[Maternal deaths in Sweden: Diagnostics and clinical management could be improved]

MM-ARG, the Swedish maternal maternity mortality group within SFOG (Swedish Society of Obstetrics and Gynecology) has, since 2008, surveyed and analysed maternal deaths in Sweden with the aim to find and give feedback on lessons learned to the medical professions.  MM-ARG consists of obstetricians, midwives and anesthetists and the strength of the working model is that the profession itself takes responsibility for the scrutiny.  A summary of 67 known maternal deaths from 2007‒2017 is presented. Direct causes of death are dominated by hypertensive disease/preeclampsia, followed by thromboembolic disease, sepsis and obstetric bleeding. Indirect death, where a known or unknown underlying disease is exacerbated by pregnancy, is dominated by cardiovascular disease. This review shows that the diagnostics and clinical management could be improved. Besides obstetrics/gynecology, maternal mortality affects other specialties and thus holds important lessons to many.

Gaps in obstetric care processes - we can only improve what is being measured

A multifaceted intervention at all six obstetric units in the Stockholm Health Region was performed in 2008-2011 in order to increase safety for the newborn infants. Case-controlled criterion-based reviews of care processes during labor and delivery have been used to assess factors associated with suboptimal care during labor and delivery. Categories of increased risk of adverse outcome during labor and delivery were defined. Cases with low Apgar scores and healthy controls were scrutinized and compared to data from a study with an identical design performed before the intervention. The risk of suboptimal care increased twice among controls and three times among cases when reviewing specific criteria after a multifaceted intervention. There are still gaps in care processes that need attention. Improving guidelines is important but not enough alone, and the management of fetal surveillance needs further improvement. The complexity of reviewing care processes using criterion-based research methodology is highlighted.

Single versus pairwise interpretation of cardiotochography, a comparative study from six Swedish delivery units

OBJECTIVE

The aim of the study was to evaluate whether interpreting CTG pairwise brings about a higher level of correctly classified CTG recordings in a non-selected population of midwives and physicians.

STUDY DESIGN

A comparative study.

SETTING

Five delivery units in Stockholm and one delivery unit in Uppsala, with 1589, 3740, 3908, 4539, 6438, and 7331 deliveries in 2011, respectively.

SUBJECTS

536 midwives and physicians classified one randomly selected CTG recording individually followed by a pairwise classification. The pairs consisted of two midwives (119 pairs) or one midwife and one physician (149 pairs), a total of 268 pairs.

MAIN OUTCOME MEASURE

The proportion of individually correctly classified CTG recordings versus the proportion of pairwise correctly classified CTG recordings.

RESULTS

The proportion of individually correctly classified CTG's was 75% and the proportion of pairwise correctly classified CTG's was 80% (difference 5%, p = 0.12).

CONCLUSIONS

There was no statistically significant difference when CTG's were classified pairwise compared to individual classifications. The proportion of individually correctly classified CTG's was high (75%). There were differences in the proportion of correctly classified CTG recordings between the delivery units, indicating potential areas of improvement.

Survival and neonatal outcome after fetoscopic guided laser occlusion (FLOC) of twin-to-twin transfusion syndrome (TTTS) in Sweden

AIM

To determine infant survival and neonatal outcome after fetoscopic laser treatment of twin-to-twin transfusion syndrome (TTTS).

RESULTS

In 53/71(75%) laser-treated TTTS cases, at least one twin was liveborn and in 42/71(59%) cases at least one twin survived infancy. Fetal survival did not differ between donors [41/71(58%)] and recipients [46/71(65%), P=0.36]. Among liveborns, infant survival was 29/41(71%) in donors and 36/46(78%) in recipients (P=0.12). Infant survival did not correlate to maternal characteristics (age, BMI, smoking or parity), gestational age at treatment or severity of TTTS (Quintero stage). No TTTS infant born before 25 weeks of gestation survived the first week. Among the 87 infant survivors, 26 (30%) had an Apgar score <7 at 5 min, 47 (54%) developed respiratory distress syndrome, 10 (11%) showed signs of severe brain damage, nine (10%) renal failure, eight (9%) bronchopulmonary dysplasia, and five (6%) infants developed retinopathy of prematurity ≥stage 3. There was no significant difference in neonatal morbidity between recipients and donors.

CONCLUSIONS

Fetal survival after laser treatment was comparable to that reported by other international centers. There was no significant difference in survival or neonatal morbidity between donors and recipients. Major neonatal morbidity was common, and combined with extremely preterm delivery the prognosis of TTTS is poor.

