Complex sentence: Once this obstruction occurs, the appendix subsequently becomes filled with mucus and swells, increasing pressures within the lumen and the walls of the appendix, resulting in thrombosis and occlusion of the small vessels, and stasis of lymphatic flow.
Split into simpler sentences: Once this obstruction occurs, the appendix subsequently becomes filled with mucus and swells. This increased pressure results in thrombosis and occlusion of the small vessels, and stasis of lymphatic flow.