Prognosis of the co-twin following spontaneous single intrauterine fetal death in twin pregnancies: a systematic review and meta-analysis

BACKGROUND

Single intrauterine fetal death affects approximately 6% of twin pregnancies and can have serious sequelae for the surviving co-twin.

OBJECTIVES

Determine the prognosis of the surviving co-twin following spontaneous single intrauterine fetal death to aid counselling patients and highlight future research areas.

SEARCH STRATEGY

Medline, Embase, Web of Science, and Cochrane Library, from 1980 to June 2017.

SELECTION CRITERIA

Studies of five or more cases of spontaneous single intrauterine fetal death after 14 weeks gestation, in diamniotic twin pregnancies.

DATA COLLECTION AND ANALYSIS

Summary event rates were calculated and stratified by chorionicity. Monochorionic and dichorionic twins, and sub-groups, were compared by odds ratios.

MAIN RESULTS

In monochorionic twins, when single intrauterine fetal death occurred at less than 28 weeks' gestation, this significantly increased the rate of co-twin intrauterine fetal death [odds ratio (OR) 2.31, 95% confidence interval (CI) 1.02-5.25, I²  = 0.0%, 12 studies, 184 pregnancies] and neonatal death (OR 2.84, 95% CI 1.18-6.77, I²  = 0.0%, 10 studies, 117 pregnancies) compared with when the single intrauterine fetal death occurred at more than 28 weeks' gestation. Neonatal death in monochorionic twins was significantly higher if the pregnancy was complicated by fetal growth restriction (OR 4.83, 95% CI 1.14-20.47, I²  = 0.0%, six studies, 60 pregnancies) or preterm birth (OR 4.95, 95% CI 1.71-14.30, I²  = 0.0%, 11 studies, 124 pregnancies). Abnormal antenatal brain imaging was reported in 20.0% (95% CI 12.8-31.1, I²  = 21.9%, six studies, 116 pregnancies) of surviving monochorionic co-twins. The studies included in the meta-analysis demonstrated small study effects and possible selection bias.

CONCLUSIONS

Preterm birth was the commonest adverse outcome affecting 58.5 and 53.7% of monochorionic and dichorionic twin pregnancies. Outcomes regarding brain imaging and neurodevelopmental comorbidity are an important area for future research, but meta-analysis may be limited due to different methods of assessment.

TWEETABLE ABSTRACT

Preterm birth is the highest risk in single co-twin death. Abnormal antenatal brain imaging was found in 1/5 surviving MC twins.

Early prognostic factors of outcomes in monochorionic twin pregnancy: systematic review and meta-analysis

BACKGROUND

Monochorionic twin pregnancies are high-risk, however at present, no screening test is available to predict which monochorionic twin pregnancy will develop complications.

OBJECTIVE

We sought to assess ability of first-trimester pregnancy-related factors (ultrasound measurements, maternal characteristics, biomarkers) to predict complications in monochorionic twin pregnancies.

DATA SOURCES

Data sources were MEDLINE, Embase, ISI Web of Science, CINAHL, the Cochrane Central Registration of Controlled Trials and Research Registers, and Google Scholar, from inception to May 12, 2017. Gray literature and bibliographies of articles were checked.

STUDY ELIGIBILITY CRITERIA

Studies that reported ultrasound measurements, maternal characteristics, or potential biomarkers, measured in the first trimester in monochorionic-diamniotic twin pregnancies, where the potential prognostic ability between the variable and twin-twin transfusion syndrome, growth restriction, or intrauterine fetal death could be assessed, were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

Quality assessment was evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology checklist by 2 reviewers independently. For meta-analysis, odds ratios using a random effects model, or standardized mean difference were calculated. If a moderate association was found, the prognostic ability was evaluated by calculating the sensitivity and specificity. Risk of heterogeneity was reported as I² and publication bias was visually assessed by funnel plots and quantitatively by Egger test.

RESULTS

In all, 48 studies were eligible for inclusion. Twenty meta-analyses could be performed. A moderate association was demonstrated in 3 meta-analyses, between: nuchal translucency >95th centile in one/both fetuses and twin-twin transfusion syndrome (odds ratio, 2.29 [95% confidence interval, 1.05-4.96], I² = 6.6%, 4 studies, 615 pregnancies); crown-rump length discordance ≥10% and twin-twin transfusion syndrome (odds ratio, 2.43 [95% confidence interval, 1.13-5.21], I² = 14.1%, 3 studies, 708 pregnancies); and maternal ethnicity and twin-twin transfusion syndrome (odds ratio, 2.12 [95% confidence interval, 1.17-3.83], I² = 0.0%, 5 studies, 467 pregnancies), but none demonstrated a prognostic ability for any outcome under investigation.

