11/13/24, 7\:31 PM Guide | Blood bottles guide
Blood bottles guide
Table of contents
Introduction
Knowing which blood bottles to use for di
essential when you start work on the wards afterwards. It is one of those practical things which tends to be poorly taught at
medical school, if at all. Instead, you are seemingly expected to just pick it up on your
blood tests correctly will suddenly become a massive cornerstone of your workload. Even though most hospitals now have
printable stickers for bottles which tell you which ones to use, it is still vital to have a basic understanding of which bottles are
used and why to prevent embarrassing mistakes and/or awkward phone calls from the lab.
The colours of the vacutainer bottles are standardised, but depending which hospital you end up working in there may be
some variation in preferences between individual laboratories, especially when it comes to tests which are performed less
commonly. I have used as many sources as possible to compile the information below, so hopefully, it is as accurate as
possible, but obviously I cannot guarantee it will be applicable to all hospitals. Always check local guidelines if you're not sure.
Purple blood bottle
Overview
Purple blood bottles are generally used for haematology tests where whole blood is required for analysis.
Additive
Purple blood bottles contain EDTA (ethylenediaminetetraacetic acid), which acts as a potent anticoagulant by binding to
calcium in the blood. EDTA also binds metal ions in the blood and is used in chelation therapy to treat iron, lead or mercury
poisoning. Its blood-binding capacity also means it can be labelled with radioisotopes and used as an EDTA scan to assess
renal glomerular
Tests
Common tests
Common tests performed using the purple blood bottle include\:
Full blood count (FBC)
Erythrocyte sedimentation rate (ESR)
Blood
Reticulocytes
Red cell folate
Monospot test for EBV
HbA1C for diabetic control
Parathyroid hormone (PTH)*
Less common tests
Less common tests performed using the purple blood bottle include\:
Ciclosporin/tacrolimus levels
Some viral PCR tests
G6PD
ACTH level*
Porphyria screen*
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Plasma metanephrines*
Fasting gut hormone screen*
Tips for use
The purple tube needs inverting about 8 times to mix the sample with the EDTA. About 1ml of blood is su
full blood count, however, to get an ESR you will need a full purple bottle.
Purple bottle
Pink blood bottle
Overview
The pink bottles work in the same way as the purple ones but are speci
the transfusion lab.
Additive
Pink blood bottles also contain the anticoagulant EDTA.
Tests
Common tests
Common tests performed using the pink blood bottle include\:
Group and save (G&S)\: this simply means the patient's blood is typed and tested for antibodies, then saved in the lab in case
it is required; it DOES NOT get you blood products for transfusion. If you need blood products you have to request a
crossmatch.
Crossmatch (XM)\: this means that the patient's blood is typed and tested as above, then matched to speci
platelets or other products for transfusion. You need to specify on the form how many units you need, why you need them
and when they are required. A full crossmatch takes about 45-60 minutes in the lab - if you have an unstable bleeding
patient and think you'll need blood products sooner than this, you still need to send a crossmatch sample, but you can ask
the lab for units of type-speci
negative blood from the fridge.
Direct Coomb's test (a.k.a. direct antiglobulin test) for autoimmune haemolytic anaemia.
Less common tests
Less common tests performed using the pink blood bottle include\:
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Testing for speci
Haematology tests such as FBC (if the ward runs out of purple bottles).
Tips for use
The pink tube needs inverting about 8 times to mix the sample with the EDTA. It should contain at least 1ml of blood, but
more is preferred by the labs if at all possible. It has a special label which needs to be carefully
to ensure the correct patient details are used, preventing potentially catastrophic mismatched blood transfusions. If you need
blood for a patient urgently or have any unusual or complicated requests, you must ring the transfusion lab and let them know,
or you risk invoking their wrath.
For more details on performing blood transfusions safely see our OSCE guide.
Pink bottle
Blue blood bottle
Overview
The blue bottle is used for haematology tests involving the clotting system, which require inactivated whole blood for
analysis.
