Severe head injuries cause unconsciousness for hours or many days, followed by loss of memory before and after that period of unconsciousness. The skull may be fractured; there may be ?ts in the ?rst week; and there may develop a blood clot in the brain (intracerebral haematoma) or within the membranes covering the brain (extradural and subdural haematomata). These clots compress the brain, and the pressure inside the skull – intracranial pressure – rises with urgent, life-threatening consequences. They are identi?ed by neurologists and neurosurgeons, con?rmed by brain scans (see COMPUTED TOMOGRAPHY; MRI), and require urgent surgical removal. Recovery may be complete, or in very severe cases can be marred by physical disabilities, EPILEPSY, and by changes in intelligence, rational judgement and behaviour. Symptoms generally improve in the ?rst two years.
A minority of those with minor head injuries have complaints and disabilities which seem disproportionate to the injury sustained. Referred to as the post-traumatic syndrome, this is not a diagnostic entity. The complaints are headaches, forgetfulness, irritability, slowness, poor concentration, fatigue, dizziness (usually not vertigo), intolerance of alcohol, light and noise, loss of interests and initiative, DEPRESSION, anxiety, and impaired LIBIDO. Reassurance and return to light work help these symptoms to disappear, in most cases within three months. Psychological illness and unresolved compensation-claims feature in many with implacable complaints.
People who have had brain injuries, and their relatives, can obtain help and advice from Headwat and from www.neuro.pmr.vcu.edu and www.biausa.org... Medical Dictionary
It is important for a paediatrician to determine that such events are not epileptic (see EPILEPSY). Generally they require no treatment other than reassurance, as recovery is spontaneous and rapid – although a small number of severely a?ected children have been helped by a PACEMAKER. Parents should avoid dramatising the attacks.... Medical Dictionary
Symptoms Attacks generally come on at night, following a cold caught during the previous couple of days. The breathing is hoarse and croaking (croup), with a barking cough and harsh respiratory noise. The natural tendency for the laryngeal airway to collapse is increased by the child’s desperate attempts to overcome the obstruction. Parental anxiety, added to that of the child, only exacerbates the situation. After struggling for up to several hours, the child ?nally falls asleep. The condition may recur.
Treatment Most children with croup should be looked after at home if the environment is suitable. Severe episodes may require hospital observation, with treatment by oxygen if needed and usually with a single dose of inhaled steroid or oral PREDNISONE. For the very few children whose illness progresses to respiratory obstruction, intubation and ventilation may be needed for a few days. There is little evidence that putting the child in a mist tent or giving antibiotics is of any value. Of greater importance is the reassurance of the child, and careful observation for signs of deterioration, together with the exclusion of other causes such as foreign-body inhalation and bacterial tracheitis.... Medicinal Plants Glossary
Examination of the ear includes inspection of the external ear. An auriscope is used to examine the external ear canal and the ear drum. If a more detailed inspection is required, a microscope may be used to improve illumination and magni?cation.
Tuning-fork or Rinne tests are performed to identify the presence of DEAFNESS. The examiner tests whether the vibrating fork is audible at the meatus, and then the foot of the fork is placed on the mastoid bone of the ear to discover at which of the two sites the patient can hear the vibrations for the longest time. This can help to di?erentiate between conductive and nerve deafness.
Hearing tests are carried out to determine the level of hearing. An audiometer is used to deliver a series of short tones of varying frequency to the ear, either through a pair of headphones or via a sound transducer applied directly to the skull. The intensity of the sound is gradually reduced until it is no longer heard and this represents the threshold of hearing, at that frequency, through air and bone respectively. It may be necessary to play a masking noise into the opposite ear to prevent that ear from hearing the tones, enabling each ear to be tested independently.
