We need to cure 'merger mania' - or more accurately, to take the mania out of mergers. In April, the first wave of trust mergers will kick- start radical change to the shape of acute services. Mergers have always been a political hot potato, causing local headaches for the government, unsettling staff, and often confusing the public. But if the aim of reconfiguration is to improve services, why do mergers cause so much bother?

It's often not what you do but the way you do it that matters. Communicating with clinical staff and patients - sharing the vision of where you're going - is central to successfully managing mergers. When nurses and doctors are fully on board, the trust has done a good job communicating the need for change. If it feels like an old boys' stitch-up between top consultants and senior managers, the reasons for merger are at best muddled and at worst self-interested.

Communication is key. If a when a patient is discharged from hospital the nurses say it's because 'we need the bed', the patient leaves feeling anxious and distressed. If told everything has gone well and it's now safe to leave, most people would rather recover at home. Clinical staff's morale directly affects clinical outcomes. If clinical staff understand the reasons for change, it rubs off on patients. If they feel disempowered or shut out of the dialogue, that's also going to have an impact on patient care. Researchers in Australia told one group of patients having surgery they had been chosen to 'fast track' through the system. Though their care was no different from other, similar patients, the 'fast track' patients believed they were getting the best quality care. They had fewer complications and lower rates of analgesia.

Mergers and reconfiguration have always been good fodder for conspiracy theorists. Local newspapers know that 'save our hospital' campaigns boost sales, but there's often a yawning gap between the media debate and discussions around the real need to change how health services are delivered. Last time, reconfiguration was linked only to cutting costs. This time, the political framework is different. The aim, mapped out in the NHS white papers, is to make services work better for patients. As a result, the government seems to be having an easier job selling the idea of mergers to the public. If you are clear that mergers are in patients' best interests, people understand. Parents will travel the length of the country to visit a specialist at Great Ormond Street because they believe it's the best care available for their sick child. They wouldn't expect to receive that kind of specialist care at their local hospital, but they do expect basic services to be easily accessible. The public understands that in specialist units, expertise grows with the number of cases nurses and doctors see. If we spread that too thinly, quality suffers.

Paediatric intensive care is a good example. The government's report on paediatric intensive care units last summer showed the service as patchy at best. Services were delivered in a wide range of settings, often in small units of fewer than three beds. The report starkly proposed the immediate closure of single paediatric intensive care beds and phasing out ICU beds on general children's wards within a year. But it also recommended a minimum standard of care and investment in designated lead-centres covering 500,000 children.

Put like this, the logic is easy to appreciate. But too often with reconfiguration, the wrong arguments are put to the public. Mergers are shrouded in the language of management-speak. Often overly defensive, the rationale seems to be that if that if you can bamboozle the public, people won't ask any questions. The irony is that the public clearly understands economy of scale. People make exactly the same kind of choices every time they shop at the supermarket rather than their local shop. Supermarkets offer greater choice, high quality and lower prices, local shops offer an accessible and friendly service that cannot be replicated by big corporate supermarkets. There are clearly some services it doesn't make sense to provide at every acute trust. Equally, for many other services, it is vital that care is accessible and local.

There needs to be a clearly articulated reason for mergers. If there's no benefit for patients, it's not surprising when staff and patients' groups object. If staff are not consulted then it's not surprising that morale is low while staff turnover and wastage increase. If there's no clinical evidence for change, it's not surprising when professional staff are disenchanted about merger proposals. If consultation is inadequate, it's not surprising people are confused. Mergers need to make sense - and not just to clinicians and managers, but to the public.

The process always involves change, and staff need support to cope. Cheap rhetoric about cutting bureaucracy only acts to heighten insecurity and push down morale. Cutting numbers of managers is not a by-product of merger. All the evidence shows that if staff are treated fairly - and if their jobs are protected - the transition can be smooth.

Yet not all mergers are so clear cut. In some community trusts, district nurses, health visitors and school nurses are being decimated in the name of reconfiguration. This is happening at the same time as the government has launched the public health green paper, which can only be delivered with the energy of all community nurses. Elsewhere, mergers have left rural communities without basic services, closing cottage hospitals and minor injuries units which play a crucial part in the vision which the NHS white papers outline. There seems to be no rationale other than saving cash.

If trusts can't fully explain the reasons for reconfiguration, they deserve a rough ride. Where the only reason is cutting budgets, it's no surprise that NHS staff - and the public - can smell a rat.

Christine Hancock is general secretary of the Royal College of Nursing.