles, neck, and lower jaw.
(2) 4 – 12 hours after death: RM develops throughout the body. The order wherein it develops after the smaller muscle groups in the stated order is the wrists and ankles, knees, elbows and hips.
(3) 12 - 36 hours after death: The maximum peak of RM is reached within 12 hours and persists (remains constant) in the body for approximately 12 - 36 hours depending on circumstances.
(4) Over the course of the next 12 hours: RM gradually disappears again in the same order it appeared; thus RM disappears in the small muscle groups first. This period is also known as Secondary Relaxation/Flaccidity.
Factors that the onset and persistence of rigor mortis is subject to.
- Environmental Temperature (If it is extremely hot, RM develops and disappears within 9-12 hours. If it is very cold, RM lasts for 3 - 4 days).
- In malnourished and severely underweight individuals, RM sets in more rapidly, while in individuals with a high body mass, RM will slow down.
- The onset of RM is accelerated in individuals who engaged in strenuous physical activity immediately before death (e.g. a gym workout).
- Any disease which raised the body’s temperature before death accelerates the onset of RM (e.g. infections which caused fever).
- Rapid onset of RM is indicative of possible brain hemorrhaging, epileptic seizure before death and strychnine poisoning.
Deduce the criminalistic value of rigor mortis.
- The pathologist can estimate the time of death because RM develops according to a predictable timetable, which is also known as Nysten’s Law.
- The pathologist can, by studying the posture of the body, determine if there was movement of the body. If a body is found in an unnatural position, movement of the body may be assumed after RM had developed .
Explain the importance of the pugilistic posture in forensic pathology.
- The Pugilistic Posture occurs in bodies that were charred in a fire.
- Exposure to severe heat causes coagulation of the muscle protein, which results in the contraction (stiffening and shortening) of the muscles.
- The body would assume this posture even if death occurred before being exposed to the extreme heat source.
Explain the significance of Cadaveric Spasm in forensic pathology in detail.
- It is a very rare phenomenon.
- Also called Instantaneous Rigor Mortis, Cataleptic Rigidity, or the Death Grip.
- Occurs when the tense muscles at the time of death, retain their tense state immediately after death and persists into the period of RM.
- Most often observed in the isolated muscles of the arm and hand.
- If CS occurs, an object being clenched in a hand, will be very difficult or mostly impossible to release from the hand.
- Manipulation of the muscles in cases of CS would be impossible.
- Cadaveric Spasm has been documented before under the following circumstances:
(a) If a victim is thought to have committed suicide, and the weapon is grasped so tightly in the hand that it is not possible to remove the weapon.
(b) Homicides where buttons, hair or pieces of clothing (e.g. a pocket torn off a shirt) are found grasped tightly in victims’ hands.
(c) Drowning and mountain accidents where stones, grass and branches are found grasped tightly in victims’ hands.
(d) Car, airplane and train accidents where victims are found grasping onto objects (e.g. steering wheel, seats, cell phones etc.).
(e) Deaths on the battlefield in wartime.
Explain four (4) differences between rigor mortis and cadaveric
spasm in detail.
- Rigor mortis can be used to estimate the time of death because it develops according to a predictable timetable, which is also known as Nysten’s Law whereas Cadaveric Spasm has no period of development (rigidity in specific muscles is immediate).
- Rigor Mortis can be manipulated by force (e.g. a hardened/stiff/rigid arm can be pushed into a different position) whereas Manipulation of the muscles in cases of Cadaveric Spasm would be impossible.
- Rigor Mortis occurs as a result of the formation of lactic acid in the muscles and causes the body to stiffen and limbs to be locked “in place” whereas Cadaveric Spasm is a very rare phenomenon.
- Rigor Mortis occurs in smaller muscle groups in the eyelids, facial muscles, neck, and lower jaw, the ankles, knees, elbows and hips whereas Cadaveric Spasm occurs in isolated muscles of the arm and hand.
Explain what hypostasis is and state the period of development.
Hypostasis is described as the purplish-red discoloration of the most dependent parts of the body (lowest points) after the heart stopped beating, where blood settles/pools in the blood vessels under the influence of gravity.
The Period of Development is as follows:
(1) 1 – 2 hours after death the first signs will be noticed.
(2) 4 hours after death hypostasis will be well developed.
(3) 8 – 12 hours after death hypostasis will reach a maximum peak.
(4) After 12 hours, hypostasis will fixate due to the coagulation (clotting) of the blood.
