P-745 The efficacy of Buscopan® in reducing pain during ultrasound-guided manual vacuum aspiration (USG-MVA): A double-blind randomised placebo-controlled trial

Study question

Does Buscopan® reduce abdominal pain experienced by women undergoing ultrasound-guided manual vacuum aspiration (USG-MVA)?

Summary answer

The addition of 20mg Buscopan® intravenous injection was not associated with a statistical reduction in pain score but leads to a higher patient satisfaction score.

What is known already

Ultrasound-guided Manual Vacuum aspiration is a feasible and effective out-patient treatment option for treating early pregnancy loss. However, it is associated with a moderate amount of pain due to uterine contraction.

Study design, size, duration

This randomised, double-blinded, placebo-controlled trial was conducted in a university-affiliated tertiary hospital. The study assessed whether 1 ml of 20mg Buscopan® intravenous injection 5 minutes before the USG-MVA will reduce the abdominal pain experienced by the women immediately and 2 hours after the procedure. Participants were randomised between June 2018 to January 2020 using a computer-generated number series in a 1:1 ratio.

Participants/materials, setting, methods

Women aged 18 years or older with first-trimester miscarriage undergoing the USG-MVA procedure were eligible. In total, 122 participants out of 128 eligible were included. Of whom, 111 underwent the USG-MVA procedure, 60 randomised to the Buscopan® group, and 62 to the placebo group.

Main results and the role of chance

The median abdominal pain scores in the Buscopan® group were 16.0% and 21.2% lower than the placebo group immediately post-procedure and 2 hours after the procedure in the Buscopan® group. Repeated measures ANOVA indicated that the both vaginal and abdominal pain scores improved significantly with the time (Vaginal F(1,108)= 180.1,p<0.0001;

Abdominal

F(1,108)=83.41,p<0.001) but not with group. No difference was noted in the complications and side effects profile. The physiological stress measured by Log10 sAA levels reduced significantly with time (F(2.8,286.1)= 6.3, p < 0.001) but not with group (F = 0.1, p = 0.96). Women randomised to Buscopan® had a significantly higher (p = 0.032) mean VAS satisfaction scores compared to those receiving placebo (79.0±17.3 vs 73.4±24.1).

Limitations, reasons for caution

This study was a single-centre study, thus one should be cautious in the overall generalisability of the results.

Wider implications of the findings

Few studies have evaluated the use of anti-spasmodic agents to minimise uterine contraction pain in women undergoing outpatient uterine evacuation. We consider Buscopan® a useful adjunct in the pain control of USG-MVA to specifically reduce uterine cramps. Further larger studies are required to evaluate its efficacy

Trial registration number

ChiCTR1800014590

P–745 The efficacy of Buscopan® in reducing pain during ultrasound-guided manual vacuum aspiration (USG-MVA): A double-blind randomised placebo-controlled trial

Study question

Does Buscopan® reduce abdominal pain experienced by women undergoing ultrasound-guided manual vacuum aspiration (USG-MVA)?

Summary answer

The addition of 20mg Buscopan® intravenous injection was not associated with a statistical reduction in pain score but leads to a higher patient satisfaction score.

What is known already

Ultrasound-guided Manual Vacuum aspiration is a feasible and effective out-patient treatment option for treating early pregnancy loss. However, it is associated with a moderate amount of pain due to uterine contraction.

Study design, size, duration

This randomised, double-blinded, placebo-controlled trial was conducted in a university-affiliated tertiary hospital. The study assessed whether 1 ml of 20mg Buscopan® intravenous injection 5 minutes before the USG-MVA will reduce the abdominal pain experienced by the women immediately and 2 hours after the procedure. Participants were randomised between June 2018 to January 2020 using a computer-generated number series in a 1:1 ratio.

Participants/materials, setting, methods

Women aged 18 years or older with first-trimester miscarriage undergoing the USG-MVA procedure were eligible. In total, 122 participants out of 128 eligible were included. Of whom, 111 underwent the USG-MVA procedure, 60 randomised to the Buscopan® group, and 62 to the placebo group.

