An overview of the selection of anaesthesia and analgesia and describing some of them and also dangers of anaesthesia in obstetrics also describing the effects of some situations.

Different obstetric situations require the use of different agents or combination of agents. A suggested scheme is laid out below. In each section the method of choice is listed first. Dystocia especially minor disproportion and inco ordinate action Pethidine and phenothiazine infusion Epidural nerve block Paracervical nerve block Intra uterine manipulations

General inhalational anaesthesia, using halothane in closed circuit or open ether Pudendal nerve block, supplemented by intravenous pethidine 100 mg. and chlorpromazine 25 mg. diluted in 10 ml. of normal saline, and injected slowly General inhalational anaesthesia Spinal or epidural anaesthesia Low forceps delivery, episiotomy repair Perineal infiltration Pudendal nerve blocks 5. Breech delivery Thiopentone, intravenous, with birth of fetal abdomen Caesarean section General inhalational anaesthesia Spinal anaesthesia

If an excessive dose of a local anaesthetic agent is given, or if the drug is injected intravenously in error, toxic manifestations may occur. The maximal permissible single injection of lignocaine is 60 ml. of a 1 % solution and 20 ml. of a 2% solution. The toxic manifestations initially are drowsiness and cerebral depression or mental confusion. These may be followed by muscular twitching and convulsions, with cardiac and respiratory failure as terminal events. Treatment is to maintain high oxygenation, and if convulsions occur to control them with intravenous suxamethonium or thiopentone, and ventilate the patient’s lungs with oxygen.

Hypoxia from respiratory paralysis is the main danger. A further hazard is hypotension which requires the use of a rapidly active hypertensive agent, such as ephedrine 25 to 50 mg. intravenously. Postoperative headache, often severe, and difficulties of micturition occur in 30 % of patients.

Apart from overdosage, which should never occur if the anaesthetic is given by trained staff, the great hazard of inhalational anaesthetic agents in obstetrics is inhalation of regurgitated vomit. Statistics indicate that one woman in every 40,000 delivered dies from this cause and the condition accounts for 4 % of all maternal deaths.

Two types of accident can occur: (1) the obstructive type due to blockage of the main bronchus by solid food particles; and (2) the pneumonitic type due to aspiration of acid stomach contents into the small bronchioles which causes a marked allergic bronchiolar spasm. Aspiration of solid vomitus causes immediate signs of anoxia, whilst the onset of symptoms from inhalation of acid stomach contents may be immediate or delayed for some hours. The patient becomes acutely ill with respiratory distress, bronchospasm, cyanosis and tachycardia. Pulmonary oedema appears later in some cases if the pH of the aspirate is very low.

As soon as vomiting is recognized the patient should be placed head down and the mouth and pharynx aspirated with a sucker. If it is thought that either solid food particles or acid vomit has been inhaled, a bronchoscope is passed and suction of the bronchial tree carried out. Oxygen is given by positive pressure. Cortisone and a wide spectrum antibiotic is administered in an attempt to combat shock and prevent infection.

An overview of radiology in obstetrics explaining about the processes and the genetical effects of radiology also looking at fetal indication which are diagnosis of pregnancy fetal presentation.

Following the radiological investigations of pelvic architecture by Caldwell and Moloy and Thorns in the (1930s) routine radiological pelvimetry carne to be considered an essential prenatal investigation, the omission of which rendered the obstetrician liable to a charge of neglect or malpraxis. In the postwar years the dangers of the indiscriminate radiation have become increasingly obvious, with the result that radiological investigations in pregnancy are now used with much greater discrimination and consideration.

Most mammalian cells, including those of man, are susceptible to radiation damage and possible genetic mutation, particularly at a time of rapid frequent mitosis. In the human embryo organogenesis occurs most rapidly during the 1st to 10th week of the gestation interval and continues in lesser degree until delivery. It follows that no period of intrauterine life is free from radiation hazard, but this is most marked in the first 6 to 8 weeks after fertilization. For this reason no female who might be pregnant should ever undergo any pelvic radiological investigation in the second half of the menstrual cycle, or during pregnancy, unless there is a good reason. Genetic mutation is cumulative and related to dosage in a linear fashion, so that care should be taken at all times before recommending radiological investigations and this applies particularly in pregnancy when two individuals are at risk. The hazards of radiation will be reduced further if a high speed screen and film are used, and if long tube film distances are adopted.

In most cases radiology is contra indicated as a means of diagnosing early pregnancy, as rapid immunological tests can be more easily performed and radiation hazards to the young fetus avoided. Fetal parts cannot be detected with regularity or accuracy before the 18th week of pregnancy, but after this time the absence of fetal parts in a pregnant woman is suggestive of trophoblastic tumor.

