Hi dear,  I think the answer of your question is yes.  The underlying mechanism is that: in anemic patients,  the platelets are defective in their adhesion to the endothelium.  That's why these patients are liable to bleeding. 

Dear Hala

Thanks for your answer.Do you think this bleeding could reach to the level of hazard?

I think the answer is yes as it depends on the severity of anemia.  In addition to the surgical procedure in terms of minor or major surgery. The major surgeries carry a high risk of extensive bleeding.  That's why the surgeons prepare their patients before going on their surgical manoeuvres. 

My best wishes, and you are welcome

 Dear Al-Moraissi,

Strictly speaking, Anemia is the reduction in the oxygen carrying capacity of blood that may be caused by reduced hemoglobin content or reduced number of RBCs. 

Since red blood cells and hemoglobin have no particular role to play in bleeding, anemia, unless accompanied by a reduction in the number or dysfunction of platelets, should not add to the risk of post-surgical hemorrhage.

Aplastic anemia may be associated with excessive bleeding since the production of all blood cells including platelets are affected.

Dear Mandana Donoghue ,

Thank you for your answer. 

As you know, anemia is reduction of oxygen capacity of blood throughout the tissue and organs, so the normal process of wound healing would affected that give chance to bleeding and infection. 

What is ur opion ? 

An interesting point Essam,  I agree that healing could be definitely affected since oxygenation will be below expected levels. However, to my knowledge, there are no reports that have examined the extent of such an effect. 

Any delay in healing could certainly increase the chance of infection, however, to my knowledge changes in the healing process and infection can not cause bleeding. Since both the immediate stopping of  bleeding by the temporary platelet plug and the irreversible clot formation with the help of clotting factors occur before inflammation cascade completes. Healing will only begin later. 

I don't really expect a subsequent delay in healing or infection to cause bleeding.

What is your  practical experience?

Dear Mandana Donoghue ,

Again for your helpful answer

Actually, based on my personal experience , I did not find any relation between them.However, we have been hearing that there is limited level of hemoglobin in which a surgery should be performed or avoided. Was this consideration based on scientific evidence or mythology ?

Dear Essam Al-Moraissi. 

Your observation is very correct, Anemia is a very common condition in India due to various nutritional, infectious and inflammatory conditions and often it can be very severe. I know that severe anemia with HB levels below 7g/dL is considered a contraindication for any surgical procedure and in emergencies patients receive blood transfusions. 

As to the reason, at low  Hb levels  anaesthesia and maintenance of oxygen saturation without causing increased cardiac stress becomes difficult.   

As a surgeon, you will find this article useful "  Detection, evaluation, and management of preoperative anaemia in the elective orthopaedic surgical patient: NATAguidelines

http://bja.oxfordjournals.org/content/106/1/13.long

Dear Mandana Donoghue ,

Thanks for this helpful paper

Dear Mandana,

actually I think that anemia might contribute to bleeding, due to the fact that if there are less red blood cells in the blood flow, platelets tend to swim in the middle of the vessel, rather than closer to the vessel wall (where you´ll normally find the damage, and von Willebrand factor bound to phospholipids or collagen). A hematokrit over 30% is improving this situation, as red blood cells seem to sort of push platelets to the vessel wall.

So, to a smaller but sometimes significant extent, anemia might contribute to bleeding.

 Dear Julian,

You present an intriguing concept, and I have to agree it got me checking some books.

I can't get the link, though. My understanding has been that the initial aggregation of platelets is caused by the transient vasoconstriction after injury and amplified or enhanced by the release of factors after that. 

Applying the rule of 3, arbitrary as it may be, a hematocrit of 30% translates roughly to 10g/dL of Hb or mild anemia. So far have not come across any cases with increased bleeding time at that level or even with hemoglobin as low as 7g/dL. 

At what Hb level have you found the increased risk of bleeding?

Can you explain this further or point me to relevant literature on this.  

Dear Mandana,

it is actually not my idea - we copied it from the paper in the link below. It is very probably not a factor rising the risk of bleeding excessively, but might contribute to bleeding, like hypothermia does. So, if a patient is bleeding, we suggest that if possible a hematocrit of about 30% should be achieved in order to eliminate this problem...

http://ajpheart.physiology.org/content/264/4/H1239.long

Dear Julian, Thank you , for the information and the link 

Dear Sir, - what i believe is the bleeding time and the clotting factors do make a calculation to know any person may bleed more or less during surgery but if the patient is anemic then the MCH --- mean carpuscular hemoglobin do make a difference of effective clotting mechanism by enhancing the factor eight  and the fibrin formation so patient with low MCH will bleed more during and after surgery. Thanks

Dear Julian Strobel, 

Thanks to your answer, but could you support your answer by scentfic evidence