Main results and the role of chance

The median abdominal pain scores in the Buscopan® group were 16.0% and 21.2% lower than the placebo group immediately post-procedure and 2 hours after the procedure in the Buscopan® group. Repeated measures ANOVA indicated that the both vaginal and abdominal pain scores improved significantly with the time (Vaginal F(1,108)=180.1,p<0.0001; Abdominal: F(1,108)=83.41,p<0.001) but not with group. No difference was noted in the complications and side effects profile. The physiological stress measured by Log10 sAA levels reduced significantly with time (F(2.8,286.1)= 6.3, p < 0.001) but not with group (F = 0.1, p = 0.96). Women randomised to Buscopan® had a significantly higher (p = 0.032) mean VAS satisfaction scores compared to those receiving placebo (79.0±17.3 vs 73.4±24.1).

Limitations, reasons for caution

This study was a single-centre study, thus one should be cautious in the overall generalisability of the results.

Wider implications of the findings: Few studies have evaluated the use of anti-spasmodic agents to minimise uterine contraction pain in women undergoing outpatient uterine evacuation. We consider Buscopan® a useful adjunct in the pain control of USG-MVA to specifically reduce uterine cramps. Further larger studies are required to evaluate its efficacy.

Trial registration number

ChiCTR1800014590

First-trimester pre-eclampsia biomarker profiles in Asian population: multicenter cohort study

OBJECTIVES

To (i) evaluate the applicability of the European-derived biomarker multiples of the median (MoM) formulae for risk assessment of preterm pre-eclampsia (PE) in seven Asian populations, spanning the east, southeast and south regions of the continent, (ii) perform quality-assurance (QA) assessment of the biomarker measurements and (iii) establish criteria for prospective ongoing QA assessment of biomarker measurements.

METHODS

This was a prospective, non-intervention, multicenter study in 4023 singleton pregnancies, at 11 to 13 + 6 weeks' gestation, in 11 recruiting centers in China, Hong Kong, India, Japan, Singapore, Taiwan and Thailand. Women were screened for preterm PE between December 2016 and June 2018 and gave written informed consent to participate in the study. Maternal and pregnancy characteristics were recorded and mean arterial pressure (MAP), mean uterine artery pulsatility index (UtA-PI) and maternal serum placental growth factor (PlGF) were measured in accordance with The Fetal Medicine Foundation (FMF) standardized measurement protocols. MAP, UtA-PI and PlGF were transformed into MoMs using the published FMF formulae, derived from a largely Caucasian population in Europe, which adjust for gestational age and covariates that affect directly the biomarker levels. Variations in biomarker MoM values and their dispersion (SD) and cumulative sum tests over time were evaluated in order to identify systematic deviations in biomarker measurements from the expected distributions.

RESULTS

In the total screened population, the median (95% CI) MoM values of MAP, UtA-PI and PlGF were 0.961 (0.956-0.965), 1.018 (0.996-1.030) and 0.891 (0.861-0.909), respectively. Women in this largely Asian cohort had approximately 4% and 11% lower MAP and PlGF MoM levels, respectively, compared with those expected from normal median formulae, based on a largely Caucasian population, whilst UtA-PI MoM values were similar. UtA-PI and PlGF MoMs were beyond the 0.4 to 2.5 MoM range (truncation limits) in 16 (0.4%) and 256 (6.4%) pregnancies, respectively. QA assessment tools indicated that women in all centers had consistently lower MAP MoM values than expected, but were within 10% of the expected value. UtA-PI MoM values were within 10% of the expected value at all sites except one. Most PlGF MoM values were systematically 10% lower than the expected value, except for those derived from a South Asian population, which were 37% higher.

CONCLUSIONS

Owing to the anthropometric differences in Asian compared with Caucasian women, significant differences in biomarker MoM values for PE screening, particularly MAP and PlGF MoMs, were noted in Asian populations compared with the expected values based on European-derived formulae. If reliable and consistent patient-specific risks for preterm PE are to be reported, adjustment for additional factors or development of Asian-specific formulae for the calculation of biomarker MoMs is required. We have also demonstrated the importance and need for regular quality assessment of biomarker values. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Expected-value bias: is it time to remove features from ultrasound machines?

Linked Comment: Ultrasound Obstet Gynecol 2020; 55:375-382.