General symptoms The following are some of the chief symptoms of ear disease: DEAFNESS (see DEAFNESS). EARACHE is most commonly due to acute in?ammation of the middle ear. Perceived pain in this region may be referred from other areas, such as the earache commonly experienced after tonsillectomy (removal of the TONSILS) or that caused by carious teeth (see TEETH, DISORDERS OF). The treatment will depend on the underlying cause. TINNITUS or ringing in the ear often accompanies deafness, but is sometimes the only symptom of ear disease. Even normal people sometimes experience tinnitus, particularly if put in soundproofed surroundings. It may be described as hissing, buzzing, the sound of the sea, or of bells. The intensity of the tinnitis usually ?uctuates, sometimes disappearing altogether. It may occur in almost any form of ear disease, but is particularly troublesome in nerve deafness due to ageing and in noise-induced deafness. The symptom seems to originate in the brain’s subcortical regions, high in the central nervous system. It may be a symptom of general diseases such as ANAEMIA, high blood pressure and arterial disease, in which cases it is often synchronous with the pulse, and may also be caused by drugs such as QUININE, salicylates (SALICYLIC ACID and its salts, for example, ASPIRIN) and certain ANTIBIOTICS. Treatment of any underlying ear disorder or systemic disease, including DEPRESSION, may reduce or even cure the tinnitis, but unfortunately in many cases the noises persist. Management involves psychological techniques and initially an explanation of the mechanism and reassurance that tinnitus does not signify brain disease, or an impending STROKE, may help the person. Tinnitus maskers – which look like hearing aids – have long been used with a suitably pitched sound helping to ‘mask’ the condition.
Diseases of the external ear
WAX (cerumen) is produced by specialised glands in the outer part of the ear canal only. Impacted wax within the ear canal can cause deafness, tinnitis and sometimes disturbance of balance. Wax can sometimes be softened with olive oil, 5-per-cent bicarbonate of soda or commercially prepared drops, and it will gradually liquefy and ‘remove itself’. If this is ineffective, syringing by a doctor or nurse will usually remove the wax but sometimes it is necessary for a specialist (otologist) to remove it manually with instruments. Syringing should not be done if perforation of the tympanic membrane (eardrum) is suspected. FOREIGN BODIES such as peas, beads or buttons may be found in the external ear canal, especially in children who have usually introduced them themselves. Live insects may also be trapped in the external canal causing intense irritation and noise, and in such cases spirit drops are ?rst instilled into the ear to kill the insect. Except in foreign bodies of vegetable origin, where swelling and pain may occur, syringing may be used to remove some foreign bodies, but often removal by a specialist using suitable instrumentation and an operating microscope is required. In children, a general anaesthetic may be needed. ACUTE OTITIS EXTERNA may be a di?use in?ammation or a boil (furuncle) occurring in the outer ear canal. The pinna is usually tender on movement (unlike acute otitis media – see below) and a discharge may be present. Initially treatment should be local, using magnesium sulphate paste or glycerine and 10-per-cent ichthaminol. Topical antibiotic drops can be used and sometimes antibiotics by mouth are necessary, especially if infection is acute. Clotrimazole drops are a useful antifungal treatment. Analgesics and locally applied warmth should relieve the pain.
CHRONIC OTITIS EXTERNA producing pain and discharge, can be caused by eczema, seborrhoeic DERMATITIS or PSORIASIS. Hair lotions and cosmetic preparations may trigger local allergic reactions in the external ear, and the chronic disorder may be the result of swimming or use of dirty towels. Careful cleaning of the ear by an ENT (Ear, Nose & Throat) surgeon and topical antibiotic or antifungal agents – along with removal of any precipitating cause – are the usual treatments. TUMOURS of the ear can arise in the skin of the auricle, often as a result of exposure to sunlight, and can be benign or malignant. Within the ear canal itself, the commonest tumours are benign outgrowths from the surrounding bone, said to occur in swimmers as a result of repeated exposure to cold water. Polyps may result from chronic infection of the ear canal and drum, particularly in the presence of a perforation. These polyps are soft and may be large enough to ?ll the ear canal, but may shrink considerably after treatment of the associated infection.
Diseases of the middle ear
OTITIS MEDIA or infection of the middle ear, usually occurs as a result of infection spreading up the Eustachian tubes from the nose, throat or sinuses. It may follow a cold, tonsillitis or sinusitis, and may also be caused by swimming and diving where water and infected secretions are forced up the Eustachian tube into the middle ear. Primarily it is a disease of children, with as many as 1.5 million cases occurring in Britain every year. Pain may be intense and throbbing or sharp in character. The condition is accompanied by deafness, fever and often TINNITUS.
