A term used to describe a procedure, usually a surgical operation, that is not urgent and can be performed at a scheduled time.
Arrhythmias An abnormal rate or rhythm of the heartbeat. The reason is a disturbance in the electrical impulses within the heart. Sometimes a person may have an occasional irregular heartbeat: this is called an ECTOPIC beat (or an extrasystole) and does not necessarily mean that an abnormality exists. There are two main types of arrhythmia: bradycardias, where the rate is slow – fewer than 60 beats a minute and sometimes so slow and unpredictable (heartblock) as to cause blackouts or heart failure; and tachycardia, where the rate is fast – more than 100 beats a minute. A common cause of arrhythmia is coronary artery disease, when vessels carrying blood to the heart are narrowed by fatty deposits (ATHEROMA), thus reducing the blood supply and damaging the heart tissue. This condition often causes myocardial infarction after which arrhythmias are quite common and may need correcting by DEFIBRILLATION (application of a short electric shock to the heart). Some tachycardias result from a defect in the electrical conduction system of the heart that is commonly congenital. Various drugs can be used to treat arrhythmias (see ANTIARRHYTHMIC DRUGS). If attacks constantly recur, the arrhythmia may be corrected by electrical removal of dead or diseased tissue that is the cause of the disorder. Heartblock is most e?ectively treated with an arti?cial CARDIAC PACEMAKER, a battery-activated control unit implanted in the chest.
Cardiomyopathy Any disease of the heart muscle that results in weakening of its contractions. The consequence is a fall in the e?ciency of the circulation of blood through the lungs and remainder of the body structures. The myopathy may be due to infection, disordered metabolism, nutritional excess or de?ciency, toxic agents, autoimmune processes, degeneration, or inheritance. Often, however, the cause is not identi?ed. Cardiomyopathies are less common than other types of heart diseases, and the incidence of di?erent types of myopathy (see below) is not known because patients or doctors are sometimes unaware of the presence of the condition.
The three recognised groups of cardiomyopathies are hypertrophic, dilated and restrictive.
•Hypertrophic myopathy, a familial condition, is characterised by great enlargement of the muscle of the heart ventricles. This reduces the muscle’s e?ciency, the ventricles fail to relax properly and do not ?ll suf?ciently during DIASTOLE.
In the dilated type of cardiomyopathy, both ventricles overdilate, impairing the e?ciency of contraction and causing congestion of the lungs.
In the restrictive variety, proper ?lling of the ventricles does not occur because the muscle walls are less elastic than normal. The result is raised pressure in the two atria (upper cavities) of the heart: these dilate and develop FIBRILLATION. Diagnosis can be di?cult and treatment is symptomatic, with a poor prognosis. In suitable patients, heart TRANSPLANTATION may be considered. Disorders of the heart muscle may also be
caused by poisoning – for example, heavy consumption of alcohol. Symptoms include tiredness, palpitations (quicker and sometimes irregular heartbeat), chest pain, di?culty in breathing, and swelling of the legs and hands due to accumulation of ?uid (OEDEMA). The heart is enlarged (as shown on chest X-ray) and ECHOCARDIOGRAPHY shows thickening of the heart muscle. A BIOPSY of heart muscle will show abnormalities in the cells of the heart muscle.
Where the cause of cardiomyopathy is unknown, as is the case with most patients, treatment is symptomatic using DIURETICS to control heart failure and drugs such as DIGOXIN to return the heart rhythm to normal. Patients should stop drinking alcohol. If, as often happens, the patient’s condition slowly deteriorates, heart transplantation should be considered.
Congenital heart disease accounts for 1–2 per cent of all cases of organic heart disease. It may be genetically determined and so inherited; present at birth for no obvious reason; or, in rare cases, related to RUBELLA in the mother. The most common forms are holes in the heart (atrial septal defect, ventricular septal defect – see SEPTAL DEFECT), a patent DUCTUS ARTERIOSUS, and COARCTATION OF THE AORTA. Many complex forms also exist and can be diagnosed in the womb by fetal echocardiography which can lead to elective termination of pregnancy. Surgery to correct many of these abnormalities is feasible, even for the most severe abnormalities, but may only be palliative giving rise to major diffculties of management as the children become older. Heart transplantation is now increasingly employed for the uncorrectable lesions.
