Geoffrey Chamberlain

OUTCOME OF PREGNANCY AMONG WOMEN IN ANÆSTHETIC PRACTICE

A survey has been made of the outcome of the pregnancies of 5700 women doctors first registered in England and Wales in 1950 or later. Conceptions that occurred when the mother was in an anaesthetic appointment resulted in smaller babies, higher stillbirth-rates, and more congenital malformations of the cardiovascular system than the pregnancies of other women doctors. There was no significant difference in the spontaneous-abortion rate between the two groups. A pronounced effect of age on this rate was evident among all groups examined.

Predictive value of ultrasound measurement in early pregnancy: a randomized controlled trial

Summary. Early fetal biparietal diameter (BPD) measurements were obtained with ultrasound in 1062 women attending for antenatal care; a random half had the results withheld from the obstetricians. Of the 1026 women who were sure of the dates of their last normal menstrual period, 829 (81%) were found to have appropriate biparietal diameter measurements, in 3% the pregnancy was more than 2 weeks further advanced and in 14% more than 2 weeks less than calculated. In 30% of the women whose results were intended to be withheld, the code had to be broken because of clinical concern. There were no differences in fetal outcome (birthweight centile, Apgar score at 1 min and perinatal mortality) in the women whose BPD results were known compared with those whose results were withheld from the obstetrician. But a significantly larger number of labours were induced for suspected growth retardation when the gestational age was known.

ABC of antenatal care. Small for gestational age.

I Certain1 ~--Uncertain The diagnosis of a small fetus is made more specific by examining the ratio of birth weight (or estimated birth weight) to gestational age. Both these measures have inherent problems. Obstetricians estimate fetal weight either clinically or from measuring ultrasound determined diameters of the fetus in utero. Gestational age is derived from the mothers menstrual dates, which are usually confirmed by an ultrasound scan measuring the biparietal diameter performed before 20 weeks. In the British Births Survey (1970) of 16 797 women only 13 634 (81 * 1%) were sure of their dates. The figures show the distribution of length of gestation for women according to whether they were sure of their dates and that the frequency of heavier babies was increased among those uncertain of the date of their last menstrual period. All women with unsure dates should have gestational age established by ultrasonography, as should those in whom there is a discrepancy between the dates derived from the last menstrual period and fetal size in early pregnancy. Obstetricians consider a baby to be small for gestational age when abdominal circumference readings fall below the second standard deviation of the mean; this is approximately 2 3 centile on serial ultrasonography.

ABC of labour care. Relief of pain.

Labour is usually painful. Exceptionally, a very few women may not feel pain; others can control their response so as to reduce pain. Most women think that pain is going to be a major part of giving birth. Professionals can help to reduce womens fears by giving precise, accurate, and relevant information beforehand and explaining what pain relief will be available at the place where the woman will be in labour. If a women has plans about the sort of pain relief she wants, these should be discussed in advance with the woman and her partner. ### Causes of labour pain View this table: Percentages of women using pain relief (based on the reports of the National Birthday Trust surveys) The National Birthday Trust has performed nationwide surveys since the second world war, and the table shows the proportions of women going through labour using various methods of analgesia. Chloroform and trilene are no longer used; pethidine achieved a popularity that is now waning;nitrous oxide is a mainstay; and epidural and spinal methods are increasing in use. Equipment for self administration of nitrous oxide and oxygen (Entonox) with a mouth piece (top) and a face mask (bottom The trusts 1990 report, Pain Relief in Labour , is based on the experiences of over 10 000 women who delivered in the United Kingdom during one week. It is the best source of national statistics on both pharmacological and non-pharmacological analgesics. Much of this article is based on the report; some practices may have changed in the years since the survey—for example, the increased use of epidural and spinal anaesthesia for caesarean section. ### Nitrous oxide Premixed nitrous oxide and oxygen is now provided …

Doppler ultrasound of the uteroplacental circulation as a screening test for severe pre-eclampsia with intra-uterine growth retardation

Two hundred primiparae underwent continuous-wave Doppler investigation of the uteroplacental circulation at 18-20 weeks gestation as a possible screening test for hypertension in pregnancy. Seventy-five women with abnormal waveforms suggestive of high uteroplacental resistance were tested again at 24 weeks when 21 demonstrated a persistent abnormality. Only nine (43%) of these went on to have an uncomplicated pregnancy, as compared with 150 (84%) of the remainder. Seventeen (8.5%) of the women in the study developed a hypertensive disorder of pregnancy, five of whom had abnormal waveforms at 18-20 weeks and at 24 weeks. These five women had a more severe degree of hypertension with proteinuria or intra-uterine growth retardation, and two required clinical intervention before term. The remaining 12 women were delivered at term of average, or heavier than average babies. Doppler investigation of the uteroplacental circulation at 24 weeks may prove to be a sensitive screening test for later severe pre-eclampsia with intra-uterine growth retardation.

