Combining Postmortem Cerebrospinal Fluid Biochemistry With Lung-to-Body Ratio to Aid the Diagnosis of Salt Water Drowning.

Diagnosing drowning as a cause of death can pose many challenges for the forensic pathologist and a number of ancillary tests have been proposed to assist in the diagnosis, whether the body was in salt water or fresh water. Although elevated vitreous humor sodium and chloride is a reliable marker, its limitation to prolonged immersion has resulted in the recent investigation of cerebrospinal fluid (CSF) sodium and chloride as alternative matrix in cases of longer or unknown immersion times. This study investigated postmortem CSF from lumbar puncture (CSF_L_Na_Cl) and ventricular aspiration (CSF_Vent_Na_Cl), as well as lung/body (LB) ratio in the diagnosis of salt water drowning and performed comparison and combination testing of methods to improve diagnostic accuracy of the drowning diagnosis. This study found that CSF_L_Na_Cl was the most accurate method (89%) in the given cohort, but that CSF_Vent_Na_Cl and LB combined was the second most accurate method (83%), exceeding CSF_Vent_Na_Cl (77%) and LB (81%) used alone. These findings are useful for stratifying and prioritizing postmortem samples in the investigation of salt water drowning and also have significance for future studies using this methodology to combine and compare the accuracy of different investigations.

Postmortem Tryptase Level in 120 Consecutive Nonanaphylactic Deaths: Establishing a Reference Range as <23 µg/L.

Postmortem tryptase is a useful biochemical test to aid the diagnosis of anaphylaxis. Multiple perimortem and postmortem factors have been documented to cause an elevation in postmortem tryptase level. One factor that was recently recognized to have an impact on postmortem tryptase level is correct sampling technique. A recent study recommended aspirating blood samples from a clamped femoral/external iliac vein to be used for reliable postmortem tryptase analysis. This study sampled 120 consecutive nonanaphylactic deaths in which all the peripheral bloods were sampled as recommended. Postmortem interval, resuscitation, different nonanaphylactic causes of death, sex, and age did not show any statistical significant relation to postmortem tryptase level in Student t test, Pearson correlation, and univariate and multivariate analyses. The mean (SD) postmortem tryptase level was 8.4 (5.2) µg/L (minimum, 1.0 µg/L; maximum, 36.1 µg/L; median, 7.3 µg/L). Using nonparametric methods, the postmortem tryptase reference range in nonanaphylactic death was established as <23 µg/L (97.5th percentile).

Elevation of Postmortem Cerebrospinal Fluid Sodium and Chloride Levels Is a Potential Adjunct Test in the Diagnosis of Salt Water Drowning.

Postmortem vitreous humor biochemistry is a useful test in the diagnosis of salt water drowning (SWD). A significant limitation of vitreous humor is the potential effect of prolonged immersion. A recent animal study and case report suggested that cerebrospinal fluid biochemistry may be an alternative to vitreous because it is more resistant to the effects of immersion, given its protected anatomical location. This study compared postmortem cerebrospinal fluid sodium and chloride (PMCSC) levels collected via ventricular aspiration (PMCSC_V) and via lumbar puncture (PMCSC_L) in 13 SWD and 31 nonimmersion deaths. It showed a significant elevation in PMCSC levels in SWD deaths for both PMCSC_V and PMCSC_L (P < 0.05). The areas under the curve on the receiver operating characteristic curves for PMCSC_V and PMCSC_L were 0.73 and 0.83, respectively. The optimal cutoff for PMCSC_V was 216 mmol/L (sensitivity, 0.60; specificity, 0.72; likelihood ratio, 1.80; positive predictive value, 0.45) and for PMCSC_L was 241 mmol/L (sensitivity, 0.78; specificity, 0.73; likelihood ratio, 2.89; positive predictive value, 0.46). This study supports PMCSC levels as another biochemical test that can potentially aid in the diagnosis of SWD, particularly in cases where vitreous humor samples are unavailable or uninterpretable.

Black Esophagus (Acute Necrotizing Esophagitis) and Wischnewsky Lesions in a Death From Diabetic Ketoacidosis: A Possible Underlying Mechanism.

Acute esophageal necrosis (AEN), also known as black esophagus, is a rare clinical entity. It is recently described to be associated with diabetic ketoacidosis (DKA) in a few case reports. Wischnewsky lesions (WLs) are a classic postmortem finding seen in fatal hypothermia but are recently described to be associated with DKA. Interestingly, the pathogenesis and morphology of AEN and WLs appear to share similar characteristics. Both AEN and WLs are reported to be seen simultaneously in hypothermic deaths and deaths related to alcohol abuse, but not in DKA. We report a death in a 67-year-old woman who died of DKA. At postmortem examination, the esophagus and stomach showed AEN and WLs, respectively. Although not previously reported together, both AEN and WLs have separately been described in cases of DKA. This case raises a possible unifying etiology of AEN and WLs in DKA (and probably also in hypothermic deaths and deaths related to alcohol abuse), manifested in different parts of the gastrointestinal tract.

Elevated Cerebrospinal Fluid Sodium and Chloride Levels in a Saltwater Drowning Death.

To ascribe a cause of death from drowning in a body immersed in water can be difficult because of the absence of specific postmortem findings and unreliable ancillary tests. Postmortem vitreous biochemical analysis is documented to be a useful adjunct ancillary test to aid the diagnosis of saltwater drowning. A major confounding factor in using postmortem vitreous is the effect of electrolyte diffusion and water osmosis during immersion. A recent animal study suggested that cerebrospinal fluid (CSF) biochemical analysis, which is unaffected by immersion, may be an alternative. However, to date, there are no human data to support this. We report a saltwater drowning death from presumed suicide in which the postmortem CSF sodium and chloride level was elevated compared with nonimmersion deaths. This case gives evidence to support the potential use of postmortem CSF sodium and chloride level as an adjunct to the diagnosis of saltwater drowning.

Rapid Streptococcus Pneumonia Antigen Detection on Postmortem Urine in a Death Due to Pneumococcal Meningitis.

Streptococcus pneumoniae is the leading cause of adult bacterial meningitis. Differing from Neisseria meningitidis (the second most common cause of acute bacterial meningitis), contact tracing and chemoprophylaxis are not required. At postmortem, the differentiation between S. pneumoniae and N. meningitidis is traditionally done by culture and polymerase chain reaction performed on blood or cerebrospinal fluid, but may take hours, if not days, to analyze. We present a death from bacterial meningitis in a 73-year-old woman in which a rapid urinary pneumococcal antigen testing was able to identify S. pneumoniae as the causative organism within 1 hour. This was confirmed by subsequent brain swab culture. The rapid urinary pneumococcal antigen test in the case prevented the need for contact tracing and chemoprophylaxis. This case highlights the potential use of this test to rapidly identify the culprit organism at postmortem examination when acute bacterial meningitis is detected.