Coronary artery disease Also known as ischaemic heart disease, this is a common cause of symptoms and death in the adult population. It may present for the ?rst time as sudden death, but more usually causes ANGINA PECTORIS, myocardial infarction (heart attack) or heart failure. It can also lead to a disturbance of heart rhythm. Factors associated with an increased risk of developing coronary artery disease include diabetes, cigarette smoking, high blood pressure, obesity, and a raised concentration of cholesterol in the blood. Older males are most affected.
Coronary thrombosis or acute myocardial infarction is the acute, dramatic manifestation of coronary-artery ischaemic heart disease – one of the major killing diseases of western civilisation. In 1999, ischaemic heart disease was responsible for about 115,000 deaths in England and Wales, compared with 153,000 deaths in 1988. In 1999 more than 55,600 people died of coronary thrombosis. The underlying cause is disease of the coronary arteries which carry the blood supply to the heart muscle (or myocardium). This results in narrowing of the arteries until ?nally they are unable to transport su?cient blood for the myocardium to function e?ciently. One of three things may happen. If the narrowing of the coronary arteries occurs gradually, then the individual concerned will develop either angina pectoris or signs of a failing heart: irregular rhythm, breathlessness, CYANOSIS and oedema.
If the narrowing occurs suddenly or leads to complete blockage (occlusion) of a major branch of one of the coronary arteries, then the victim collapses with acute pain and distress. This is the condition commonly referred to as a coronary thrombosis because it is usually due to the affected artery suddenly becoming completely blocked by THROMBOSIS. More correctly, it should be described as coronary occlusion, because the ?nal occluding factor need not necessarily be thrombosis.
Causes The precise cause is not known, but a wide range of factors play a part in inducing coronary artery disease. Heredity is an important factor. The condition is more common in men than in women; it is also more common in those in sedentary occupations than in those who lead a more physically active life, and more likely to occur in those with high blood pressure than in those with normal blood pressure (see HYPERTENSION). Obesity is a contributory factor. The disease is more common among smokers than non-smokers; it is also often associated with a high level of CHOLESTEROL in the blood, which in turn has been linked with an excessive consumption of animal, as opposed to vegetable, fats. In this connection the important factors seem to be the saturated fatty acids (low-density and very low-density lipoproteins [LDLs and VLDLs] – see CHOLESTEROL) of animal fats which would appear to be more likely to lead to a high level of cholesterol in the blood than the unsaturated fatty acids of vegetable fats. As more research on the subject is carried out, the arguments continue about the relative in?uence of the di?erent factors. (For advice on prevention of the disease, see APPENDIX 2: ADDRESSES: SOURCES OF INFORMATION, ADVICE, SUPPORT AND SELFHELP.)
Symptoms The presenting symptom is the sudden onset, often at rest, of acute, agonising pain in the front of the chest. This rapidly radiates all over the front of the chest and often down over the abdomen. The pain is frequently accompanied by nausea and vomiting, so that suspicion may be aroused of some acute abdominal condition such as biliary colic (see GALLBLADDER, DISEASES OF) or a perforated PEPTIC ULCER. The victim soon goes into SHOCK, with a pale, cold, sweating skin, rapid pulse and dif?culty in breathing. There is usually some rise in temperature.
Treatment is immediate relief of the pain by injections of diamorphine. Thrombolytic drugs should be given as soon as possible (‘rapid door to needle time’) and ARRHYTHMIA corrected. OXYGEN is essential and oral ASPIRIN is valuable. Treatment within the ?rst hour makes a great di?erence to recovery. Subsequent treatment includes the continued administration of drugs to relieve the pain; the administration of ANTIARRHYTHMIC DRUGS that may be necessary to deal with the heart failure that commonly develops, and the irregular action of the heart that quite often develops; and the continued administration of oxygen. Patients are usually admitted to coronary care units, where they receive constant supervision. Such units maintain an emergency, skilled, round-the-clock sta? of doctors and nurses, as well as all the necessary resuscitation facilities that may be required.
The outcome varies considerably. The ?rst (golden) hour is when the patient is at greatest risk of death: if he or she is treated, then there is a 50 per cent reduction in mortality compared with waiting until hospital admission. As each day passes the prognosis improves with a ?rst coronary thrombosis, provided that the patient does not have a high blood pressure and is not overweight. Following recovery, there should be a gradual return to work, care being taken to avoid any increase in weight, unnecessary stress and strain, and to observe moderation in all things. Smoking must stop. In uncomplicated cases patients get up and about as soon as possible, most being in hospital for a week to ten days and back at work in three months or sooner.
