An overview of ovo fetal causes explaining about the causes of defects in conception also the maternal causes and paternal causes plus describing mechanism of abortion.

Careful studies of abortuses show that in about 60 % of cases the ovum is defective and has failed to develop, or the fetus is malformed. In many cases the defect occurs at the time of conception, and chromosome studies of first trimester abortions show that at least 20 % have chromosomal abnormalities. As the defect affects all parts of the ovum, the trophoblast does not implant adequately, and is unable to synthesize progesterone in adequate amounts.

General maternal disease, especially acute fevers, favors abortion perhaps by the transplacental passage of viruses or bacteria, or perhaps due to the general metabolic affects of pyrexia and diminished oxygen release through the placenta.

Local disorders of the genital tract, such as retroversion, myomata and developmental defects were, at one time, considered to be important causes of abortion. It is now known that only when the retroverted uterus is fixed in the pelvis, or when the myomata distort the uterine cavity do these conditions increase the risk. Developmental defects are relatively uncommon, and of them a bicornute uterus may cause abortion, especially after the 12 th week of pregnancy. Another cause of late abortion is cervical incompetence which may be due to a congenital weakness, but is usually due to previous rough dilatation of the cervix. Psychosomatic causes. It is known that environmental stress operating through the cerebrum affects the secretion of substances by the medial eminence of the hypothalamus.

This area is richly supplied with nerves which are in intimate connection with the pituitary portal vessels. These carry the substances which regulate the release of pituitary hormones, which in turn affect uterine function. Stress can therefore affect uterine activity, and may lead to abortion. This is most clearly seen in the patient who habitually aborts, and the only common factor in the success of the many treatments offered is the interest shown in the patient by the obstetrician.

Since the paternal spermatozoa give to the ovum half of its chromosomes, defects may result in abortions. This is difficult to determine, but it is known that some women abort habitually with one partner and on marrying a different man have normal pregnancies. The immediate cause of the abortion is the separation of the ovum by minute haemorrhages in the deoidua. The altered uterine environment stimulates the onset of uterine contractions, and the process of abortion begins.

Before the 8 th week the ovum, covered with villi and some attached decidua, tends to be expelled. If the internal os dilates but the external os of the cervix fails to dilate, the sac may be retained in the cervix.

Between the 8th and the 14th week, the mechanism may be as described, or, more commonly, the membranes rupture expelling the defective fetus but the placenta is only partially separated and protrudes through the cervical os into the vagina or remains attached to the uterine wall. This type of abortion is attended by considerable haemorrhage. After the 14 th week, the fetus is usually expelled, followed by the placenta after an interval. Less commonly, the placenta is retained. Bleeding is not marked and the process of abortion resembles a ‘miniature labor’.

An overview of causes of bleeding in the first trimester and looking at varieties of abortion and threatened abortions plus describing the treatment options and prognosis.

Although abortion accounts for 95 % of cases of bleeding in the first trimester, the rarer causes such as ectopic gestation (1 %), hydatidiform mole (0.2 to 1 %), cervical ‘erosion’ or polyp (1 %) and cervical carcinoma (00.5 %) must be considered in each case.

For descriptive purposes the abortion is classified according to the findings when the patient is first seen, but obviously one kind may change into the next with the passage of time. The following clinical types are recognized:

Threatened abortion, inevitable abortion, incomplete abortion, complete abortion, missed abortion.

Any of the above types, but usually the inevitable or incomplete types, may be complicated by infection, when the term septic abortion is used.

Habitual abortion indicates that the woman has had three or more known successive abortions, and therapeutic abortion indicates that the pregnancy was terminated legally for a specific medical indication. Induced or criminal abortion indicates that the abortion was induced illegally for social reasons.

An abortion is presumed to threaten when a woman who is known to be pregnant develops vaginal bleeding during the first 28 weeks of pregnancy, whether this bleeding is associated with uterine contractions or not A few patients bleed slightly at the time of the first missed period when the trophoblast is implanting deeply, and this is called implantation haemorrhage. It may be difficult to distinguish this type of bleeding from threatened abortion, but in the former the amount is slight, the color bright red, and the bleeding settles quickly.

Threatened abortion is diagnosed by (1) determining that the patient is pregnant; (2) determining that the bleeding is coming from inside the cervix; (3) deciding that the uterine contractions, if present, are only slight and that the cervix is not dilated. It is sometimes advised that a speculum or bimanual examination should not be carried out on a patient threatening to abort, as this may precipitate the abortion or introduce infection. This is bad advice, and provided the examination is done gently no harm will result, and the occasional mistake in diagnosis will be avoided. To avoid infection the speculum should be passed and the bimanual examination performed with attention to aseptic technique.