In infants, crying may be the only sign that something is wrong – though this is usually accompanied by some localising manifestation such as rubbing or pulling at the ear. Examination of the ear usually reveals redness, and sometimes bulging, of the ear drum. In the early stages there is no discharge, but in the later stages there may be a discharge from perforation of the ear drum as a result of the pressure created in the middle ear by the accumulated pus. This is usually accompanied by an immediate reduction in pain.
Treatment consists of the immediate administration of an antibiotic, usually one of the penicillins (e.g. amoxicillin). In the majority of cases no further treatment is required, but if this does not quickly bring relief then it may be necessary to perform a myringotomy, or incision of the ear drum, to drain pus from the middle ear. When otitis media is treated immediately with su?cient dosage of the appropriate antibiotic, the chances of any permanent damage to the ear or to hearing are reduced to a negligible degree, as is the risk of any complications such as mastoiditis (discussed later in this section). CHRONIC OTITIS MEDIA WITH EFFUSION or glue ear, is the most common in?ammatory condition of the middle ear in children, to the extent that one in four children in the UK entering school has had an episode of ‘glue ear’. It is characterised by a persistent sticky ?uid in the middle ear (hence the name); this causes a conductive-type deafness. It may be associated with enlarged adenoids (see NOSE, DISORDERS OF) which impair the function of the Eustachian tube. If the hearing impairment is persistent and causes problems, drainage of the ?uid, along with antibiotic treatment, may be needed – possibly in conjunction with removal of the adenoids. The insertion of grommets (ventilation tubes) was for a time standard treatment, but while hearing is often restored, there may be no long-term gain and even a risk of damage to the tympanic membrane, so the operation is less popular than it was a decade or so ago. MASTOIDITIS is a serious complication of in?ammation of the middle ear, the incidence of which has been dramatically reduced by the introduction of antibiotics. In?ammation in this cavity usually arises by direct spread of acute or chronic in?ammation from the middle ear. The signs of this condition include swelling and tenderness of the skin behind the ear, redness and swelling inside the ear, pain in the side of the head, high fever, and a discharge from the ear. The management of this condition in the ?rst instance is with antibiotics, usually given intravenously; however, if the condition fails to improve, surgical treatment is necessary. This involves draining any pus from the middle ear and mastoid, and removing diseased lining and bone from the mastoid.
Diseases of the inner ear
MENIÈRE’S DISEASE is a common idiopathic disorder of ENDOLYMPH control in the semicircular canals (see EAR), characterised by the triad of episodic VERTIGO with deafness and tinnitus. The cause is unknown and usually one ear only is a?ected at ?rst, but eventually the opposite ear is a?ected in approximately 50 per cent of cases. The onset of dizziness is often sudden and lasts for up to 24 hours. The hearing loss is temporary in the early stages, but with each attack there may be a progressive nerve deafness. Nausea and vomiting often occur. Treatment during the attacks includes rest and drugs to control sickness. Vasodilator drugs such as betahistine hydrochloride may be helpful. Surgical treatment is sometimes required if crippling attacks of dizziness persist despite these measures. OTOSCLEROSIS A disorder of the middle ear that results in progressive deafness. Often running in families, otosclerosis a?ects about one person in 200; it customarily occurs early in adult life. An overgrowth of bone ?xes the stapes (the innermost bone of the middle ear) and stops sound vibrations from being transmitted to the inner ear. The result is conductive deafness. The disorder usually a?ects both ears. Those a?ected tend to talk quietly and deafness increases over a 10–15 year period. Tinnitus often occurs, and occasionally vertigo.
Abnormal hearing tests point to the diagnosis; the deafness may be partially overcome with a hearing aid but surgery is eventually needed. This involves replacing the stapes bone with a synthetic substitute (stapedectomy). (See also OTIC BAROTRAUMA.)... Medical Dictionary
Common features of IBS include:
altered bowel habit.
colicky lower abdominal pain, eased by defaecation.
mucous discharge from rectum.
feelings of incomplete defaecation.
Investigations usually produce normal results. Positive diagnosis in people under 40 is usually straightforward. In older patients, however, barium ENEMA, X-rays and COLONOSCOPY should be done to exclude colorectal cancer.