Additive
Blue blood bottles contain bu
blood and subsequently disrupting the clotting cascade. Sodium citrate is also added to blood products for transfusion and
acts as a preservative by stopping them from clotting in the bag.
Tests
Common tests
Common tests performed using the blue blood bottle include\:
Coagulation screen\: including bleeding time for platelet function, prothrombin time (PT) for assessment of the extrinsic
pathway, activated partial thromboplastin time (APTT) for assessment of the intrinsic pathway, and a thrombin time (TT)
or
D-dimer to assist with ruling out thrombosis (e.g. deep vein thrombosis).
INR for monitoring patients on warfarin (this is calculated from the prothrombin time).
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Activated partial thromboplastin ratio (APTR) for monitoring patients on intravenous heparin infusions (this is calculated
from the APTT).
Anti-Xa assay for monitoring patients on high-dose low molecular weight heparins like tinzaparin.
Less common tests
Less common tests performed using the blue blood bottle include\:
Speci
Thrombophilia screen
Lupus anticoagulant
Tips for use
The blue bottle needs to be inverted 3-4 times to mix the sample with the anticoagulant. The sodium citrate liquid in the bottle
dilutes the blood sample, and the machines in the lab are speci
blood to anticoagulant. It is, therefore, essential that the bottle is
are interpreted accurately - otherwise, the samples may be over-anticoagulated.
If your
obtain a full sample. This is because when you attach the
is unable to
remove the air (i.e.
Some clotting tests need to be taken at speci
be taken 3-4 hours after tinzaparin is given. APTR timings are often indicated on the prescription algorithm.
Blue bottle
Yellow/gold blood bottle
Overview
These bottles are used for a huge variety of tests requiring separated serum for analysis, including biochemistry,
endocrinology, oncology, toxicology, microbiology and immunology.
Additive
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This tube is known in the lab as the SST (serum separating tube). It contains two agents; silica particles and a serum
separating gel. The silica particles work to activate clotting and cause the blood cells to clump together. The serum
separator consists of an inert polymer gel which
barrier between them. This means that the sample can be centrifuged (spun) in the lab and the separated serum easily
removed.
Tests
Biochemistry tests
Biochemistry tests are the ones you will encounter most commonly\:
Urea and electrolytes (U&Es)\: this includes urea, creatinine, sodium and potassium.
C-reactive protein (CRP)
Liver function tests(LFTs)\: this includes bilirubin, ALP, AST/ALT, GGT, total protein and albumin.
Amylase assay
Bone pro
Magnesium assay
Iron studies\: this includes serum iron, ferritin, transferrin saturation and total iron-binding capacity.
Lipid pro
Thyroid function tests (TFTs)\: this includes TSH, free T4 and sometimes free T3.
Vitamins\: including vitamin B12.
Troponins\: this requires 2 samples to be taken at di
Creatine kinase (CK)
Urate
Serum osmolality\: this requires a urine sample to be taken at the same time.
Endocrinology tests
Endocrinology tests that can be performed using a yellow blood bottle include\:
Beta-hCG
Calcitonin*
Cortisol
EPO
Sex hormones
Growth hormone
IGF-1
Tumour marker tests
Tumour marker tests that can be performed using a yellow blood bottle include\:
PSA
CEA
CA-125
CA19-9
AFP
Lactate dehydrogenase (LDH)
Toxicology tests
Toxicology tests that can be performed using a yellow blood bottle include\:
Ethanol
Cannabis
Opiates
Benzodiazepines
Other drugs (e.g. cocaine, amphetamines)
Drug level tests
Drug level tests that can be performed using a yellow blood bottle include\:
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Paracetamol
Salicylates (aspirin)
Digoxin
Lithium
Gentamicin
Carbamazepine
Microbiology/virology tests
The yellow blood bottle can be used to test for a wide variety of bacterial, viral, fungal and parasitic infections including HIV
and viral hepatitis.
