Let us take the example of an elderly woman with diabetic retinopathy. She tripped and fell due to poor eyesight from diabetes and then broke her hip. She was admitted to hospital for surgical repair but developed a pulmonary embolism 5 days after surgery and subsequently demised.  In this case the underlying cause of death would be the accidental fall, which caused a fractured hip, which in its turn caused the pulmonary embolism. Diabetes mellitus and diabetic retinopathy would go in Part 2 as contributing factors to death.