Obstetrics and Gynaecology

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Obstetrics is the medical specialty dealing with the care of women during pregnancy, childbirth and the puerperium (the period shortly after birth)

Gynaecology literally means 'the science of women', but in medicine this is the specialty of diseases of the female reproductive system (uterus, vagina and ovaries).

Obstetrics and gynaecology form a single specialty, with a combined postgraduate training program. This is quite arduous (in Australia it is among the longest, six years, matched only by neurosurgery).

Some generalists can work as obstetricians, mainly in rural areas.

All gynaecologists, therefore, are trained obstetricians, and vice versa. However, some doctors drop their obstetric practice, especially as they get older. This is due to the double burden of very late hours and high rates of litigation.

Obstetrics

Antenatal care

In obstetric practice, the obstetrician will see a pregnant woman on a regular basis as her pregnancy progresses. The exact schedule varies depending on resources and risk factors, such as diabetes.

The main rationale for these visits is surveillance for diseases of pregnancy which are detectable. Some examples are:

  1. pre-eclampsia. The blood-pressure and urine of a pregnant woman is checked at every opportunity to check for this.
  2. placenta praevia. On ultrasound, the placenta is visible obstructing the birth canal.
  3. abnormal presentation (late pregnancy only). The foetus maybe feet-first (breech), side-on (transverse), or at an angle (oblique presentation).
  4. IUGR (Intrauterine Growth Restriction) , this is a general

designation, where the foetus is too small for its age. Causes can be intrinsic (in the foetus) or extrinsic (usually placental problems).

Induction

An obstetrician may recommend a woman have her labour induced if it is felt that continuation would be more dangerous to her, the foetus, or both. Reasons to induce include:

  1. pre-eclampsia;
  2. IUGR;
  3. diabetes;
  4. other general medical condition, such as renal disease.

Induction usually occurs at 38 weeks gestation. At this age the foetal lung is fully mature. Note that pre-eclampsia is a reason to induce earlier.

If a women does not eventually labour by 41-42 weeks, induction is performed, as the placenta becomes unstable after this date.

Induction is achieved by 3 methods:

  1. pessiary of Prostin cream, prostaglandin E2.
  2. surgical induction, by piercing the amniotic sac.
  3. infusion of oxytocin.


Labour

During labour itself, the obstetrician may be called on to do a number of things:

  1. monitor the progress of labour, by reviewing the midwife's notes, performing vaginal examination, and assessing the trace produced by a foetal monitoring device (the cardiotocograph)
  2. accelerate the progress of labour by infusion of the hormone oxytocin.
  3. provide pain relief, either by nitrous oxide, or opiates (epidurals are done by anaethestists).
  4. mechanically assisting labour, by forceps or the Ventouse (a suction cap applied to the foetus' head.)
  5. Caesarean section, if vaginal delivery is impossible. Caesarean section can either be elective, that is, arranged before labour, or an emergency (during labour).

Emergencies in obstetrics

Two main emergencies are eclampsia and ectopic pregnancy.

Ectopic pregnancy is when an embryo implants in the Fallopian tube or (rarely) on the ovary or inside the peritoneal cavity. Tubal pregnancies are very dangerous, as at about 4-10 weeks the tube bursts, causing massive internal bleeding.

Ectopic pregnancy must be considered in any women with abdominal pain who has the slightest chance of being pregnant. Diagnosis is by a positive pregnancy test and a uterus empty on ultrasound. Treatment is by laparoscopy, and the tube is incised and excavated.

Pre-eclampsia is a disease caused by mysterious toxins secreted by the placenta. These toxins act on the vascular endothelium, causing hypertension and proteinuria. If severe, it progresses to fulminant pre-eclampsia, with headaches and visual disturbances.

This is a prelude to eclampsia, where a convulsion occurs, which is often fatal.

The only treatment for eclampsia, or advancing pre-eclampsia is delivery, either by induction or Caesarean section. Women can be stabilised temporarily with magnesium sulphate. Delivery as early as 28 weeks is not unknown.

Gynaecology

Examination

Gynaecology is a consultant specialty. In most countries, women must see a general practitioner first. If their condition knowledge or equipment unavailable the GP, they are referred to a gynaecologist.

As in all of medicine, the main tools of diagnosis are clincial history and examination. Gynaecological examination is special in that it is quite intimate, and that it involves special equipment -- the speculum. The speculum consists of two hinged blades of flat metal, which are used to open the vagina, to permit examination of the cervix uteri. Gynaecologists may also do a bimanual examination (one hand on the abdomen, two fingers in the vagina), to palpate the uterus and ovaries. Male gynaecologists often have a female chaperone (nurse or medical student) for their examination.Virgins are not usually examined vaginally. an abdominal ultrasound is used normally to confirm the bimanual examination.

Investigations

Some of the investigations used in gynaecology are:

  1. abdominal ultrasound, to give a low-power view of the pelvic organs.
  2. vaginal ultrasound. A probe is passed into the vagina, which allows a detailed view of the uterus and its contents. Good in early pregnancy.
  3. blood tests. Levels of hormones such as oestradiol, luteinising hormone, follicle-stimulating hormone and progesterone are measured.
  4. hysteroscopy -- a fine tube is passed into the uterus via the cervix under a general anaesthesic.
  5. laparoscopy -- tubes are passed into the peritoneal cavity, which is then insufflated with carbon dioxide. This is commonly used to diagnose endometriosis.

MRI and CT scans are not used. Pelvic X-ray is rare. It can be used to delineate the uterine cavity with an injected dye (hystero-salpingogram) and to measure the pelvic girdle.

Diseases

The main conditions dealt with by a gynaecologist are:

  1. cancer of the cervix. The Papanicalou (Pap) smear is a means of detecting this, by obtaining a sample of cervial epithelial cells and examining them under a microscope for malignant changes. All women are encouraged to have pap smears at regular intervals (2 years in Australia) after commencing intercourse.
  2. incontinence of urine.
  3. amenorrhoea (absent periods)
  4. dysmenorrhoea (painful periods)
  5. infertility
  6. menorrhagia (heavy periods). This is a main indication for hysterectomy.

Obviously there is some crossover in these areas. Amenorrhoea in a young girl may be referred to a paediatrician, incontinence to a urologist.

Therapies

Occasionally gynaecologists will use drugs, such as clomiphene (which stimulates ovulation), and, most famously, oral contraceptives (which are also used for dysmenorrhoea).

However, surgery is the main area of therapy. For historical reasons, gynaecologists are not actually surgeons (this is the source of some tension).

Operations that gynaecologists do include:

  1. termination of pregnancy (the most common)
  2. dilatation and curettage (removal of the uterine contents, for various reasons, including miscarriage and menorrhagia; procedurally very similar to the above);
  3. hysterectomy (removal of the uterus);
  4. colposuspension ('tightening' of the ligaments around the vagina, a common therapy for incontinence and discomfort in older women);
  5. Large Loop Excision of the Transition Zone (LLETZ), where the surface of the cervix, containing pre-cancerous cells identified on Pap smear are removed).


Reference


Llewellyn-Jones, Derek, Fundametals of Obstetrics and Gynaecology, 7th ed.,Mosby, 1999.


See also Vulvovaginal health, Sexually transmitted diseases, Pelvic inflammatory disease