Immunology tests
Immunology tests that can be performed using a yellow blood bottle include\:
Immunoglobulin levels
Complement levels
Autoantibody screen
Rheumatoid factor
Thyroid antibodies
Ξ±1AT
ACE
Tips for use
The yellow bottle needs to be inverted about 5 times to mix the sample with the silica and separator. Don't panic if the blood
starts to clot or separate in the bottle, it's supposed to! The amount of blood required will depend on how many tests you're
doing, but at least 1ml is ideal. You can usually get about 12 tests from one full yellow bottle. Remember that di
be located in di
microbiology samples in separate yellow bottles to go to their respective laboratories.
Yellow bottle
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Grey blood bottle
Overview
The grey bottle is only used for two tests, so compared to the yellow one it's fairly easy to remember! It is used for
biochemistry tests requiring whole blood for analysis.
Additive
Contains two main agents. Sodium
occurs within the sample after it is taken. Potassium oxalate acts as an anticoagulant. Some variants of the grey bottle use
EDTA as the anticoagulant instead.
Tests
Common tests
Common tests performed using the grey blood bottle include\:
Glucose\: this can be fasting or non-fasting, or part of a glucose tolerance test (GTT)
Lactate
Less common tests
Less common tests performed using the grey blood bottle include\:
Blood ethanol (if not for legal purposes)
Tips for use
The grey bottle needs to be inverted about 8 times to mix the sample with the
blood is required for a glucose test, but to assess lactate levels the bottle should ideally contain at least 1ml of blood. Venous
glucose results are generally more accurate than
patients, but can take a while to come back from the lab. If you require a blood glucose test urgently then kindly ask one of the
nurses to perform a capillary blood glucose for you on the ward. Samples for venous lactate need to be sent to the lab
immediately. Again, the results tend to take a while to come back, so if you're desperate to quickly assess a patient's lactate
level see if you can get access to an ABG machine that does arterial lactates - these are often available in A&E or ITU and take
about 2 minutes to process.
Grey bottle
Red blood bottle
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Overview
The red bottle is less common - it is used for biochemistry tests requiring serum which might be adversely a
separator gel used in the yellow bottle.
Additive
The additive in red blood bottles contains silica particles which act as clot activators.
Tests
Common tests
The use of this bottle varies greatly, some hospitals use it for many sensitive tests, including hormones, toxicology, drug
levels, bacterial and viral serology and antibodies, whereas others seem to only use it for a few very speci
use the yellow bottle for most things.
My hospital de
Less common tests
Less common tests performed using the red blood bottle include\:
Fluoride
Cryoglobulins
Cold agglutinins
Tips for use
The red bottle needs inverting 5 times to mix the sample with the clot activator. There is also another version of the red bottle
made out of glass, which contains no additives whatsoever.
Red bottle
Dark green blood bottle
Overview
This less commonly used bottle is for biochemistry tests which require heparinized plasma or whole blood for analysis.
Additive
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The additive of dark green blood bottles contains sodium heparin, which acts as an anticoagulant.
Tests
Common tests
Common tests performed using the dark green blood bottle include\:
Ammonia*
Insulin*
Renin and aldosterone
Less common tests
Less common tests performed using the dark green blood bottle include\:
Aluminium
Gut hormones
Amino acids
Homocysteine
Chromosomal tests
Tips for use
The green bottle needs to be inverted about 8 times to mix the sample with the heparin. This bottle cannot be reliably used to
assess sodium levels.
Dark green bottle
Light green blood bottle
Overview
This rare species of blood bottle is used for biochemistry tests requiring separated heparinized plasma. I have never actually
used one but have seen them on a dermatology ward once.
Additive
This bottle is known as the plasma separator tube (PST). It contains lithium heparin, which acts as an anticoagulant, and a
plasma separator gel similar to that used in the yellow bottle, which acts to separate out the plasma layer.
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Tests
It can be used for routine biochemistry, but most hospitals seem to use the yellow bottle for this. It can also be used for blood
ethanol provided the sample is not for legal purposes.
Tips for use
The light green bottle needs inverting about 8 times to mix the sample with the heparin and separator. This bottle cannot be
reliably used to assess lithium levels.