Describe the period of development for cataleptic congestion.
(1) 1 – 2 hours after death the first signs will be noticed.
(2) 4 hours after death hypostasis will be well developed.
(3) 8 – 12 hours after death hypostasis will reach a maximum peak.
(4) After 12 hours, hypostasis will fixate due to the coagulation (clotting) of the blood.
Discuss the fixation or non-fixation of livor mortis.
- Whether or not hypostasis is fixed can be determined by the so-called Blanching Test, which entails that the thumb of the observer is pressed on the livid area (where the blood pooled) for approximately a minute and ten released.
(a) If the area becomes pale after the thumb is removed, the hypostasis is not fixed, whereas if the area remains purplish-red the hypostasis is fixed.
(b) However, after 12 hours the blood coagulates and hypostasis becomes fixated (does not change); thus if a body is found with hypostasis development and pale patches that do not match the position the body is found in, it is assumed that the body was moved after 12 hours into a new position. - Include the Period of development of Hypostasis.
Discuss the criminalistic value of hypostasis.
- Because there is a predictable period of development, it can be used to estimate the time of death.
- It is helpful to determine movement of the body when hypostasis development does not correspond with the position the body is discovered in.
- The colour of hypostasis can be indicative of the cause of death:
(a) Cherry-red hypostasis is usually observed in cases of carbon monoxide.
(b) Pink hypostasis is usually observed in cases of cyanide poisoning and deaths as a result of hypothermia (cold temperatures).
(c) Brown hypostasis is typically seen in cases of nitrate poisoning.
Explain what the blanching test entails and describe what the forensic pathologist who uses it can deduce.
The Blanching Test entails that the thumb of the observer is pressed on the livid area (where the blood pooled) for approximately a minute and then released.
The pale patches illustrate the areas of the body that were in contact with the surface (blood vessels under pressure due to weight of body) when hypostasis developed.
Provide a detailed discussion of the significance of algor mortis in forensic pathology.
- During algor mortis the body temperature lowers until it matches environmental temperature.
- Three distinct periods of algor mortis are identified:
(a) The Initial Phase or Temperature Plateau when the temperature remains relatively stable for 30 minutes to three hours.
(b) The Intermediate Phase in which the body cools rapidly and at a relatively linear rate.
(c) The Terminal Phase when the rate of body cooling slows as the core temperature reaches the environmental temperature. - Several factors can influence the rate at which a body cools down:
(a) The difference between body temperature and environmental temperature - the greater the difference between the temperature of the body and the environment, the faster the cooling rate.
(b) The body will cool down faster if the surrounding area is well ventilated or humid.
(c) Clothing will isolate the body and slow the rate down.
(d) Body weight. - After the body has cooled down to reach environmental temperature, the cooling rate is no longer useful to estimate the time of death.
- The post mortem interval cannot be accurately estimated during the first three to five hours after death due to the effect of the actual body temperature at death and the length of the temperature plateau following death.
Clearly distinguish between autolysis and putrefaction in forensic pathology.
- Autolysis, or Aerobic Decomposition, which begins immediately after death is not visible to the naked eye and is also known as the fresh stage of decomposition. Putrefaction, or Anaerobic Decomposition, is the process of decomposition that is visible to the naked eye.
- During autolysis, the cells inside the body begin to leak enzymes into the surrounding tissue, and the bacteria, which are still living in the intestines, begin to consume the internal organs. Insects have a very keen sense of smell and will be attracted to the body because of these chemical processes.
- Putrefaction is separated into the bloating phase, the decay phase, the post decay phase, and the dry stage.
Describe the main events during each of the four (4) phases of putrefaction.
- The Bloating Phase: The first noticeable sign is 2-3 days after death when a greenish discolouration appears on the lower abdomen. This greenish discoloration spreads over the entire abdomen soon and later the entire body. The tongue and eyes may also protrude. This bloating process continues for approximately 5–6 days.
- The Decay Phase: Lasts for approximately 11 days.The body takes on a wet appearance as fluids start to drain from the natural body orifices and the sweat pores. The internal organs have broken down (also known as Liquefaction), which produces the fluids which drain from the body. The drainage of fluids is called Post Mortem Purging.
- The Post Decay Phase: Begins around the 12th day after death. Most of the flesh would have been consumed (by insects or other animals) or have decomposed. Therefore, this phase is also known as The Start Of Skeletonisation.