Valvular heart disease primarily affects the mitral and aortic valves which can become narrowed (stenosis) or leaking (incompetence). Pulmonary valve problems are usually congenital (stenosis) and the tricuspid valve is sometimes involved when rheumatic heart disease primarily affects the mitral or aortic valves. RHEUMATIC FEVER, usually in childhood, remains a common cause of chronic valvular heart disease causing stenosis, incompetence or both of the aortic and mitral valves, but each valve has other separate causes for malfunction.
Aortic valve disease is more common with increasing age. When the valve is narrowed, the heart hypertrophies and may later fail. Symptoms of angina or breathlessness are common and dizziness or blackouts (syncope) also occur. Replacing the valve is a very e?ective treatment, even with advancing age. Aortic stenosis may be caused by degeneration (senile calci?c), by the inheritance of two valvular leaflets instead of the usual three (bicuspid valve), or by rheumatic fever. Aortic incompetence again leads to hypertrophy, but dilatation is more common as blood leaks back into the ventricle. Breathlessness is the more common complaint. The causes are the same as stenosis but also include in?ammatory conditions such as SYPHILIS or ANKYLOSING SPONDYLITIS and other disorders of connective tissue. The valve may also leak if the aorta dilates, stretching the valve ring as with HYPERTENSION, aortic ANEURYSM and MARFAN’S SYNDROME – an inherited disorder of connective tissue that causes heart defects. Infection (endocarditis) can worsen acutely or chronically destroy the valve and sometimes lead to abnormal outgrowths on the valve (vegetations) which may break free and cause devastating damage such as a stroke or blocked circulation to the bowel or leg.
Mitral valve disease leading to stenosis is rheumatic in origin. Mitral incompetence may be rheumatic but in the absence of stenosis can be due to ISCHAEMIA, INFARCTION, in?ammation, infection and a congenital weakness (prolapse). The valve may also leak if stretched by a dilating ventricle (functional incompetence). Infection (endocarditis) may affect the valve in a similar way to aortic disease. Mitral symptoms are predominantly breathlessness which may lead to wheezing or waking at night breathless and needing to sit up or stand for relief. They are made worse when the heart rhythm changes (atrial ?brillation) which is frequent as the disease becomes more severe. This leads to a loss of e?ciency of up to 25 per cent and a predisposition to clot formation as blood stagnates rather than leaves the heart e?ciently. Mitral incompetence may remain mild and be of no trouble for many years, but infection must be guarded against (endocarditis prophylaxis).
Endocarditis is an infection of the heart which may acutely destroy a valve or may lead to chronic destruction. Bacteria settle usually on a mild lesion. Antibiotics taken at vulnerable times can prevent this (antibiotic prophylaxis) – for example, before tooth extraction. If established, lengthy intravenous antibiotic therapy is needed and surgery is often necessary. The mortality is 30 per cent but may be higher if the infection settles on a replaced valve (prosthetic endocarditis). Complications include heart failure, shock, embolisation (generation of small clots in the blood), and cerebral (mental) confusion.
PERICARDITIS is an in?ammation of the sac covering the outside of the heart. The sac becomes roughened and pain occurs as the heart and sac rub together. This is heard by stethoscope as a scratching noise (pericardial rub). Fever is often present and a virus the main cause. It may also occur with rheumatic fever, kidney failure, TUBERCULOSIS or from an adjacent lung problem such as PNEUMONIA or cancer. The in?ammation may cause ?uid to accumulate between the sac and the heart (e?usion) which may compress the heart causing a fall in blood pressure, a weak pulse and circulatory failure (tamponade). This can be relieved by aspirating the ?uid. The treatment is then directed at the underlying cause.... heart, diseases of
Pregnancy lasts about 280 days and is calculated from the ?rst day of the last menstrual period – see MENSTRUATION. Pregnancy-testing kits rely on the presence of the hormone beta HUMAN CHORIONIC GONADOTROPHIN (b HCG) which is excreted in the woman’s urine as early as 30 days from the last menstrual period. The estimated date of delivery can be accurately estimated from the size of the developing fetus measured by ULTRASOUND (see also below) between seven and 24 weeks. ‘Term’ refers to the time that the baby is due; this can range from 38 weeks to 41 completed weeks.
Physical changes occur in early pregnancy – periods stop and the abdomen enlarges. The breasts swell, with the veins becoming prominent and the nipples darkening. About two in three women will have nausea with a few experiencing such severe vomiting as to require hospital admission for rehydration.
