Sterilisation Health Dictionary

  1. Health Encyclopedia
  2. Sterilisation

Sterilisation: From 1 Different Sources

Sterilisation means either (1) the process of rendering various objects – such as those which come in contact with wounds, and various foods – free from microbes, or (2) the process of rendering a person incapable of producing children.

The manner of sterilising bedding, furniture, and the like, after contact with a case of infectious disease, is given under DISINFECTION; whilst the sterilisation of instruments, dressings, and skin surfaces, necessary before surgical procedures, is mentioned in the same article and also under ANTISEPTICS, ASEPSIS, and WOUNDS. For general purposes, one of the cheapest and most e?ective agents is boiling water or steam.

Bacteriological sterilisation may be e?ected in many ways, and di?erent methods are used in di?erent cases.

Reproductive sterilisation In women, this is performed by ligating (cutting) and then tying the FALLOPIAN TUBES – the tubes that carry the OVUM from the ovary (see OVARIES) to the UTERUS. Alternatively, the tubes may be sealed-o? by means of plastic and silicone clips or rings. The technique is usually performed (by LAPAROSCOPY) through a small incision, or cut, in the lower abdominal wall. It has no e?ect on sexual or menstrual function, and, unlike the comparable operation in men, it is immediately e?ective. The sterilisation is usually permanent (around 0·05 pregnancies occur for every 100 women years of use), but occasionally the two cut ends of the Fallopian tubes reunite, and pregnancy is then again possible. Removal of the uterus and/or the ovaries also sterilises a woman but such procedures are only used when there is some special reason, such as the presence of a tumour.

The operation for sterilising men is known as VASECTOMY.

Health Source: Medical Dictionary
Author: Health Dictionary

Disinfection

Killing of infectious agents outside the body by chemical or physical means directly applied. 1. Concurrent disinfection is the application of disinfective measures as soon as possible after the discharge of infectious material from the body of an infected person, or after the soiling of articles with such infectious discharges. All personal contact with such discharges or articles being prevented prior to such disinfection. 2. Terminal disinfection is application of disinfective measures after the patient has been removed by death or to a hospital, or has ceased to be a source of infection, or after isolation practices have been discontinued. Terminal disinfection is rarely practised; terminal cleaning generally suffices along with airing and sunning of rooms, furniture and bedding. It is necessary only for diseases spread by indirect contact; steam sterilisation of bedding was considered desirable after smallpox (now eradicated).... disinfection

Acupuncture

A traditional Chinese method of healing by inserting thin needles into certain areas beneath the skin and rotating them. Its rationale is that disease is a manifestation of a disturbance of Yin and Yang energy in the body, and that acupuncture brings this energy back into balance by what is described as ‘the judicious stimulation or depression of the ?ow of energy in the various meridians’. What is still unclear to western doctors is why needling, which is the essence of acupuncture, should have the e?ect it is claimed to have. One theory is that the technique stimulates deep sensory nerves, promoting the production of pain-relieving ENDORPHINS. Of its e?cacy in skilled hands, however, there can be no question, and in China the technique is an alternative to anaesthesia for some operations. Acupuncture is increasingly used in the west, by medically quali?ed doctors as well as other practitioners of complementary medicine. As long as proper sterilisation procedures are followed, the treatment is safe: two recent and extensive UK studies detected no serious adverse effects.... acupuncture

Laparoscope

An instrument consisting, essentially, of a rigid or ?exible cylinder, an eyepiece and a light source, which is inserted through a small incision into the abdominal cavity (which has already been distended with carbon dioxode gas). The laparoscope allows the contents of the abdominal cavity to be examined without performing a LAPAROTOMY. Some operations may be performed using the laparoscope to guide the manipulation of instruments inserted through another small incision – for example, STERILISATION; CHOLECYSTECTOMY. (See also ENDOSCOPE; MINIMALLY INVASIVE SURGERY (MIS).)... laparoscope

