'Haemostasis' is derived from two Greek terms 'haima' and 'stasis'. It is defined according to the Medical Dictionary as the stoppage of bleeding. The mechanism of haemostasis requires three important steps including

·         Vascular spasm

The first response of the blood vessels to injury which helps reduce the amount of blood flow to the damaged area

·         Platelet plug formationPlatelets in circulation become adhered to the damaged endothelium and form a temporary seal to cover the break in the vessel wall called 'platelet plug'.

·         Blood coagulationThrough coagulation cascade, fibrinogen is converted to fibrin. Fibrin threads act as a molecular glue that reinforce the platelet plug.

Intraoperative bleeding is one of the common complications during gynaecologic surgery. The inability to control bleeding can result in a life-threatening situation. Several methods can be used to achieve haemostasis. Primary approaches include direct pressure, ligature, suturing, hemoclips, and electro-cauterisation. However, in circumstances when conventional surgical techniques are not feasible such as bleeding near vital structures, at needle-holes, from raw surface areas, in friable tissue, or in patients who have abnormal coagulation, topical haemostatic agents may serve as adjunctive treatments.

Characteristics for an ideal haemostatic agent comprise high efficacy, non-antigenicity, complete absorbability, quick preparation, easy application, and inexpensiveness. Unfortunately, this agent does not exist. Topical haemostatic products currently available vary in composition, mechanism of action, method of use, and specific advantages and adverse reactions. They are broadly divided into three categories including physical, biologic, and synthetic agents.

·         Physical agents

Mechanism of action - promote haemostasis by providing physical matrix for clotting initiation

Examples:
- Gelatin (Gelfoam)
- Oxidized regenerated cellulose (Surgicel)
- Microfibrillar collagen(Avitene)

·         Biologic agents

Mechanism of action - stimulate the coagulation cascade through transformation of fibrinogen to fibrin by thrombin’s enzymatic action

Examples:    
- Topical thrombin(FloSeal)
- Fibrin Sealants (Tisseel)
- Platelet Gel (Vitagel)

·         Synthetic agents

Examples:
- Cyanoacrylates (Dermabond)
- Polyethylene Glycol Hydrogel (CoSeal)
- Glutaraldehyde Cross-Linked Albumin (BioGlue)

Possible adverse reactions of topical haemostatic agents are as follows:

·         Risk of thrombosis if injected into circulatory system

·         Risk of transmitting infectious disease due to human plasma component

·         Hypersensitivity reactions to biologically active substances

In summary, topical haemostatic agents are intended to be adjuncts, not substitutes, for meticulous surgical technique and conventional methods to control haemorrhage. As a result, careful consideration of their risks and benefits are crucial before utilising individual agent.