A template for broad consent in biobank research. Results and explanation of an evidence and consensus-based development process.

BACKGROUND: Biobanks increasingly presume long-term storage of biomaterials and data that shall be used for future research projects which are today unspecified. Appropriate consent documents for sample donors must therefore explain the breadth of consent and other elements of the biobank governance framework. Recent reviews demonstrated high variability in what issues these documents mention or not and how the issues are explained. This might undermine the protection of sample donors, complicate networked biobank research, create research waste and impact on public trust. METHODS: A systematic analysis of international research guidelines and existing broad consent templates was performed. Based on this information an interdisciplinary expert group from the AKMEK (Permanent Working Party of German RECs) developed a draft template and organized a comprehensive stakeholder consultation. After revision the final template was consented by all 53 German RECs. RESULTS: This paper briefly explores the spectrum of potentially relevant issues for broad consent forms. It then elaborates the template and how it was designed to be applicable in different types of biobanks. DISCUSSION: To further improve the validity and applicability of broad consent forms in biobank and other big data research, practice evaluations are needed. We hope that in this regard the presented template supports the development of new consent forms as well as the evaluation and revision of existing ones.

Postmortem determination of concentrations of stress hormones in various body fluids--is there a dependency between adrenaline/noradrenaline quotient, cause of death and agony time?

To find out whether a certain cause of death or a certain length of an agonal period shows specific adrenaline or noradrenaline profiles, heart blood, femoral vein blood, liquor, urine and vitreous humour were taken from corpses (n = 98) at the Medical School Hannover, and noradrenaline and adrenaline were determined using high-performance liquid chromatography (HPLC). Corpses were classified according to the following five categories: short agony, long agony, state after hanging, state after asphyxiation and state after CPR with documented administration of epinephrine. Once results were collected the adrenaline/noradrenaline quotient was determined. It became clear that there were no significant differences regarding the concentration of adrenaline and noradrenaline in the various body fluids in relation to the above-mentioned categories. The means adrenaline/noradrenaline quotients in femoral vein blood were 0.21 +/- 0.29 for hanged persons, 0.38 +/- 0.47 for asphyxiated persons, 0.17 +/- 0.19 for those with short agony and 0.42 +/- 0.43 for those with long agony, significantly below 1 (p < 0.001; p = 0.001; p = 0.003). For condition after CPR we found an adrenaline/noradrenaline quotient of 2.81 +/- 5.8. In liquor the adrenaline/noradrenaline quotients for short agony was 0.17 +/- 0.17, for hanged persons 0.18 +/- 0.19 and for asphyxiated ones 0.30 +/- 0.38, significantly lower than 1 (p < 0.001). In urine the adrenaline/noradrenaline quotients for all categories are lower than 1 (p < 0.001); short agony (0.13 +/- 0.09), long agony (0.21 +/- 0.16), hanged (0.15 +/- 0.16), asphyxiated (0.14 +/- 0.08) and CPR (0.14 +/- 0.06). In vitreous humour the quotients for short agony (0.14 +/- 0.28), long agony (0.13 +/- 0.12), hanged (0.07 +/- 0.09) and asphyxiated (0.09 +/- 0.11) are lower than 1 (p < 0.001). The spread of data for the adrenaline/noradrenaline quotient did not allow for any conclusions about cause of death and length of agony in individual cases.

Evaluation of the correlation between time corpses spent in in-ground graves and findings at exhumation.