Milk

The natural food of all mammalia for a considerable period following their birth. It is practically the only form of animal food in which protein, fat, carbohydrate and salt are all represented in su?cient amount, and it therefore contains all the constituents of a standard diet. Milk is important in human nutrition because it contains ?rst-class animal protein of high biological value; because it is exceptionally rich in calcium; and because it is a good source of vitamin A, thiamine and ribo?avine. It also contains a variable amount of ascorbic acid (vitamin C) and of vitamin D – the amount of the latter being higher during the summer months than during the winter months. Raw milk yields 67 Calories (see CALORIE) per 100 millilitres, in which are present (in grams) 87·6 of water, 3·3 of protein, 3·6 of fat, 4·7 of carbohydrate, and 0·12 of calcium. Heat has no e?ect on the vitamin A or D content of milk, or on the ribo?avine content, but it causes a considerable reduction in the vitamin C and thiamine content.

Preparation of milk Milk may be prepared for food in various ways. Boiling destroys the bacteria, especially any Mycobacteria tuberculosis which the milk may contain. It also partly destroys vitamin C and thiamine, as does pasteurisation. Curdling of milk is e?ected by adding rennet, which carries out the initial stage of digestion and thus renders milk more suitable for people who could not otherwise tolerate it. Souring of milk is practised in many countries before milk is considered suitable for food; it is carried out by adding certain organisms such as the LACTIC ACID bacillus, the Bulgarian bacillus, and setting the milk in a warm place for several hours. Sterilisation, which prevents fermentation and decomposition, is usually carried out by raising the milk to boiling temperature (100 °C) for 15 minutes and then hermetically sealing it. Condensed, unsweetened milk – usually known as evaporated milk – is concentrated in vacuo at low temperature; the milk is then placed in tins, which are sealed, and is sterilised by heat at a temperature of 105 °C. This destroys 60 per cent of the vitamin C and 30–50 per cent of the thiamine. Sweetened condensed milk is not exposed to such a high temperature. The sugar, which prevents the growth of micro-organisms, is added before the condensing, and ?nally reaches a concentration of about 40 per cent.

Dried milk is prepared by evaporating all the ?uid so that the milk is reduced to the form of powder. Humanised milk is cow’s milk treated to render it closely similar to human milk.... milk

Spore

Part of the lifecycle of certain BACTERIA when the vegetative cell is encapsulated and metabolism falls to a low level. The spore is resistant to changes in the environment and, when these are unfavourable, the spore remains dormant; when they improve, it starts to grow. Certain dangerous bacteria, such as CLOSTRIDIUM, produce resistant ubiquitous spores, so sterilisation procedures need to be very e?ective.... spore

Contraception

A means of avoiding pregnancy despite sexual activity. There is no ideal contraceptive, and the choice of method depends on balancing considerations of safety, e?ectiveness and acceptability. The best choice for any couple will depend on their ages and personal circumstances and may well vary with time. Contraceptive techniques can be classi?ed in various ways, but one of the most useful is into ‘barrier’ and ‘non-barrier’ methods.

Barrier methods These involve a physical barrier which prevents sperm (see SPERMATOZOON) from reaching the cervix (see CERVIX UTERI). Barrier methods reduce the risk of spreading sexually transmitted diseases, and the sheath is the best protection against HIV infection (see AIDS/HIV) for sexually active people. The e?ciency of barrier methods is improved if they are used in conjunction with a spermicidal foam or jelly, but care is needed to ensure that the preparation chosen does not damage the rubber barrier or cause an allergic reaction in the users. CONDOM OR SHEATH This is the most commonly used barrier contraceptive. It consists of a rubber sheath which is placed over the erect penis before intromission and removed after ejaculation. The failure rate, if properly used, is about 4 per cent. DIAPHRAGM OR CAP A rubber dome that is inserted into the vagina before intercourse and ?ts snugly over the cervix. It should be used with an appropriate spermicide and is removed six hours after intercourse. A woman must be measured to ensure that she is supplied with the correct size of diaphragm, and the ?t should be checked annually or after more than about 7 lbs. change in weight. The failure rate, if properly used, is about 2 per cent.