CONCLUSION

It is not currently possible to predict adverse outcomes in monochorionic twin pregnancies. We have revealed a lack of research investigating first-trimester biomarkers in monochorionic twin pregnancies. Different assessment methods and definitions of each variable and outcome were an issue and this highlights the need for a large cohort study to evaluate these factors.

Association of maternal serum PAPP-A levels, nuchal translucency and crown-rump length in first trimester with adverse pregnancy outcomes: retrospective cohort study

OBJECTIVE

Are first trimester serum pregnancy-associated plasma protein-A (PAPP-A), nuchal translucency (NT) and crown-rump length (CRL) prognostic factors for adverse pregnancy outcomes?

METHOD

Retrospective cohort, women, singleton pregnancies (UK 2011-2015). Unadjusted and multivariable logistic regression.

OUTCOMES

small for gestational age (SGA), pre-eclampsia (PE), preterm birth (PTB), miscarriage, stillbirth, perinatal mortality and neonatal death (NND).

RESULTS

A total of 12 592 pregnancies: 852 (6.8%) PTB, 352 (2.8%) PE, 1824 (14.5%) SGA, 73 (0.6%) miscarriages, 37(0.3%) stillbirths, 73 perinatal deaths (0.6%) and 38 (0.30%) NND. Multivariable analysis: lower odds of SGA [adjusted odds ratio (aOR) 0.88 (95% CI 0.85,0.91)], PTB [0.92 (95%CI 0.88,0.97)], PE [0.91 (95% CI 0.85,0.97)] and stillbirth [0.71 (95% CI 0.52,0.98)] as PAPP-A increases. Lower odds of SGA [aOR 0.79 (95% CI 0.70,0.89)] but higher odds of miscarriage [aOR 1.75 95% CI (1.12,2.72)] as NT increases, and lower odds of stillbirth as CRL increases [aOR 0.94 95% CI (0.89,0.99)]. Multivariable analysis of three factors together demonstrated strong associations: a) PAPP-A, NT, CRL and SGA, b) PAPP-A and PTB, c) PAPP-A, CRL and PE, d) NT and miscarriage.

CONCLUSIONS

Pregnancy-associated plasma protein-A, NT and CRL are independent prognostic factors for adverse pregnancy outcomes, particularly PAPP-A and SGA with lower PAPP-A associated with increased risk. © 2017 John Wiley & Sons, Ltd.

The prediction, diagnosis and management of complications in monochorionic twin pregnancies: the OMMIT (Optimal Management of Monochorionic Twins) study

BACKGROUND

Monochorionic twin pregnancies are at increased risk of complications due to sharing a single placenta and potentially developing unbalanced vascular anastomoses. Complications include twin-twin transfusion syndrome (TTTS) which affects 10-15% monochorionic twins, and if untreated has a 70-90% perinatal loss rate. We are currently unable to predict which twins will develop complications or to what severity. We have previously shown differences in angiogenic and placental growth factors in maternal blood in pregnancies complicated by TTTS compared to twin pregnancies not complicated by TTTS but matched for gestation. There is also evidence to suggest that abnormal ultrasound measurements recorded in the first trimester (nuchal translucency and crown-rump length) may be associated with severe TTTS later in pregnancy, however the detection rate is only reported as 52%. We hypothesize that if these changes precede the development of the clinical syndrome, this may increase the sensitivity and specificity of detecting adverse pregnancy outcomes.

METHODS

This cohort study has retrospective and prospective elements. In the retrospective cohort we will measure factors (decided based on preliminary work and a systematic review and meta-analysis) in stored maternal blood samples taken in the first-trimester, extract first-trimester ultrasound measurements and match these to pregnancy outcome. The prospective cohort will be divided into a "screening" cohort and "complicated" cohort. The screening cohort will undergo serial maternal blood sampling at 12, 16 and 20 weeks; we will extract ultrasound measurements and match to pregnancy outcome. The complicated cohort will comprise of women referred to the Fetal Medicine Centre with complications of monochorionicity. If the decision is taken to undergo fetoscopic laser ablation we will take maternal blood samples and amniotic fluid samples pre- and post-laser treatment. The same factors will be measured in the prospective cohort as informed by the retrospective study.

DISCUSSION

This study aims to increase knowledge surrounding the pathology of complications in monochorionic twins, to aid future diagnosis and management.