Antenatal care The aim of antenatal care is to ensure a safe outcome for both mother and child; it is provided by midwives (see MIDWIFE) and doctors. Formal antenatal care began in Edinburgh in the 1930s with the recognition that all aspects of pregnancy – normal and abnormal – warranted surveillance. Cooperation between general practitioners, midwives and obstetricians is now established, with pregnancies that are likely to progress normally being cared for in the community and only those needing special intervention being cared for in a hospital setting.
The initial visit (or booking) in the ?rst half of pregnancy will record the history of past events and the results of tests, with the aim of categorising the patients into normal or not. Screening tests including blood checks and ultrasound scans are a routine part of antenatal care. The ?rst ultrasound scan is done at about 11 weeks to date the pregnancy, with a further one done at 20 weeks – the anomaly scan – to assess the baby’s structure. Some obstetric units will check the growth of the baby with one further scan later in the pregnancy or, in the case of twin pregnancies (see below), many scans throughout. The routine blood tests include checks for ANAEMIA, DIABETES MELLITUS, sickle-cell disease and THALASSAEMIA, as well as for the blood group. Evidence of past infections is also looked for; tests for RUBELLA (German measles) and SYPHILIS are routine, whereas tests for human immunode?ciency virus (see AIDS/ HIV below) and HEPATITIS are being o?ered as optional, although there is compelling evidence that knowledge of the mother’s infection status is bene?cial to the baby.
Traditional antenatal care consists of regular appointments, initially every four weeks until 34 weeks, then fortnightly or weekly. At each visit the mother’s weight, urine and blood pressure are checked, and assessment of fetal growth and position is done by palpating the uterus. Around two-thirds of pregnancies and labours are normal: in the remainder, doctors and midwives need to increase the frequency of surveillance so as to prevent or deal with maternal and fetal problems.
Common complications of pregnancy
Some of the more common complications of pregnancy are listed below.
As well as early detection of medical complications, antenatal visits aim to be supportive and include emotional and educational care. Women with uncomplicated pregnancies are increasingly being managed by midwives and general practitioners in the community and only coming to the hospital doctors should they develop a problem. A small number will opt for a home delivery, but facilities for providing such a service are not always available in the UK.
Women requiring more intensive surveillance have their management targeted to the speci?c problems encountered. Cardiologists will see mothers-to-be with heart conditions, and those at risk of diabetes are cared for in designated clinics with specialist sta?. Those women needing more frequent surveillance than standard antenatal care can be looked after in maternity day centres. These typically include women with mildly raised blood pressure or those with small babies. Fetal medicine units have specialists who are highly skilled in ultrasound scanning and specialise in the diagnosis and management of abnormal babies still in the uterus. ECTOPIC PREGNANCY Chronic abdominal discomfort early in pregnancy may be caused by unruptured ectopic pregnancy, when, rarely, the fertilised OVUM starts developing in the Fallopian tube (see FALLOPIAN TUBES) instead of the uterus. The patient needs hospital treatment and LAPAROSCOPY. A ruptured ectopic pregnancy causes acute abdominal symptoms and collapse, and the woman will require urgent abdominal surgery. URINARY TRACT INFECTIONS These affect around 2 per cent of pregnant women and are detected by a laboratory test of a mid-stream specimen of urine. In pregnancy, symptoms of these infections do not necessarily resemble those experienced by non-pregnant women. As they can cause uterine irritability and possible premature labour (see below), it is important to ?nd and treat them appropriately. ANAEMIA is more prevalent in patients who are vegetarian or on a poor diet. Iron supplements are usually given to women who have low concentrations of HAEMOGLOBIN in their blood (less than 10.5 g/dl) or who are at risk of becoming low in iron, from bleeding, twin pregnancies and those with placenta previa (see below). ANTEPARTUM HAEMORRHAGE Early in pregnancy, vaginal bleedings may be due to a spontaneous or an incomplete therapeutic ABORTION. Bleeding from the genital tract between 24 completed weeks of pregnancy and the start of labour is called antepartum haemorrhage. The most common site is where the PLACENTA is attached to the wall of the uterus. If the placenta separates before delivery, bleeding occurs in the exposed ‘bed’. When the placenta is positioned in the upper part of the uterus it is called an abruption. PLACENTA PRAEVIA is sited in the lower part and blocks or partly blocks the cervix (neck of the womb); it can be identi?ed at about the 34th week. Ten per cent of episodes of antepartum bleeding are caused by placenta previa, and it may be associated with bleeding at delivery. This potentially serious complication is diagnosed by ultrasound scanning and may require a caesarean section (see below) at delivery. INCREASED BLOOD PRESSURE, associated with protein in the urine and swelling of the limbs, is part of a condition known as PRE-ECLAMPSIA. This occurs in the second half of pregnancy in about 1 in 10 women expecting their ?rst baby, and is mostly very mild and of no consequence to the pregnancy. However, some women can develop extremely high blood pressures which can adversely affect the fetus and cause epileptic-type seizures and bleeding disorders in the mother. This serious condition is called ECLAMPSIA. For this reason a pregnant woman with raised blood pressure or PROTEIN in her urine is carefully evaluated with blood tests, often in the maternity day assessment unit. The condition can be stopped by delivery of the baby, and this will be done if the mother’s or the fetus’s life is in danger. If the condition is milder, and the baby not mature enough for a safe delivery, then drugs can be used to control the blood pressure. MISCARRIAGE Also called spontaneous abortion, miscarriage is the loss of the fetus. There are several types:
threatened miscarriage is one in which some vaginal bleeding occurs, the uterus is enlarged, but the cervix remains closed and pregnancy usually proceeds.