To determine how long pathological findings persist after burial and which factors play a role in decomposition of a corpse, we evaluated all bodies exhumed under the auspices of the Institute of Legal Medicine at the Hannover Medical School between 1978 and 1997. A total of 87 exhumations (54 men, 33 women) were performed in this period. The time bodies remained buried varied between 5 days and 16.8 years (mean 1.5 years, median 2.3 months). Fifty-six percent of the bodies were exhumed after at most 3 months, 10% remained buried for greater than 3 years. Pathomorphological changes of the soft tissues and the internal organs remained evident after several months, in some cases after several years of burial. Overall, it was possible to evaluate internal organs after 5 years of burial. Bodies became mostly decomposed after approximately 8 years at the earliest, although it was still possible to evaluate some soft tissue remnants after 16.8 years. In stepwise logistic regression, both the length of time the body was buried (p < 0.00005) and the time of year (p < 0.0019) clearly affected the rate of physical change. The variables of sex (p = 0.33), age (p = 0.61) and changes in the integrity of the body before burial (trauma, autopsy before burial; p = 0.15) did not influence the physical state of the body after exhumation. Our data show that much information may be gained from an exhumation even after significant time has passed since burial.

[The relevance of urinary bladder filling in suprapubic bladder catheterization]. / Die Relevanz der Harnblasenfüllung bei der suprapubischen Blasenkatheterisierung.

Suprapubic punction of the urinary bladder (cystostomy) may cause typical, sometimes lethal injuries of pelvic organs especially in cases of an insufficient bladder filling. Some of these cases were described in the literature of legal medicine. To verify the importance of the cranial displacement of the vulnerable intestine by a filled bladder, the distances between the upper end of the symphysis and apex vesicae were measured in 76 forensic autopsies in situ and correlated with the filling volume of the urinary bladder. 69,2% of cases with a bladder filling volume up to 200 ml showed a suprapubic distance of only < or =4 cm. However, this distance collides with the preferred clinical intervention point, 2 fingers above the symphysis. In all cases with a bladder filling volume > or =300 ml, the distances were > or =5 cm. Based on our measurements, we recommend a preoperative bladder filling of > or =300 ml for an uncomplicated insertion of a suprapubic catheter.

[Cricothyroidotomy training on cadavers - experiences in the education of medical students, anaesthetists, and emergency physicians]. / Koniotomieübungen an der Leiche - Erfahrungen in der Ausbildung mit Medizinstudenten, Anästhesisten und Notärzten.

OBJECTIVE: Should the technique of surgical cricothyroidotomy be practiced on cadavers and should it be a compulsory part of the teaching curriculum? Is it wise to use a speculum for the insertion of the endotracheal tube? What is the optimum size of the tube? METHODS: A surgical cricothyroidotomy with a speculum was carried out on 30 cadavers from the Institute of Legal Medicine, Medical School Hannover. This took place as part of a official and voluntary course for students of advanced semesters, anaesthetists and emergency doctors with the subjects "cricothyroidotomy, chest drainage and venous cut-down". The surgical cricothyroidotomy without the use of a speculum was carried out on 5 cadavers by two clinicians well practiced in this technique. The elapsed time between skin incision and the insertion of the endotracheal tube was measured on all five subjects. After the course the participants were asked if they were able to carry out a cricothyroidotomy in an emergency. They were also asked whether this course should be a compulsory part of their curriculum and whether practical sessions should take place. During autopsies at the Institute of Legal Medicine the length of the ligamentum conicum was measured on 40 corpses with reclined and non-reclined heads. RESULTS: The average time of storage of the cadavers was 4.2 days +/- 1.9 days. The cricothyroidotomy was possible on all 35 cadavers. In one case (3,3 %) the result was a complete rupture of the cricoid cartilage. In 5 cases (16.7 %) the horizontal incision was torn due to prising with the speculum. Difficult situations always occured when the skin incision was not exactly in the midline. The average time to place the endotracheal tube into the trachea by the surgical procedure of cricothyroidotomy was 22.4 seconds +/- 3.1 seconds (minimum 18 seconds, maximum 26 seconds). 10 % of the medical students and 50 % of the anaesthetists and emergency doctors felt they would be prepared to carry out a cricothyroidotomy in an emergency. 90 % of the students and respectively 80 % of the anaesthetists and emergency doctors stated that they would like to practice the technique on a cadaver again. Almost all participants were of the opinion that the course should be integrated as a compulsory course in a future educational curriculum. The average distance between the thyroid cartilage and the cricoid cartilage was 9.5 mm +/- 1.9 mm with non-reclined head (minimum 6 mm, maximum 14 mm) and 11.9 mm +/- 2.5 mm with reclined head (minimum 7 mm, maximum 18 mm). The average difference of distances was 2.4 mm +/- 1.2 mm (minimum 1 mm, maximum 6 mm) in reclined and non-reclined heads. CONCLUSIONS: In our opinion it is highly recommended that the technique of cricothyroidotomy should be practiced on cadavers and that the course should become a compulsory part in a future educational curriculum. In addition the incision of the ligamentum conicum using dilators or a speculum is not to be recommended from the point of view of this study. The tracheal tube used in this study (reinforced wire tube, ID 6.0) was best suited for surgical cricothyroidotomy.