Non-barrier methods These do not provide a physical barrier between sperm and cervix and so do not protect against sexually transmitted diseases, including HIV. COITUS INTERRUPTUS This involves the man’s withdrawing his penis from the vagina before ejaculation. Because some sperm may leak before full ejaculation, the method is not very reliable. SAFE PERIOD This involves avoiding intercourse around the time when the woman ovulates and is at risk of pregnancy. The safe times can be predicted using temperature charts to identify the rise in temperature before ovulation, or by careful assessment of the quality of the cervical mucus. This method works best if the woman has regular menstrual cycles. If used carefully it can be very e?ective but requires a highly disciplined couple to succeed. It is approved by the Catholic church.

SPERMICIDAL GELS, CREAMS, PESSARIES, ETC.

These are supposed to prevent pregnancy by killing sperm before they reach the cervix, but they are unreliable and should be used only in conjunction with a barrier method.

INTRAUTERINE CONTRACEPTIVE DEVICE (COIL) This is a small metal or plastic shape, placed inside the uterus, which prevents pregnancy by disrupting implantation. Some people regard it as a form of abortion, so it is not acceptable to all religious groups. There is a risk of pelvic infection and eventual infertility in women who have used coils, and in many countries their use has declined substantially. Coils must be inserted by a specially trained health worker, but once in place they permit intercourse at any time with no prior planning. Increased pain and bleeding may be caused during menstruation. If severe, such symptoms may indicate that the coil is incorrectly sited, and that its position should be checked. HORMONAL METHODS Steroid hormones have dominated contraceptive developments during the past 40 years, with more than 200 million women worldwide taking or having taken ‘the pill’. In the past 20 years, new developments have included modifying existing methods and devising more e?ective ways of delivering the drugs, such as implants and hormone-releasing devices in the uterus. Established hormonal contraception includes the combined oestrogen and progesterone and progesterone-only contraceptive pills, as well as longer-acting depot preparations. They modify the woman’s hormonal environment and prevent pregnancy by disrupting various stages of the menstrual cycle, especially ovulation. The combined oestrogen and progesterone pills are very e?ective and are the most popular form of contraception. Biphasic and triphasic pills contain di?erent quantities of oestrogen and progesterone taken in two or three phases of the menstrual cycle. A wide range of preparations is available and the British National Formulary contains details of the commonly used varieties.

The main side-e?ect is an increased risk of cardiovascular disease. The lowest possible dose of oestrogen should be used, and many preparations are phasic, with the dose of oestrogen varying with the time of the cycle. The progesterone-only, or ‘mini’, pill does not contain any oestrogen and must be taken at the same time every day. It is not as e?ective as the combined pill, but failure rates of less than 1-per-100 woman years can be achieved. It has few serious side-effects, but may cause menstrual irregularities. It is suitable for use by mothers who are breast feeding.

Depot preparations include intramuscular injections, subcutaneous implants, and intravaginal rings. They are useful in cases where the woman cannot be relied on to take a pill regularly but needs e?ective contraception. Their main side-e?ect is their prolonged action, which means that users cannot suddenly decide that they would like to become pregnant. Skin patches containing a contraceptive that is absorbed through the skin have recently been launched.

HORMONAL CONTRACEPTION FOR MEN There is a growing demand by men worldwide for hormonal contraception. Development of a ‘male pill’, however, has been slow because of the potentially dangerous side-effects of using high doses of TESTOSTERONE (the male hormone) to suppress spermatogenesis. Progress in research to develop a suitable ANDROGEN-based combination product is promising, including the possibility of long-term STEROID implants. STERILISATION See also STERILISATION – Reproductive sterilisation. The operation is easier and safer to perform on men than on women. Although sterilisation can sometimes be reversed, this cannot be guaranteed and couples should be counselled in advance that the method is irreversible. There is a small but definite failure rate with sterilisation, and this should also be made clear before the operation is performed. POSTCOITAL CONTRACEPTION Also known as emergency contraception or the ‘morning after pill’, postcoital contraception can be e?ected by two di?erent hormonal methods. Levonorgesterol (a synthetic hormone similar to the natural female sex hormone PROGESTERONE) can be used alone, with one pill being taken within 72 hours of unprotected intercourse, but preferably as soon as possible, and a second one 12 hours after the ?rst. Alternatively, a combined preparation comprising ETHINYLESTRADIOL and levonorgesterol can be taken, also within 72 hours of unprotected intercourse. The single constituent pill has fewer side-effects than the combined version. Neither version should be taken by women with severe liver disease or acute PORPHYRIAS, but the ethinylestradiol/levonorgesterol combination is unsuitable for women with a history of THROMBOSIS.