inevitable miscarriage usually occurs before the 16th week and is typi?ed by extensive blood loss through an opened cervix and cramp-like abdominal pain; some products of conception are lost but the developing placental area (decidua) is retained and an operation may be necessary to clear the womb.
missed miscarriages, in which the embryo dies and is absorbed, but the decidua (placental area of uterine wall) remains and may cause abdominal discomfort and discharge of old blood.
THERAPEUTIC ABORTION is performed on more than 170,000 women annually in England and Wales. Sometimes the woman may not have arranged the procedure through the usual health-care channels, so that a doctor may see a patient with vaginal bleeding, abdominal discomfort or pain, and open cervix – symptoms which suggest that the decidua and a blood clot have been retained; these retained products will need to be removed by curettage.
Septic abortions are now much less common in Britain than before the Abortion Act (1967) permitted abortion in speci?ed circumstances. The cause is the passage of infective organisms from the vagina into the uterus, with Escherichia coli and Streptococcus faecalis the most common pathogenic agents. The woman has abdominal pain, heavy bleeding, usually fever and sometimes she is in shock. The cause is usually an incomplete abortion or one induced in unsterile circumstances. Antibiotics and curettage are the treatment. INTRAUTERINE GROWTH RETARDATION describes a slowing of the baby’s growth. This can be diagnosed by ultrasound scanning, although there is a considerable margin of error in estimates of fetal weight. Trends in growth are favoured over one-o? scan results alone. GESTATIONAL DIABETES is a condition that is more common in women who are overweight or have a family member with diabetes. If high concentrations of blood sugar are found, e?orts are made to correct it as the babies can become very fat (macrosomia), making delivery more di?cult. A low-sugar diet is usually enough to control the blood concentration of sugars; however some women need small doses of INSULIN to achieve control. FETAL ABNORMALITIES can be detected before birth using ultrasound. Some of these defects are obvious, such as the absence of kidneys, a condition incompatible with life outside the womb. These women can be o?ered a termination of their pregnancy. However, more commonly, the pattern of problems can only hint at an abnormality and closer examination is needed, particularly in the diagnosis of chromosomal deformities such as DOWN’S (DOWN) SYNDROME (trisomy 21 or presence of three 21 chromosomes instead of two).
Chromosomal abnormalities can be de?nitively diagnosed only by cell sampling such as amniocentesis (obtaining amniotic ?uid – see AMNION – from around the baby) done at 15 weeks onwards, and chorionic villus sampling (sampling a small part of the placenta) – another technique which can be done from 12 weeks onwards. Both have a small risk of miscarriage associated with them; consequently, they are con?ned to women at higher risk of having an abnormal fetus.
