Archive for March 11th, 2009


March 11th, 2009

Tests to detect genetic abnormalities.

These may be advised if there is any family history of genetic disease or if the mother is over 35 years of age. The most common genetic disorder is Down’s syndrome. About half the children with Down’s syndrome are born to mothers over 35 years of age. Other genetic disorders that can be diagnosed before 20 weeks include cystic fibrosis, hereditary disorders of red blood cell formation such as thalassaemia, and many rare disorders of body chemistry resulting from congenital lack of particular enzymes. Hereditary disorders that are sex-linked (transmitted through the mother’s genes to all or half of all conceptions, but causing disease only in male offspring) can be predicted by detecting whether the foetus is male.

The chromosomes in the nuclei of foetal cells must be examined to detect genetic abnormalities. Chromosome tests will also discover the sex of your foetus, which you can be told if you wish. Foetal cells may be obtained in several ways.


This is a test to analyse the foetus’s chromosomes and genes. A sample of amniotic fluid can be obtained by inserting a hollow needle through the abdominal wall and the wall of the uterus into the amniotic sac. The procedure is done with local anaesthetic and the guidance of ultrasound. Amniocentesis takes about 10 minutes, though the needle is in the amniotic sac only for about 30 seconds. The miscarriage rate after amniocentesis is one in a hundred or less.

The fluid obtained is centrifuged to separate the cells from the liquid. The cells are placed in a nutrient broth and incubated until they have grown enough to be examined. This can take from a few days up to four weeks. When the specimen is ready, the chromosomes in the cells’ nuclei are examined. If certain genetic disorders are suspected, the genes concerned are identified by special techniques to see whether the foetus is affected by Down’s syndrome or other less common genetic problems.

Some foetal disorders that are not inherited may be discovered by amniocentesis. The amniotic liquid may be analysed
for alpha-fetoprotein and nine out of ten cases of spina bifida can be detected in this way. The degree of foetal anaeimia from Rh iso-immunisation and other disorders of red-cell formation can also be assessed from the amniotic fluid. In preterm labour, amniotic fluid can be examined to see whether the foetal lungs have produced surfactant.

Amniocentesis can’t be performed until
14-16 weeks, which means that the results of genetic tests may not be available until 18-20 weeks. If genetic abnormality is discovered and termination of pregnancy is chosen, it must usually be by induced labour.

Chorionic Villus Sampling (CVS)

This is a method of obtaining foetal cells by passing a slender tube through the cervical canal and using gentle suction to withdraw a fragment of the outer membrane (chorion) of the amniotic sac. CVS may also be performed through the abdominal wall. Both procedures are performed with ultrasound guidance.

More cells are obtained than by amniocentesis, so they can be examined immediately or after a short period of culture. Results are usually available within 10 days, often sooner. CVS can be performed from the eleventh week of pregnancy. The earlier diagnosis of genetic abnormalities allows termination of pregnancy, if necessary, by the safer method of suction aspiration. The test is not suitable for diagnosis of spina bifida. The risk of miscarriage after CVS through the cervix is about three per hundred, and a bit less if performed through the abdomen; less than 1 per cent higher than the risk of miscarriage at 10 weeks among women who haven’t had CVS.

Tests in the future

Researchers in Adelaide have developed a blood test to detect some foetal abnormalities from as early as eight weeks. The new test, which poses no risk for the pregnancy, is performed simply by taking a sample of the mother’s blood and isolating the foetal cells: some cells from the foetal placenta always enter the mother’s blood. The cells may then be cultured and examined for genetic defects. The test is not yet available outside the research centre, but in the future this Australian advance in antenatal diagnosis is expected to be used worldwide.

No doubt in future there will be more and better ways of diagnosing and monitoring foetal health. But it’s important to remember that there are no tests that can tell you for sure that you will have a normal baby.



March 11th, 2009

Over the past 25 years, more and more couples who feel that their families are complete are deciding on permanent methods of contraception: that is, sterilisation. A medical journal article in 1990 mentioned that in at least 60 per cent of Australian couples, one partner is eventually sterilised. This seems a very high rate, perhaps because it includes women who have had hysterectomy for reasons other than sterilisation.

