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Private Blood Results Have Come Back 36mg/100ml blood. Back Calculation ?


I was involved in an RTA at just after midnight 12:00am - 3 weeks ago, taken to hospital and bloods taken at 03:00am.

I sent off my bloods and they came back at 36mg/100ml blood today (blood was taken at hospital exactly 3 hours after RTA, injories to myself, badly cut lip, bleeding nose, airbags deployed.)

I left the scene as 3 hooded youths approched me after getting out of the vehicle and i was in shock and left scence (the 3 hoodies actually stayed for police and they turned out to be witnesses, so me leaving the scene due to being in shock and being approached by hooded lads and me being covered in blood, in an unfamilar place at the time, i said i didnt know there intention....leaving the scene charge was dropped)

Rta involved a very small section of a wall, my van hit the corner and flipped off the side of it.

I told police the next morning during interview that i had drank between 5-7 large beers (however they did not ask over what period of time in the interview)

I did not feel drunk at all, id just had new tyres fitted all round a couple days before and the driving felt a bit off (have receipt as proof), i slightly clipped the curb, and it sent me to the wall. (Have not had chance to explain this yet)

Im tallish, and was just over 14 stone 3 weeks ago, (13 stone now as barley ate or drank because of stress of this) im physically quite fit, so must be reason for my very low bac reading?. I had around 10 pints but over about 11 hours, had an arguement with partner and drove off about 5 mins down the road from where we were staying, but did not feel unfit to drive (hence the blood result!)

Even if they did a back calculation, id probably be right at about 80mg if the average clearance is 15mg/hour? (Or so ive read)

What are the chances of a back calculation given all the above circumstances? Is it really only used in serious accident that have injured/killed others, or wrecked lots of property, or if its been like 8 hours since they were able to get a specimen?

Also i admitted guilty to drink driving in interview (should have went no bloody comment) but after the crash i was in complete shock, and didnt understand about how bac drops scientifically and you can drink over a period and not technically be over, and just assumed id had quite a few that day, and to hold my hands up and accept my fate... but legally at the moment its well under and im shocked... (unless my lab has made a giant booby?, i hope not for how much i paid!)

Any helpful insight as to potential outcome? They have not asked what time period i consumed the alcohol, my weight, height, food consumed etc as of yet (i doubt they will have their blood results back for another few weeks yet)


Im really starting to wonder if the lab have made an error.

I had 14 x 440ml cans at 4 % = 25.2 units over the space of 10 - 11 hours (1.30pm to around 11:30pm) crashed 12:00am, bloods taken at 03:00am.

How am I only showing 36mg/100ml of blood. I have read many (and i mean alot) of similar stories of calculations, and would have thought id be over based on others readings and drinks/times consumed, and also studies on general elimination in peoples bac's.

Just really confused now.

I have the certificate from the lab stating a total of 36mg (after the 6mg mandatory reduction) all the info is correct on the cettificate i.e. the dates they received the bloods, the barcode on the unsealed bag, the doctor who took the bloods.

Really need advice. :-S


Well-known member
It would seem fairly unlikely the lab result will be substantially wrong. Often the testing methods used by the police are more accurate, and expensive, then the ones used by drivers, but the result should be pretty much the same.

It is not possible to accurately calculate the rate at which alcohol is eliminated over such a long time frame and number of drinks, the lab result is the best guide. It does seem lower than expected, but then by your own admission you didn't feel drunk.

As such the likely question is whether the police would seek to do a back calculation. There is not much you can do about that - if you have told them you have had five to seven drinks they may be more inclined to, as for most people that would be seen as a large amount before driving. You also have the aggravating factors of the accident and leaving the scene which delayed police contact.

I think essentially your fate is in the hands of the police investigating officer and that decision.
That reading is quite reasonable, especially if you have physical characteristics that mean you metabolise alcohol quicker. A lot of the stuff you read online is unreliable and really worst case scenario. I once drank some 27 units over an 8 hour period, and 14 hours after I started drinking my breath reading was 17mcg (approximately 40mg in blood). I must state that I was not driving at all during this time.

It is very unlikely that the police would pursue a back calculation in this type of incident. I would be interested to hear the outcome of this.