Cephalopelvic disproportion Health Dictionary

Cephalopelvic Disproportion: From 2 Different Sources


A complication of childbirth (see childbirth, complications of) in which the mother’s pelvis is too narrow in proportion to the size of the baby’s head.
Health Source: BMA Medical Dictionary
Author: The British Medical Association
(CPD) the state in which the diameter of the fetal head is greater than the pelvic outlet, preventing successful vaginal delivery. This may be relative when there is *malposition of the vertex (back of the head) or absolute when the vertex is in the occipitoanterior position (see occiput), and can only be considered when the cervix is fully dilated.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Acute Respiratory Distress Syndrome (ards)

Formerly known as adult respiratory distress syndrome. A form of acute respiratory failure in which a variety of di?erent disorders give rise to lung injury by what is thought to be a common pathway. The condition has a high mortality rate (about 70 per cent); it is a complex clinical problem in which a disproportionate immunological response plays a major role. (See IMMUNITY.)

The exact trigger is unknown, but it is thought that, whatever the stimulus, chemical mediators produced by cells of the immune system or elsewhere in the body spread and sustain an in?ammatory reaction. Cascade mechanisms with multiple interactions are provoked. CYTOTOXIC substances (which damage or kill cells) such as oxygen-free radicals and PROTEASE damage the alveolar capillary membranes (see ALVEOLUS). Once this happens, protein-rich ?uid leaks into the alveoli and interstitial spaces. SURFACTANT is also lost. This impairs the exchange of oxygen and carbon dioxide in the lungs and gives rise to the clinical and pathological picture of acute respiratory failure.

The typical patient with ARDS has rapidly worsening hypoxaemia (lack of oxygen in the blood), often requiring mechanical ventilation. There are all the signs of respiratory failure (see TACHYPNOEA; TACHYCARDIA; CYANOSIS), although the chest may be clear apart from a few crackles. Radiographs show bilateral, patchy, peripheral shadowing. Blood gases will show a low PaO2 (concentration of oxygen in arterial blood) and usually a high PaCO2 (concentration of carbon dioxide in arterial blood). The lungs are ‘sti?’ – they are less e?ective because of the loss of surfactant and the PULMONARY OEDEMA.

Causes The causes of ARDS may be broadly divided into the following:... acute respiratory distress syndrome (ards)

Brain Injuries

Most blows to the head cause no loss of consciousness and no brain injury. If someone is knocked out for a minute or two, there has been a brief disturbance of the brain cells (concussion); usually there are no after-effects. Most patients so affected leave hospital within 1–3 days, have no organic signs, and recover and return quickly to work without further complaints.

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... brain injuries

Caesarean Section

The operation used to deliver a baby through its mother’s abdominal wall. It is performed when the risks to mother or child of vaginal delivery are thought to outweigh the problems associated with operative delivery. One of the most common reasons for Caesarean section is ‘disproportion’ between the size of the fetal head and the maternal pelvis. The need for a Caesarean should be assessed anew in each pregnancy; a woman who has had a Caesarean section in the past will not automatically need to have one for subsequent deliveries. Caesarean-section rates vary dramatically from hospital to hospital, and especially between countries, emphasising that the criteria for operative delivery are not universally agreed. The current rate in the UK is about 23 per cent, and in the USA, about 28 per cent. The rate has shown a steady rise in all countries over the last decade. Fear of litigation by patients is one reason for this rise, as is the uncertainty that can arise from abnormalities seen on fetal monitoring during labour. Recent research suggesting that vaginal delivery is becoming more hazardous as the age of motherhood rises may increase the pressure from women to have a Caesarean section – as well as pressure from obstetricians.

The operation is usually performed through a low, horizontal ‘bikini line’ incision. A general anaesthetic in a heavily pregnant woman carries increased risks, so the operation is often performed under regional – epidural or spinal – ANAESTHESIA. This also allows the mother to see her baby as soon as it is born, and the baby is not exposed to agents used for general anaesthesia. If a general anaesthetic is needed (usually in an emergency), exposure to these agents may make the baby drowsy for some time afterwards.