Healthcare system intervention for prevention of birth injuries - process evaluation of self-assessment, peer review, feedback and agreement for change

BACKGROUND

Patient safety is fundamental in high quality healthcare systems but despite an excellent record of perinatal care in Sweden some children still suffer from substandard care and unnecessary birth injuries. Sustainable patient safety improvements assume changes in key actors' mental models, norms and culture as well as in the tools, design and organisation of work. Interventions positively affecting team mental models on safety issues are a first step to enhancing change. Our purpose was to study a national intervention programme for the prevention of birth injuries with the aim to elucidate how the main interventions of self-assessment, peer review, feedback and written agreement for change affected the teams and their mental model of patient safety, and thereby their readiness for change. Knowledge of relevant considerations before implementing this type of patient safety intervention series could thereby be increased.

METHODS

Eighty participants in twenty-seven maternity units were interviewed after the first intervention sequence of the programme. A content analysis using a priori coding was performed in order to relate results to the anticipated outcomes of three basic interventions: self-assessment, peer review and written feedback, and agreement for change.

RESULTS

The self-assessment procedure was valuable and served as a useful tool for elucidating strengths and weaknesses and identifying areas for improvement for a safer delivery in maternity units. The peer-review intervention was appreciated, despite it being of less value when considering the contribution to explicit outcome effects (i.e. new input to team mental models and new suggestions for actions). The feedback report and the mutual agreement on measures for improvements reached when signing the contract seemed exert positive pressures for change.

CONCLUSIONS

Our findings are in line with several studies stressing the importance of self-evaluation by encouraging a thorough review of objectives, practices and outcomes for the continuous improvement of an organisation. Even though effects of the peer review were limited, feedback from peers, or other change agents involved, and the support that a clear and well-structured action plan can provide are considered to be two important complements to future self-assessment procedures related to patient safety improvement.

Satisfaction with a modified form of in-hospital birth center care compared with standard maternity care

BACKGROUND

For safety reasons an in-hospital birth center was replaced by a modified form of birth center care with the same medical guidelines and equipment as in standard care. The aim of this study was to investigate women's and men's satisfaction with modified care compared with standard care.

METHODS

Women in both groups gave birth from July 2007 to July 2008. The same medical low-risk criteria during pregnancy applied to both groups. Of those invited to the study, 547 (82.7%) women in modified birth center care and 445 (66.7%) men returned a questionnaire posted 2 months after the birth, and 786 (71.6%) women and 639 (58.2%) men in standard care. Odds ratios (ORs) for being satisfied were calculated with 95 percent confidence intervals (CIs) and adjusted for possible confounders. We also explored the effects of different components of care on overall satisfaction.

RESULTS

Adjusted ORs for being satisfied overall were approximately doubled in the modified birth center group compared with the standard care group: antenatal care-OR: 2.1 (95% CI: 1.6-2.7) in women and OR: 2.2 (95% CI: 1.5-2.8) in men; intrapartum care-OR: 2.2 (95% CI: 1.7-2.9) in women and OR: 1.7 (95% CI: 1.3-2.4) in men; and postpartum care-OR: 1.7 in women (95% CI: 1.4-2.2) and OR: 2.1 (95% CI: 1.6-2.8) in men. Important explanations of these differences included perception of the midwife as being more supportive, the presence of a calmer environment and atmosphere (intrapartum), and the option for fathers to stay overnight (postpartum).

CONCLUSION

In-hospital birth center with medical equipment on site increased overall satisfaction with all episodes of care compared with standard care. (BIRTH 39:2 June 2012).

In-hospital birth center with the same medical guidelines as standard care: a comparative study of obstetric interventions and outcomes

BACKGROUND

A challenge of obstetric care is to optimize maternal and infant health outcomes and the mother's experience of childbirth with the least possible intervention in the normal process. The aim of this study was to investigate the effects of modified birth center care on obstetric procedures during delivery and on maternal and neonatal outcomes.

METHODS

In a cohort study 2,555 women who signed in for birth center care during pregnancy were compared with all 9,382 low-risk women who gave birth in the standard delivery ward in the same hospital from March 2004 to July 2008. Odds ratios (OR) were calculated with 95% confidence interval (CI) and adjusted for maternal background characteristics, elective cesarean section, and gestational age.