Biochemical markers present in the pregnant woman’s blood at di?erent stages of pregnancy may have undergone changes in those carrying an abnormal fetus. The ?rst such marker to be routinely used was a high concentration of alpha-fetol protein in babies with SPINA BIFIDA (defects in the covering of the spinal cord). Fuller research has identi?ed a range of diagnostic markers which are useful, and, in conjunction with other factors such as age, ethnic group and ultrasound ?ndings, can provide a predictive guide to the obstetrician – in consultation with the woman – as to whether or not to proceed to an invasive test. These tests include pregnancy-associated plasma protein assessed from a blood sample taken at 12 weeks and four blood tests at 15–22 weeks – alphafetol protein, beta human chorionic gonadotrophin, unconjugated oestriol and inhibin A. Ultrasound itself can reveal physical ?ndings in the fetus, which can be more common in certain abnormalities. Swelling in the neck region of an embryo in early pregnancy (increased nuchal thickness) has good predictive value on its own, although its accuracy is improved in combination with the biochemical markers. The e?ectiveness of prenatal diagnosis is rapidly evolving, the aim being to make the diagnosis as early in the pregnancy as possible to help the parents make more informed choices. MULTIPLE PREGNANCIES In the UK, one in 95 deliveries is of twins, while the prevalence of triplets is one in 10,000 and quadruplets around one in 500,000. Racial variations occur, with African women having a prevalence rate of one in 30 deliveries for twins and Japanese women a much lower rate than the UK ?gure. Multiple pregnancies occur more often in older women, and in the UK the prevalence of fertility treatments, many of these being given to older women, has raised the incidence. There is now an o?cial limit of three eggs being transferred to a woman undergoing ASSISTED CONCEPTION (gamete intrafallopian transfer, or GIFT).
Multiple pregnancies are now usually diagnosed as a result of routine ultrasound scans between 16 and 20 weeks of pregnancy. The increased size of the uterus results in the mother having more or worse pregnancy-related conditions such as nausea, abdominal discomfort, backache and varicose veins. Some congenital abnormalities in the fetus occur more frequently in twins: NEURAL TUBE defects, abnormalities of the heart and the incidence of TURNER’S SYNDROME and KLINEFELTER’S SYNDROME are examples. Such abnormalities may be detected by ultrasound scans or amniocentesis. High maternal blood pressure and anaemia are commoner in women with multiple pregnancies (see above).
The growth rates of multiple fetuses vary, but the di?erence between them and single fetuses are not that great until the later stages of pregnancy. Preterm labour is commoner in multiple pregnancies: the median length of pregnancy is 40 weeks for singletons, 37 for twins and 33 for triplets. Low birth-weights are usually the result of early delivery rather than abnormalities in growth rates. Women with multiple pregnancies require more frequent and vigilant antenatal assessments, with their carers being alert to the signs of preterm labour occurring. CEPHALOPELVIC DISPROPORTION Disparity between the size of the fetus and the mother’s pelvis is not common in the UK but is a signi?cant problem in the developing world. Disparity is classi?ed as absolute, when there is no possibility of delivery, and relative, when the baby is large but delivery (usually after a dif?cult labour) is possible. Causes of absolute disparity include: a large baby – heavier than 5 kg at birth; fetal HYDROCEPHALUS; and an abnormal maternal pelvis. The latter may be congenital, the result of trauma or a contraction in pelvic size because of OSTEOMALACIA early in life. Disproportion should be suspected if in late pregnancy the fetal head has not ‘engaged’ in the pelvis. Sometimes a closely supervised ‘trial of labour’ may result in a successful, if prolonged, delivery. Otherwise a caesarean section (see below) is necessary. UNUSUAL POSITIONS AND PRESENTATIONS OF THE BABY In most pregnant women the baby ?ts into the maternal pelvis head-?rst in what is called the occipito-anterior position, with the baby’s face pointing towards the back of the pelvis. Sometimes, however, the head may face the other way, or enter the pelvis transversely – or, rarely, the baby’s neck is ?exed backwards with the brow or face presenting to the neck of the womb. Some malpositions will correct naturally; others can be manipulated abdominally during pregnancy to a better position. If, however, the mother starts labour with the baby’s head badly positioned or with the buttocks instead of the head presenting (breech position), the labour will usually be longer and more di?cult and may require intervention using special obstetric forceps to assist in extracting the baby. If progress is poor and the fetus distressed, caesarean section may be necessary. HIV INFECTION Pregnant women who are HIV positive (see HIV; AIDS/HIV) should be taking antiviral drugs in the ?nal four to ?ve months of pregnancy, so as to reduce the risk of infecting the baby in utero and during birth by around 50 per cent. Additional antiviral treatment is given before delivery; the infection risk to the baby can be further reduced – by about 40 per cent – if delivery is by caesarean section. The mother may prefer to have the baby normally, in which case great care should be taken not to damage the baby’s skin during delivery. The infection risk to the baby is even further reduced if it is not breast fed. If all preventive precautions are taken, the overall risk of the infant becoming infected is cut to under 5 per cent.
