Multilayered numerical modelling of bio-thermal aspects during laser assisted treatment of internal haemorrhoid developed in rectum.

Haemorrhoids are swollen blood vessels developed around the anus. Internal haemorrhoids are generally not visible from outside due to its growth inside the rectum and it is generally considered as painless. However, a prolapsed internal haemorrhoid may cause discomfort, pain and irritation. For the treatment of internal haemorrhoid, laser assisted therapy would be helpful due to its rooted advantages such as post-surgery minimal pain, lesser bleeding, quicker healing, shorter recovery period, shorter surgical and overall treatment duration, lower risk of recurrence and least risk of post-surgical infections. The genesis of present research work deals with the development of mathematical modelling to capture the bio-thermal response during laser assisted therapy of internal haemorrhoid developed in the rectum. The explicit form of finite difference method is employed as numerical tool for the mathematical study and the physical domain is considered as multilayered tissue (three different layers of rectum: muscle, submucosa and mucosa). A Gaussian laser beam is considered as heat source to destroy the abnormal growth inside the rectum. Temperature variation in multi-layered tissue is investigated for laser heat input and absorption radius along the temporal and spatial coordinate. Temperature drop has been evidenced in the interfaces of multi-layered rectum tissue. The research outcome is verified with the published numerical model with negligible variation.