RESULTS

The modified birth center group included fewer emergency cesarean sections (primiparas: OR: 0.69, 95% CI: 0.58-0.83; multiparas: OR: 0.34, 95% CI: 0.23-0.51), and in multiparas the vacuum extraction rate was reduced (OR: 0.42, 95% CI: 0.26-0.67). In addition, epidural analgesia was used less frequently (primiparas: OR: 0.47, 95% CI: 0.41-0.53; multiparas: OR: 0.25, 95% CI: 0.20-0.32). Fetal distress was less frequently diagnosed in the modified birth center group (primiparas: OR: 0.72, 95% CI: 0.59-0.87; multiparas: OR: 0.45, 95% CI: 0.29-0.69), but no statistically significant differences were found in neonatal hypoxia, low Apgar score less than 7 at 5 minutes, or proportion of perinatal deaths (OR: 0.40, 95% CI: 0.14-1.13). Anal sphincter tears were reduced (primiparas: OR: 0.73, 95% CI: 0.55-0.98; multiparas: OR: 0.41, 95% CI: 0.20-0.83).

CONCLUSION

Midwife-led comprehensive care with the same medical guidelines as in standard care reduced medical interventions without jeopardizing maternal and infant health.

Uncertainty in nuchal translucency reference ranges at 11-14 weeks of gestation--comparison to Swedish centiles

OBJECTIVE

To generate a regression equation for the nuchal translucency (NT) median for the Swedish population and compare this with other median values.

SETTING

Eight Swedish hospitals.

SAMPLE

The data set included 20 887 unaffected fetuses.

METHODS

Calculation and generation of an NT centile chart for the Swedish population.

RESULTS

The NT centiles for crown-rump length (CRL) from 45 to 84 mm were calculated and compared with the medians from Glasgow, from the Fetal Medicine Foundation (FMF, London, UK; FMF-original) and those published recently (FMF-new). The NT medians cease to increase at CRLs between 70 and 75 mm. The Swedish, FMF-new and Glasgow medians followed the same pattern, but the Glasgow NT median curve was systematically lower by around 20%. Swedish, FMF-new and Glasgow medians differed in shape from the FMF-original medians, which continuously increase throughout the whole range of CRLs.

CONCLUSIONS

Our results demonstrate that there are substantial differences in the NT medians and centiles between countries.

How often is a low Apgar score the result of substandard care during labour?

Please cite this paper as: Berglund S, Pettersson H, Cnattingius S, Grunewald C. How often is a low Apgar score the result of substandard care during labour? BJOG 2010;117:968-978. Objective To increase our knowledge of the occurrence of substandard care during labour. Design A population-based case-control study. Setting Stockholm County. Population Infants born in the period 2004-2006 in Stockholm County. Methods Cases and controls were identified from the Swedish Medical Birth Register, had a gestational age of >/=33 complete weeks, had planned for a vaginal delivery, and had a normal cardiotocographic (CTG) recording on admission. We compared 313 infants with an Apgar score of <7 at 5 minutes of age with 313 randomly selected controls with a full Apgar score, matched for year of birth. Main outcome measure Substandard care during labour. Results We found that 62% of cases and 36% of controls were subject to some form of substandard care during labour. In half of the cases and in 12% of the controls, CTG was abnormal for >/=45 minutes before birth. Fetal blood sampling was not performed in 79% of both cases and controls, when indicated. Oxytocin was provided without signs of uterine inertia in 20% of both cases and controls. Uterine contractions were hyperstimulated by oxytocin in 29% of cases and in 9% of controls, and the dose of oxytocin was increased despite abnormal CTG in 19% and 6% of cases and controls, respectively. Assuming that substandard care is a risk factor for low Apgar score, we estimate that up to 42% of the cases could be prevented by avoiding substandard care. Conclusions There was substandard care during labour of two-thirds of infants with a low Apgar score. The main reasons for substandard care were related to misinterpretation of CTG, not acting on an abnormal CTG in a timely fashion and incautious use of oxytocin.

How often is a low Apgar score the result of substandard care during labour?

OBJECTIVE

To increase our knowledge of the occurrence of substandard care during labour.

DESIGN

A population-based case-control study.

SETTING

Stockholm County.

POPULATION

Infants born in the period 2004-2006 in Stockholm County.

METHODS

Cases and controls were identified from the Swedish Medical Birth Register, had a gestational age of +/-33 complete weeks, had planned for a vaginal delivery, and had a normal cardiotocographic (CTG) recording on admission. We compared 313 infants with an Apgar score of < 7 at 5 minutes of age with 313 randomly selected controls with a full Apgar score, matched for year of birth.

MAIN OUTCOME MEASURE

Substandard care during labour.

RESULTS

We found that 62% of cases and 36% of controls were subject to some form of substandard care during labour. In half of the cases and in 12% of the controls, CTG was abnormal for > or = 45 minutes before birth. Fetal blood sampling was not performed in 79% of both cases and controls, when indicated.Oxytocin was provided without signs of uterine inertia in 20% of both cases and controls. Uterine contractions were hyperstimulated by oxytocin in 29% of cases and in 9% of controls, and the dose of oxytocin was increased despite abnormal CTG in 19% and 6% of cases and controls, respectively. Assuming that substandard care is a risk factor for low Apgar score, we estimate that up to 42% of the cases could be prevented by avoiding substandard care.