TRIAL REGISTRATION

ISRCTN 13114861 (retrospectively registered).

Comparison of Solomon technique with selective laser ablation for twin-twin transfusion syndrome: a systematic review

OBJECTIVE

To compare the Solomon and selective techniques for fetoscopic laser ablation (FLA) for the treatment of twin-twin transfusion syndrome (TTTS) in monochorionic-diamniotic twin pregnancies.

METHODS

This was a systematic review conducted in accordance with the PRISMA statement. Electronic searches were performed for relevant citations published from inception to September 2014. Selected studies included pregnancies undergoing FLA for TTTS that reported on recurrence of TTTS, occurrence of twin anemia-polycythemia sequence (TAPS) or survival.

RESULTS

From 270 possible citations, three studies were included, two cohort studies and one randomized controlled trial (RCT), which directly compared the Solomon and selective techniques for FLA. The odds ratios (OR) of recurrent TTTS when using the Solomon vs the selective technique in the two cohort studies (n = 249) were 0.30 (95% CI, 0.00-4.46) and 0.45 (95% CI, 0.07-2.20). The RCT (n = 274) demonstrated a statistically significant reduction in risk of recurrent TTTS with the Solomon technique (OR, 0.21 (95% CI, 0.04-0.98); P = 0.03). The ORs for the development of TAPS following the Solomon and the selective techniques were 0.20 (95% CI, 0.00-2.46) and 0.61 (95% CI, 0.05-5.53) in the cohort studies and 0.16 (95% CI, 0.05-0.49) in the RCT, with statistically significant differences for the RCT only (P < 0.001). Observational evidence suggested overall better survival with the Solomon technique, which was statistically significant for survival of at least one twin. The RCT did not demonstrate a significant difference in survival between the two techniques, most probably owing to the small sample size and lack of power.

CONCLUSION

This systematic review of observational, comparative cohort and RCT data suggests a trend towards a reduction in TAPS and recurrent TTTS and an increase in twin survival, with no increase in the occurrence of complications or adverse events, when using the Solomon compared to the selective technique for the treatment of TTTS. These findings need to be confirmed by an appropriately-powered RCT with long-term neurological follow-up.

Outcome in fetal lower urinary tract obstruction: a prospective registry study

OBJECTIVE

To describe influences on decision-making and prognostic variables in the prenatal management of fetal lower urinary tract obstruction (LUTO).

METHODS

This was a prospective registry study of pregnant women with a male fetus with LUTO from centers within the British Isles and The Netherlands. Women and/or their clinicians were given the treatment option of either conservative management or vesicoamniotic shunting (VAS). Baseline characteristics of women in the registry, reasons for entry to the registry and pregnancy outcomes were assessed. The main study outcomes were survival to 28 days after delivery, further survival to 2 years and renal function. Logistic regression analysis was used to examine prognostic variables that affected outcome. Results were compared with those of women in a randomized controlled trial (RCT) who were allocated randomly to a treatment option.

RESULTS

Forty-five women were registered, of whom 78% (35/45) underwent conservative management. Twenty-seven women entered the registry owing to their clinician's preference for management and 18 because of their own preference. Compared to the conservative-management group of the RCT, a higher proportion of women in the registry opting for conservative management had a normal amniotic fluid volume at diagnosis (P = 0.05) and a diagnosis of LUTO ≥ 24 weeks' gestation (P = 0.003). On multivariable logistic regression analysis, these variables showed a significant association with perinatal survival (P < 0.001). Survival to 28 days after delivery was higher in the conservative-management group, at 69% (24/35), compared to 40% (4/10) in the VAS group (P = 0.02) but this difference had limited statistical significance owing to small study size (relative risk, 0.58 (95% CI, 0.26-1.29); P = 0.14).

CONCLUSION

In our prospective registry, the majority of fetuses with LUTO received conservative management, which was associated with better short- and long-term outcomes. A significant proportion of these pregnancies had normal amniotic fluid volume and a gestational age at diagnosis of ≥ 24 weeks, characteristics shown to be associated with improved survival.

When is birthweight at term (≥37 weeks' gestation) abnormally low? A systematic review and meta-analysis of the prognostic and predictive ability of current birthweight standards for childhood and adult outcomes

BACKGROUND

Health outcomes throughout the life course have been linked to fetal growth restriction and low birthweight. A variety of measures exist to define low birthweight, with a lack of consensus regarding which predict adverse outcome.

OBJECTIVES

To evaluate the relationship between birthweight standards and childhood and adult outcomes in term-born infants (≥37 weeks' gestation).