P39 Cross-sectional analysis of 6-minute walk distance and diastolic function in a Hong Kong cohort of community-living older adults

Funding Acknowledgements

CUHK Direct Grant, CUHK Lui Che Woo Institute of Innovative Medicine, Food and Health Bureau of HKSAR (EF); Hong Kong Jockey Club Charities Trust (JW)

Background/Introduction

6-min walk distance (6MWD) can indicate frailty extent, cardiac dysfunction, and heart failure (HF) trajectory. Association of 6MWD with diastolic dysfunction (DD) or cardiac biomarker in community-living elderly without a history of HF remains underexplored.

Purpose

This study aims to determine the association between 6MWD, serum N-terminal prohormone of B-type natriuretic peptide (NT-proBNP), and DD in a community-living elderly population without known HF.

Methods

Between Nov 2017 and Aug 2018, 302 Hong Kong Chinese aged ≥60 y and without known HF were recruited into the Undiagnosed heart Failure in Older individuals (UFO) study consisting of robust, pre-frail and frail older adults stratified by FRAIL scale in a ratio of 1:1:1. 6MWD was divided into tertiles. Transthoracic echocardiography and serum NT-proBNP were used to assess cardiac dysfunction. Diastolic function was classified according to international guidelines and NT-proBNP >300 pg/ml was considered elevated.

Results

The ages of participants in the bottom, middle and top tertiles were 80.3 ± 7.4, 73.9 ± 6.3 and 70.0 ± 5.7 years (P < 0.01), respectively, corresponding to a female preponderance of 85.0%, 75.2%, 46.5% (P < 0.01). The highest prevalence rates of hypertension (HT, 76.0% vs 68.3% vs 51.5%, P < 0.01), diabetes mellitus (DM, 41.0% vs 30.7% vs 12.9%, P < 0.01), and ischaemic heart disease (IHD, 14.0% vs 4.0% vs 2.0%, P < 0.01) were observed in the bottom tertile of 6MWD. However, the prevalence of atrial fibrillation (AF) was distributed equally across tertiles (2.0% vs 2.0% vs 2.0%). Frail (63.0% vs 25.7% vs 3.0%, P < 0.01) and pre-frail (36.5% vs 44.6% vs 24.8%, P < 0.01) individuals were most frequently seen in the bottom and middle tertiles of 6MWD.

Using multiple linear regression analysis, S’ velocity, E:E’ ratio and E’ velocity were associated with 6MWD independent of age and sex. Associations between 6MWD and S’, left atrial volume index, E’ and E:E’ remained statistically significant even after adjusting for HT, DM, IHD, AF, stroke, chronic pulmonary disease and arthritis. No correlation was observed between 6MWD and left ventricular ejection fraction. 

Compared with the top tertile of 6MWD, the bottom tertile was associated with increased risks for grade II–IV DD (odds ratio (OR) 3.47, 95% confidence interval (CI) 1.52–7.96, P < 0.01) and NT-proBNP >300pg/ml (OR 10.20, CI 3.74–27.85, P < 0.01, respectively, after adjusting for co-morbidities. The association between reduced 6MWD and elevated NT-proBNP, but not between 6MWD and DD, remained significant (OR 6.00, CI 2.06–17.46) after adjusting for age and sex. The middle tertile was not significantly associated with an increased risk for grade II–IV DD or elevated NT-proBNP.

Conclusion(s)

In this cohort of community-living Hong Kong Chinese elderly recruited equally by frailty status, performance of 6MWD in the bottom and top tertiles was inversely associated with NT-proBNP levels but not with DD.

Quality assessment of uterine artery Doppler measurement in first-trimester combined screening for pre-eclampsia

OBJECTIVE

To assess the quality of mean uterine artery (UtA) pulsatility index (PI) measurement in a first-trimester pre-eclampsia screening program.

METHODS

Consecutive women with a singleton pregnancy attending first-trimester screening for fetal chromosomal abnormalities also had combined screening for pre-eclampsia based on the Fetal Medicine Foundation (FMF) algorithm, at a large practice in Sydney, Australia, from May 2014 to February 2017. Distributions of mean UtA-PI multiples of the median (MoM) on a logarithmic scale were plotted in relation to the normal median with 95% CI for each operator and for each month. Central tendency and dispersion and cumulative sum charts were produced. Mean UtA-PI MoM values between 0.95 and 1.05 were considered ideal and those between 0.90 and 1.10 were considered acceptable. The screen-positive rates for preterm pre-eclampsia in different groups of sonographers according to their mean log₁₀ UtA-PI MoM were calculated and compared using the chi-square test.