Another problem with delivery by Caesarean section is, of course, that the mother must recover from the operation whilst coping with the demands of a small baby. (See PREGNANCY AND LABOUR.)... caesarean section

Pregnancy And Labour

Pregnancy The time when a woman carries a developing baby in her UTERUS. For the ?rst 12 weeks (the ?rst trimester) the baby is known as an EMBRYO, after which it is referred to as the FETUS.

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

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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

Anxiety

n. generalized pervasive *fear. Anxiety disorders are conditions in which anxiety dominates the patient’s life or is experienced in particular situations; they include *panic disorder, *post-traumatic stress disorder, and *generalized anxiety disorder. Symptoms include excessive worrying, disproportional fears, and a variety of physical symptoms. Treatment usually includes antidepressants, cognitive behavioural therapy, and anxiety management techniques.... anxiety

Discrimination

n. treating individuals differently on the basis of morally insignificant characteristics, such as race, sex, or religion. In medicine, any discrimination of this kind (e.g. when deciding on treatments or allocating resources) offends against the ethical principle of *justice. Legally, discrimination can be direct (i.e. overtly differentiating between people and groups) or indirect (i.e. behaviour that will disproportionately affect particular people or some groups more than others). See also equality; stigma.... discrimination

Corticosteroids

The generic term for the group of hormones produced by the ADRENAL GLANDS, with a profound e?ect on mineral and glucose metabolism.

Many modi?cations have been devised of the basic steroid molecule in an attempt to keep useful therapeutic effects and minimise unwanted side-effects. The main corticosteroid hormones currently available are CORTISONE, HYDROCORTISONE, PREDNISONE, PREDNISOLONE, methyl prednisolone, triamcinolone, dexamethasone, betamethasone, paramethasone and de?azacort.

They are used clinically in three quite distinct circumstances. First they constitute replacement therapy where a patient is unable to produce their own steroids – for example, in adrenocortical insu?ciency or hypopituitarism. In this situation the dose is physiological – namely, the equivalent of the normal adrenal output under similar circumstances – and is not associated with any side-effects. Secondly, steroids are used to depress activity of the adrenal cortex in conditions where this is abnormally high or where the adrenal cortex is producing abnormal hormones, as occurs in some hirsute women.

The third application for corticosteroids is in suppressing the manifestations of disease in a wide variety of in?ammatory and allergic conditions, and in reducing antibody production in a number of AUTOIMMUNE DISORDERS. The in?ammatory reaction is normally part of the body’s defence mechanism and is to be encouraged rather than inhibited. However, in the case of those diseases in which the body’s reaction is disproportionate to the o?ending agent, such that it causes unpleasant symptoms or frank illness, the steroid hormones can inhibit this undesirable response. Although the underlying condition is not cured as a result, it may resolve spontaneously. When corticosteroids are used for their anti-in?ammatory properties, the dose is pharmacological; that is, higher – often much higher – than the normal physiological requirement. Indeed, the necessary dose may exceed the normal maximum output of the healthy adrenal gland, which is about 250–300 mg cortisol per day. When doses of this order are used there are inevitable risks and side-effects: a drug-induced CUSHING’S SYNDROME will result.

Corticosteroid treatment of short duration, as in angioneurotic OEDEMA of the larynx or other allergic crises, may at the same time be life-saving and without signi?cant risk (see URTICARIA). Prolonged therapy of such connective-tissue disorders, such as POLYARTERITIS NODOSA with its attendant hazards, is generally accepted because there are no other agents of therapeutic value. Similarly the absence of alternative medical treatment for such conditions as autoimmune haemolytic ANAEMIA establishes steroid therapy as the treatment of choice which few would dispute. The use of steroids in such chronic conditions as RHEUMATOID ARTHRITIS, ASTHMA and DERMATITIS needs careful assessment and monitoring.

Although there is a risk of ill-effects, these should be set against the misery and danger of unrelieved chronic asthma or the incapacity, frustration and psychological trauma of rheumatoid arthritis. Patients should carry cards giving details of their dosage and possible complications.

The incidence and severity of side-effects are related to the dose and duration of treatment. Prolonged daily treatment with 15 mg of prednisolone, or more, will cause hypercortisonism; less than 10 mg prednisolone a day may be tolerated by most patients inde?nitely. Inhaled steroids rarely produce any ill-e?ect apart from a propensity to oral thrush (CANDIDA infection) unless given in excessive doses.

