Laboratory investigation should be ordered only when indicated by the patient’s medical status, drug therapy, or the nature of the proposed procedure. Investigation should not be ordered on a routine basis. It should be selective and individualized.

 In general the result of many investigations may be predicted if a detailed history and physical examination have been performed. Before ordering extensive investigations, the following questions should be considered. 1. Will this investigation yield information not revealed by clinical assessment ? 2. Will the results of the investigation alter the management of the patient ?

1. Urine analysis 2. Complete blood count. 3. Sickle cell screen. 4. International normalized ratio (INR) 5. Activated partial thrombo-plastin time. 6. Electrolytes and creatinine levels. 7. Fasting glucose level. 8. Pregnancy (b-HCG). 9. Electro-cardiograph. 10. Chest radiograph.

An inexpensive test it may occasionally reveal undiagnosed diabetes or the presence of urinary tract infection

Indications:  Major surgery requiring group and screen or group and match  Chronic cardiovascular, pulmonary, renal, or hepatic disease  Malignancy  Known or suspected anemia, bleeding diathesis,  Patient less than 1 year of age

Indication:  Genetically predisposed patient (hemoglobin electrophoresis if screen is positive)

Indications:  Anticoagulant therapy  Bleeding diathesis  Liver disease

Indications:  Hypertension  Renal disease  Diabetes  Pituitary or adrenal disease  Digoxin or diuretic therapy or other drug therapies affecting electrolytes.

Indication:  Diabetes (should be repeated on day of surgery).

Indication:  Woman who may be pregnant.

Indications:  Heart disease, hypertension, diabetes.  Other risk factors for cardiac disease (may include age).  Subarachnoid or intracranial hemorrhage, cerebrovascular accident, head trauma.

Indications:  Cardiac or pulmonary disease.  Malignancy.  For older population (over 60 yrs of age).

 Cervical spine x-ray should be done in any patient in whom there is a possibility of vertebral instability for example in the presence of rheumatoid arthritis.  Thoracic inlet x rays are required in patients with thyroid enlargement.

There are several common reasons for postponing surgery for example:  Acute upper respiratory tract infection: Non-urgent surgery should be postponed for a few weeks until the patient has recovered.  Emergency surgery for which the patient has not been resuscitated adequately. For only 1-2h to permit restoration of circulating blood volume.  Recent ingestion of food.  Failure to obtain consent.

The practice of pre-operative fasting aims to: Minimize residual gastric volume and acidity prior to surgery or other procedures. This helps to prevent: Regurgitation,inhalation and aspiration of gastric contents which may otherwise occur during: General anesthesia Regional anesthesia Intravenous sedation.

 However, prolonged periods of fasting are unnecessary as it may cause: ◦ Distress, dehydration, biochemical imbalance and hypoglycemia, especially in children. ◦ The tendency for gastric volume increase after a prolonged fast may occur. ◦ Fasting policies should vary to take into account age and pre-existing medical conditions and should apply to all forms of anesthesia, including monitored anesthesia care.

 Clear fluids include: Water, diluting juice, black tea and black coffee.  Patients may drink clear fluids up to 2 hours  Be aware : 1. Milk (non-human) and milk-containing drinks NOT a clear fluid because they become semi- solid in the stomach and should be considered as solids. 6 hrs prior to surgery. 2. Breast fed infants should have their last feed 4 hours prior to surgery. 3. Alcohol containing drinks should not be consumed within the 24 hours prior to surgery as this may increase gastric emptying time.

 Solids and milk-containing drinks should not be consumed within 6 hours of the beginning of the operating list.  8 hr after a meal that includes meat, fried or fatty foods, should be waited.

 Consent for anaesthesia is a vital part of preoperative preparation.  It must obtained by an individual with sufficient knowledge of the procedure and the risks involved.  In order for consent to be valid, it must include three elements: 1. The patient must have the capacity to consent to the treatment offered. 2. The patient must have sufficient info to enable him to make a balanced decision to consent. 3. The consent must be voluntary.