RESULTS

A total of 21 010 women attended for first-trimester ultrasound and had screening for pre-eclampsia. The overall median UtA-PI MoM was 1.042 (interquartile range (IQR), 0.85-1.26). Of 46 sonographers, 42 (91.3%) performed more than 50 examinations and, of those, 41 (97.6%) measured UtA-PI within the acceptable range. Sonographers measuring UtA-PI MoM on average below 0.95 and those measuring it above 1.05 had, respectively, lower and higher screen-positive rates when compared with those with measurements within the 0.95-1.05 UtA-PI MoM interval (7.2% and 13.2% vs 11.2%, respectively, P < 0.001).

CONCLUSION

UtA Doppler is measured well among trained operators when following an established protocol. While slight variations are expected, systematic error in this measurement impacts on the screen-positive rate. Therefore, a quality control process should be in place and retraining of staff may be required. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Transverse technique: complementary approach to measurement of first-trimester uterine artery Doppler

OBJECTIVES

To define a protocol for the first-trimester assessment of uterine artery pulsatility index (UtA-PI) using the new transverse technique, to evaluate UtA-PI measured using the transverse approach vs that obtained using the conventional sagittal approach and to determine if accelerated onsite training (in both methods) of inexperienced sonographers can achieve reproducible UtA-PI measurements comparable with those obtained by an experienced sonographer.

METHODS

This was a prospective observational study of women with a singleton pregnancy attending for routine combined first-trimester screening at 11 to 13 + 6 weeks' gestation. The study consisted of two parts, each conducted at a different center (Part 1 in Calgary, Canada and Part 2 in Hong Kong). In Part 1, UtA-PI measurements were performed using the transverse and sagittal techniques by four sonographers trained in both methods, in 10 cases each, and measurement indices (PI), time required and subjective difficulty in obtaining satisfactory measurements were compared. The one sample t-test and Wilcoxon signed rank test were used when appropriate. Bland-Altman plots were used to assess measurement agreement, and intraclass correlation coefficient (ICC) was used to evaluate measurement reliability. A target plot was used to assess measures of central tendency and dispersion. In Part 2, one experienced and three inexperienced sonographers prospectively measured UtA-PI using both approaches in 42 and 35 women, respectively. Inexperienced sonographers underwent accelerated onsite training by the experienced sonographer. Measurement approach and sonographer order were on a random basis. ICC, Bland-Altman and Passing-Bablok analyses were performed to assess measurement agreement and reliability and effect of accelerated training.

RESULTS

In Part 1, no difference was observed between the two techniques in mean time to acquire the measurements (118 s for sagittal vs 106 s for transverse; P = 0.38). The four sonographers reported that the transverse technique was subjectively easier to perform (P = 0.04). Bias and ICC for mean UtA-PI between sagittal and transverse measurements were -0.05 (95% limits of agreement, -0.48 to 0.37) and 0.94, respectively. Measurements obtained using the transverse technique after correcting for gestational age were significantly closer to the expected distribution than those obtained using the sagittal technique. In Part 2, there were no significant differences in median UtA-PI measured using the different approaches for both experienced and inexperienced sonographers (P > 0.05 for all sonographers). Mean UtA-PI measurement reliability between approaches was high for the experienced (ICC = 0.92) and inexperienced (ICC > 0.80) sonographers. UtA-PI measurement approaches did not deviate from linearity, while bias ranged from -0.10 to 0.07. The median time required was similar between the techniques (56.1 s for sagittal vs 49.3 s for transverse; P = 0.054).

CONCLUSIONS

This novel transverse approach for the measurement of UtA-PI in the first trimester appears to be comparable with the sagittal approach in terms of reliability, reproducibility and time required, and may be easier to perform. Providing accelerated onsite training can be helpful for improving the reliability of UtA-PI measurements and could potentially facilitate the broad implementation of first-trimester pre-eclampsia screening. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Assessing quality standards in measurement of uterine artery pulsatility index at 11 to 13 + 6 weeks' gestation

OBJECTIVES

To assess the effect of audit and feedback on the performance of first-trimester uterine artery pulsatility index (UtA-PI) measurement, to determine whether operator experience affects performance and whether an operator's measurement profile affects the screen-positive rate for early-onset pre-eclampsia (PE).