- The Dry Stage: Begins approximately 3 to 4 weeks after death. It involves the decomposition of the dry remains, usually the bones, nails, hair, cartilage, and dehydrated skin. Specific insects start a life cycle on the remains. Other 27 insects like house moths will also start a life cycle on the dry tissue of the mummified body and the hair.
Explain how insects and other animals who use human remains as a source of food may complicate post mortem findings.
- Cockroaches and ants produce post mortem injuries to bodies when using the body as a source of food.
- Terrestrial animals like rats, dogs and cats choose to eat soft exposed tissue around the eyes, ears, lips, and genitals. Moreover, they tend to choose to eat areas of the body where the skin is already broken; thus, wounds sustained ante mortem (before death) will be enlarged.
- Bodies disposed off in water are also used as a source of food by aquatic animals. Leeches in particular attach themselves around the eyes which produce lesions that resemble a black eye.
- Turtles, crabs, and fish eat tissue around the eyes, nose, ears, and genitals, as well as around ante mortem wounds where the skin is already broken.
Name and discuss the factors that may influence the rate of decomposition.
- Sepsis (severe infection throughout body) before death may cause faster decomposition.
- The hotter and more humid the environmental temperature, the faster decomposition will occur.
- Optimal temperature for accelerated decomposition is between 25 and 38 degrees Celsius.
- In bodies with multiple external open injuries, decomposition is accelerated.
- A body in open-air will putrefy faster than one which is buried or submerged in water.
- If the temperature of the body is low, the onset and rate of autolysis will be retarded, while higher temperature caused by fever or high levels of exertion prior to death, will accelerate the rate and onset of decomposition.
Explain what Casper’s dictum entails.
“Casper’s dictum” states that a body decomposes twice as fast in open air than a body submerged in water; and eight times faster than one buried in soil.
Discuss two (2) post mortem phenomena that may arrest the progression of putrefaction.
- Mummification
(a) Should not be confused with the deliberate mummification of bodies by the Egyptians, because it is a natural process.
(b) In a dry atmosphere, a body may lose fluids so rapidly (dehydrate), that it dries out before normal decomposition can proceed as discussed.
(c) The rapid elimination of fluids from the tissue, circumvents the process of bacterial putrefaction.
(d) In such instances the skin shrinks and is converted into a parchment-like mass of skin which surrounds the bones – mummified tissues are rigid and hard.
(e) The natural mummification process takes approximately 6 to 12 months to conclude; but in extreme conditions the time can be rapidly reduced.
(f) Mummification persists for decades, and even centuries; therefore, the body goes into a state of preservation.
(g) External marks on the skin, such as strangulation marks, remain preserved in the skin which becomes like leather.
(h) As a result of the shrinking of the skin, large tears/splits may occur in the groin and neck-area, which mimic injuries sustained before death and may lead to misinterpretation. - Adipocere
(a) Under moist conditions, body fat (triglycerides in particular) converts into a substance which is described as soapy, waxy, greasy, cheese-like.
(b) The process of conversion is defined as The Saponification Of Body Fats Into Grave Wax or corpse wax, and the colour is typically off-white to grey.
(c) Adipocere can persist for decades, even centuries; therefore, the body goes into a state of preservation.
(d) Burial ground which is acidic, where enough moisture is present, and oxygen absent (exposure to oxygen inhibits adipocere), can result in adipocere.
(e) Types of soil where bodies may develop adipocere are peat bogs (characterised by acidic soil), which are wetlands where dead plant material accumulates; for this reason, such bodies are also called Bog Bodies.
(f) Similar to mummification, it allows for the preservation of marks and injuries on the skin.
(g) The phenomenon is most pronounced in body parts which contain more fat, such as the cheeks, buttocks, and breasts of women.
(h) Adipocere is also more common in women, toddlers, and obese individuals, because they have more body fat.
(i) It is seen as a complicating factor because once it sets in, it becomes very difficult to estimate the post mortem interval.
(j) Depending on environmental conditions, adipocere may be observed as early as five weeks after death; however, as a rule the presence of adipocere is usually an indication of a post mortem interval of at least three to six months.
The manifestation of adipocere in buried bodies depends on a variety of factors such as?
- The geographical location of the burial site.
- The season of the burial.
- Vegetation surrounding the burial site.
- Depth of the grave.
- Insect infestation before burial (a body that is accessible to insects is unlikely to form adipocere).
- The composition of a coffin, if used.
- The chemical and physical soil properties.