INTRODUCTION

Whereas blood is something that most surgeons prefer not to see too much of whilst operating, we all depend heavily on normal quantities and qualities of the various components of circulating blood to ensure a successful outcome after surgery and to prevent peri-operative complications. The main functional components of blood that are important to the surgeon are:

• oxygen (O2) carrying (haemoglobin);

• haemostasis (endothelial cells, platelets, coagulation, fibrinolysis);

• inflammation (granulocytes, humoral mediators, endothelial cells, fibroblasts);

• immunity (lymphocytes, macrophages, antibodies).

On some occasions surgery is performed on patients with known deficiencies in one or several of their blood components and it is important to be aware of the potential intra-and post-operative problems which constitute a risk.

In this chapter the anatomy and physiology of the haemo-poietic and lymphoreticular systems, and abnormalities of these systems relevant to surgical practice are reviewed.

The haemopoietic system refers to the blood-forming aspects of the bone marrow and the released circulating cells. The lymphoreticular system refers to the secondary lymphoid tissues such as the spleen and lymph glands, as well as blood cells resident in the tissues such as macrophages, lymphocytes and mast cells. Although this is a somewhat artificial anatomical classification, it separates the functional components of blood cell formation (haemopoiesis) and blood cell function (immune response). Blood cells from both anatomical compartments interact and are involved with both haemopoiesis and immunity.