METHODS

This was a prospective cohort study in which UtA-PI measurements were collected between 11 to 13 + 6 weeks' gestation by 12 operators and were entered into individualized calculators to convert them to multiples of a locally-derived median (MoM). Individual sonographer cumulative sum (CUSUM) and target charts were generated to assess central tendency and dispersion to identify systematic measurement errors and deviation from expected measurement performance. Six of the operators received regular feedback whilst the remaining six received no feedback. Each group consisted of four experienced operators and two relatively inexperienced operators. The average MoM for each operator was compared with their respective screen-positive rates for early-onset PE.

RESULTS

The group that received feedback performed better than that which received none, with results more closely matching the expected measurement distribution. UtA-PI measurements were comparable between the experienced and inexperienced sonographers (mean log10 lowest PI MoM, -0.0089 vs 0.0124, respectively); however the inexperienced sonographers had a higher overall screen-positive rate for early-onset PE (10.0% vs 2.7%, respectively). There was a significant positive correlation between the mean MoM for each operator and the screen-positive rate (r = 0.63).

CONCLUSIONS

CUSUM and target graphs are an effective method of audit for first-trimester UtA-PI measurement. Feedback to operators resulted in improved measurement performance, which will ultimately result in improved screening accuracy for PE.

Comparison between phytoestrogens and estradiol in the preventionof atheroma in ovariectomized cholesterol-fed rabbits

OBJECTIVES

There is increasing interest in the role of complementary and alternative medicines for the treatment of menopause-related problems. This study compared the preventive effect on atheroma formation of a commercially available mixed phytoestrogen concentrate with that of estradiol.

METHODS

An ovariectomized cholesterol-fed rabbit model of atheroma formation was used. Rabbits were ovariectomized before the commencement of the 12-week treatment period. There were two control groups. Control Group 1 received isoflavone-free rabbit chow whilst Control Group 2 received 1% cholesterol-enriched isoflavone-free rabbit chow. Rabbits in Group 3 received 1% cholesterol-enriched isoflavone-free rabbit chow plus a 500 mg tablet containing a concentrated extract of Trifolium pretense (red clover). Rabbits in Group 4 received 1% cholesterol-enriched isoflavone-free rabbit chow plus a 0.5 mg tablet of oral estradiol. Atheroma formation was measured by, first, calculation of the area of atheroma on the intimal surface, and, second, measuring the cholesterol content in the aorta.

RESULTS

There were no significant differences in serum cholesterol between the cholesterol-fed control Group 2 and the treatment Groups 3 and 4. However, there was significantly less staining for atheroma and significantly less cholesterol accumulation in the aorta in Group 4 (estradiol-treated) rabbits compared with either control Group 2 or Group 3 (phytoestrogen-treated) rabbits.

CONCLUSION

In this study, only estradiol was shown to have a significant protective effect against atheroma formation.

Screening for trisomy 21 by maternal age, fetal nuchal translucency thickness, free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A

OBJECTIVES

To derive a model and examine the performance of first-trimester combined screening by maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A).

METHODS

Prospective combined screening for trisomy 21 was carried out at 11 + 0 to 13 + 6 weeks in 56,771 singleton pregnancies, including 56,376 cases with a normal karyotype or delivery of a phenotypically normal baby (unaffected group) and 395 cases with trisomy 21. The blood test and ultrasound scan were carried out in the same visit. In each case the maternal age-related risk for trisomy 21 at term was calculated and adjusted according to the gestational age at the time of screening to derive the a-priori risk. The measured NT was transformed into a likelihood ratio using the mixture model of NT distributions. The measured free beta-hCG and PAPP-A were converted into a multiple of the median (MoM) for gestational age, adjusted for maternal weight, ethnicity, smoking status, method of conception and parity, and a likelihood ratio was subsequently calculated. The likelihood ratios for NT and for the biochemical markers were multiplied by the a-priori risk to derive the patient-specific risk. Detection rates and false-positive rates were calculated by taking the proportions with risks above a given risk threshold after adjustment for maternal age according to the distribution of pregnancies in England and Wales in 2000-2002. These standardized rates were compared with detection and false-positive rates estimated using Monte Carlo methods to sample from the modeled Gaussian distributions.

