Medical treatment that results in harm or injury because of improper care or treatment is what's termed as clinical or medical negligence.
The procedure in pursing a complaint of medical negligence is significantly different from standard personal injury claims.
However, as with other types of personal injury claims the law in medical negligence claims require that you satisfy 4 keys tests:

1. That a duty of care existed between the parties,
2. There was a breach of that duty of care (negligence)
3. There must be established a causal link between the negligent act and the injury suffered (known as causation)
4. Injury and or loss must have been sustained

All four of the above criteria must be present for a claim to exist.
If a claimant cannot prove on a balance of probabilities the existence of all 4 criteria, the claim must fail.
The significant difference in medical negligence claims however is in how one goes about establishing breach of duty of care or negligence.
In your standard road traffic accident, the question of whether a driver was careless or not is usually relatively straightforward e.
g driving on the wrong side of the road at the time of the accident.
In medical negligence claims, proving breach of duty of care is much more problematic.
The test used is known as the Bolam test, named after the leading test case on medical negligence which states that in order to establish whether there has been negligence one must demonstrate that the care provided to a patient fell below the standard expected of any responsible body of practitioners in the same field of expertise.
Clinical or medical negligence cases covers a very wide variety of circumstances for example:

• Birth Injuries
• Misdiagnosis
• Surgical Errors
• Medical Establishments
• General Clinical Negligence such as a failure to treat sufficiently quickly
• mis-prescription
• A lack of informed consent

Procedure For Bringing A Medical Negligence Complaint Step 1 The first step before legal proceedings are instigated in the even that medical negligence is suspected is to make a complaint to the NHS Trust or GP.
If upon consideration of the reply to the complaint you are still unsatisfied, then an independent review by the Commission for Healthcare Audit & Improvement can take place.
While the referral to the Commission will not result in a compensation award, the results of the review can provide valuable evidence in possible future court proceedings.
Step 2 Obtain a full set of the the medical records from the relevant health authority.
A solicitor will review the medical notes and records and consider whether a medical specialist should be instructed to report on the potential claim upon reviewing all the medical evidence at the solicitors disposal.
The medical consultant instructed will examine the patient and conduct any further additional tests necessary before submitting his initial report dealing with his opinion on whether there was any breach of duty of care.
Step 3 If the consultant is supportive of a claim, the solicitor will then go about prepare a claim for filing with the County Court or High Court following the proscribed pre-action protocol for medical negligence claims.
These protocols are a set of judicial guidelines on how the courts wish the parties to the litigation to behave in the exchange of information and conduct of the case.
If the parties cannot agree a mutually acceptable compromise for settlement of the claim, the case is set down for a trial for determination by a judge upon consideration of all gathered and disclosed evidence.
However, it should be noted here that more than 95% of cases are resolved before the case ever reaches trial.