The trend in favour of sterilisation has been influenced by the move towards smaller families and more acceptance of sterilisation by the public and doctors, as well as improved techniques, some of which can be done with local anaesthetic in clinics and day surgeries.

Most doctors take requests for sterilisation very seriously and counsel patients carefully before going ahead. It’s generally preferred that both partners take part in counselling.

Sterilisation must be considered permanent. Though reversal can be attempted and is sometimes achieved, success can’t be guaranteed. Women and men considering sterilisation should discuss all aspects of the procedure and its possible
consequences with their partner and their doctor.

• You must understand clearly your reasons for wanting to be sterilised.

• You must intend it to be permanent. If you have any thoughts about future reversal, you probably aren’t totally sure about your decision.

• You must have thought of all future circumstances that could make you regret the decision. These include break-up of your marriage or death of your spouse; future relationships; loss of one or more of your existing children; improvement in your health or finances; changes in your life plans.

• You must know how the procedure is done, how it works, time taken for surgery and recovery, length of convalescence and cost.

• You must be aware of all possible side-effects and complications of the procedure, both short and long term. Doctors usually give out written information as well as telling you about the procedure and its possible consequences. This gives you a chance to read and think about it at your leisure.

The decision for sterilisation is usually straightforward when a couple believe they have as many children as they want or when another pregnancy would be a health risk for a woman. I believe that it may be an easier decision for a woman, who may feel sure that she doesn’t want to bear any more children regardless of her future circumstances, than for a man who may regret that he can’t father children in a future relationship. It is a decision that shouldn’t be made hastily or forced by circumstances.

Most individuals or couples have already thought the matter out carefully before the request is made. However, some people have unrealistic grounds for seeking sterilisation, and in such cases there are most likely to be regrets. These instances include:

• coercion to sterilisation by partner, doctor, relatives, peers or political authorities

• sterilisation of an uncertain or unwilling partner to please or for the sake of the other partner. However, as long as the one to be sterilised is certain about wanting no more children, it is valid for, say, a man to have a vasectomy because another pregnancy would be risk to his wife’s health, or for a woman to have a tubal sterilisation because her husband believes they can’t afford more children

• dislike of or lack of confidence j reversible methods of contraception, though this may also be a sound reason as long as the one to be sterilized is certain about wanting no more children

• a belief that sterilisation will solve chronic and deep-seated sexual problems within the individual or the relationship.

There may also be regrets for men if they hold the belief that virility or potent is connected with fertility.



March 11th, 2009

Slow-release injections of progestogens for contraception have been used since the early 1960s – for almost as long as has oral contraception. Two different hormones are used at present.

1 Depot medroxyprogesterone acetate (DPMA, brand name Depo-Provera) This is injected into a muscle (usually the buttock) every 12 weeks. DPMA is available in Australia, and may be used for contraception by women for whom it is most suitable. It can also be used for the treatment of endometriosis, certain cancers and some uterine bleeding problems.

2 Norethisterone oenanthate (NET EN) is injected every eight weeks. It is not available in all countries.

How do injections work?

Mainly they work by stopping ovulation through inhibiting the release of FSH. Also, the progestogen makes the endometrium and cervical mucus anti-fertile; this effect is similar to but more steady than the effect of the mini-Pill.

How effective are contraceptive injections?

Slow-release injections of progestogens are the most effective reversible method of contraception. Theoretical efficacy is nearly total; the only mistake in using this form of contraception would be forgetting to have the next injection on time.

Side-effects of injections

The main side-effect is unpredictable uterine bleeding. Most women will have no periods after six months of treatment.

During the first six months there may be frequent spotting or prolonged episodes of light bleeding. Other side-effects that have been reported are similar to those of the Pill, including moodiness and loss of libido, breast enlargement and tenderness, weight gain, aggravation of acne, bloatedness and headache. None of the oestrogenic side-effects of the Pill occur, such as facial pigmentation and nausea.

Two other problems may arise after stopping DPMA due to the residual effect of the injection which, though releasing too little progestogen to be relied on for contraception, can take months to be completely eliminated.

