Retro-orbital

Please read the general principles of blood sampling page before attempting any blood sampling procedure.

Technique

Also referred to as peri-orbital, posterior-orbital and orbital venous sinus bleeding. Retro-orbital bleeding should always be performed as a terminal procedure. Adverse effects reported for this procedure are described in the summary below.

Where its use is unavoidable, retro-orbital bleeding should only be used under general anaesthesia. Because of the severity of the adverse effects that can occur with this technique, even in skilled hands, it is essential that it is conducted only by staff members competent (practiced) in the technique.

Blood is collected from the venous sinus. The mouse is restrained, the neck gently scruffed and the eye made to bulge. A capillary tube/pipette is inserted medially, laterally or dorsally. Blood is allowed to flow by capillary action into the capillary tube/pipette, ensure proper aseptic technique is used. The sample obtained is a mixture of venous blood and tissue fluid, and is not representative of venous blood.

Summary

Number of samples It is recommended that only one sample be taken.
Sample volume Up to 0.2 ml with recovery; Up to 0.5 ml non-recovery.
Equipment A glass capillary tube or Pasteur pipette.
Staff resource One person is required to take the blood sample.
Other Careful monitoring for adverse effects is necessary both peri- and post-operatively.
Adverse effects
  • Retro-orbital haemorrhage resulting in haematoma and excessive pressure on the eye
  • Corneal ulceration, keratitis, pannus formation, rupture of the globe and micro-ophthalmia caused by proptosis of the globe
  • Damage to the optic nerve and other intra-orbital structures which can lead to deficits in vision and blindness
  • Fracture of the fragile bones of the orbit and neural damage by the micro-pipette
  • Penetration of the eye globe itself with a loss of vitreous humour

Resources and references

Retro-orbital technique in other animals

Click here for information on retro-orbital blood sampling techniques in the rat.Click here for information on retro-orbital blood sampling techniques in the hamster.

All blood sampling techniques in the mouse

Click here for information on blood vessel cannulation in the mouse Click here for information on tail snip blood sampling in the mouse Click here for information on tail vessel microsampling in the mouse Click here for information on tail vein blood sampling in the mouse Click here for information on saphenous vein blood sampling in the mouse Click here for information on abdominal/thoracic blood vessel blood sampling in the mouse Click here for information on cardiac puncture blood sampling in the mouse Click here for information on schedule 1 stunning followed by decapitation in the mouse Click here for information on decapitation blood sampling techniques in the mouse