CONCLUSIONS

There was substandard care during labour of two thirds of infants with a low Apgar score. The main reasons for substandard care were related to misinterpretation of CTG, not acting on an abnormal CTG in a timely fashion and incautious use of oxytocin.

Neonatal resuscitation after severe asphyxia--a critical evaluation of 177 Swedish cases

AIM

To evaluate neonatal resuscitation of infants born with severe asphyxia.

METHOD

All case records of the 472 claims for financial compensation due to suspected medical malpractice in conjunction with childbirth in Sweden between 1990 and 2005 were scrutinized. Inclusion criteria were: gestational age > or =33 completed weeks, planned vaginal onset of delivery, a reactive CTG at onset of labour, neonatal asphyxia (defined as metabolic acidosis [pH of < 7.05 and/or a base excess of < -12]), or an Apgar score <7 at 5 min. It was assessed that 177 infants suffered from cerebral palsy or early death due to severe asphyxia presumably caused by malpractice around labour.

RESULTS

Median Apgar score at 5 min was 3, indicating that all infants needed immediate and extensive resuscitation. There was insufficient adherence to guidelines concerning neonatal resuscitation, including delayed initiation of excessive resuscitation in 19 infants, lack of satisfactory ventilation in 79 infants, and untimely interruption of resuscitation in 38 infants.

CONCLUSIONS

Compliance with guidelines for resuscitation of severely asphyctic newborn may be improved, especially concerning ventilation and prompt paging for skilled personnel in cases of imminent asphyxia. Documentation of neonatal resuscitation must be improved to enable reliable evaluation.

Severe asphyxia due to delivery-related malpractice in Sweden 1990-2005

Objective

To describe possible causes of delivery-related severe asphyxia due to malpractice.

Design and setting

A nationwide descriptive study in Sweden.

Population

All women asking for financial compensation because of suspected medical malpractice in connection with childbirth during 1990–2005.

Method

We included infants with a gestational age of ≥33 completed gestational weeks, a planned vaginal onset of delivery, reactive cardiotocography at admission for labour and severe asphyxia-related outcomes presumably due to malpractice. As asphyxia-related outcomes, we included cases of neonatal death and infants with diagnosed encephalopathy before the age of 28 days.

Main outcome measure

Severe asphyxia due to malpractice during labour.

Results

A total of 472 case records were scrutinised. One hundred and seventy-seven infants were considered to suffer from severe asphyxia due to malpractice around labour. The most common events of malpractice in connection with delivery were neglecting to supervise fetal wellbeing in 173 cases (98%), neglecting signs of fetal asphyxia in 126 cases (71%), including incautious use of oxytocin in 126 cases (71%) and choosing a nonoptimal mode of delivery in 92 cases (52%).

Conclusion

There is a great need and a challenge to improve cooperation and to create security barriers within our labour units. The most common cause of malpractice is that stated guidelines for fetal surveillance are not followed. Midwives and obstetricians need to improve their shared understanding of how to act in cases of imminent fetal asphyxia and how to choose a timely and optimal mode of delivery.

Please cite this paper as:Berglund S, Grunewald C, Pettersson H, Cnattingius S. Severe asphyxia due to delivery-related malpractice in Sweden 1990–2005. BJOG 2008;115:316–323.

Perception of risk in relation to ultrasound screening for Down's syndrome during pregnancy

OBJECTIVE

to explore how information about being at risk of carrying a fetus with Down's syndrome was understood, and whether the actual risk and the woman's perception of risk was associated with worry or depressive symptoms during and after pregnancy.

DESIGN AND SETTING

observational study. The sample was drawn from the intervention group of a Swedish randomised controlled trial of ultrasound screening for Down's syndrome by nuchal translucency measurement.

MEASUREMENTS

data were collected by three questionnaires. Questions were asked about recall of the risk score and perception of risk. The Cambridge Worry Scale and the Edinburgh Postnatal Depression Scale measured worry and depressive symptoms, respectively, on all three occasions.

FINDINGS

of the 796 women who provided data for this study, one in five was unaware that the risk score was noted in her case record. In total, 620 women stated that they had received a risk score, but only 64% of them recalled the figure exactly or approximately. The actual risk was associated with the perceived risk, but of the 31 women who perceived the risk to be high, only 14 were actually at high risk. A high-risk score was not associated with worry or depressive symptoms in mid-pregnancy, in contrast to a woman's own perception of being at high risk. Two months postpartum, no associations were found between maternal emotional well-being and actual or perceived risk.