In the UK the law allows women over the age of 16 to buy the morning-after pill ‘over the counter’ from a registered pharmacist.... contraception

Hepatitis

In?ammation of the LIVER which damages liver cells and may ultimately kill them. Acute injury of the liver is usually followed by complete recovery, but prolonged in?ammation after injury may result in FIBROSIS and CIRRHOSIS. Excluding trauma, hepatitis has several causes:

Viral infections by any of hepatitis A, B, C, D, or E viruses and also CYTOMEGALOVIRUS (CMV), EPSTEIN BARR VIRUS, and HERPES SIMPLEX.

Autoimmune disorders such as autoimmune chronic hepatitis, toxins, alcohol and certain drugs – ISONIAZID, RIFAMPICIN, HALOTHANE and CHLORPROMAZINE.

WILSON’S DISEASE.

Acute viral hepatitis causes damage throughout the liver and in severe infections may destroy whole lobules (see below).

Chronic hepatitis is typi?ed by an invasion of the portal tract by white blood cells (mild hepatitis). If these mononuclear in?ammatory cells invade the body (parenchyma) of the liver tissue, ?brosis and then chronic disease or cirrhosis can develop. Cirrhosis may develop at any age and commonly results in prolonged ill health. It is an important cause of premature death, with excessive alcohol consumption commonly the triggering factor. Sometimes, cirrhosis may be asymptomatic, but common symptoms are weakness, tiredness, poor appetite, weight loss, nausea, vomiting, abdominal discomfort and production of abnormal amounts of wind. Initially, the liver may enlarge, but later it becomes hard and shrunken, though rarely causing pain. Skin pigmentation may occur along with jaundice, the result of failure to excrete the liver product BILIRUBIN. Routine liver-function tests on blood are used to help diagnose the disease and to monitor its progress. Spider telangiectasia (caused by damage to blood vessels – see TELANGIECTASIS) usually develop, and these are a signi?cant pointer to liver disease. ENDOCRINE changes occur, especially in men, who lose their typical hair distribution and suffer from atrophy of their testicles. Bruising and nosebleeds occur increasingly as the cirrhosis worsens, and portal hypertension (high pressure of venous blood circulation through the liver) develops due to abnormal vascular resistance. ASCITES and HEPATIC ENCEPHALOPATHY are indications of advanced cirrhosis.

Treatment of cirrhosis is to tackle the underlying cause, to maintain the patient’s nutrition (advising him or her to avoid alcohol), and to treat any complications. The disorder can also be treated by liver transplantation; indeed, 75 per cent of liver transplants are done for cirrhosis. The overall prognosis of cirrhosis, however, is not good, especially as many patients attend for medical care late in the course of the disease. Overall, only 25 per cent of patients live for ?ve years after diagnosis, though patients who have a liver transplant and survive for a year (80 per cent do) have a good prognosis.

Autoimmune hepatitis is a type that most commonly occurs in women between 20 and 40 years of age. The cause is unknown and it has been suggested that the disease has several immunological subtypes. Symptoms are similar to other viral hepatitis infections, with painful joints and AMENORRHOEA as additional symptoms. Jaundice and signs of chronic liver disease usually occur. Treatment with CORTICOSTEROIDS is life-saving in autoimmune hepatitis, and maintenance treatment may be needed for two years or more. Remissions and exacerbations are typical, and most patients eventually develop cirrhosis, with 50 per cent of victims dying of liver failure if not treated. This ?gure falls to 10 per cent in treated patients.

Viral hepatitis The ?ve hepatic viruses (A to E) all cause acute primary liver disease, though each belongs to a separate group of viruses.

•Hepatitis A virus (HAV) is an ENTEROVIRUS

which is very infectious, spreading by faecal contamination from patients suffering from (or incubating) the infection; victims excrete viruses into the faeces for around ?ve weeks during incubation and development of the disease. Overcrowding and poor sanitation help to spread hepatitis A, which fortunately usually causes only mild disease.

