- 期刊
疑似溺水案件法醫解剖檢體矽藻分布之研究
Diatom Analysis in Forensic Autopsy Samples from Suspected Drowning Cases
摘要
僅藉由法醫解剖欲診斷出水中發現屍體之死亡原因著實為一項艱難的任務，尤其水中屍體不易被尋獲，死後變化會因浸泡時間愈長，腐敗狀態愈明顯，解剖病理能得到的資訊相對也更少。為輔助辨別診斷死亡原因是否為生前溺水死亡，關於各種診斷方法之研究層出不窮，其中以矽藻檢驗被認是最具診斷價值的方法之一，但台灣目前仍未將矽藻分析納入輔助診斷生前溺水死亡之常規檢驗流程中。因此本實驗藉由分析疑似溺水案件之法醫解剖檢體矽藻分布情形，包含矽藻定量及矽藻定性分析，探討矽藻檢驗於診斷溺水死亡之實用性。本實驗共收集99件疑似溺水案件及20件非疑似溺水案件，所有案件均收集自台灣法務部法醫研究所法醫解剖案件，由法醫解剖採集矽藻分析用檢體，包含5公克肺臟下葉組織、蝶竇內所含液體及一段肋骨╱鎖骨刮取內部骨髓約5公克，以上檢體經酸處理萃取出矽藻製成玻片後，於相位差顯微鏡下計數所有矽藻數量（矽藻定量）及辨識出各種不同的矽藻屬別（矽藻定性）。其中20件非疑似溺水案件之所有檢體均未檢出矽藻。99件疑似溺水案件經法醫解剖及司法調查後，91件確認為生前溺水死亡，其中半數以上案件可同時在蝶竇液及肺臟檢體中檢出矽藻。本研究顯示矽藻分析於蝶竇液、肺臟及肋骨╱鎖骨檢體內的敏感度分別為87.50%（± 7.25%）、68.18%（± 9.73%）、6.49%（± 5.50%）；特異度分別為81.25%（± 19.13%）、88.89%（± 14.52%）、100.00%（± 0.0%）。季節分析及水域環境分析結果顯示冬季╱春季及海水環境對於肺臟矽藻陽性檢出率有明顯影響，以上因素均會造成肺臟偽陰性機率上升；本實驗中5件肋骨╱鎖骨矽藻陽性的案件，其肺臟矽藻密度均大於70個矽藻╱每5公克肺臟。矽藻定性結果則顯示Achnanthes、Nitzschia、Navicula、Cyclotella及Thalassiosira以上五屬矽藻出現頻率較高。綜合以上所述，本研究認為蝶竇液及肺臟內之矽藻分析對於診斷生前溺水死亡有一定的參考價值，但仍需配合其他調查，包含解剖結果、病理結果、毒物學檢驗結果、現場鑑識調查及司法調查，才能夠研判鑑定出最正確的死亡原因。
並列摘要
The diagnosis of drowning is one of the most difficult parts in the determination of cause of death, especially when there is delay in recovering the victims. The longer the body remain immersed in water, the lesser the pathological proof can be identified. Among various reported methods for drowning diagnosis, the diatom test is still considered as the golden standard. But so far the diatom analysis is still not the routine examination for the diagnosis of drowning in Taiwan. In this study, the quantitative and qualitative analysis of diatoms in the forensic autopsy samples was performed for confirming the applicability of diatom analysis to the diagnosis of death by drowning. The specimens comprise 99 suspected drowning cases and 20 non-suspected drowning cases collected from Institute of Forensic Medicine, Ministry of Justice, Taipei, Taiwan. Five grams of peripheral lung tissue, whole fluid of sphenoid sinus and bone marrow from one rib or clavicle were taken during autopsy. After diatom extraction using strong acid digestion method, diatom counting and genera distribution were performed under the phase contrast microscope. All non-suspected drowning samples showed negative results. Among 99 suspected drowning cases, 91 cases were certified by the forensic pathologists as drowning and approximately half victims showed positive outcomes of diatom test in both sphenoid sinus and lung samples. The sensitivity of diatom analysis form sphenoid sinus fluid, lungs, and rib were 87.50% (± 7.25%)、68.18% (± 9.73%)、6.49% (± 5.5%) respectively and the specificity were 81.25% (± 19.13%)、88.89% (± 14.52%)、100.00% (± 0.0%) respectively. Winter/spring months and sea water environment had the highest false negative rate of diatom analysis in lung samples. There are more than 70 diatoms per 5 gram lungs observed in five cases with positive diatom tests in rib/clavicle. The qualitative results showed Achnanthes, Nitzschia, Navicula, Cyclotella and Thalassiosira are most commonly genera in our experiment. It has been suggested that the diatoms extracted from sphenoid sinus fluid and lungs may indicate drowning, but the results must be interpreted in conjunction with other autopsy findings, pathological proof, toxicological results and police investigation including crime scene investigation.