Applied anatomy of the superior vena cava-the carina as a landmark to guide central venous catheter placement.

BACKGROUND: Cardiac tamponade is a serious complication of central venous catheter (CVC) insertion. Current guidelines strongly advise that the CVC tip should be located in the superior vena cava (SVC) and outside the pericardial sac. This may be difficult to verify as the exact location of the pericardium cannot be seen on a normal chest x-ray. The carina is an alternative radiographic marker for correct CVC placement, suggested on the basis of studies of embalmed cadavers. METHODS: We set out to confirm this radiographic landmark in 39 fresh cadavers (age 58.4 (3.4) (mean and SE) yr) and to compare the results with those from ethanol-formalin-fixed cadavers. RESULTS: We found that the carina was 0.8 (0.05) cm above the pericardial sac as it transverses the SVC. In no case was the carina inferior to the pericardial reflection and our study confirmed the previous findings. All the measured distances were significantly greater in fresh cadavers. CONCLUSIONS: We confirm that the carina is a reliable, simple anatomical landmark that can be identified in vivo for the correct placement of CVCs outside the boundaries of the pericardial sac.

Nasal-associated lymphoid tissue (NALT): frequency and localization in young children.

In mucosal immunology nasal-associated lymphoid tissue (NALT) is taken as a constitutive structure of the nasal immune system and as a target tissue in strategies of local defence and an induction site for vaccination. These concepts are based on findings in rodents, but it has not been investigated systematically whether NALT also is present in humans and if so in which amount and localization. In a postmortem study the presence of NALT in humans is documented as a morphologically distinct structure additional to the lymphoid structures of the Waldeyer's ring. Human nasal tissue blocks of 150 children who had died in the first two years of life either of sudden infant death (n = 109) without signs of respiratory tract infections or of different traumatic (n = 22) and natural causes of death (n = 19) were obtained using a specific autopsy-technique and were investigated systematically using histology. Clearly in contrast to rodents human NALT was found disseminated in the nasal mucosa with typical morphological features in 38% of all children, mainly in the middle concha, with similar morphology and frequency in the examined groups. No correlation was found between the presence of NALT and the cause of death and especially the grade of inflammation in general. Therefore, NALT might be the morphological basis for inhalative vaccination strategies in young children and play a role in mucosal host defence.

Accidental autoerotic deaths between 1978 and 1997. Institute of Legal Medicine, Medical School Hannover.

