General hospital psychiatry is the practice of psychiatry in a particular type of medical setting, whilst liaison psychiatry, the principal focus of this chapter, refers to the clinical expertise and practice relating to psychological and psychiatric problems and treatments in patients presenting to general medical care. The practice of liaison psychiatry evolved in the first half of the twentieth century well before it was given the name. Hindsight allows us to see general hospital and liaison psychiatry services being established around the world, developing in response to local demands and in ways that reflected individual enthusiasms. Liaison psychiatry' is incomprehensible to fellow psychiatrists and to medical colleagues. It severely handicaps the task of publicizing a clinically important activity. Although the history of liaison psychiatry as a special interest (or sub-speciality) is rather brief and progress has been relatively slow, it is now well established and widely accepted.

Every referral to liaison psychiatry presents its own clinical dilemmas. Some cases are straightforward and can be assessed and managed easily. Others are complex and require a whole host of liaison skills and a large investment of time. This chapter is composed of a number of 'problem cases'. They are intended to replicate the process of referral, assessment and management by liaison psychiatry. The cases have provided a different perspective and way of thinking about liaison psychiatry which is more familiar to the clinician. It is important to remember that liaison psychiatrists cannot possibly be familiar with the latest developments across the whole of the field of medicine, but they may well be expected to provide advice about patients with a wide range of physical and psychological problems. Mentoring is also useful for newly appointed consultant liaison psychiatrists, where a more experienced liaison psychiatrist can provide support and guidance.