Hepatitis B (HBV) is caused by a hepadna virus, and humans are the only reservoir of infection, with blood the main agent for transferring it. Transfusions of infected blood or blood products, and injections using contaminated needles (common among habitual drug abusers), are common modes of transfer. Tattooing and ACUPUNCTURE may spread hepatitis B unless high standards of sterilisation are maintained. Sexual intercourse, particularly between male homosexuals, is a signi?cant infection route.

Hepatitis C (HCV) is a ?avivirus whose source of infection is usually via blood contacts. E?ective screening of blood donors and heat treatment of blood factors should prevent the spread of this infection, which becomes chronic in about 75 per cent of those infected, lasting for life. Although most carriers do not suffer an acute illness, they must practise life-long preventive measures.

Hepatitis D (HDV) cannot survive independently, needing HBV to replicate, so its sources and methods of spread are similar to the B virus. HDV can infect people at the same time as HBV, but it is capable of superinfecting those who are already chronic carriers of the B virus. Acute and chronic infection of HDV can occur, depending on individual circumstances, and parenteral drug abuse spreads the infection. The disease occurs worldwide, being endemic in Africa, South America and the Mediterranean littoral.

Hepatitis E virus (HEV) is excreted in the stools, spreading via the faeco-oral route. It causes large epidemics of water-borne hepatitis and ?ourishes wherever there is poor sanitation. It resembles acute HAV infection and the patient usually recovers. HEV does not cause chronic infection. The clinical characteristics of the ?ve hepatic

viruses are broadly similar. The initial symptoms last for up to two weeks (comprising temperature, headache and malaise), and JAUNDICE then develops, with anorexia, nausea, vomiting and diarrhoea common manifestations. Upper abdominal pain and a tender enlarged liver margin, accompanied by enlarged cervical lymph glands, are usual.

As well as blood tests to assess liver function, there are speci?c virological tests to identify the ?ve infective agents, and these are important contributions to diagnosis. However, there is no speci?c treatment of any of these infections. The more seriously ill patients may require hospital care, mainly to enable doctors to spot at an early stage those developing acute liver failure. If vomiting is a problem, intravenous ?uid and glucose can be given. Therapeutic drugs – especially sedatives and hypnotics – should be avoided, and alcohol must not be taken during the acute phase. Interferon is the only licensed drug for the treatment of chronic hepatitis B, but this is used with care.

Otherwise-?t patients under 40 with acute viral hepatitis have a mortality rate of around

0.5 per cent; for those over 60, this ?gure is around 3 per cent. Up to 95 per cent of adults with acute HBV infection recover fully but the rest may develop life-long chronic hepatitis, particularly those who are immunode?cient (see IMMUNODEFICIENCY).

Infection is best prevented by good living conditions. HVA and HVB can be prevented by active immunisation with vaccines. There is no vaccine available for viruses C, D and E, although HDV is e?ectively prevented by immunisation against HBV. At-risk groups who should be vaccinated against HBV include:

Parenteral drug abusers.

Close contacts of infected individuals such as regular sexual partners and infants of infected mothers.

Men who have sex with men.

Patients undergoing regular haemodialysis.

Selected health professionals, including laboratory sta? dealing with blood samples and products.... hepatitis

Ventilation

(1) Passage of air into and out of the RESPIRATORY SYSTEM.

(2) The process by which air is puri?ed and circulated in domestic, occupational, industrial, and other settings. Ideally, the air we breathe should be of the right temperature and humidity, and free of dust, smoke, pollen, and other contaminants. Ventilation aims to produce such an atmosphere. Air-conditioning is frequently used in hospitals, o?ces, and other

public places. Special ?lters may be used to reduce the risk of airborne infections and allergies (see ALLERGY), but poorly maintained and contaminated systems may result in outbreaks of serious disorders, such as LEGIONNAIRE’S DISEASE. Sterilisation of air is rarely required, but ultraviolet light is sometimes used to kill pathogenic organisms. (See also ASTHMA; BRONCHITIS; HUMIDIFICATION.)... ventilation


Health encyclopedia icon Health Encyclopedia

Recent Searches