Between 1978 and 1997 the Institute of Legal Medicine of the Hannover Medical School examined 17 fatal autoerotic deaths. The incidence for the Hannover region was 0.49 cases per million inhabitants per year. The victims included 17 men with an average age of 36.8 years; a peak in the age distribution was seen between 20 and 29 years. Twelve of the men were found by friends or family in a domestic environment, while other situations in which the victims were found included the victim's own car, a hotel room, a canal embankment, a public parking lot as well as the holding cell of the youth detention center. The men were of varying socioeconomic status and held a number of different types of jobs or still attended school. Five of the men were found completely nude, while five were only undressed below the waist. Four men wore women's clothes and two were fully clothed with exposed genitals. Besides women's clothes, other objects found at the scene included various types of sexual aids, including ropes, chains, metal bars, locks, sex magazines, condoms, plastic bags, rubber items, etc. In four cases blood alcohol levels between 0.1 and 2.5 per thousand (urine alcohol levels between 0.2 and 2.5 per thousand ) were found. Toxicologic examination revealed chloroform, ketamine, a propane-butane gas mixture in one case each, and in two cases cocaine and morphine. Causes of death included central paralysis after strangulation (seven cases), asphyxiation (4), subarachnoid hemorrhage (2), intoxication (1), hypothermia (1), left heart failure (1), and drowning (1). The history, findings at scene, and autopsy findings and, in individual cases, other investigations are of utmost importance to accurately reconstruct a fatal autoerotic accident.

The time-dependent expression of fibronectin, MRP8, MRP14 and defensin in surgically treated human skin wounds.

Fibronectin, MRP8, MRP14 and defensin were detected immunohistochemically in 46 surgically treated, fresh (hours old) human wounds and in wounds of 13 individuals who died immediately from fatal trauma (airplane crashes or train rollovers). In immediate fatal trauma, it was not possible to detect fibronectin outside of bleeding areas nor could inflammatory cells be visualized in the interstitium using MRP8, MRP14, or defensin antibodies. Fibronectin staining could be regularly demonstrated in wounds at least 20 min-old. Granulocytic infiltrates limited to the perivasal space could be detected 20-30 min after infliction of the wound expressing MRP8, MRP14 and defensin. It was also possible to detect fibronectin networks and MRP8-, MRP14-, and defensin-positive granulocytes and macrophages in particular wounds up to 30 days-old. No differences between the expression of MRP8 and MRP14 could be demonstrated in the wounds, the majority of which were only several hours old. As wound age increased, the number of defensin-positive granulocytes detected decreased. The immunohistochemical detection of fibronectin is a useful way to demonstrate vitality in fresh wounds, beginning about 20-30 min post-trauma. However, detection of MRP8, MRP14 and defensin provides no advantage over the routine histological detection of granulocytes and macrophages in wounds under 1-2 days old.

Lethal child neglect.

The jurisdiction of the Hannover Institute of Legal Medicine recently experienced an unusually high incidence of lethal child neglect, with three cases in a 5-month period in 1999. Case 1: A girl received an inappropriate and inadequate diet of tea and oatmeal. The child was never breastfed, nor did it ever receive any other formula. The parents report the infant to have been healthy until she suddenly began projectile vomiting at the age of 13 weeks. For the next 3 days the infant was not able to maintain an adequate intake. The mother reports finding the child dead in its bed on the morning of the fourth day. Attempts by medical personnel to revive the child were unsuccessful. Case 2: A mother began spoon-feeding the infant puree on the fourth day of life, which according to the manufacturer's specifications is suitable for children between 4 and 8 months of age. At the age of 5 weeks, the infant was reported to have vomited half the just previously ingested meal, after which she took a nap. Some time later the parents observed the infant to be quite pale, however, assumed this was a result of sleep. When the mother finally did pick her up, the child was lifeless, and the parents brought her to the hospital. Medical personnel could however, only declare the infant dead, documenting a rectal temperature of 30 degrees C. Case 3: A 3.5-year-old girl died after her mother left the locked apartment and did not return for several weeks. The body of the child was found lying dressed on the floor in a state of advanced decay and mummification. Common findings in all three cases include lack of prenatal care, home birth without the help of a midwife, low socioeconomic status or maternal alcohol abuse, body weights below the 3rd percentile, extreme dehydration, fatty hepatic degeneration, thymic atrophy and signs of aspiration.

Fatal aviation accidents in Lower Saxony from 1979 to 1996.

