Chapter 13 Contraception and STIs

• pregnancy 


  possible outcome of sexual activity

  another possible consequence is acquiring a sexually transmitted infection
• advances in human biological sciences have enabled us to

  understand the reproductive system to facilitate safe sex practices

  allows individuals to plan pregnancies and reduce chance of infections
• only relatively recent times that 


  people have been able to plan a family

  although some family planning techniques have been used for centuries, they were notoriously unreliable
• modern science has made

  older methods more effective and has also introduced new and highly reliable methods of birth control
• ability to control reproduction has led to many 


  social changes for women and men

  people can now decide whether or not they want to have children
• if they decide to have a family

  the number of children and the time interval between babies can be planned
• most methods of family planning or birth control involve

  prevention of fertilisation and hence of conception
• contraception 


  measure that prevent a woman from having a child
• abstinence 


  not having sexual intercourse at all

  only option that has no risk of either pregnancy or side effects
• spermicides work in two ways

  they contain a substance that immobilises and destroys sperm

  they react with moisture in the vagina to form bubbles of carbon dioxide, which present a physical barrier to the sperm
• spermicides are available as

  creams, tablets, pessaries or aerosol foam
• spermicides may be used with

  condom, diaphragm and cervical cap

  they are very unreliable when used alone, but they do add to the effectiveness of barrier devices
• sterilisation 


  permanent method of birth control for both men and women where the anatomy of the reproductive system is altered so that the sperm and egg are unable to meet
• choice of sterilisation as a birth control method

  should be considered only when no further children are wanted

  while it is able to be reversed in some people, it should be thought of as a permanent procedure
• vasectomy 


  sterilisation operation of male has traditionally involved the removal of a small pieced of each vas deferens
• vasectomy process


  relatively simple: a small cut is made on each side of the scrotum

  small segment is then removed from each vas deferens and then cut ends are tied or sealed with heat

  cuts in scrotum are then closed

  most operations are done under local anaesthesia, but a general anaesthetic can be used
• sterilisation does not result in

  any loss of sexual desire or pleasure
• new, non-surgical vasectomy is being

  tested in animals with some success

  this technique involves injecting a gel into the vas deferens that blocks the path of the sperm
• female sterilisation

  achieved by performing a tubal ligation/occlusion

  relatively simple procedure, requiring only short stay in hospital
• tubal ligation

  under general anaesthetic, a small incision is made in the abdomen and the uterine tubes are located

  each tube is then cut, a small piece is removed, and the ends are tied
• alternatively,

  instrument called laparoscope may be used

  passed into abdominal cavity through small 1cm cut at lower edge of navel

  once inside abdominal cavity, doctor is able to locate uterine tubes and fit metal clips to each, crushing the section of the uterine tube
• after tubal ligation

  sperm cannot reach egg, and the egg cannot reach the uterus

  a female has no decrease in sexual desire as a result of this operation
• castration

  removal of the testes
• oophorectomy

  removal of ovaries
• castration and oophorectomy affect

  the balance of the reproductive hormones and have profound effects on sexual drive and body characteristics

  usually performed when the organs are diseased
• hysterectomy 


  removal of the uterus also results in sterility
• some methods of birth control rely on

  female ability to determine the time of ovulation
• periodic abstinence or 'safe period' technique 


  abstain from sexual intercourse on the days when fertilisation is most likely

  number of ways of determining the safe period
• rhythm method

  based on the fact that an egg is available for fertilisation during a period of only 3-5 days in each menstrual cycle

  if a female has a regular 28-day menstrual cycle, ovulation is likely to occur in about the 14th day
• as the egg can survive for only

  2 days unless it is fertilised, and sperm can survive in female reproductive tract for 4 days at most, sexual intercourse should not occur between 4 days before and 4 days after ovulation, if pregnancy is to be avoided
• an extra allowance should then be made in case (rhythm method)


  egg is not released exactly on the day 14, but a day or so earlier or later
• most women do not have

  cycles that are exactly the same each month, and the cycle is seldom exactly 28 days

  for this reason, the rhythm method is now usually used in combination with other methods
• temperature method

  refinement of the rhythm method of predicting ovulation

  a female can take her body temp each morning to determine the time of ovulation more accurately
• ovulation is accompanied by

  sharp drop in body temp and then a rise
• using temperature method

  a women then knows she can safely have intercourse three days after the temperature rise has occurred
• mucus method 


  developed by an Australian doctor, another way of predicting the safe period more accurately

  probable time of ovulation is predicted by observing a change in mucus in the cervix
• immediately after menstruation

  the tissues of the vaginal opening feel dry
• as ovulation approaches

  mucus can be detected

  at first it is cloudy and sticky, but as the cervix secretes more mucus its nature changes: mucus becomes clearer, feels slippery and strands ill stretch without breaking
• on day of ovulation

  peak of clear mucus is reached, after which it becomes cloudy again
• sexual intercourse is safe when

  there is no mucus, and more than three days after the last day of clear mucus