Mechanisms of parturition: The transfer of prostaglandin E2 and 5-hydroxyeicosatetraenoic acid across fetal membranes

Prostaglandin E2 production by amnion is thought to be an important event in the onset of human labor. It has been suggested that 5-hydroxyeicosatetraenoic acid, also produced in the amnion, may mediate prelabor contractions. For either of these compounds to play a paracrine role they need to cross the chorion, which has a high capacity to metabolize prostaglandins. With the use of an in vitro system we have shown that both prostaglandin E2 and 5-hydroxyeicosatetraenoic acid cross either amnion or intact amnion-chorion-decidua at a rate similar to that of an extracellular marker sucrose. Analysis by high performance liquid chromatography revealed that at physiologic concentrations neither prostaglandin E2 nor 5-hydroxyeicosatetraenoic acid were metabolized by amnion alone. Moreover, 100% of the 5-hydroxyeicosatetraenoic acid and 72% of the prostaglandin E2 remained in the active form after passage across intact amnion-chorion-decidua. There did not appear to be any difference in the rate of transfer or permeability of the membranes before or after spontaneous labor. We conclude that both 5-hydroxyeicosatetraenoic acid and prostaglandin E2 synthesised in the amnion can cross the membranes by diffusion through the extracellular space, remaining largely unmetabolized, and may play a role in the onset of human labor.

What is the correct caesarean section rate

What is the correct rate of caesarean sections for this country in 1993? How long is a piece of string? These two philosophical conundrums are not quite equal in their sophistry. Until we know what the piece of string is to be used for, we are completely in the dark. On the other hand, a caesarean section has a use capable of analysis: it is to avoid a vaginal delivery. Putting to one side the very small number of women having a postmortem operation (the original indication), the other caesarean sections are performed to avoid perceived risks of vaginal delivery for the mother, the fetus or both. Obvious indications are a grossly contracted pelvis, a very big fetus or a lower segment occupied by placenta praevia of some considerable degree. Other relative indications have, in some cases, plenty of data to help the obstetricians make up their minds, such as the neonatal mortality or morbidity following fetal distress and hypoxia. A perceived view would be that a fetus with a scalp blood pH of 7.10 with a base deficit of 10 pmol/l at 5 cm cervical dilation would be damaged by staying in the uterus much longer. On the balance of probabilities, a swift caesarean section can deliver that baby safely, compared with the three or four hours the baby may have to stay inside the uterus on the wrong side of a failing placental bed. In those cases there are studies from which obstetricians could draw reasonable conclusions. In other incidences, randomised controlled trials have been performed of therapies; these may show results of such strength that by themselves would justify a course of action. As an extension of this, meta-analyses of groups of suitably chosen smaller trials have been able to condense results of several studies; sometimes valid conclusions can be drawn. In addition to all these gold and relatively gold standards, obstetric opinion has been known to move before full scientific proof, for example the wide use of caesarean section for the delivery of a mature fetus presenting by the breech. The nudge from American obstetrics to do a caesarean section on every breech presentation has led many in the United Kingdom to follow. This came long before the recent paper from the Northwest Thames Regional Health Authority, which purported to show that mature babies presenting by the breech were better off delivered by caesarean section (Thorpe-Beeston et al. 1992). Here again, all is not clear. Lilford showed this three years ago (Lilford et af . 1990) but British obstetricians went on in their old ways. Judging by the correspondence in the British Medical Journal following the St Mary’s publication, they will probably do the same now. Usually, valid background data can be found and assessed, helping to place the individual case in its context of reinforcing or diminishing the proposed decision. The length of this piece of string, therefore, can be gauged roughly by the relative probabilities of a better result of one course of action rather than another. If the factors are multiple, regression analyses may help to put some of the picture into its correct perspective. All opinions backed by good epidemiological evidence could help us to arrive at an optimal level of caesarean section for a given population. Yet caesarean section rates vary widely; in 1988 two nearby countries, Holland and Denmark, quoted rates of 6.5% and 12-1%, respectively (Stephenson et al. 1993). These, however are all outbalanced by a few imponderable indications for surgery which some consider important but cannot be justified statistically. Litigation is a much quoted risk in the US and the UK. Since the midnineteen seventies, caesarean section rates have accelerated, it is alleged, for medico-legal reasons. On page 493 of the present issue, Savage and Francome (1993) show that 42% of British obstetricians considered that the perceived reason for the raised caesarean section rate is fear of medico-legal action. This would swamp any measurable indication that has been considered so far. Another group of indications hard to quantify is the woman’s own wishes. Having had a difficult forceps rotation of a big baby on the last occasion, the woman dreads labour at this time. An increasing number are asking their obstetricians at early visits to the antenatal clinic if they can bypass this miserable experience with an elective caesarean section; it would be a hard-hearted obstetrician who would say no. By agreeing early (and writing the decision in the records), the women has a much more relaxed and comfortable pregnancy than if she feared that she was foredoomed to another difficult labour, very possibly ending with a caesarean section anyhow. Unfortunately, much of the labour ward obstetrics is in the hands of registrars and other relatively junior staff at present. Consultants may be contacted about a doubtful case by telephone, but often the easier answer is tell the registrar to carry on with a section. As the registrars mature, they may present the case to their senior with a different emphasis and so get the answer to continue the labour. Such data are imponderable. Because of these wide variations of human behaviour among professionals and the women they look after, it is virtually impossible to determine what an optimal rate for caesarean section would be for any population. In extreme circumstances of limited facilities, such as too few anaesthetists or too little theatre space, a range of con-