So far no national or regional studies have been published in Germany regarding the number of fatal aviation accidents and results of autopsy findings. Therefore, we evaluated all fatal aviation accidents occurring in Lower Saxony from 1979 to 1996. A total of 96 aviation accidents occurred in this period involving 73 aeroplanes. The crashes resulted in the death of 154 people ranging in age from 19 to 68 years. The greatest number of victims in a single crash of an aircraft was (n=7). Other types of fatal accidents were crashes of aircraft and helicopter while on the ground (n=5), hot-air balloons (n=2), parachutes (n=10), hang glider accidents (n=5) and the striking of a bystander by a model airplane. Autopsies were performed on 68 of the 154 victims (44.2%), including 39 of the 73 pilots (53.4%). Some of the autopsies yielded findings relevant to the cause of the accident: gunshot wounds, the presence of alcohol or drugs in blood and preexisting diseases. Our findings emphasize the need for autopsy on all aviation accident victims, especially pilots, as this is the only reliable method to uncover all factors contributing to an accident.

Reliability of SE33 typing by capillary electrophoresis.

A ladder of 24 ACTBP2 (SE33) alleles was separated 175 times by denaturing capillary electrophoresis on an ABI Prism 310 Genetic Analyzer using polymer POP-4. The mean standard deviation of fragment size determination was 0.083 bp. Fragments in the whole allelic range of ACTBP2 could be typed with high precision and reproducibility if adjacent fragments differed by at least two nucleotides. The capacity of resolving 1 bp differences was tested by repeatedly running a ACTBP2*14.2/14.3/31.2/31.3 allelic mixture. The 14.2/14.3 fragment pair could be separated in 98%, the 31.2/31.3 fragment pair only in 65% of all runs. Reliable separation of this difficult fragment mixture could exclusively achieved by using POP-6.

The effect of lethal electrical shock on postmortem serum myoglobin concentrations.

Postmortem serum myoglobin concentrations in blood from the femoral vein (peripheral withdrawal) and the heart (central withdrawal) of nine electrical fatalities were compared with those of 74 individuals who had died of other causes. Independent of the cause of death or topographical site, serum myoglobin concentrations rose dramatically with the passage of postmortem time (maximum concentrations in the control group: 975,100 micrograms/l). In 59% of the total sample (electrical fatalities plus controls), serum myoglobin concentrations were higher in the central blood, in the other 41% the concentrations were higher in the peripheral blood. The differences in concentrations between the peripheral and the central withdrawal area correlated with neither the postmortem interval nor the cause of death. Up to the second day postmortem there was a statistically significant difference in serum myoglobin concentrations between electrical fatalities and controls. The individual values within each group, however, varied widely and overlapped between groups. Controls who had also suffered muscle injury (polytrauma, myocardial infarction) did not have significantly higher serum myoglobin concentrations than controls without muscle injury. Myoglobin concentrations appear to be greatly influenced by the extent and duration of the muscle cramps induced by the electrical current. Correct interpretation of serum myoglobin concentrations depends on the knowledge of events surrounding the lethal electrical shock. Postmortem determination of serum myoglobin concentrations alone is, therefore, not sufficient to establish intravital exposure to electrical current and can aid the diagnosis only in special cases.

Unexpected findings in the investigation of an airplane crash.

We report on the discovery at autopsy of an unexpected cause of a crash during landing of a small sports plane with four people on board. Surprisingly, an intact bullet and fragments of the casing were found in the body of the pilot. As expected, autopsy of the other passengers predominantly revealed signs of polytraumatization. In addition, one passenger had a tunnel wound to the left hand and another, a soft tissue tear between the thumb and forefinger of the right hand. These wounds were considered to be associated with a shooting incident in the cabin. The autopsy findings and additional gunpowder trace investigations suggested that the pilot had been incapacitated by a shot from behind, resulting in the plane crash. The present findings underscore the importance of conducting autopsies on all air crash victims.