Premature birth This is a birth that takes place before the end of the normal period of gestation, usually before 37 weeks. In practice, however, it is de?ned as a birth that takes place when the baby weighs less than 2·5 kilograms (5••• pounds). Between 5 and 10 per cent of babies are born prematurely, and in around 40 per cent of premature births the cause is unknown. Pre-eclampsia is the most common known cause; others include hypertension, chronic kidney disease, heart disease and diabetes mellitus. Multiple pregnancy is another cause. In the vast majority of cases the aim of management is to prolong the pregnancy and so improve the outlook for the unborn child. This consists essentially of rest in bed and sedation, but there are now several drugs, such as RITODRINE, that may be used to suppress the activity of the uterus and so help to delay premature labour. Prematurity was once a prime cause of infant mortality but modern medical care has greatly improved survival rates in developing countries.
Labour Also known by the traditional terms parturition, childbirth or delivery, this is the process by which the baby and subsequently the placenta are expelled from the mother’s body. The onset of labour is often preceded by a ‘show’ – the loss of the mucus and blood plug from the cervix, or neck of the womb; this passes down the vagina to the exterior. The time before the beginning of labour is called the ‘latent phase’ and characteristically lasts 24 hours or more in a ?rst pregnancy. Labour itself is de?ned by regular, painful contractions which cause dilation of the neck of the womb and descent of the fetal head. ‘Breaking of the waters’ is the loss of amniotic ?uid vaginally and can occur any time in the delivery process.
Labour itself is divided into three stages: the ?rst is from the onset of labour to full (10 cm) dilation of the neck of the womb. This stage varies in length, ideally taking no more than one hour per centimetre of dilation. Progress is monitored by regular vaginal examinations, usually every four hours. Fetal well-being is observed by intermittent or continuous monitoring of the fetal heart rate in relation to the timing and frequency of the contractions. The print-out is called a cardiotocograph. Abnormalities of the fetal heart rate may suggest fetal distress and may warrant intervention. In women having their ?rst baby (primigravidae), the common cause of a slow labour is uncoordinated contractions which can be overcome by giving either of the drugs PROSTAGLANDIN or OXYTOCIN, which provoke contractions of the uterine muscle, by an intravenous drip. Labours which progress slowly or not at all may be due to abnormal positioning of the fetus or too large a fetus, when prostaglandin or oxytocin is used much more cautiously.
The second stage of labour is from full cervical dilation to the delivery of the baby. At this stage the mother often experiences an irresistible urge to push the baby out, and a combination of strong coordinated uterine contractions and maternal e?ort gradually moves the baby down the birth canal. This stage usually lasts under an hour but can take longer. Delay, exhaustion of the mother or distress of the fetus may necessitate intervention by the midwife or doctor. This may mean enlarging the vaginal opening with an EPISIOTOMY (cutting of the perineal outlet – see below) or assisting the delivery with specially designed obstetric forceps or a vacuum extractor (ventouse). If the cervix is not completely dilated or open and the head not descended, then an emergency caesarean section may need to be done to deliver the baby. This procedure involves delivering the baby and placenta through an incision in the mother’s abdomen. It is sometimes necessary to deliver by planned or elective caesarean section: for example, if the placenta is low in the uterus – called placenta praevia – making a vaginal delivery dangerous.
The third stage occurs when the placenta (or afterbirth) is delivered, which is usually about 10–20 minutes after the baby. An injection of ergometrine and oxytocin is often given to women to prevent bleeding.
Pain relief in labour varies according to the mother’s needs. For uncomplicated labours, massage, reassurance by a birth attendant, and a warm bath and mobilisation may be enough for some women. However, some labours are painful, particularly if the woman is tired or anxious or is having her ?rst baby. In these cases other forms of analgesia are available, ranging from inhalation of NITROUS OXIDE GAS, injection of PETHIDINE HYDROCHLORIDE or similar narcotic, and regional local anaesthetic (see ANAESTHESIA).
Once a woman has delivered, care continues to ensure her and the baby’s safety. The midwives are involved in checking that the uterus returns to its normal size and that there is no infection or heavy bleeding, as well as caring for stitches if needed. The normal blood loss after birth is called lochia and generally is light, lasting up to six weeks. Midwives o?er support with breast feeding and care of the infant and will visit the parents at home routinely for up to two weeks.