CONCLUSIONS

information about fetal risk is complicated and women's perception of risk does not always reflect the actual risk, at least not when presented as a numerical risk score. The possibility that the information may cause unnecessary emotional problems cannot be excluded.

IMPLICATIONS FOR PRACTICE

caregivers should ascertain that information about fetal risk is interpreted correctly by pregnant women.

Miscarriage after a normal scan at 12-14 gestational weeks in women at low risk of carrying a fetus with chromosomal anomaly according to nuchal translucency screening

OBJECTIVES

To estimate the risk of second-trimester miscarriage in women with low risk of carrying a fetus with chromosomal abnormality, according to nuchal translucency (NT) screening, and to determine whether NT thickness or other factors affect the risk.

METHODS

The study population comprised 14 278 singleton pregnancies with a risk of Down syndrome < 1:250 at NT scan, and where no fetal karyotyping was performed < 25 weeks. Risk factors for miscarriage were investigated by logistic regression.

RESULTS

The median risk of Down syndrome was 1 : 3138 (range 1 : 9651-1 : 251) and median NT was 1.7 (range 0.4-3.0) mm. The miscarriage rate was 0.5% (77/14 278; 95% CI 0.4-0.6). After having controlled for maternal age, we found the number of previous deliveries and miscarriages to independently predict miscarriage: odds ratio (OR) for each previous delivery 1.48, 95% CI 1.22-1.94, P < 0.0001; OR for each previous miscarriage 1.34, 95% CI 1.07-1.68, P = 0.01. Excluding women with any previous miscarriage and adjusting for parity, we found a U-shaped relationship between maternal age and miscarriage (P = 0.04).

CONCLUSION

In singleton pregnancies with estimated risk of Down syndrome < 1:250 according to NT screening at 12-14 weeks, the spontaneous fetal loss rate before 25 weeks is likely to be around 0.5%. NT thickness up to 3 mm does not seem to affect the risk of miscarriage in such pregnancies. Instead, the risk seems to increase with number of previous miscarriages and deliveries, and possibly the risk is highest in the youngest and oldest women.

By how much does increased nuchal translucency increase the risk of adverse pregnancy outcome in chromosomally normal fetuses? A study of 16,260 fetuses derived from an unselected pregnant population

OBJECTIVE

In this study we aimed to estimate the magnitude of a possible increase in risk of adverse outcome in fetuses with normal karyotype and increased nuchal translucency (NT), and to determine how well NT measurements can distinguish between fetuses with normal and adverse outcome.

METHODS

We studied 16,260 consecutive fetuses with normal karyotype derived from an unselected pregnant population. The following cut-offs for increased risk of adverse outcome were chosen a priori: NT > or = 95th percentile, > or = 3 mm, > or = 3.5 mm, and > or = 4.5 mm. The positive and negative likelihood ratios (+LR, - LR) of the risk cut-offs with regard to fetal malformation, miscarriage, perinatal death, termination of pregnancy and total adverse outcome were calculated, and receiver-operating characteristics (ROC) curves were drawn.

RESULTS

The total rate of adverse outcome was 2.7%. + LR and - LR of NT > or = 3.0 mm were: for lethal or severe malformation, + LR 15.0 (95% CI 7.0-28.6), - LR 0.89 (95% CI 0.81-0.95); for malformation of at least intermediate severity, + LR 8.1 (95% CI 4.3-14.0), - LR 0.95 (95% CI 0.92-0.97); for termination of pregnancy, + LR 41.6 (95% CI 17.1-86.6), - LR 0.67 (95% CI 0.41-0.85); for any adverse outcome, + LR 6.4 (95% CI 3.4-11), - LR 0.96 (95% CI 0.94-0.98). The odds for these adverse outcomes increased with increasing NT. NT > or = 3 mm did not significantly increase the risk of miscarriage or perinatal death. Areas under ROC curves for NT were small, with 95% CI below or only slightly above 0.5.

CONCLUSION

Our likelihood ratios can be used to calculate the individual risk of unfavorable outcome, but NT screening cannot reliably distinguish between normal and adverse outcome in fetuses with normal karyotype.

Routine ultrasound examination at 12 or 18 gestational weeks for prenatal detection of major congenital heart malformations? A randomised controlled trial comprising 36,299 fetuses

OBJECTIVE

To compare the rate of prenatal diagnosis of heart malformations between two policies of screening for heart malformations.

DESIGN

Randomised controlled trial.

SETTING

Six university hospitals, two district general hospitals.

SAMPLE

A total of 39 572 unselected pregnancies randomised to either policy.