[Forensic evaluation of manual temperature estimation]. / Die forensische Bewertung manueller Temperaturschätzungen.

The policemen sometimes feel the bonnet of a car for warmth to check wether it had been used just before. But in court it is difficult to quantify the temperature of the car. Therefore, 541 volunteers were given warmed steel plates to feel at different ambient temperatures between -8 degrees C and 30 degrees C and were asked to estimate their temperature. Highest and lowest temperatures for estimating metal plates as hot, warm, slightly warm or cold were measured. Combined with the known decrease of temperature after using an engine, the time at which the engine stopped can be estimated after this study. The sense of warmth and coldness turned out to be significantly influenced by the ambient temperature, by the time of day and by the volunteers' energy balance. In the morning volunteers estimated temperatures 2.5 degrees C higher and more precisely than in the afternoon and evening. For hungry volunteers the seemed 2.5 degrees C colder than for volunteers with a postprandially elevated energy balance. The lowest necessary temperature to cause a slightly warm sensation was 16 degrees C lower at -8 degrees C ambient temperature than at 30 degrees C ambient temperature. The risk of estimating a plate as warm by mistake was found in only 0.57%. Confirmed by this study, estimated temperatures can be considered reliable enough to cite in court.

Body and head position, covering of the head by bedding and risk of sudden infant death (SID).

We examined the position of the body and head, and the covering of the head by bedding on discovery in cases of sudden infant death (SID) in Lower Saxony. Between 1.1.1986 and 31.12.1992 structured, questionnaire-based interviews were carried out with parents of 140 SID victims. Control data were taken from a population-based cross-sectional study on infant sleeping position performed by the German Health Office (BGA) in autumn 1991. Of the SID cases 86.4% were discovered in the prone position [odds ratio (OR) = 7.4, 95% confidence interval (CI) = 4.3, 12.7] and 41.4% were found with the head covered. These infants were significantly older than those where the head was uncovered (p < 0.001) and covering of the head showed a significant association with a risk of SID (OR = 20.8; 95% CI = 11.5-37.6). Of the SID cases 27.9% were discovered in the face-down position. These infants were significantly younger than the infants who were discovered with the head in a side or supine position (p < 0.001). This study confirms the increased risk of SID associated with the prone position and suggests that this association could be related to the development of hypoxaemia or hypercapnia. Together with other factors such as heat stress or an infection, hypoxaemia or hypercapnia could culminate in SID if the arousal from sleep and auto-resuscitation apparently fails.

Larynx-associated lymphoid tissue (LALT) in young children.

BACKGROUND: Mucosa-associated lymphoid tissue (MALT) plays a central role in mucosal immunity. Whereas the characteristics and function of MALT in the intestine are well established, almost nothing is known about MALT in the larynx. METHODS: In this study we examined the morphology and the lymphocyte subset composition of MALT in the larynges of children who had died of sudden infant death or various defined traumatic or nontraumatic causes. RESULTS: Organized lymphoid tissue was found in the supraglottic parts of the larynx in nearly 80% of the children in both groups. This lymphoid tissue showed all morphological signs of MALT, such as typical lymphoid follicles with germinal centers, infiltration of the overlying epithelium by lymphocytes, and high endothelial venules (HEV). Thus we will use the term LALT (larynx-associated lymphoid tissue) to refer to this tissue. The lymphoid follicles of LALT contained mainly B lymphocytes with some CD4+ lymphocytes in the germinal centers. Remarkably, T lymphocytes of both subset types and B lymphocytes were observed in comparable numbers in the parafollicular area. CONCLUSIONS: We assume that LALT is a physiological structure of the larynx in young children. The morphology and the distribution of lymphocyte subsets are similar to those of MALT in the human gut. LALT may be a regular part of the mucosal immune system in young children with the role of respiratory inductive site for mucosal immunity.