• When periods return, they may be heavy and irregular for a while.

• Return of fertility may be delayed for 12 months or more, though many studies have shown that after two years the pregnancy rate for women who have used DPMA is the same as for women of the same age who have used no contraception.

In case of failure, what is the effect on pregnancy?

There’s no evidence of an increase in the number of ectopic pregnancies or miscarriages. A few female babies conceived while the mother was using DPMA have slight enlargement of the clitoris. This returns to normal soon after birth. No other foetal abnormalities have been reported, but the number of pregnancies occurring is low because DPMA is such an effective contraceptive. There have been no effects on pregnancies of women who have recently been using contraceptive injections.



March 11th, 2009

The ovarian cycle and ovulation

Ovarian tissue contains immature (resting) ova (eggs) and stromal cells. Each ovum is surrounded by a ball of closely packed, specialised stromal cells, which is separated from the surrounding, looser ovarian tissue by a thin membrane.

An ovum and its surrounding cells form an ovarian follicle. We are born with about 300 000 follicles in each ovary. They remain in a resting state until puberty. From then on, between 10 and 20 follicles will begin to mature each month, of which only one is likely to reach full maturity and be released.

The maturing follicle

As we have seen, the trigger that starts a testing follicle on the path to maturity is FSH from the pituitary. Under the influence of FSH the ovum enlarges and its nucleus prepares to halve its number of chromosomes. At the same time the cells surrounding the ovum multiply and produce fluid that separates them from each other. Ovarian stromal cells outside the follicular membrane multiply and become packed together to form a capsule for the follicle. The cells in the inner layers of this capsule produce progressively more oestrogen as the ovum matures. The outer capsule has an important function after ovulation, as we shall see.

As maturation proceeds, the fluid between the cells surrounding the ovum runs into a central lake that pushes the ovum to one side. A mature follicle is a fluid-filled ball up to 2 cm in diameter that bulges from the surface of the ovary. Development of a follicle from resting to maturity takes about 14 days.

I have mentioned that only one ovum reaches maturity in each cycle. What happens to the other 9-19 ova? They fall by the wayside. The follicle that grows fastest has more cells to attract FSH and keep its growth going, and knocks the others out of the race – the survival of the fittest.

You may also be wondering about the 300 000 resting ova per ovary with which we are born. Even with an ovarian cycle every month for 35 years (which doesn’t often happen because the ovarian cycle is suspended during pregnancy and lactation), only about 8000 of these would ever begin to mature, and at the most around 450 would be released as mature eggs. What happens to the rest? The answer is that from birth to the menopause immature ova are constantly dying, disintegrating and disappearing. The few that a left by the age of 50 are mostly defective and none can be found after the menopause.


As the follicle matures it produces mol and more oestrogen. Shortly before the ovum is ready to be released (usual about 12 days after the beginning q the cycle), the amount of oestrogen in the blood reaches a certain level, which stimulates the pituitary to release a surge of LH. The LH surge causes the follicular wall to produce chemicals that make it weaken and rupture. The ovum is pushed out of the follicle.

This is ovulation. The fronds at the ovarian end of the tube are waiting to sweep up the ovum and send it on its journey towards the uterus. If it is not fertilised within about 12 hours after ovulation, the ovum dies and disintegrates.

The ovary after ovulation

The follicle collapses after its fluid and the ovum are ejected, and the break in its wall seals. The inner layer of its capsule continues to produce some oestrogen, and the outer cells are now stimulated by LH to make the other important hormone of the ovarian cycle, progesterone. This hormone gives the cells a yellowish colour, and the follicle now becomes the corpus luteum (which means ‘yellow body’): hence, also, the name ‘luteinising hormone’. The main function of progesterone is to prepare the lining of the uterus for pregnancy (see below under menstrual cycle).

During the first 3-4 days after ovulation the corpus luteum produces increasing amounts of progesterone. The combined effect of oestrogen and progesterone in the blood has a feedback effect on the pituitary, which stops releasing LH. Without LH, the corpus luteum gradually stops making progesterone over the next 8-9 days, and shrivels up and dies. The ovarian cycle has finished. However, unless pregnancy has occurred, a new cycle begins at once.