RESULTS

The performance of screening based on the model was in good agreement with that observed in our population. In a strategy for first-trimester combined screening where the blood test and scan are carried out in the same visit it was estimated that, for false-positive rates of 3% and 5%, the detection rates were 92% and 94%, respectively, at 11 weeks, 85% and 90% at 12 weeks, and 79% and 83% at 13 weeks. In an alternative strategy, with the blood taken at 10 weeks and the measurement of NT performed at 12 weeks, the estimated detection rates were 94% and 96% for false-positive rates of 3% and 5%, respectively.

CONCLUSIONS

The aim of the first-trimester scan is not just to screen for trisomy 21 but also to diagnose an increasing number of fetal malformations. In this respect the ability to visualize fetal anatomy is better at 12-13 weeks than at 11 weeks. Consequently, the ideal gestation for combined testing in the same visit would be 12 weeks. An alternative strategy, with the blood taken at 10 weeks and the measurement of NT performed at 12 weeks, is associated with higher detection rates of trisomy 21. However, the cost of two-stage screening would be higher and, in addition, the potential advantage in terms of detection rate may be eroded by the likely increased non-compliance with the additional step.

Rate of rise in maternal plasma corticotrophin-releasing hormone and its relation to gestational length

OBJECTIVE

To assess the relationship between rate of increase in maternal plasma corticotrophin-releasing hormone and gestational length.

DESIGN

A prospective observational study.

SETTING

Department of Obstetrics and Gynaecology, Prince of Wales Hospital, Hong Kong.

METHODS

Serial venous samples taken at four to six week intervals from 81 pregnant Chinese subjects were assayed for corticotrophin-releasing hormone concentrations. The investigators responsible for the laboratory assay were blinded to the obstetric outcome.

RESULTS

A total of 380 blood samples were taken. Each subject provided three to seven samples (median = 5). Seven of the 81 subjects had preterm delivery. Maternal corticotrophin-releasing hormone levels increased exponentially as gestation advanced. A negative correlation between the rate of rise of logarithmic equivalence of corticotrophin-releasing hormone concentrations (Ln-corticotrophin releasing hormone) per week and the gestational age at delivery was demonstrated (r = -0.45, P < 0.001). The rate of increase of Ln-corticotrophin releasing hormone concentrations per week was also significantly greater for those who delivered preterm before 37 weeks compared with those with uncomplicated term deliveries (0.27 Vs 0.22, P = 0.018).

CONCLUSIONS

The rate of increase in maternal plasma corticotrophin-releasing hormone is inversely proportional to gestational length. Results in a Chinese population confirm and extend results from previous caucasian populations. This study provides another piece of evidence on the close link between maternal plasma corticotrophin-releasing hormone and the timing of human parturition. As the hormone is synthesized by the placenta, it supports the suggestion that the human placenta has an important role in determining gestational length.

The fetal electrocardiogram: relationship with acidemia at delivery

OBJECTIVE

This study was undertaken to analyze the relationship between the fetal electrocardiogram and arterial pH and base excess at delivery.

STUDY DESIGN

In the labor wards of three teaching hospitals a retrospective observational study was conducted on fetal monitor recordings of 679 women for whom there was an indication for continuous fetal monitoring during labor. These women had been recruited as part of either observational studies or a prospective randomized trial related to the Nottingham fetal electrocardiographic project. Fetal heart and uterine contraction data were obtained with the Nottingham fetal electrocardiographic analyzer. Morphologic and time interval analyses of the fetal electrocardiogram were performed. Evaluation was carried out for the last half hour before delivery. Main outcome measures were umbilical arterial pH and base excess at delivery.

RESULTS

The study demonstrated a relationship between time interval analysis of the fetal electrocardiogram and a low umbilical arterial pH and base excess at delivery. Analysis of the morphologic characteristics of the fetal electrocardiogram (ST segment and T-wave height) showed no significant relationship.

CONCLUSIONS

Time interval analysis of the fetal electrocardiogram during labor is related to relative acidemia at delivery.