[Methods of suicide in an autopsy sample of the Institute of Forensic Medicine of the Hannover Medical School]. / Suizidmethoden im Sektionsgut des Instituts für Rechtsmedizin der Medizinischen Hochschule Hannover.

Between 1978 and 1987 513 cases of suicide were examined at the Institute of Legal Medicine of the Medical School of Hannover (337 males (65.7%) and 176 females (34.3%). The greatest share of the suicides was found in the age group 18 to 30. 42.1% of the cases showed positive alcohol concentrations with men accounting for a relatively higher share. The most frequently used methods for committing suicide were intoxications (28.1%), hanging (25.3%), firearms (17.2%), falling from great height (9.7%) and drowning (7.6%). The incidence in terms of sex showed marked differences in distribution, however. Women mostly used the following methods for committing suicide: Intoxication (37.4%), falling (17.6%) and hanging (17%). With men we found the following order: Hanging (29.7%), firearms (24.3%) and intoxications (23.1%). Compared with other institutes of legal medicine the five most frequent suicide methods showed similar distributions, but with a higher rate of intoxications. On the other hand there were distinct differences as to the relative frequency of the individual suicide methods in the total population and the respective number of autopsies performed. Especially in cases of gunshot wounds the number of autopsies performed to rule out homicide was higher. Of 2390 case of suicide registered in Greater Hannover an autopsy was ordered by the court in only 6.7%. According to our experience the autopsy rate seems too low, because homicide in the form of pretended suicide is not too rare.

Influence of postmortem changes on immunohistochemical reactions in skin.

The influence of postmortem damage of tissues on the immunohistochemical diagnosis of wound age has not as yet been clarified. We utilized antibodies against the proteinase inhibitors alpha-1-antichymotrypsin and alpha-2-macroglobulin, fibronectin and lysozyme to study samples of skin which had been intact intravitally, but were damaged postmortem either by autolysis or compression with a surgical clamp at the time of dissection. Even in the absence of autolysis, antibodies against the proteinase inhibitors and fibronectin exhibited staining of tissue margins. Autolysis caused an increase in false positive results. In contrast, antibodies against lysozyme did not give false positive staining. There were no antigens sensitive to postmortem clamping and false positive results were not observed. Antibodies against proteinase inhibitors are not useful for the diagnosis of wound age because of a high number of false positive reactions in marginal areas. Fibronectin also showed false positive band-shaped staining patterns at the tissue margin. In addition, autolytic processes increase the number of false positives. The antibody against lysozyme is much less sensitive to autolysis and no false positive reactions were observed in our series of tests.

Backspatter from experimental close-range shots to the head. II. Microbackspatter and the morphology of bloodstains.

Backspatter is the ejection of biological material from a gunshot entrance wound against the line of fire. Backspatter of blood was investigated experimentally in transverse gunshots to the heads of calves (n = 9) from shooting distances of 0-10 cm. The resulting bloodstains were documented on white paper placed horizontally 60 cm below the impact site. The morphology of bloodstains and the distribution of microstains (diameter < 0.5 mm) is reported. The number of microbackspatter stains per gunshot varied between 39 and 262 and the maximum travelling distance was 69 cm while the vast majority of micro-droplets accumulated between 0 and 40 cm. The direction a single droplet can take comprises every possible angle between the most tangential ones to the skin surface. Microstains exclusively were circular to slightly oval. The morphology of macrobackspatter stains (diameter > 0.5 mm) varied from round to elongated with circular, drop-like and stains in the form of exclamation marks predominating. Small macrostains (0.5-4 mm) made up more than 90% of the macrostains and no systematic relationship between distance travelled and size of the stains could be established. The necessity of appropriate lighting and magnification in the investigation of surfaces for backspatter is stressed because many microstains are located in the proximity of the entrance wound where the firearm and the shooting hand are located in cases of close-range shots.