No abstract

ANNOTATIONSHowever, some recent studies8, l o seem to be reasonably reassuring. Nevertheless, until more is known about the possible harmful effects, it would seem advisable to reduce the number of scans carried out during pregnancy. This, of course, will apply more to scans in early pregnancy rather than t o measurements of the biparietal diameter. Assessments of the biparietal diameter are impossible before ten weeks since the fetal head is not formed and measurements are unsatisfactory before sixteen weeks. The most accurate time for maturity assessments is between twenty and thirty-four weeks. Accurate assessments of the duration of pregnancy can be made in the very early weeks, and such measurements would be of obvious value in doing serial estimations to assess fetal growth.Keeping in mind the possible inaccuracies, and limiting the number of scans done during pregnancy, ultrasonic measurement of the biparietal diameter is an extremely useful aid to the obstetrician. IAN MACGILLIVR.4Y . (1965) 'Fetal develoonient as deter-Gynaec. Brit. Cwlth, 71, 11. mined by ultrasonic pulse echo'techniques." Anivr.' J . Obsret. Gyitec., 92, 44. and complicated pregnancy.' Ann. Chir. Gynec, Fenn., 59, 71. diameter.'J. Ohstet. Gynaec. Brit. Cwlth, 76, 603. Gynec., 29, 842. 12, 114. detector.' Brit. nied. J . , 2, 92. Lancet, i, 11 33. 3 . Ojala, A., Ylostalo, P., Jouppila, P., Jarvinen, P. A. (1970) 'Fetal cephalometry by ultrasound in normal 4. Campbell, S. (1969) 'The prediction of fetal maturity by ultrasonic measurement of the biparietal 5. Hibbard, L. T., Anderson, G. V. (1967) 'Clinical applications of ultrasonic fetal cephalornetry.' Obster. 6. Kato, M . (1966) 'Visible mutation induced in Drosophila by ultrasonic vibration.' Bid/.

No abstract

In contrast, epidural techniques are extensively used for obstetric analgesia in many North American centres (Bush, 1959;Hingson et al., 1961; Hellmann, 1965;Moore, 1966) following on the pioneer work of Hingson and Edwards (1943). The reasons for this difference in practice are several.Firstly, British obstetric opinion is generally in favour of encouraging spontaneous delivery where this can safely be achieved, and most spontaneous deliveries are conducted by midwives in hospital and at home. Epidural analgesia, because it produces perineal anaesthesia and so abolishes the reflex expulsive efforts of the second stage of labour, is usually associated with a high forceps delivery rate.Secondly, epidural analgesia may be required at any time of the day or night, and its safe conduct necessitates the presence of an anaesthetist experienced in the technique for as long as the block is maintained. This demands a 24-hour obstetric anaesthetic service by experienced anaesthetists who are not itted to other duties. This service exists in few hospitals in Great Britain today, though in our experience the benefits are substantial and not confined to the administration of epidural analgesia.Finally was incoordinate uterine action. The present review was undertaken to assess the contribution made by epidural analgesia to the management of these cases. Anaesthetic TechniqueThe lumbar rather than the caudal approach to the epidural space is preferred because of the higher success rate, the lower dose of local anaesthetic drug, and because the skin of the lumbar region seems less open to contamination than the skin over the sacral hiatus. The caudal approach is used when abnormalities of the lumbar spine are present.Lumbar epidural puncture is performed with the patient in the sitting position to encourage spinal fleion, which may be difficult to achieve in the lateral position because of the gravid uterus. A 16 S.W.G. Tuohy needle is used and the epidural space is identified by the loss-of-resistance technique. A plastic catheter (Lee, 1962) with a blunt tip (Moir and Hesson, 1965) is then advanced into the epidural space, the needle is withdrawn, and the catheter is connected to a sterile plastic 50-ml. syringe filled with local anaesthetic solution. This syringe is now sealed inside a transparent bag (Cole, 1964) and strapped to the abdominal wall. This system allows top-up injections to be given without scrubbing-up and seems to avoid the risk of accidental overdosage associated with at least one of the drip techniques (Edmonds-Seal, 1964