General side-effects may include weight gain, fat distribution of the cushingoid type, ACNE and HIRSUTISM, AMENORRHOEA, striae and increased bruising tendency. The more serious complications which can occur during long-term treatment include HYPERTENSION, oedema, DIABETES MELLITUS, psychosis, infection, DYSPEPSIA and peptic ulceration, gastrointestinal haemorrhage, adrenal suppression, osteoporosis (see BONE, DISORDERS OF), myopathy (see MUSCLES, DISORDERS OF), sodium retention and potassium depletion.... corticosteroids

Anaemia: Sickle Cell

A form of anaemia growing into an acute social problem, affecting people of African, Asian, and Mediterranean origin. Thalassaemias are caused by defects of a gene that produces the globin part of haemoglobin. Such defects in the DNA can now be detected in the womb before birth. The name derives from sickle-shaped cells instead of circular red blood cells. Few sufferers survive beyond their 40th year.

Symptoms. Unhealthy pallor, listlessness, sore tongue, dizziness, vague aches and pains, rapid pulse and breathing, tinnitus, palpitation. The skull may be disproportionately large, resistance to infection feeble, chances of survival poor. This form of anaemia is linked with defective colour vision. Impaired liver function. Stunted growth, great pain. Sufferers have a higher risk of infection.

Malaria. Sufferers are less likely to die of malaria because their red cells do not support the growth of malaria parasites very well.

Carriers: Carriers of the sickle-cell gene can now be identified by a simple blood test.

Treatment. No specifics exist but supportive herbal treatment has been known to increase output of red cells and raise haemoglobin levels:– Red Clover flowers, Yellow Dock, Echinacea, Burdock, Wild Indigo, Gentian, Nettles, Birch leaves, Sage, Walnut leaves, Centaury, Gota Kola (Indian Pennywort). Alternatives:– Tea. Mix equal parts: Iceland Moss, Nettles, Red Clover flowers. 2 teaspoons to each cup boiling water; infuse 15 minutes; 1 cup morning and evening.

Decoction. Mix equal parts; Echinacea, Walnut leaves, Balm of Gilead buds; 1 teaspoon to each cup water gently simmered for 20 minutes. Half-1 cup, cold, 3 times daily, before meals.

Tablets/capsules. Sarsaparilla. Ginseng. Iceland Moss. Red Clover. Echinacea. Gentian.

Powders. Formula: Echinacea 1; Fringe Tree half; Ginseng half; White Poplar bark 1. Dose: 500mg (two 00 capsules or one-third teaspoon) thrice daily before meals.

Liquid extracts. Formula. Echinacea 2; Dandelion 1; Oat Husk (avena sativa) 1. Mix. Dose, 1-2 teaspoons before meals, in water or one of the above teas or decoctions.

Tinctures. Same combination. Dose: 2-3 teaspoons.

Dong quai. See entry.

Pollen. Claimed to be of value.

Diet. Dandelion coffee. Molasses. Desiccated liver. Calf liver, fresh. Green leafy vegetables contain chlorophyll, iron and folic acid. Cider vinegar. Dried beans, apricots and shellfish. Dandelion leaves in salads. Milk, eggs, meats, Soya. Carrot juice to increase red cells.

Supplements. Daily. Vitamin B12. Vitamin C, 1g; Folic acid 400mcg, Floradix. Of particular value: Vitamin E 400iu. Zinc.

