{"id":3156,"date":"2016-12-16T15:42:13","date_gmt":"2016-12-16T02:42:13","guid":{"rendered":"http:\/\/microbiologymatters.com\/?p=3156"},"modified":"2016-12-16T15:42:13","modified_gmt":"2016-12-16T02:42:13","slug":"the-fishing-expedition","status":"publish","type":"post","link":"https:\/\/microbiologymatters.com\/?p=3156","title":{"rendered":"&#8220;The Fishing Expedition&#8221;"},"content":{"rendered":"<p><span style=\"color: #0000ff;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-medium wp-image-3158\" src=\"https:\/\/i0.wp.com\/microbiologymatters.com\/wp-content\/uploads\/2016\/12\/fishingexpedition.jpg?resize=300%2C225\" alt=\"\" width=\"300\" height=\"225\" srcset=\"https:\/\/i0.wp.com\/microbiologymatters.com\/wp-content\/uploads\/2016\/12\/fishingexpedition.jpg?resize=300%2C225&amp;ssl=1 300w, https:\/\/i0.wp.com\/microbiologymatters.com\/wp-content\/uploads\/2016\/12\/fishingexpedition.jpg?w=500&amp;ssl=1 500w\" sizes=\"(max-width: 300px) 100vw, 300px\" data-recalc-dims=\"1\" \/><\/span><\/p>\n<p><span style=\"color: #0000ff;\">As a clinical microbiologist I occasionally get asked to recommend suitable microbiology\u00a0tests for a patient, e.g. a returned traveller with a fever, a patient with encephalitis, an immunocompromised patient with CXR changes, etc., etc.<\/span><\/p>\n<p><span style=\"color: #0000ff;\">It is always tempting to show off, and display\u00a0whatever knowledge you have\u00a0of exotic and peculiar diseases, and give to the requestor an exhaustive (and exhausting) list of investigations to carry out&#8230;<\/span><\/p>\n<p><span style=\"color: #0000ff;\">There are however a few things to reflect on before constructing such a list:<\/span><\/p>\n<ul>\n<li><span style=\"color: #0000ff;\"><span style=\"color: #ff0000;\">Common things are common:-<\/span> It is important to exclude all the common diagnoses, before considering the more unusual causes of the patient&#8217;s symptoms. Returned travellers get flu as well&#8230;<\/span><\/li>\n<li><span style=\"color: #0000ff;\"><span style=\"color: #ff0000;\">Familiarity leads to competence:-<\/span> Laboratories are not as good at testing for conditions which they don&#8217;t see that often, with the consequent increased likelihood of a false negative or a false positive result. Trust me, you would not want me trying to diagnose your sleeping sickness..<\/span><\/li>\n<li><span style=\"color: #0000ff;\"><span style=\"color: #ff0000;\">The laboratory can&#8217;t be perfect all the time:-<\/span> If you request sufficient tests on the one patient,\u00a0then the odds are\u00a0you will eventually\u00a0generate a (false) positive result.<\/span><\/li>\n<li><span style=\"color: #0000ff;\"><span style=\"color: #ff0000;\">For each test, think about pre-test probability:-<\/span> The more exotic your test requests become (&#8220;long shots&#8221;), the lower the pre-test probability and\u00a0\u00a0positive predictive value.<\/span><\/li>\n<\/ul>\n<p><span style=\"color: #0000ff;\">Fishing expeditions need planning and experience. I also prefer a staged approach&#8230; &#8220;If tests A &amp; B are negative, only\u00a0then consider tests C &amp; D.&#8221;<\/span><\/p>\n<p><span style=\"color: #0000ff;\">And whilst on a fishing expedition, don&#8217;t forget to treat the patient&#8230;\u00a0 There will always be a proportion of patients where you will <span style=\"color: #ff0000;\">never<\/span> get the diagnosis, no matter how hard you try. In the midst of an &#8220;investigative frenzy&#8221;, don&#8217;t forget to cover for the most common and most serious differentials. <\/span><\/p>\n<p><span style=\"color: #0000ff;\">No patient was ever cured by investigation alone&#8230;<\/span><\/p>\n<p><em>Michael<\/em><\/p>\n<p><em>Just to let you know\u00a0that the Microbiology Matters website has now accumulated 200,000 &#8220;visits&#8221; since its inception in 2013. It may be some time however\u00a0before it reaches a million!<\/em><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>As a clinical microbiologist I occasionally get asked to recommend suitable microbiology\u00a0tests for a patient, e.g. a returned traveller with a fever, a patient with encephalitis, an immunocompromised patient with CXR changes, etc., etc. It is always tempting to show off, and display\u00a0whatever knowledge you have\u00a0of exotic and peculiar diseases, and give to the requestor &hellip; <a href=\"https:\/\/microbiologymatters.com\/?p=3156\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">&#8220;The Fishing Expedition&#8221;<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[1],"tags":[492,21],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p37jIp-OU","jetpack-related-posts":[{"id":3894,"url":"https:\/\/microbiologymatters.com\/?p=3894","url_meta":{"origin":3156,"position":0},"title":"&#8220;When the patient and the microbiology lab don&#8217;t agree&#8221;","author":"michael","date":"May 16, 2019","format":false,"excerpt":"I am signing out blood culture results. A patient has an E. coli resistant to amoxycillin clavulanate (augmentin) in both their blood culture and urine specimen. I ring up the patient's doctor to see how the patient is doing. The patient is currently on augmentin but is nevertheless feeling much\u2026","rel":"","context":"In \"clinical microbiologist\"","block_context":{"text":"clinical microbiologist","link":"https:\/\/microbiologymatters.com\/?tag=clinical-microbiologist"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/microbiologymatters.com\/wp-content\/uploads\/2019\/05\/iamcured-211x300.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":1094,"url":"https:\/\/microbiologymatters.com\/?p=1094","url_meta":{"origin":3156,"position":1},"title":"&#8220;Dubious Reasons for Microbiological Sampling&#8221;","author":"michael","date":"March 20, 2013","format":false,"excerpt":"We would like to think that every sample that comes into the microbiological laboratory is of great importance and has been taken for the right reasons. However having been in the business for several years now I know that this is not always the case. 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I am a big believer in the 80\/20 rule, although the ratio is of course an arbitrary one. How can\u2026","rel":"","context":"In \"clinical benefit\"","block_context":{"text":"clinical benefit","link":"https:\/\/microbiologymatters.com\/?tag=clinical-benefit"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/microbiologymatters.com\/wp-content\/uploads\/2016\/05\/vilfredo-pareto-1848-1923-240x300.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":3233,"url":"https:\/\/microbiologymatters.com\/?p=3233","url_meta":{"origin":3156,"position":4},"title":"&#8220;Something for the weekend?&#8221;","author":"michael","date":"January 11, 2017","format":false,"excerpt":"I know it is difficult to believe, but\u00a0patients\u00a0tend to be just\u00a0as sick on Saturday and Sunday as they are from Monday to Friday. I am not sure if the concept of the \"weekend\" is secondary to religion or the industrial revolution. 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