Elective surgery
Elective surgery or elective procedure is surgery that is scheduled in advance because it does not involve a medical emergency. Semi-elective surgery is a surgery that must be done to preserve the patient's life, but does not need to be performed immediately. Most surgeries are elective, scheduled at a time to suit the surgeon, hospital, and patient. By contrast, an urgent surgery is one that can wait until the patient is medically stable, but should generally be done within 2 days, and an emergency surgery is one that must be performed without delay; the patient has no choice other than immediate surgery if permanent disability or death is to be avoided. Many surgeries can be performed as either elective or emergency surgeries, depending on the patient's needs. Description 
An elective surgery or elective procedure (from the , meaning to choose) is surgery that is scheduled in advance because it does not involve a medical emergency. Semi-elective surgery is a surgery that must be done to preserve the patient's life, but does not need to be performed immediately. Types

Elective 
Most surgical medical treatments are elective, that is, scheduled at a time to suit the surgeon, hospital, and patient. These include inguinal hernia surgery, cataract surgery, mastectomy for breast cancer, and the donation of a kidney by a living donor. Elective surgeries include all optional surgeries performed for non-medical reasons. This includes cosmetic surgery, such as facelifts, breast implants, liposuction, and breast reduction, which aim to subjectively improve a patient's physical appearance. Another optional surgery is LASIK—currently the top elective surgery in the United States—where a patient weighs the risks against increased quality of life expectations. Semi-elective 

When a condition is worsening but has not yet reached the point of a true emergency, surgeons speak of semi-elective surgery: the problem must be dealt with, but a brief delay is not expected to affect the outcome. Semi-elective procedures are typically scheduled within a time frame deemed appropriate for the patient's condition and disease. Removal of a malignancy, for example, is usually scheduled as semi-elective surgery, to be performed within a set number of days or weeks. Urgency

In a patient with multiple medical conditions, problems classified as needing semi-elective surgeries may be postponed until emergent conditions have been addressed and the patient is medically stable. For example, whenever possible, pregnant women typically postpone all elective and semi-elective procedures until after giving birth. In some situations, an urgently needed surgery will be postponed briefly to permit even more urgent conditions to be addressed. In other situations, emergency surgery may be performed at the same time as life-saving resuscitation efforts. Many surgeries can be performed as either elective or emergency surgeries, depending on the patient's needs. A sudden worsening of gallbladder disease may require immediate removal of the gallbladder by emergency surgery, but this surgery is more commonly scheduled in advance. An appendectomy is considered emergency surgery, but depending upon how early the diagnosis was made, the patient may have more time before the appendix risks rupturing or the infection spreads. Also, in certain emergency conditions, even ones like a heart attack or stroke, surgery may or may not need to be utilized. Best practices

Preoperative carbohydrates may decrease amount of time spent in hospital recovering. Non-elective surgery 
Non-elective surgeries may be classifies as urgent or emergency. An urgent surgery is one that can wait until the patient is medically stable, but should generally be done within 2 days. An emergency surgery is one that must be performed without delay; the patient has no choice other than immediate surgery if permanent disability or death is to be avoided. Urgent surgery is typically performed with 48 hours of diagnosis and emergency surgery is performed as soon as a surgeon is available. References

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Medical terminology
Surgery