This is the most important part of treatment, as it increases uterine blood flow and reduces mechanical stimuli. The patient should remain in bed for from 5 to 7 days, or so long as the bleeding is bright red.

The only drugs of any value are mild sedatives such as phenobarbitone, which should be given both to reduce emotional stimuli, and to convince the patient that some treatment is being given. There is no evidence that progesterone, in whatever dosage and by whatever route, is of any value in the treatment of threatened abortion.

If the uterine contractions become strong, analgesics such as pethidine 100 to 150 mg. or morphine 15 mg. may be required.

Since the diagnosis of threatened abortion in many cases is uncertain, it is difficult to say what the outcome will be. Of all patients diagnosed as threatening to abort in the first trimester, 70 to 8070 continue their pregnancy. The character of the bleeding is of some prognostic help. If the bleeding is bright red and rapidly tapers off to brown only 1070 will abort. If the initial loss is brown and this persists 5570 will abort, whilst if the initial brown loss becomes red 6670 of patients will abort. The association of severe uterine contractions increases the likelihood of abortion.

An overview of an inevitable abortion explaining the procedures of this condition and also looking at incomplete abortion and complete abortion and treatment of these conditions.

The abortion becomes inevitable if, in addition to the signs described in threatened abortion, the uterine contractions become increasingly painful and strong. And lead to dilatation of the cervix. The patient complains of severe colicky uterine pain, and vaginal examination shows a dilated os with some part of the conception sac bulging through. This sequence may follow signs of threatened abortion, or, more commonly, may occur without warning, the whole process being speeded up. Quite soon after the onset of the symptoms, the abortion occurs, either completely, when all the products of conception are expelled, or incompletely when either the pregnancy sac, or placental tissue remains in the uterine cavity or distends the cervical canal. This last can produce considerable shock, even in the absence of marked haemorrhage.

The majority of patients present with an incomplete abortion. The amount of bleeding may have been considerable, associated with cramp like uterine contractions and the patient claims that she has passed ‘something’. This may mean that all the products of conception have been passed and the uterus is empty or it may mean that only part has been passed. If the obstetrician has not had the opportunity to examine everything that has been expelled, he should consider the abortion to be incomplete.

Unless the patient has aborted completely when seen or the abortion is imminent, she should be transferred to hospital. Should she have bled considerably and be in shock, the emergency obstetric service should be called and blood given. Whilst waiting for the arrival of the ‘flying squad’, morphine 15 mg. or pethidine 100 mg. should be given if the patient is in pain. A sterile vaginal examination must be made, as placental tissue distending the cervix can cause considerable shock. Any tissue in the cervix should be removed with finger or sponge forceps, and if there is any degree of haemorrhage, ergometrine 05 mg. should be given intramuscularly. Once this has been done, the patient’s condition usually improves and evacuation of the uterus can be completed by curettage in a calm and deliberate way when convenient.

In hospital, treatment is conservative only if the abortion is proceeding quickly and with minimal blood loss. On admission, the general condition is assessed and compatible blood obtained. A vaginal examination is carried out and if products of conception are distending the cervix, these are removed with a sponge forceps or the finger. Pethidine 100 mg. or morphine 15 mg. is given to relieve the pain, and ergometrine 025 mg. intravenously to control bleeding.

If the entire products of conception are not rapidly expelled, active intervention is required and the sooner the uterus is emptied the better. Evacuation of the pregnant uterus should be done with care as in unskilled hands damage can easily occur. Under general anaesthesia the patient is examined, and if the cervix is sufficiently dilated to admit a finger, this is used to detach any remnants of placental tissue.

It is by far the safest instrument! Alternatively, a sponge forceps can be used. The sponge forceps is introduced until the tip reaches the endometrium at the fundus, and then the two jaws are opened and closed again whilst rotating the forceps. In this way products of conception are grasped without danger to the myometrium. Finally the uterine cavity is curetted. A large sharp curette, used gently, is safer than a blunt curette used roughly. Towards the end of the operation ergometrine 025 mg. is given intravenously and intramuscularly.

After a complete abortion the bloody discharge diminishes and ceases in about when placental remnants have been left in the uterus, bleeding continues beyond this time and varies in severity from day to day, and may be accompanied by periodic uterine cramps. Examination shows a bulky uterus, with a patulous os. Careful curettage should be performed in these cases, and all tissue examined histologically in case the rare choriocarcinoma is present.

An overview of perineal infiltration explaining how this process is done? Also looking at pudendal nerve block and the procedures of doing so plus anaesthesia for mid forceps operations.