Cardiotocography only versus cardiotocography plus PR-interval analysis in intrapartum surveillance: a randomised, multicentre trial. FECG Study Group

BACKGROUND

There is a need to improve the sensitivity and specificity of fetal monitoring during labour. We compared the gold standard, cardiotocography, with cardiotocography plus time-interval analysis of the fetal electrocardiogram in fetal surveillance. The aim was to find out whether time-interval analysis decreased the need for operative intervention due to fetal distress.

METHODS

We did a randomised, prospective trial in five hospitals in the UK, Hong Kong, the Netherlands, and Singapore. 1038 women undergoing high-risk labours were randomly assigned fetal monitoring by cardiotocography alone, or cardiotocography plus fetal electrocardiography (ECG). Outcomes measured were rates of operative intervention, and neonatal outcome. Analysis was by intention to treat.

FINDINGS

515 women were assigned management by cardiotocography, and 523 cardiotocography plus fetal ECG. There was a trend towards fewer operative interventions for presumed fetal distress in the time-interval analysis plus cardiotocography group (63 [13%] vs 78 [16%]), but this was not significant (relative risk 0.80 [95% CI 0.59-1.08], p=0.17). There was no significant difference between groups in the proportion of babies who had an umbilical arterial pH of 7.15 or less (51 [11%] vs 49 [11%]; 1.01 [0.7-1.47]), or in the frequency of unsuspected acidaemia (42 [9%] vs 35 [8%]; 1.17 [0.76-1.79]).

INTERPRETATION

The addition of time-interval analysis of the fetal electrocardiogram during labour did not show a significant benefit in decreasing operative intervention. There was no significant difference in neonatal outcome.

Comparison of unstimulated and stimulated behaviour in human fetuses with congenital abnormalities

Unstimulated (passive) and stimulated behaviour [fetal heart rate (FHR) and movements (FA)] was studied in 32 normal fetuses and 10 fetuses with congenital abnormalities (CA). FHR and FA were recorded using a single 1.5-MHz ultrasound transducer and analysed by computer. A 5-second vibroacoustic stimulus (VAS) ('electronic artificial larynx') was used for the stimulation studies. Thus, passive and stimulated behaviour could be studied in a group of fetuses with known pathologies. One hour was used as the recording time for the passive studies and 20 min for the stimulation studies (10 min pre- and 10 min post-VAS). All CA fetuses had abnormalities of FHR and/or FA on recording passive behaviour compared to normal fetuses. However, 4 of the 10 fetuses with CA had responses to VAS that were within the normal range for both FHR and FA. We do not feel that computerised assessment of stimulated behaviour in fetuses with CA confers any advantage over analysis of passive behaviour.

Computerised analysis of unstimulated and stimulated behaviour in fetuses with intrauterine growth restriction

Unstimulated (passive) and stimulated behaviour, in the form of fetal heart rate (FHR) and activity (FA)) was studied in 32 normal fetuses and 14 fetuses with intrauterine growth restriction (IUGR). FHR and FA were recorded using a single 1.5 MHz ultrasound transducer and analysed by computer. A 5 s vibroacoustic stimulus (VAS) (electronic artificial larynx) was used for the stimulation studies. The IUGR fetuses had significantly different patterns of both unstimulated and stimulated behaviour compared to normally grown fetuses. When unstimulated they had lower FA rates than the normally grown fetuses but this was only statistically significant at 28-31 weeks. They also spent a significantly lower proportion of time exhibiting high FHR variation at 28-31 weeks. Following VAS the IUGR fetuses had lower FA responses at all gestations and lower FHR responses from 32 weeks, though only the differences in FA response at 28-31 weeks were statistically significant. Of the 14 fetuses with IUGR, all but one exhibited passive behaviour (ERR and/or FA) that was outside the 10-90th range, for normally grown fetuses, whilst 6 of the 14 had responses to VAS that were within the normal range. We do not feel that computerised assessment of stimulated behaviour in preterm IUGR fetuses confers any advantage over passive observations.

Computerised estimation of the baseline fetal heart rate in labour: the low frequency line

OBJECTIVE

To develop and evaluate a computerised algorithm for the estimation of the fetal heart rate baseline (low frequency line) during labour.

DESIGN

Retrospective observational study.