Note: Those at risk should submit themselves for screening. The disease cannot be cured but can be controlled largely by orthodox measures and sometimes by natural medicine. ... anaemia: sickle cell

Dystocia

n. difficult birth, caused by abnormalities in the fetus or the mother (see obstructed labour). Dystocia may arise due to uterine *inertia, which is more common in a first labour; abnormal fetal lie or presentation; absolute or relative *cephalopelvic disproportion; or (rarely) a massive fetal tumor, such as a sacrococcygeal teratoma. Synthetic oxytocin (Syntocinon) is commonly used to treat uterine inertia. However, pregnancies complicated by dystocia often end with assisted deliveries, including forceps, ventouse, or (commonly) Caesarean section. See also shoulder dystocia.... dystocia

Bun

blood urea nitrogen: a measurement of nitrogen in the form of urea in the blood, usually reported as mg/dl, in common usage in the USA (each molecule of urea has two nitrogen atoms, each of molar mass 14 g/mol). Elsewhere, the concentration of urea in the serum is reported as mmol/L:

BUN or serum urea is used as a measure of kidney function but is less precise than the serum creatinine or estimates of glomerular filtration rate based on the serum creatinine (see eGFR). A disproportionate rise in blood urea nitrogen (or serum urea) compared with creatinine may be seen with volume depletion, cardiac failure, high protein diets, gastrointestinal bleeding, loss of muscle (the classic example is the bilateral amputee), and catabolic states associated with severe burns and fevers.... bun

Doctrine Of Double Effect

the principle that, where it is foreseen that a single action will have both a good and a bad outcome, a person may perform such an action provided that (a) he or she intends only the positive outcome, (b) the bad outcome is not disproportionate to the good, and (c) the good outcome is not a direct consequence of the bad. The classic example occurs where a terminally ill patient requires high doses of opiates for pain relief that may also depress respiratory function and hasten his or her death. In such a case the law holds that the doctor may supply the necessary dosage without this being considered tantamount to *euthanasia, even though the outcome will be the same, i.e. the morality of the action does not lie in its consequences (see consequentialism).... doctrine of double effect

Extraordinary Means

life-prolonging treatments that are not regarded as beneficial (i.e. they do nothing to promote recovery or relieve suffering) and that may even be burdensome to the patient. It has been argued that there is no moral obligation to prolong life and/or to impose greater suffering by extraordinary means. ‘Extraordinary’ does not mean unusual: treatments that are considered routine may be classed as extraordinary when they are no longer clinically effective or are considered *futile. Another way to describe the appropriateness of such interventions is to talk of ‘proportionate’ and ‘disproportionate’ means. See artificial nutrition and hydration.... extraordinary means

Nitrogen Balance

the relationship between the nitrogen taken into the body and that excreted, denoting the balance between the manufacture and breakdown of the body mass. A negative nitrogen balance, when excretion exceeds intake, is usual after injury or operations as the energy requirements of the body are met disproportionately from endogenous sources.... nitrogen balance

Nonmaleficence

n. one of the *four principles and common to many theories of medical ethics: doctors should avoid causing harm to patients (see primum non nocere). As almost all medical interventions carry some risk of harm, however small, in practice a doctor should avoid risking unnecessary harm or any harm that is disproportionate to the benefit intended. Consequently, risks should be minimized and considered along with the intended benefits when evaluating specific interventions. Harm can include psychological, emotional, or social harm as well as physical damage. Compare beneficence.... nonmaleficence

Obstructed Labour

failure of the presenting part to descend in spite of uterine contractions, which implies a mechanical cause. Obstruction is usually due to (1) an abnormality in the woman’s pelvis (a contracted pelvis); (2) an abnormality in her baby (e.g. hydrocephaly); or (3) an abnormality in the relationship between them, either (a) an abnormal *lie (e.g. transverse) or *malpresentation, or (b) *cephalopelvic disproportion (CPD). CPD and impacted transverse lie are the most important causes. Much of the purpose of antenatal care is to screen mothers who are at risk from obstructed labour, which can be detected early by means of a *partogram. If undetected, it can lead to rupture of the uterus, death of the fetus, obstetric fistulae, or maternal death.... obstructed labour

Sotos Syndrome

(cerebral gigantism) a rare inherited disorder resulting in excessive physical growth during the first 2–3 years of life. It presents in childhood with a characteristic facial appearance, a disproportionately large head, large hands and feet, abnormally widely spaced eyes (ocular *hypertelorism), developmental delay, and tall stature for age. Children with Sotos syndrome tend to be large at birth and taller and heavier, stabilizing after about five years to achieve normal adult height. Most cases occur sporadically, although familial cases have been reported. [J. F. Sotos (1927– ), U.S. paediatrician]... sotos syndrome



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