METHODS

The 12-week policy implied one routine scan at 12 weeks including measurement of nuchal translucency (NT), and the 18-week policy implied one routine scan at 18 weeks. Fetal anatomy was scrutinised using the same check-list in both groups, and in both groups, indications for fetal echocardiography were ultrasound findings of any fetal anomaly, including abnormal four-chamber view, or other risk factors for heart malformation. In the 12-week scan group, NT >or=3.5 mm was also an indication for fetal echocardiography.

MAIN OUTCOME MEASURE

Prenatal diagnosis of major congenital heart malformation.

RESULTS

In the 12-week scan group, 7 (11%) of 61 major heart malformations were prenatally diagnosed versus 9 (15%) of 60 in the 18-week scan group (P= 0.60). In four (6.6%) women in the 12-week scan group, the routine scan was the starting point for investigations resulting in a prenatal diagnosis versus in 9 (15%) women in the 18-week scan group (P=0.15). The diagnosis was made <or=22 weeks in 5% (3/61) of the cases in the 12-week scan group versus in 15% (9/60) in the 18-week scan group (P=0.08).

CONCLUSIONS

The prenatal detection rate of major heart malformations was low with both policies. The 18-week scan policy seemed to be superior to the 12-week scan policy, although the differences in prenatal detection rates were not statistically significant.

Detection of malformations in chromosomally normal fetuses by routine ultrasound at 12 or 18 weeks of gestation-a randomised controlled trial in 39,572 pregnancies

OBJECTIVE

To compare the antenatal detection rate of malformations in chromosomally normal fetuses between a strategy of offering one routine ultrasound examination at 12 gestational weeks (gws) and a strategy of offering one routine examination at 18 gws.

DESIGN

Randomised controlled trial.

SETTING

Multicentre trial including eight hospitals.

POPULATION

A total of 39,572 unselected pregnant women.

METHODS

Women were randomised either to one routine ultrasound scan at 12 (12-14) gws including nuchal translucency (NT) measurement or to one routine scan at 18 (15-22) gws. Anomaly screening was performed in both groups following a check-list. A repeat scan was offered in the 12-week scan group if the fetal anatomy could not be adequately seen at 12-14 gws or if NT was >or=3.5 mm in a fetus with normal or unknown chromosomes.

MAIN OUTCOME MEASURES

Antenatal detection rate of malformed fetuses.

RESULTS

The antenatal detection rate of fetuses with a major malformation was 38% (66/176) in the 12-week scan group and 47% (72/152) in the 18-week scan group (P= 0.06). The corresponding figures for detection at <22 gws were 30% (53/176) and 40% (61/152) (P= 0.07). In the 12-week scan group, 69% of fetuses with a lethal anomaly were detected at a scan at 12-14 gws.

CONCLUSIONS

None of the two strategies for prenatal diagnosis is clearly superior to the other. The 12-week strategy has the advantage that most lethal malformations will be detected at <15 gws, enabling earlier pregnancy termination. The 18-week strategy seems to be associated with a slightly higher detection rate of major malformations, although the difference was not statistically significant.

Is measurement of nuchal translucency thickness a useful screening tool for heart defects? A study of 16,383 fetuses

OBJECTIVE

To determine the performance of nuchal translucency thickness (NT) measurement as a screening method for congenital heart defects (CHD) among fetuses with normal karyotype.

METHODS

An NT measurement was made in 16 383 consecutive euploid fetuses derived from an unselected pregnant population. The cut-offs for increased risk of heart defects, chosen a priori and tested prospectively, were: NT >or= 95th centile for crown-rump length, NT >or= 3 mm, and NT >or= 3.5 mm. The sensitivity and false-positive rate (FPR; 1 minus specificity) of the risk cut-offs and their positive and negative likelihood ratios (+LR and -LR) with regard to CHD were calculated.

RESULTS

Among the 16 383 fetuses with an NT measurement there were 127 cases with a diagnosis of heart defect confirmed by cardiac investigations after birth or at autopsy. Of these, 55 defects were defined as major, of which 52 were isolated (no other defects or chromosomal aberrations), corresponding to a prevalence of major heart defects in chromosomally normal fetuses/newborns of 3.3/1000. The sensitivity, FPR, +LR and -LR for NT >or= 95th centile with regard to an isolated major heart defect were: 13.5%, 2.6%, 5.2 and 0.9, respectively. For NT >or= 3.0 mm these values were: 9.6%, 0.8%, 12.0 and 0.9, and for NT >or= 3.5 mm they were: 5.8%, 0.3%, 19.3 and 0.9.