Using a 75 cm. 22 gauge needle, and 20 ml. of 1 % lignocaine, the perineum is infiltrated in a fan like manner, the base being the posterior fourchette at the midline. Three lines of infiltration are required: one medially as far as the anal sphincter and midway between the skin and the vaginal mucosa, and two others at 450 to block the nerves as they reach the perineum. Perineal infiltration enables the delivery to be made with little discomfort, permits the making and repair of episiotomy wounds and, if Trilene inhalations are used in addition, permits outlet forceps to be performed painlessly. The anaesthesia is effective in about 3 minutes and lasts between 45 and 90 minutes.

A 10 cm. 20 gauge needle, and if available, a needle director are required. Two fingers are introduced into the vagina and palpate the ischial spine; the guide containing the needle is introduced in the groove between the index and middle finger to impinge on the spine. It is then directed to lie just medial to, and below, the ischial spine and the needle is advanced 1 cm. beyond the guide if no guide is available the needle is introduced between the fingers to the same site and pushed through the sacrospinous ligament. Ten millilitres of 1% lignocaine is injected behind each ischial spine, and a further 10 ml. is used to make a perineal infiltration. Anaesthesia is effective within 5 minutes, and the lower vagina and perineum become insensitive to pain. The degree of anaesthesia obtained by pudendal nerve block is adequate for all low forceps and some mid forceps deliveries. But it is insufficient for most forceps rotations and all manual rotations of the head arrested in the transverse diameter of the mid pelvis.

Local anaesthesia can be supplemented by intravenous anaesthesia in these cases or other methods described in the next section can be used. The supplementation is to give an intravenous injection of pethidine 100 mg. levallorphan 125 mg. and promazine 25 mg. The drugs are mixed with 20 ml. of normal saline and injected slowly over a period of 3 minutes. About 10 minutes after the injection the patient will be asleep and although she stirs during manipulations, does not resist or remember them. After a pudendal nerve block has been introduced, Kielland’s forceps rotation or manual rotation of the head can be performed. The patient sleeps for 1 to 2 hours after delivery and awakens refreshed.

An overview of anaesthesia for difficult operative deliveries and describing some different types of anaesthetic procedures and also older techniques and modern techniques and the procedures of them.

Although Caesarean section and a difficult forceps delivery can be performed without pain if an epidural block has been instituted, the time taken for the block to become effective makes this method inadequate in most cases. The patient must therefore be given some other form of anaesthesia.

This has been recommended as being easy to administer, efficient and causing no fetal depression. Unfortunately it is attended in a large proportion of cases by an episode of hypotension; there may be serious depression of respiration from intercostal paralysis; severe postspinal headache occurs in up to 30 % of patients, and a similar percentage have difficulties in micturition after spinal anaesthesia. These hazards must be taken into account when choosing an anaesthetic agent.

The preferable alternative is inhalational anaesthesia, the main hazard of which is that vomiting may occur during induction of anaesthesia and the regurgitated vomit may be inhaled causing immediate obstruction and asphyxia, or a chemical pneumonitis which may be fatal. Every year obstetric patients are killed in this way. These deaths are preventable, provided that the anaesthetic is given by a trained anaesthetist to a patient who has had no solid food during labour. In some hospitals vomiting is induced by giving an injection of apomorphine prior to administration of the anaesthetic.

Whatever are the dangers of inhalational anaesthesia from the physician’s point of view, from the patient’s point of view this form of anaesthesia is the best, particularly when modem techniques are used, and the anaesthetic is given by a trained anaesthetist. The aim in using inhalational anaesthesia is to induce anaesthesia rapidly without vomiting, and since all the agents traverse the placenta, to use as small an amount as is compatible with effectiveness, safety and satisfactory operating conditions. If no skilled anaesthetist is available induction of anaesthesia with ethyl chloride followed by ether administered via a Schimmelbusch mask is by far the safest method. The anaesthetic agent is irritating to the lung and corneal epithelia but if vomiting occurs it is projectile and inhalation unlikely. The use of ethyl chloride ether is recommended if skilled anaesthetic assistance cannot be obtained.

When a trained anaesthetist is available several techniques are used but most are variants of the following method. After premedication with atropine 0.6 mg. anaesthesia is induced with thiopentone 100 to 250mg. given as 4 to 10 ml. of a 25 % solution. A rapidly acting muscle relaxant, such as succinyicholine, is given in a dose of 30 to 100 mg. to enable a cuffed endotracheal tube to be passed. The intubation is preceded by inflation of the lungs with pure oxygen with the patient in a head up position to prevent regurgitation and inhalation of vomit. Anaesthesia is maintained using cyclopropane or halothane but this is cut off when the uterus is incised in Caesarean section so that the patient’s blood is well oxygenated during the birth of the baby.

anaesthesia, atropine