Some complications of labour All operative deliveries in the UK are now done in hospitals, and are performed if a spontaneous birth is expected to pose a bigger risk to the mother or her child than a specialist-assisted one. Operative deliveries include caesarean section, forceps-assisted deliveries and those in which vacuum extraction (ventouse) is used. CAESAREAN SECTION Absolute indications for this procedure, which is used to deliver over 15 per cent of babies in Britain, are cephalopelvic disproportion and extensive placenta praevia, both discussed above. Otherwise the decision to undertake caesarean section depends on the clinical judgement of the specialist and the views of the mother. The rise in the proportion of this type of intervention (from 5 per cent in the 1930s to its present level of over 23 per cent
P
of the 600,000 or so annual deliveries in England) has been put down to defensive medicine
– namely, the doctor’s fear of litigation (initiated often because the parents believe that the baby’s health has suffered because the mother had an avoidably di?cult ‘natural’ labour). In Britain, over 60 per cent of women who have had a caesarean section try a vaginal delivery in a succeeding pregnancy, with about two-thirds of these being successful. Indications for the operation include:
absolute and relative cephalopelvic disproportion.
placenta previa.
fetal distress.
prolapsed umbilical cord – this endangers the viability of the fetus because the vital supply of oxygen and nutrients is interrupted.
malpresentation of the fetus such as breech or transverse lie in the womb.
unsatisfactory previous pregnancies or deliveries.
a request from the mother.
Caesarean sections are usually performed using regional block anaesthesia induced by a spinal or epidural injection. This results in loss of feeling in the lower part of the body; the mother is conscious and the baby not exposed to potential risks from volatile anaesthetic gases inhaled by the mother during general anaesthesia. Post-operative complications are higher with general anaesthesia, but maternal anxiety and the likelihood that the operation might be complicated and di?cult are indications for using it. A general anaesthetic may also be required for an acute obstetric emergency. At operation the mother’s lower abdomen is opened and then her uterus opened slowly with a transverse incision and the baby carefully extracted. A transverse incision is used in preference to the traditional vertical one as it enables the woman to have a vaginal delivery in any future pregnancy with a much smaller risk of uterine rupture. Women are usually allowed to get up within 24 hours and are discharged after four or ?ve days. FORCEPS AND VENTOUSE DELIVERIES Obstetric forceps are made in several forms, but all are basically a pair of curved blades shaped so that they can obtain a purchase on the baby’s head, thus enabling the operator to apply traction and (usually) speed up delivery. (Sometimes they are used to slow down progress of the head.) A ventouse or vacuum extractor comprises an egg-cup-shaped metal or plastic head, ranging from 40 to 60 mm in diameter with a hollow tube attached through which air is extracted by a foot-operated vacuum pump. The instrument is placed on the descending head, creating a negative pressure on the skin of the scalp and enabling the operator to pull the head down. In mainland Europe, vacuum extraction is generally preferred to forceps for assisting natural deliveries, being used in around 5 per cent of all deliveries. Forceps have a greater risk of causing damage to the baby’s scalp and brain than vacuum extraction, although properly used, both types should not cause any serious damage to the baby.
Episiotomy Normal and assisted deliveries put the tissues of the genital tract under strain. The PERINEUM is less elastic than the vagina and, if it seems to be splitting as the baby’s head
moves down the birth canal, it may be necessary to cut the perineal tissue – a procedure called an episiotomy – to limit damage. This is a simple operation done under local anaesthetic. It should be done only if there is a speci?c indication; these include:
to hasten the second stage of labour if the fetus is distressed.
to facilitate the use of forceps or vacuum extractor.
to enlarge a perineum that is restricted because of unyielding tissue, perhaps because of a scar from a previous labour. Midwives as well as obstetricians are trained
to undertake and repair (with sutures) episiotomies.
(For organisations which o?er advice and information on various aspects of childbirth, including eclampsia, breast feeding and multiple births, see APPENDIX 2: ADDRESSES: SOURCES OF INFORMATION, ADVICE, SUPPORT AND SELF-HELP.)... pregnancy and labour
Elective mutism is a rare childhood disorder (usually starting before age 5), in which the child can speak properly but refuses to do so most of the time.
Akinetic mutism describes a state of passivity caused by some brain tumours or by hydrocephalus. People with akinetic mutism are incontinent, require feeding, and respond at most with a whispered “yes” or “no”.... mutism
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