CONCLUSIONS

NT measurement is a poor screening method for isolated major CHD. A method with a much higher detection rate and with a reasonably low FPR is needed. However, increased NT indicates increased risk of fetal heart defect, and women carrying fetuses with increased NT should be offered fetal echocardiography in the second trimester.

If nuchal translucency screening is combined with first-trimester serum screening the need for fetal karyotyping decreases

BACKGROUND

This case-control study was performed to evaluate whether adding first-trimester maternal serum testing to nuchal translucency measurement would improve the antenatal detection of Down's syndrome and decrease the number of women offered fetal karyotyping.

METHODS

In the Swedish Nuchal Translucency Trial (the NUPP trial), 39,572 pregnant women were randomized to a routine scan at 12-14 gestational weeks including nuchal translucency screening for Down's syndrome, or a routine scan at 16-18 gestational weeks. From the early scan group 47 pregnancies with Down's syndrome were identified and for each case three controls were chosen. Of the 189 women asked to participate, 31 cases and 108 controls with a singleton pregnancy and frozen serum from 8-14 gestational weeks available for analysis accepted participation. Maternal sera were analyzed for free beta human chorionic gonadotrophin and pregnancy-associated plasma protein A. The risk for Down's syndrome was calculated using combinations of maternal age, crown-rump length, nuchal translucency, and biochemistry. A risk > or =1/250 was considered increased and an indication for fetal karyotyping.

RESULTS

Risk calculated on the basis of maternal age alone would have identified 21 of the 31 Down's syndrome cases by karyotyping 61 of the 139 fetuses. Maternal age and nuchal translucency would have identified 29 cases by karyotyping 51 fetuses. Maternal age, nuchal translucency, and biochemistry would also have identified 29 cases by karyotyping 37 fetuses.

CONCLUSIONS

By adding first trimester biochemistry to nuchal translucency measurement the detection rate of fetuses with Down's syndrome seems to remain unchanged whereas the antenatal risk group to be offered fetal karyotyping decreases.

Ultrasound dating at 12-14 weeks of gestation. A prospective cross-validation of established dating formulae in in-vitro fertilized pregnancies

OBJECTIVES

To determine the accuracy of established ultrasound dating formulae when used at 12-14 weeks of gestation.

METHODS

One-hundred and sixty-seven singleton pregnancies conceived after in-vitro fertilization (IVF) underwent a dating scan at 12-14 weeks of gestation. Gestational age at the dating scan was calculated by adding 14 days to the number of days between the date of oocyte retrieval and the date of the ultrasound scan. Gestational age according to oocyte retrieval was regarded as the true gestational age. True gestational age was compared to gestational age calculated on the basis of 21 dating formulae based on fetal crown-rump length (CRL) measurements and to three dating formulae based on fetal biparietal diameter (BPD) measurements. In a previous study the three BPD formulae tested here had been shown to be superior to four other BPD formulae when used at 12-14 weeks of gestation. The mean of the differences between estimated and true gestational age and their standard deviation (SD) were calculated for each formula. The SD of the differences was assumed to reflect random measurement error. Systematic measurement error was assumed to exist if zero lay outside the mean difference+/-2SE (SE: standard error of the mean).

RESULTS

The three best CRL formulae were associated with mean (non-systematic) measurement errors of -0.0, -0.1 and -0.3 days, and the SD of the measurement errors of these formulae varied from 2.37 to 2.45. All but two of the remaining CRL formulae were associated with systematic over- or under-estimation of gestational age, and the SDs of their measurement error varied between 2.25 and 4.86 days. Dating formulae using BPD systematically underestimated gestational age by -0.4 to -0.7 days, and the SDs of their measurement errors varied from 1.86 to 2.09.

CONCLUSIONS

We have identified three BPD formulae that are suitable for dating at 12-14 weeks of gestation. They are superior to all 21 CRL formulae tested here, because their random measurement errors were much smaller than those of the three best CRL formulae. The small systematic negative measurement errors associated with the BPD formulae are likely to be clinically unimportant.

Screening for Down syndrome based on maternal age or fetal nuchal translucency: a randomized controlled trial in 39,572 pregnancies

OBJECTIVES

Nuchal translucency (NT) screening increases antenatal detection of Down syndrome (DS) compared to maternal age-based screening. We wanted to determine if a change in policy for prenatal diagnosis would result in fewer babies born with DS.

METHODS

A total of 39,572 pregnant women were randomized to a scan at 12-14 gestational weeks including NT screening for DS (12-week group) or to a scan at 15-20 weeks with screening for DS based on maternal age (18-week group). Fetal karyotyping was offered if risk according to NT was > or = 1:250 in the 12-week group and if maternal age was > or = 35 years in the 18-week group. Both policies included the offer of karyotyping in cases of fetal anomaly detected at any scan during pregnancy or when there was a history of fetal chromosomal anomaly. The number of babies born with DS and the number of invasive tests for fetal karyotyping were compared.

