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Biomedical subjects

A A Calder

Publications and source records attributed to A A Calder.

At least 91 records · Page 5Linked to original sources

A randomised trial to evaluate the use of a birth chair for delivery.

A randomised study of 189 deliveries was conducted to compare performance in the conventional dorsal position with that in a birth chair. There was no significant difference in the length of the second stage of labour, the time spent bearing down, or the need for operative delivery. Overall blood-loss was greater among patients delivered in the chair but more of this group had either an intact perineum or only superficial damage. The condition of the neonates in the two delivery groups was similar.

Clinical Trials as Topic↗

A comparative assessment of an automated blood microprocessor for fetal blood pH measurements in the labour ward.

A new fully automated, self-calibrating, blood pH analyser was compared with a standard reference instrument for the measurement of pH of fetal scalp and umbilical cord blood samples. The new instrument is reliable and simple to operate, the volume of blood needed for analysis is small and it does not require the availability of trained laboratory technicians for its use.

Blood Chemical Analysis↗

Cervical ripening.

When induction of labour is being considered the first step should be to assess the cervical score. If this is low, the gestational age should be confirmed since an unripe cervix is normal in earlier pregnancy and there may be a mistake in the patient's dates. If the maturity is confirmed, the choice lies between delivering the baby and waiting. Few genuine indications for induction change by waiting and increased risks may occur by postponing the date of delivery. The choice may then lie between elective caesarean section or amniotomy and intravenous oxytocin with an unripe cervix on the one hand, and cervical ripening before induction of labour on the other (Lancet, 1979). The last course has many advantages to commend it. There is still much to be learnt about cervical ripening. The success of the prostaglandins suggests that they may be the agents of choice at present. The ideal preparation would be one that could be administered vaginally to ripen the cervix without inducing uterine contractions. A major problem to date has been the absence of a commercially available PGE2 preparation for local use and this has necessitated the formulation of home-made gels and pessaries by individual hospital pharmacies. However, recently Prostin E2 vaginal tablets (each containing dinoprostone 3 mg) have been marketed and initial studies (Stewart et al, 1983) have shown promising results.

Administration, Oral↗

Pregnancy-associated changes in the physical and microscopic characteristics of the ovine cervix.

Ovine cervices were obtained at slaughter from 18 sheep comprising six groups of three--cycling ewe lambs, non-pregnant, and four groups of pregnant animals of progressively longer gestation PI to PIV. Physical and microscopic analyses carried out on these cervices showed consistent results throughout any individual tissue. A number of factors changed with increasing gestational age and some of these changes were noted from early gestation. No significant change in water content was observed through pregnancy. With increasing length of gestation the cervix increased in length and width, there were relative increases in fibroblasts, smooth muscle and softening of the tissue, and relative decreases in collagen and fibrocytes. An increased vascularity was observed in the tissues from late gestation sheep, and a change in the nature of the epithelial secretion, from neutral to acidic mucins, was also associated with late pregnancy.

Animals↗

Spontaneous labour: when should the membranes be ruptured?

Sixty-eight patients (32 multigravidae, 36 primigravidae) with intact membranes admitted in early spontaneous labour were studied. Patients were randomly allocated to two groups: group I had an immediate amniotomy and group II were allowed to retain their membranes intact until full dilatation. Early amniotomy significantly shortened the length of labour and reduced the need for augmentation and instrumental delivery. There were no differences between the two groups in fetal outcome as measured by Apgar scores, umbilical arterial and venous blood pH, neonatal jaundice or admission to the special-care baby unit. Fetal heart-rate recordings obtained in group I by applying a fetal electrode after amniotomy were of superior quality to those obtained in group II by ultrasound and were more suitable for interpretation. 'Normal' and 'suspicious' tracings occurred equally in the two groups. Our results suggest some benefits from early amniotomy and no adverse effects on the fetus.

Adult↗

Forces required for surgical dilatation of the pregnant and non-pregnant human cervix.

The force required to dilate the uterine cervix to a diameter of 8 mm has been measured in 200 non-pregnant and 40 early pregnant patients. In general, the resistance offered by the cervix was lower in parous than in nulliparous subjects and in pregnant compared with non-pregnant subjects. The phase of the menstrual cycle did not appear to influence cervical resistance but the highest recordings were seen in postmenopausal subjects. Particularly low resistance was encountered in women receiving Depo-Provera for contraceptive purposes.

Cervix Uteri↗

Induction of labour: a comparison of a single prostaglandin E2 vaginal tablet with amniotomy and intravenous oxytocin.

In a randomized controlled study of 100 women of low parity and favourable induction features, induction of labour by means of a single vaginal tablet containing 3 mg of prostaglandin E2 (PGE2) was compared with the conventional method of amniotomy and intravenous oxytocin. Four of the patients (8%) who received the prostaglandin tablet required additional intravenous oxytocin to achieve delivery. The prostaglandin group had a longer mean overall induction-delivery interval but a shorter amniotomy-delivery interval than the oxytocin group. One patient in the PGE2 group and two in the oxytocin group required caesarean section. The PGE2 treated patients expressed a higher level of satisfaction with their method of induction, they required less analgesia, had less blood loss at delivery and their babies had a lower incidence of neonatal jaundice.

Adolescent↗

A comparison of oestradiol and prostaglandin E2 for ripening the cervix.

A study was conducted to compare the cervical ripening effect of extra-amniotic prostaglandin E2 with that of extra-amniotic oestradiol valerate in preparation for induction of labour. Sixty primigravidae with an unripe cervix received one or other agent suspended in a viscous gel. The degree of cervical ripening was similar in both groups but more patients treated with prostaglandins became established in labour before planned amniotomy, and poor progress in labour was less common in this group.

Adult↗

Posture in labour.

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Evaluation Studies as Topic↗