Occasionally clinical examination fails to determine the presentation of the fetus, or whether the pregnancy is multiple. Exact information is not usually required before the 28th week of pregnancy but after this time it may be necessary to resort to radiology. The radiograph will give visual information of the presentation and can confirm the clinical impressions. If the patient is suspected of having a multiple pregnancy the confirmation of the diagnosis by radiology should be made between the 28th week and the 32nd week so that the mother may receive treatment and may make preparations for the care of two infants.

The confirmation of breech presentation should not be made radiologically until the 32nd to 34th week of gestation as prior to this time spontaneous version may occur. In most cases clinical confirmation obviates the need for radiology. Uncommon malpresentations such as brow and face need no confirmation by radiology until late pregnancy or labour reveals cephalopelvic disproportion in the case of the brow, or inexplicable findings on vaginal examination in the case of the face.

An overview of fetal maturity explaining about detection of the epiphysis and also looking at fetal skeletal malformations and radiological pelvimetry indications of radiological pelvimetry also explaining of different techniques of radiologists.

Occasionally radiological detection of fetal femoral and tibial epiphyses is used to confirm a clinical assessment of fetal maturity. Unfortunately the time of appearance of the epiphysis varies. The distal femoral epiphysis can first be detected some time between the 35th and 40th week, and by term is present in 95 % of fetuses. The proximal tibial epiphysis appears between the 37th and 42nd week, and by term is present in 75 % of cases. These variables limit the value of the investigation but if, after full consideration of all available data, doubt about fetal maturity exists, radiology may give a positive confirmation that the pregnancy has advanced beyond 36 weeks gestation.

The presence of anencephaly and hydrocephaly suspected by clinical methods can be confirmed satisfactorily by radiology. It must be remembered, however, that if the fetus presents as a breech and a standard antero posterior film is taken, since the fetal head is nearer the source, its shadow on the film will be larger, and hydrocephalus may be misdiagnosed. This can be avoided by noting the size of the face in relation to the size of the cranial vault or by taking a lateral view. Spina bifida, which may be associated with a meningomyelocele, can often be detected, but may be without clinical or radiological manifestation.

At the outset it must be observed that radiological pelvimetry does not predict the outcome of labour, at the most it gives valuable help to the obstetrician to make a prediction after examination of all the available information, particularly when clinical methods have proved inadequate. ‘Pelvimetry’ is perhaps an unfortunate term, for the information given by radiology concerns not only pelvic measurements but the architecture of the pelvis, and the size and station of the fetal head or breeches.

The indications for radiological pelvimetry are listed in the table, and the most important is the non engagement of the fetal head by the 37th week of pregnancy, in the primigravida. In pregnancy no radiological pelvimetry should be made until a clinical pelvic assessment has been made and the 37th week of pregnancy has been reached, but following difficult labour, pelvimetry can be satisfactorily performed in the puerperium and the patient told of the probable method of delivery in her next pregnancy.

Many different techniques have been devised to overcome the distortion which is inevitable when an object which has three dimensions is projected onto a two dimensional plate. Since the various pelvic diameters lie in different planes their projection onto the film will be at differing magnifications, and allowance for this must be made before the film is interpreted. These matters are properly the province of the radiologist, and most techniques have overcome them and can give measurements of ± 05 cm.

Two views are essential, the lateral and the anteroposterior of the pelvic brim; and a third, the outlet, is indicated in special cases. In labour the lateral film gives the most information and is attended by the least radiation hazard.

1. Lateral view of the pelvis

This is carried out preferably with the patient erect. An isometric scale is secured in the cleft of the buttocks and since this is on the same plane as the diameters required, a direct measurement can be obtained. The tube is centered on the greater trochanter of the femur and a tube film distance of 90 cm. is adopted. If the patient is positioned correctly the film will show a super imposition of the two acetabular notches.

In the lateral view the following information can be obtained: (1) the antero posterior diameter (AP) of the pelvic inlet, the mid pelvis and the outlet; (2) the pelvic architecture as shown by the shape of the anterior surface of the sacrum, the ischial spines and the greater sciatic notch; (3) the presentation, position and station of the fetal presenting part.

2. Antero posterior view of the pelvic brim

It is this view which requires correction because of the divergent distortion of the different pelvic levels. The use of a special isometric scale, or stereoscope projections, or of calculations will give the required information. The patient lies supine with the shoulders supported at an angle of 30° above the horizontal. This has the effect of making the pelvic brim roughly parallel to the film. The x ray tube is centered on the midpoint between the antero superior iliac spines, and a tube film distance of 90 cm. used. The antero posterior film will show the shape of the pelvic inlet, the AP and transverse measurements (Tr) of the brim, and by calculation the interspinous diameter can be found. 3. Outlet view

This view is only required in those cases where outlet contraction is suspected on clinical examination. Two methods are used: (1) the patient sits on the cassette, leaning well forward with the legs apart, and a postero anterior view of the tuberosities and pubic rami is obtained on a small film; or (2) the patient lies supine with her legs apart and a marker pressed between the ischial tuberosities. The tube is directed at the pubic arch at an angle of 450 and an antero posterior view taken.