RESULTS

Ten babies with DS were born alive with the 12-week policy vs. 16 with the 18-week policy (P = 0.25). More fetuses with DS were spontaneously lost or terminated in the 12-week group (45/19,796) than in the 18-week group (27/19 776; P = 0.04). All women except one with an antenatal diagnosis of DS at < 22 weeks terminated the pregnancy. For each case of DS detected at < 22 weeks in a living fetus there were 16 invasive tests in the 12-week group vs. 89 in the 18-week group. NT screening detected 71% of cases of DS for a 3.5% test-positive rate whereas maternal age had the potential of detecting 58% for a test-positive rate of 18%.

CONCLUSIONS

The number of newborns with DS differed less than expected between pregnancies that had been screened at 12-14 weeks' gestation by NT compared with those screened at 15-20 weeks by maternal age. One explanation could be that NT screening--because it is performed early in pregnancy--results in the detection and termination of many pregnancies with a fetus with DS that would have resulted in miscarriage without intervention, and also by many cases of DS being detected because of a fetal anomaly seen on an 18-week scan. The major advantage of the 12-week scan policy is that many fewer invasive tests for fetal karyotyping are needed per antenatally detected case of DS.

Does fetal screening affect women's worries about the health of their baby? A randomized controlled trial of ultrasound screening for Down's syndrome versus routine ultrasound screening

BACKGROUND

Screening for fetal abnormality may increase women's anxiety as attention is directed at the possibility of something being wrong with the baby. The aim of this study was to evaluate the effect of ultrasound screening for Down's syndrome on women's anxiety in mid-pregnancy and 2 months after delivery.

METHOD

Two thousand and twenty-six women were randomly allocated to an ultrasound examination at 12-14 gestational weeks (gws) including risk assessment for Down's syndrome or to a routine scan at 15-20 gws. Questionnaires including the State-Trait Anxiety Inventory (STAI), the Cambridge Worry Scale (CWS), and the Edinburgh Postnatal Depression Scale (EPDS) were filled in at baseline in early pregnancy, at 24 gws and 2 months after delivery.

RESULTS

No statistically significant differences were found between the trial groups regarding women's worries about the health of the baby, general anxiety and depressive symptoms during pregnancy or 2 months after delivery. Women's worries about something being wrong with the baby in the early ultrasound group and routine group, respectively, decreased from baseline (39.1% versus 36.0%) to mid-pregnancy (29.2% versus 27.8%), and finally to 2 months after delivery (5.2% versus 6.6%).

CONCLUSION

Fetal screening for Down's syndrome by an early ultrasound scan did not cause more anxiety or concerns about the health of the baby in mid-pregnancy or 2 months after birth than in women who had a routine scan.

Ultrasound dating at 12-14 or 15-20 weeks of gestation? A prospective cross-validation of established dating formulae in a population of in-vitro fertilized pregnancies randomized to early or late dating scan

OBJECTIVES

To determine the accuracy of established ultrasound dating formulae when used at 12-14 and 15-20 gestational weeks.

METHODS

A total of 363 singleton pregnancies conceived after in-vitro fertilization (IVF) and randomized to a dating scan at 12-14 or 15-20 gestational weeks were studied. 'True' gestational age was calculated on the basis of the day of oocyte retrieval and was compared to gestational age calculated on the basis of seven dating formulae including the fetal biparietal diameter (BPD) and three dating formulae including BPD and fetal femur length (FL). The mean of the differences between estimated and true gestational age (systematic measurement error) and their SD (random measurement error) were calculated for each formula.

RESULTS

Three formulae showed systematic errors of less than -0.7 days at both early and late scanning. Two formulae overestimated gestational age at both early and late scanning by 5.7 and 3.1 vs. 2.3 and 2.8 days, respectively, while five formulae manifested very different systematic errors at early and late scanning. The formulae used for clinical management underestimated gestational age by a mean of 3 days when dating was performed at 12-14 weeks, and by a mean of 0.8 days when dating was done at 15-20 weeks. The random error was on average 1 day less when the scan was carried out early (2 vs. 3 days; P < 0.0005). Mean true gestational age at delivery in IVF pregnancies with spontaneous start of labor was 279 days (SD 12.9); excluding preterm deliveries it was 281 days (SD 8.1).

CONCLUSIONS

Ultrasound dating formulae originally intended for use in the middle of the second trimester do not necessarily perform well when used for dating earlier in gestation. The systematic and random error of any dating formula must be assessed for the gestational age interval in which the formula is intended to be used.