Light green bottle
Other blood bottles
Despite 18 months of adventures on the wards, there are still some blood bottles I have not yet encountered. I can only assume
this means they are hardly ever used and therefore not ones you'll need to know in detail.
These other blood bottle types include\:
Dark blue\: used for toxicology and trace elements such as zinc, selenium and copper (however, the ever-versatile yellow
bottle can also be used for these).
Tan\: used to test for lead.
Orange\: contains a thrombin-based clot activator which allows stat serum testing.
Light yellow\: used for HLA phenotyping, tissue typing, DNA analysis and paternity testing.
White\: used for molecular diagnostics such as PCR and DNA ampli
Black\: for paediatric ESR.
Clear lid\: used as a discard tube, for example when taking blood from a central line.
Blood culture bottles
Blood culture bottles contain a culture medium to encourage the growth of any bacteria in the blood sample. There are
di
others, including one with a black lid for mycobacterial cultures. Until recently, many hospitals require both aerobic and
anaerobic culture samples from a patient, whilst others were happy with just aerobic samples. However, there is now a move
towards using the purple top (a.k.a.
"burgundy") anaerobic bottles as the standard receptacle for all blood cultures, as studies
have shown that they are more e
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Tips for use
Blood cultures must be obtained using an aseptic non-touch technique (ANTT) to prevent contamination of the samples with
the patient's skin
started. The blood culture bottle should always be the
chance of catching any organisms (if using an anaerobic and aerobic bottle, the aerobic bottle should be
world, you would also take another culture from a di
to come back, so if your patient is septic you need to ring microbiology and start them on some empirical antibiotic treatment
in the meantime.
Check out our guide to performing blood cultures for more information.
Blood culture bottles
Arterial blood gas syringes
Overview
An ABG is a very useful test when you
oxygenation, their acid-base balance, and in some cases their potassium and lactate as well, and the results are available
within minutes.
Tips for use
ABG syringes contain heparin to prevent the sample from clotting - you need to expel this through the needle before taking
your sample. Some
whilst others require you to pull on the plunger yourself to
above - if you can, as they are in
and much more uncomfortable for the patient. For more details and tips on how to take an ABG, see our guide.
Once you have obtained your sample it needs to be taken straight to the lab, as it will become denatured and useless within
10 minutes. To learn how to interpret an ABG, see our guide.
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ABG syringe
Tips for easy venepuncture
Invert doesn't mean shake\: be gentle with your samples or they'll haemolyse.
Tests above with a star (*) next to them need to be sent to the lab immediately on ice - to do this you either need to get a
special ice bag directly from the lab or if your ward has an ice freezer you can make one yourself by
with crushed ice. If you're not sure you're doing it right, ring the lab and check before you take the blood sample.
The bottles can be used for other non-blood pleural aspirates, ascitic taps and CSF samples obtained
by lumbar puncture. The tests each bottle is used for are the same\: the purple one is for cell count, the yellow one is for
electrolytes, albumin and LDH, the grey one is for glucose, and blood culture bottles can be used for
to specify on your request form what kind of
If you ever
than the adult ones. The colours can vary compared to adult bottles, so always check with the local lab.
If you are unsure about what you need to do for a particular blood test, ask your friendly local lab technician. They are usually
more than happy to give you advice as it means they can prevent you from making mistakes that create lots of hassle and
annoying paperwork. It's also better for you if you check, as it saves you having to do your blood tests all over again if you do it
wrong, and saves your patient from the unpleasantness of unnecessary additional stabbings.
Summary
We have summarised the di
the number of required inversions.
Table 1. Blood bottle summary
Colour Tests Inversions required
Coagulation screen
Light blue
INR
3-4
D-dimer
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Yellow/gold
U&E
CRP
LFTs
TFTs
Amylase
Calcium & phosphate
Magnesium
Lipid pro
Troponin
5-6
FBC
Blood
Purple
8-10
Source\: geekymedics.com
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