METHODS

Fetal heart rate signals were obtained from women in labour using the Nottingham fetal ECG monitor. The computerised algorithm for the baseline estimation was developed for intrapartum applications and is based on averaging modal fetal heart rate values. Evaluation was carried out on sixty cardiotocographic recordings by 12 experts and by the computer. These estimates were compared with those obtained from the computerised system using paired differences and intraclass correlation.

RESULTS

The study showed that it is possible to produce a low frequency line from data obtained from intrapartum records. The system could not estimate the low frequency line in four records, whereas experts were also unable to estimate between one and seven tracings. The 95% CI for the paired differences between computer and experts was -12 to 15 bpm, whereas between the experts this was -10 to 10. With the exception of one expert, there was a high concordance between experts and between computer and experts (intraclass correlation > 0.9).

CONCLUSIONS

The performance of this computerised algorithm cannot be distinguished from that of experienced clinicians. There were no significant differences between baseline values obtained by the computerised algorithm and those by the clinicians.

The development of a hybrid expert system for the interpretation of fetal acid-base status

This article presents the development of an expert system for the interpretation of fetal scalp acid-base status. The system consists of logistic transformations, back-propagation neural networks and decision algorithms connected in series. It checks for out-of-range errors and the physiological coherence between measurements. It then determines whether acidosis should be diagnosed, and if so, whether it is more likely to be metabolic, respiratory or mixed. It will also flag those cases where it is difficult to interpret the data in physiological terms. The system was tested on a database of 2174 scalp blood samples collected at the Queens Medical Centre, Nottingham. Of these 88 samples were rejected as erroneous; 13 because of an out-of-range pH alone (> or = 7.48); 73 because more than one measurement was marginally out of range, and two because the relationship between measurements did not make sense. A total of 527 cases (24.2%) were diagnosed as being acidotic; of these, 139 were respiratory, 114 mixed and 274 metabolic. We were unable to fault the system's interpretation when the cases at the margins between diagnostic categories were reviewed clinically.

A comparative study of the fetal electrocardiogram recorded by the STAN an Nottingham systems

OBJECTIVE

To compare the T:QRS ratio recorded by the STAN and Nottingham fetal electrocardiogram (FECG) monitors.

DESIGN

Prospective observational study.

SETTING

London teaching hospital delivery suite and research unit.

METHODS AND SUBJECTS

The T:QRS ratios generated by the STAN and Nottingham FECG monitors were simultaneously recorded and compared using signals generated from a computer-produced ECG signal and signals from 11 term fetuses recorded during labour.

RESULTS

There was an acceptable level of agreement between the two systems with the computer-generated signals, but it was not clinically acceptable with the signals from the fetuses recorded during labour. Disagreements in the T:QRS values were probably due to differences in the reference points for the measurement of the S-T segment and T-wave height.

CONCLUSION

The different points of reference for measurement of S-T segment and T-wave height can explain poor agreement between the two methods of FECG waveform analysis. The suggested adopted points of reference are those corresponding to adult electrocardiographic methodology.

Customised antenatal growth charts

Charts for fetal growth do not take physiological variables into account. We have therefore designed a computer-generated antenatal chart that can be easily "customised" for each individual pregnancy, taking the mother's characteristics and birthweights from previous pregnancies into consideration. The adjusted birthweight range expected at 40 weeks' gestation is combined with a standard, longitudinal ultrasound-derived curve for intrauterine weight gain. Review at the Queen's Medical Centre, Nottingham, UK, of 4179 pregnancies with ultrasound-confirmed dates showed that, in addition to gestation and sex, maternal weight at first antenatal-clinic visit, height, ethnic group, and parity were significant determinants of birthweight in our population. Correction factors were calculated for each of these variables and entered into a computer program to adjust the normal birthweight centile limits. With adjusted centiles we found that 28% of babies conventionally designated small for gestational age (less than 10th centile) and 22% of those designated large (greater than 90th centile) were in fact within normal limits for the pregnancy. Conversely, 24% and 26% of babies identified as small or large, respectively, with adjusted centiles were "missed" by conventional unadjusted centile assessment. Adjustment for physiological variables will make assessment of fetal growth more precise and reduce unnecessary investigations, interventions, and parental anxiety.