The phrase “differential diagnosis” caught my eye recently in light of some tendency in forensic engineering for the injured party to take the expert’s initial thought on cause as gospel and run with it.<\/p>\n
Yet the forensic expert’s initial thought – an initial hypothesis – is based on just a little evidence and likely, quite subjective evidence.\u00a0 For example, a briefing by the client, a\u00a0 read of some documents and perhaps a walk-over survey of the accident or failure site.<\/p>\n
Sometimes that thought\/hypothesis is subject to revision like happens in the scientific method – and an embarrassment to all concerned if counsel decides to take the case or the claims manager agrees a settlement.<\/p>\n
(Scientific method: A method or procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification<\/em><\/span> of hypotheses. Ref. 1)<\/p>\n Differential diagnosis is a medical process.\u00a0 It occurred to me that forensic experts could learn from medical doctors.<\/p>\n Differential diagnosis is the development of a list of possible medical conditions that might explain a patient’s symptoms.\u00a0 The list goes from the most likely and urgent at the top to the least at the bottom.\u00a0 The process involves several phases like forensic investigation involves several stages.\u00a0 The early phases\/stages are subjective in nature.\u00a0 The process is well developed in medicine as explained by a friend and also Dr. Google. (Refs 1 and 2)<\/p>\n The phases of a differential diagnosis and their similarity to a forensic investigation are a little like the following:<\/p>\n Phase #1<\/span> Take history<\/strong><\/p>\n In medicine, take a history from the patient about what she’s experiencing.\u00a0 Interrogate and ask questions like a detective.\u00a0 Try to figure out what’s going on.<\/p>\n In forensic work, take a briefing from the injured party or their counsel or claims manager about their slip and fall accident or the damage to their building.\u00a0 Ask lots of questions.\u00a0 Read existing documentation.\u00a0 Consider different categories of accidents or failures.<\/em><\/p>\n Phase #2<\/span> Physical examination<\/strong><\/p>\n Look, feel and listen.\u00a0 Take the patient’s pulse and measure his blood pressure.\u00a0 Examine him orally.\u00a0 Listen to his chest (with a stethoscope).\u00a0 Do a percussive examination (tap body with fingers and note the sound)<\/p>\n Walk over the site and visually examine the accident or failure scene and the structures there.\u00a0 Measure and determine the condition of the structure before and after the failure.\u00a0\u00a0<\/em>Photograph and measure features characterizing the scene.\u00a0 Take aerial video of the scene from a drone.\u00a0 Excavate test pits and note the subsurface conditions.\u00a0\u00a0Carry out initial skid resistance tests of the floor at a slip and fall accident.\u00a0<\/em><\/em><\/p>\n Phase #3<\/span> Additional investigative tests<\/strong><\/p>\n Carry out additional tests like blood work, X-rays, MRIs and stress tests.<\/p>\n Take samples and do laboratory tests of the physical properties of materials that failed.\u00a0 Do field tests and sample and test the physical properties of the soil in the field and laboratory.\u00a0 If necessary, do additional skid tests of the floor.<\/em><\/p>\n Phase #4<\/span> Data analysis and interpretation<\/strong><\/p>\n Analyse data and test results and identify conditions that could account for the patient’s symptoms.\u00a0 List from most likely to least likely – the differential diagnosis.\u00a0 Look at the most probable diagnosis at the top of the list then go back to Phase #3 and order more tests to confirm depending on how confidant you are.<\/p>\n Study the data, look at how different pieces of data relate and support one another and relate to possible causes of the personal injury or the crane or building collapse.\u00a0 Identify the probable cause(s) of the injury or collapse.\u00a0 If necessary, return to the site to check and confirm earlier findings.<\/em><\/p>\n Phase #5<\/span> Treatment<\/strong><\/p>\n In medicine, prescribe a treatment of the condition with medicines, life style changes, diet, etc.\u00a0 Monitor the condition and if improves good.\u00a0 If no improvement, consider the dosage of medicines and the extent of other changes.\u00a0 If none or not much go back to the previous phase and reconsider the differential diagnosis.\u00a0\u00a0Treatment is the prescription, the plan in SOAP. (Ref. 3)<\/p>\n In forensic work, report the most probable cause of the accident or failure.\u00a0 Recommend how the damage can be fixed and the cause of the accident or failure eliminated.<\/em><\/p>\n ***<\/p>\n I see the differential diagnosis process as an elaboration of the SOAP<\/strong><\/span> process that is also followed in medicine: (Ref. 3)<\/p>\n 1. Gather\u00a0S<\/span>ubjective<\/strong> data.<\/span><\/span>\u00a0\u00a0Take a history from the patient in medicine and a briefing on the problem in engineering<\/em>.\u00a0 Reflect on why the patient is hurting and\u00a0the different categories of structural failure in engineering<\/em>.<\/p>\n 2. Get some\u00a0O<\/span>bjective <\/strong>data.<\/span><\/span>\u00a0 Like blood work and X-rays in medicine and measurements and field and laboratory tests in forensic investigation.<\/em><\/p>\n 3. A<\/span>nalyse<\/strong><\/span> the data.\u00a0 Study, identify and list the different medical conditions indicated by the data that could account for the patient’s symptoms.\u00a0 And in forensic work, the different causes that could account for the personal injury or the crane or bridge collapse.<\/em>\u00a0 The list is the differential diagnosis in medicine and the possible causes in a forensic investigation, going from the most likely cause at the top to the least likely at the bottom.<\/em><\/p>\n 4. P<\/span>rescribe <\/strong><\/span>treatment.\u00a0 For example, identify life style changes, diet and\/or medications to fix the medical condition and make the symptoms disappear.\u00a0 In forensic work recommend how the damage can be repaired and the cause removed.<\/em><\/p>\n ***<\/p>\n Can you imagine the embarrassment to the medical doctor and the pain for the patient if s\/he prescribed treatment based on the results of Phase #1 of the differential diagnosis process and he was wrong and the patient dies?\u00a0 Everybody gets in trouble.<\/p>\n Fortunately, that doesn’t happen often in medicine.\u00a0 Unfortunately it happens at times in forensic work – the client runs with the expert’s initial thoughts on cause.\u00a0 A few years ago, an expert noted the occasional pressure on an expert during a forensic investigation to find support for those initial thoughts.<\/p>\n Summary<\/strong><\/p>\n So, the next time you’re getting a medical check-up think about the forensic expert and hope the doctor doesn’t go with his initial thoughts on the cause of your symptoms.\u00a0 And if you’re the forensic expert, go out of your way to help your client, the injured party, understand that an initial thought on cause is not necessarily a final diagnosis.\u00a0 It’s at the front end of the subjective-data-collection-stage and a soft thought.<\/p>\n References<\/strong><\/p>\n <\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" The phrase “differential diagnosis” caught my eye recently in light of some tendency in forensic engineering for the injured party to take the expert’s initial thought on cause as gospel and run with it. Yet the forensic expert’s initial thought … Continue reading \n