Ultrasonically guided percutaneous umbilical blood sampling in the management of intrauterine growth retardation

Ten patients, hospitalized because of severe asymmetrical fetal growth retardation before 32 weeks gestation, underwent ultra‐sonically guided percutaneous umbilical blood sampling because of concern over the fetal heart rate trace. In eight patients the fetus was judged to be acidotic and they were delivered immediately by caesarean section. In two patients the fetus was not considered to be acidotic and the pregnancy was allowed to go on. In those babies that were delivered the pH blood collected from the umbilical vein at the time of delivery was compared to the antenatal sample. There were no significant differences. The technique of antenatal umbilical vein blood sampling is readily learned and by assessment of fetal acid base status a more precise diagnosis can be made leading to appropriately planned management.

Non-Steroidal Follicular Factors Attenuate the Self-Priming Action of Gonadotropin-Releasing Hormone on the Pituitary Gonadotroph

Pituitary glands of pro-oestrous and oestrous rats were perifused in series with isolated ovarian follicles and the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responses to gonadotropin-releasing hormone (GnRH) were measured. Pituitary glands from pro-oestrous rats, perifused with the effluent medium from isolated preovulatory follicles, showed a significant reduction in the self-priming effect of GnRH as observed from the typical biphasic LH response to a continuous GnRH challenge. The initial FSH response to GnRH was also reduced. A similar trend was seen in the LH responses of pituitary glands from oestrous rats but results were not significant; there was no parallel reduction in FSH release. It is unlikely that the attenuation of GnRH self-priming was due to the steroids released by the isolated follicles. LH responses of pro-oestrous pituitaries, perifused with medium containing 200 pg oestradiol/ml, 5 ng progesterone/ml or 200 pg testosterone/ml were similar to paired controls as were the responses when all three steroids were added to the perifusing media at identical concentrations. Furthermore, when steroids were charcoal extracted from the effluent medium of perifused isolated follicles the biological activity of this medium in attenuating GnRH self-priming was not destroyed. Finally, the effects of purified bovine inhibin and steroid-free human follicular fluid (hFF) on LH responses were compared. Purified inhibin at a concentration of 20 or 50 ng/ml perifusing medium had no effect on GnRH-stimulated LH release although GnRH-stimulated FSH secretion was significantly reduced toward the end of an extended perifusing period.(ABSTRACT TRUNCATED AT 250 WORDS)

LATE COMPLICATIONS OF STERILISATION BY LAPAROSCOPY

test not only as a test for A.F.p.-producing tumours but also for prospective screening for neural-tube defects. Serum-A.F.p. levels above a critical level should be tested further, either by the H.A. test or by quantitative radioimmunoassay. By increasing the dilution of elevated serum samples a semiquantitative estimation of the A.F.P. level could be made by the H.A. test. These results could indicate whether an amniotic-fluid A.F.P. estimation should be carried out. Therefore the H.A. test may be a simple alternative test in prospective screening-trials instead of the more complicated radioimmunoassays.