An overview of the interpretation of the film explaining about the procedures of this method and also looking at minor disturbances of pregnancy heartburn, constipation and palpitations and fainting.

As was pointed out, the assessment of pelvic contraction from a single measurement may be misleading, and several mathematical approaches have been introduced:

1. The brim area

This is calculated from the formula if the brim area is more than 100 sq. cm. and the pelvic architecture favorable no difficulty in vaginal delivery need be anticipated. If the brim area is less than 85 sq. cm. vaginal delivery is unlikely.

2. Forecast graphs

In Moir’s method the fetal biparietal diameter and pelvic diameters at the inlet, narrow midplane and outlet are correlated and plotted on a graph in order to give some indication of the outcome of labor. The graphs have been prepared from the pelvic measurements of patients delivering normally. If the measurements of the unknown pelvis are plotted above the line indicating the normal, then a vaginal delivery may be expected. All the calculations necessarily ignore the importance of uterine contractions and maternal fortitude as factors in determining the outcome of labor and can only be a guide; therefore the obstetrician must never base his treatment on the forecast of the radiologist alone.

He must assess all the information available to him for each individual case. Ultimately the responsibility for obtaining a live, healthy baby, without damage to the mother, is his. Radiology is a valuable adjunct to prognosis but it should not be used as an excuse by the lazy or inadequate obstetrician for resorting to unnecessary Caesarean section.

Relaxation of the cardiac sphincter permits the regurgitation of stomach contents causing irritation of the lower oesophagus. Symptomatic relief is all that can be offered, and a variety of drugs have been given with varying success. Frequent small meals, avoidance of spices, and the use of antacid tablets may help in some cases. Extra pillows, so that the patient sleeps propped up, may also be of value.

Constipation is usual in pregnancy and is due to the lowered muscle tone of the gut, aggravated in late pregnancy by the pressure of the enlarged uterus. Treatment is by increasing the fluid intake, by re establishing the normal habit of defaecation after a meal, and by the use of purified senna or the contact laxative bisacodyl.

These are common in pregnancy and are due to the altered cardiovascular dynamics, and the introduction into the vascular system of the placental bed. The patient must be reassured that she has no organic lesion. Owing to the hypervolaemic circulation, soft systolic murmurs may be heard in pregnancy over the precordium. They have no sinister significance. A mild sedative may be required for the anxious patient, but when possible drugs should be avoided in pregnancy.

An overview of varicose veins explaining about the various procedures patient have to go through plus frequency of micturation and placidity and drowsiness and also describing the causes of backaches and pelvic osteo arthropathy and leg cramps.

Patients with varicose veins should be told to sit with their feet elevated whenever possible. Although minor to the physician, the disturbances due to altered physiology occasioned by pregnancy can be anything but minor to the patient. The physiological basis of these has been mentioned previously, and the subject is now treated systematically, from the clinical standpoint. Discomfort is great; nylon elastic stockings should be put on in the morning before the patient gets out of bed. A few surgeons inject isolated segments of the veins with sodium tetradecyl, but in general such treatment is best deferred until after the puerperium. Very occasionally deep vein thrombosis occurs in pregnancy, and is treated with heparin, all other anticoagulants being contraindicated as these cross the placenta.

This is common in the early weeks of pregnancy when it is due to the supra normal excretion of water by the kidney, and in the last weeks when pressure of the fetal head engaging in the pelvis causes direct irritation of the trigone.

These common symptoms are due to the increased circulation of progestogens and apart from explanation no treatment is required.

This is especially common in the last trimester and is felt over the sacro iliac joints. It is usually worse at night and may prevent sleep. Backache is due to relaxation of the ligaments and muscles supporting the joints. Treatment should begin in early pregnancy when the patient should be told to avoid wearing high heeled shoes except on special occasions, and given instruction in posture. The increasing weight of the uterus causes a woman to correct her balance by drawing her shoulders back, with increasing strain on the lower lumbar spine. She should be taught to straighten her whole spine, rather than the upper part only.

In a few women abnormal relaxation of the ligaments of the pubic joint occurs, with the result that the pubic bones move upon each other during walking. This also throws a strain on the sacro iliac joints. The patient complains of pubic pain and backache, which may be very severe. Examination shows tenderness over the pubis. Treatment is to put the patient to bed and to nurse her on one or other side. A firm binder around the pelvis reduces discomfort in the ambulant patient.

The cause of leg cramps in pregnancy is unknown and treatment unsatisfactory. They occur more frequently in the last trimester, usually at night, and are said to be reduced in frequency by the use of calcium lactate 2 g. taken at bedtime.