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POCT for hCG is the area where we seem to have the most "clinical incident reports" dealt with by Pathology. Getting through to Clinical Staff that it is not a pregnancy test is the first step. Getting them to look at the whole clinical picture is the next step. Getting them to use the hCG results as part of the diagnosis rather than the diagnosis is the next. Using serum hCG if in doubt is also part of their protocol. Having a good POCT Manager who can spend time with Clinical Staff explaining the limitations of the assay and training staff and following up anomalies, is also very useful in resolving problems. (that sentence is for Chris Royle!) Most false negatives are difficult to explain, but clinical staff are asked to keep the urine if in doubt and we then check the hCG using a quantitative technique in Biochemistry, unfortunately this does not happen very often as the urine is often in an unlabeled collection pot (and probably someone elses urine!) so getting to the heart of the problem is difficult None of the samples that we have checked have been different to the POCT. "False" positives are more of a problem, including patients bringing other peoples urine! Tim Hogan Basildon. -----Original Message----- From: McDonnell, Margaret [mailto:[log in to unmask]] Sent: 21 December 2005 15:55 To: [log in to unmask] Subject: Re: ?False negative urine pregnancy results/Christmas Quiz Assuming there is nothing wrong with the batch or technique, then the quality of the samples may be another possibility. The manufacturer of the cartridges that we are about to introduce claim that false negatives are very rare, but they do suggest some explanations of false negatives; 1.Urine specimens contaminated with blood may affect the fluid flow on the test strip, producing false negative results. This might be relevant for your first case. 2.If the patients were catheterized, then the lubricating gel used prior to catheterisation may also decrease fluid flow on the test strip (although experience from our current pregnancy test strips shows that the lubricating gel used by our Trust causes false positive pregnancy tests). Margaret McDonnell -----Original Message----- From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Wills Philip (Queen Elizabeth Hospital NHS Trust) Sent: 20 December 2005 17:14 To: [log in to unmask] Subject: ?False negative urine pregnancy results/Christmas Quiz I would be grateful for possible explanations for the two following cases of alleged false negative urine pregnancy testing results using a well known kit with cut-off 25 U/l. Please assume there is nothing wrong with the batch. All obvious actions are underway and the company has been informed. The kit performs perfectly well in EQA although this particular batch was not used. Staff in A/E have had training updated although there is no indication that the test was not performed correctly. CASE ONE Came to A/E with abdominal pain on 9/11/05 and also 12/11/05. Urine Pregnancy Test in A&E negative on both visits. Came to A&E again 15/11/05 with abdominal pain "Just finished period" - 13/11/05(? date of bleed prior to that.) Doctor performed a Urine Pregnancy Test approx 08.00h on 15/11/05 (despite 2 recent negatives) which was positive. Serum beta HCG taken 10.34h on 15/11/05 was 2650 U/l. The patient had an ectopic pregnancy, which had been missed on the first 2 occasions. Patient is now doing well. CASE TWO Presented 15/11/05. Known to be 8 weeks pregnant. Presented with hyperemesis, but Urine Pregnancy Test at triage, approx 15.45 was negative. Doctor repeated Urine Pregnancy Test himself on same sample - again negative. Then asked patient to provide another sample, which he tested himself, which was also negative. That is 3 negative tests on 2 samples. Doctor sent serum beta HCG, approx 16.30h on 15/11/05. The result was greater than 10000 U/L No adverse outcome in either case. PS I have just checked 20 of the "suspect" cassettes against 20 consecutive ex EQA material stored at -20 C and got 100% correct answers. Many thanks,Phil Wills ************************************************************************ *** This e-mail is confidential and privileged. If you are not the intended recipient please accept our apologies; please do not disclose, copy or distribute information in this e-mail or take any action in reliance on its contents: to do so is strictly prohibited and may be unlawful. Please inform us that this message has gone astray before deleting it. Thank you for your co-operation. ************************************************************************ *** ------ACB discussion List Information-------- This is an open discussion list for the academic and clinical community working in clinical biochemistry. Please note, archived messages are public and can be viewed via the internet. 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