Reassurance is the initial and often e?ective treatment. If this fails, treatment should be directed at the major symptoms. Several months of the antidepressant amitriptyline (see ANTIDEPRESSANT DRUGS) may bene?t patients with intractable symptoms, given at a dose lower than that used to treat depression. The majority of patients follow a relapsing/remitting course, with episodes provoked by stressful events in their daily lives. (See also INTESTINE, DISEASES OF.)... Medical Dictionary
The age at which a child achieves full control of bladder function varies considerably. Such control is sometimes achieved in the second year, but much more commonly not until 2–3 years old. Some children do not normally achieve such control until the fourth, or even ?fth, year, so that paediatricians are reluctant to make this diagnosis before a child is aged six.
The approach consists essentially of reassurance and ?rm but kindly and understanding training. In most cases the use of a ‘star chart’ and a buzzer alarm which wakens the child should he or she start passing urine is helpful. Where there are relationship or social problems, these need to be considered in treating the child. The few who have urinary infection or irritable bladders may respond to drug tretament.
Those who do not respond may be helped by DDAVP, an analogue of a pituitary hormone, which reduces the amount of urine produced overnight. It is licensed for use for three months at a time. Some children prefer to reserve it for occasions such as sleeping away from home. The antidepressant imipramine can help some children but has to be used cautiously because of side-e?ects.
For help, contact www.eric.org.uk... Medical Dictionary
However, pharmacologically inert compounds can relieve symptoms, and this is called the placebo e?ect. The reassurance that is associated with placebo administration is accompanied by measurable changes in body function which are a?ected through autonomic pathways and humoral mechanisms. Alterations in blood pressure and pulse frequency are especially common. Placebos have the ability to relieve a variety of symptoms in a consistent proportion of the population – in some studies in as many as 30 per cent. Some patients with symptoms such as pain or cough will respond to placebo medications, and an even higher proportion of patients with psychological symptoms such as anxiety or insomnia may bene?t. In judging the e?ectiveness of a drug, the comparison must be with a placebo rather than with no treatment at all.... Dictionary of Tropical Medicine
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 a?ect 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 a?ect 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
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 su?ered 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.
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.)... Medical Dictionary
Causes Vomiting is brought about by stimulation of this nervous centre, and in most cases this is e?ected through sensations derived from the stomach itself. Thus, of the drugs which cause vomiting, some act only after being absorbed into the blood and carried to the brain, although most are irritants to the mucous membrane of the stomach (see EMETICS); various diseases of the stomach, such as cancer, ulcer and food poisoning act in a similar way. Stimulation – not only of the nerves of the stomach, but also of those supplying other abdominal organs – produces vomiting; thus in obstruction of the bowels, peritonitis, gall-stone colic, renal colic, and even in some women during pregnancy, vomiting is a prominent symptom.
Severe emotional shock may cause vomiting, as may acute anxiety and unpleasant experiences such as seeing an accident, su?ering severe pain or travel sickness.
Direct disturbance of the brain itself is a cause: for example, a blow on the head, a cerebral tumour, a cerebral abscess, meningitis. Nausea and vomiting are common symptoms that may arise from local disease of the gastrointestinal tract, but they are also associated with systemic illness – for example, DIABETES MELLITUS or kidney failure (see KIDNEYS, DISEASES OF) – and also with disturbances of labyrinthine function, such as motion sickness and acute labyrinthitis.
Treatment The cause of the vomiting must be sought and treatment directed towards this. Symptomatic treatment for vomiting can be dangerous since accurate diagnosis of the cause may be hindered. If antinauseant drug treatment is indicated, the choice of drug depends on the cause of the vomiting.
Granisetron and ondansetron are 5hydroxytryptamine (5HT3) antagonists valuable in the treatment of nausea and vomiting induced by cytotoxic CHEMOTHERAPY or RADIOTHERAPY and prevention and treatment of post-operative nausea and vomiting. Prochlorperazine is valuable in the treatment of severe nausea, vomiting, VERTIGO and disorders of the LABYRINTH of the EAR, although extrapyramidal symptoms may occur, particularly in children, elderly and debilitated patients.
Vomiting may occur after surgical operations and this is due to the combined e?ects of analgesics, anaesthetic agents and the psychological stress of operation. Various drugs can be used to prevent or stop post-operative vomiting.
Nausea and vomiting are common symptoms in pregnancy. Drugs are best avoided in this situation as they may damage the developing FETUS. Simple measures, such as the taking of food before getting up in the morning and reassurance, are often all that is necessary.... Medical Dictionary