March 11th, 2009

Good health means soundness of body and mind, freedom from disease or ailment. It’s what we all want – that great feeling of vigour, happiness and optimism that makes you glad to be alive.

Throughout history people have sought good health, though advice on how to find it hasn’t been constant. There were times when it was thought that all you needed to keep well was to worship the right gods and wear a few charms to ward off evil spirits.

These days health authorities and the advertising industry bombard us with advice on what to do (and even more about what not to do) to be healthy. It’s largely a matter of common sense: eat well; get enough exercise and rest; avoid known health risks; be happy. Sounds easy, and in fact for most people it is.

We all know we must eat well to keep healthy. A good diet during puberty is especially important to provide for that growth spurt and give you energy. At any age, if you’re well nourished you’re less likely to catch infections. We hear and read so much about nutrition, healthy eating and weight control that it would be surprising if anyone hadn’t got the message about the diet that’s now believed to be best for health.

Dietary advice has changed over the past few decades. In my youth we were told that good health was the reward for eating your greens, lots of meats and dairy foods, ‘an apple a day’, and a regular dose of cod-liver oil or something like it. Filling up on cereals, bread and potatoes was believed to be ‘bad’ nutrition.

Today cereals, bread and potatoes are back in favour, fibre (in most plant foods) is ‘in’, and we are warned against eating too much fat, sugar and salt and animal protein.

Adults worry that many teenagers don’t seem to have much regard for proper nutrition. They often skip meals; they’re always snacking; they love junk food’; many seem to exist on soft drinks, potato chips, hamburgers and chocolate. What’s more, most of them seem to survive quite well, which baffles the nutrition educators!

I think the truth is that adults – parents in particular – note and remember the ‘bad’ foods that their kids eat, but they tend not to remember the ‘good’ foods also eaten and that all foods have some nutritional value, even if it’s only a quick carbohydrate ‘fix’ that teenagers seem to crave to satisfy their huge energy needs.

The main worry about snack foods is that though they provide energy they often don’t provide enough other essential nutrients, and even when they do they are often too high in sugar, fat and salt.

• Hamburgers and take-away chicken or fish contain useful protein but often have too much fat and salt. A plain hamburger, skinless chicken or grilled fish are healthy choices.

• Chips contain fibre and good complex carboyhydrate, but too much fat and salt. A jacket-baked spud (now sold at many fast-food shops) is nutritionally better if you go easy on the sour cream.

• Soft drinks are made of flavouring, sugar (nine teaspoons in a 375-ml can!) and wafer. They provide energy but no other nutrients.

It’s true that many teenagers develop I eating habits that can have some bad effects on health and lead to problems with weight control. Some of the health risks of unhealthy eating include the following.

•Tooth decay can result from too much sugar (confectionery, biscuits, cakes).

• If you eat no fruit, vegetables or whole-grain cereals you’re likely to be constipated. The high- fibre content of these plant foods also helps with weight control, and is believed to help prevent

bowel cancer and some other chronic bowel problems of later life.

•You need plenty of calcium for growing bones. It’s now thought that girls whose bones store adequate calcium during teenage growth are at less risk of developing brittle bones in later life. Dairy foods are the best source of calcium. If you’re worried about weight gain, fat-reduced milk products are available.

• Girls lose iron during menstruation. If there’s not enough iron in your diet, you’re at risk of becoming anaemic. Meat and green vegetables are good sources of iron.

• If you continue to have too much fat in your diet, it could put you at risk of heart and blood-vessel disease when you’re older.

• If you skip or skimp on breakfast you’ll be less able to think clearly and concentrate during the morning.

• Skipping meals won’t help with weight control. You’ll just get hungrier and snack on fattening foods or eat more at the next meal.

There’s such an abundance of top-quality food available in Australia that no one need be badly nourished. Good food doesn’t have to be expensive. Fresh food is generally cheaper than processed food. What’s more, a balanced diet generally provides all the vitamins and minerals a healthy person needs, so there’s no need to spend money on dietary supplements.