SEARCH STRATEGY

MEDLINE (1966-January 2011), EMBASE (1980-January 2011), and the Cochrane Library (2011:1) and MEDION were included.

SELECTION CRITERIA

Studies comprising live term-born infants (gestation ≥37 completed weeks), with weight or other anthropometric measurements recorded at birth along with childhood and adult outcomes.

DATA COLLECTION AND ANALYSIS

Data were extracted to populate 2 × 2 tables relating birthweight standard with outcome, and meta-analysis was performed where possible.

MAIN RESULTS

Fifty-nine articles (2 600 383 individuals) were selected. There was no significant relationship between birthweight <2.5 kg (odds ratio [OR] 0.98, 95% confidence intervals [CI] 0.87-1.10) and composite measure of childhood morbidity. Weight <10th centile on the population nomogram showed a small association (OR 1.49, 95% CI 1.02-2.19) for the same outcome. There was no significant association between either of the above measures and adult morbidity. The relationship between other measures and individual outcomes varied.

AUTHOR'S CONCLUSIONS

The association between low birthweight, by any definition, and childhood and adult morbidity was inconsistent. None of the current standards of low birthweight was a good predictor of adverse outcome.

Meta-analysis of test accuracy studies: an exploratory method for investigating the impact of missing thresholds

BACKGROUND

Primary studies examining the accuracy of a continuous test evaluate its sensitivity and specificity at one or more thresholds. Meta-analysts then usually perform a separate meta-analysis for each threshold. However, the number of studies available for each threshold is often very different, as primary studies are inconsistent in the thresholds reported. Furthermore, of concern is selective reporting bias, because primary studies may be less likely to report a threshold when it gives low sensitivity and/or specificity estimates. This may lead to biased meta-analysis results. We developed an exploratory method to examine the potential impact of missing thresholds on conclusions from a test accuracy meta-analysis.

METHODS

Our method identifies studies that contain missing thresholds bounded between a pair of higher and lower thresholds for which results are available. The bounded missing threshold results (two-by-two tables) are then imputed, by assuming a linear relationship between threshold value and each of logit-sensitivity and logit-specificity. The imputed results are then added to the meta-analysis, to ascertain if original conclusions are robust. The method is evaluated through simulation, and application made to 13 studies evaluating protein:creatinine ratio (PCR) for detecting proteinuria in pregnancy with 23 different thresholds, ranging from one to seven per study.

RESULTS

The simulation shows the imputation method leads to meta-analysis estimates with smaller mean-square error. In the PCR application, it provides 50 additional results for meta-analysis and their inclusion produces lower test accuracy results than originally identified. For example, at a PCR threshold of 0.16, the summary specificity is 0.80 when using the original data, but 0.66 when also including the imputed data. At a PCR threshold of 0.25, the summary sensitivity is reduced from 0.95 to 0.85 when additionally including the imputed data.

CONCLUSIONS

The imputation method is a practical tool for researchers (often non-statisticians) to explore the potential impact of missing threshold results on their meta-analysis conclusions. Software is available to implement the method. In the PCR example, it revealed threshold results are vulnerable to the missing data, and so stimulates the need for advanced statistical models or, preferably, individual patient data from primary studies.

Effectiveness of folic acid supplementation in pregnancy on reducing the risk of small-for-gestational age neonates: a population study, systematic review and meta-analysis

OBJECTIVES

To assess the effect of timing of folic acid (FA) supplementation during pregnancy on the risk of the neonate being small for gestational age (SGA).

DESIGN

A population database study and a systematic review with meta-analysis including the results of this population study.

SETTING AND DATA SOURCES

A UK regional database was used for the population study and an electronic literature search (from inception until August 2013) for the systematic review.

PARTICIPANTS AND INCLUDED STUDIES

Singleton live births with no known congenital anomalies; 111,736 in population study and 188,796 in systematic review.

OUTCOME MEASURES, DATA EXTRACTION AND ANALYSIS

The main outcome was SGA based on customised birthweight centile. Associations are presented as odds ratios (OR) and adjusted odds ratios (aOR), adjusted for maternal and pregnancy-related characteristics.

RESULTS

Of 108,525 pregnancies with information about FA supplementation, 92,133 (84.9%) had taken FA during pregnancy. Time of commencement of supplementation was recorded in 39,416 pregnancies, of which FA was commenced before conception in 10,036, (25.5%) cases. Preconception commencement of FA supplementation was associated with reduced risk of SGA <10th centile (aOR 0.80, 95% CI 0.71-0.90, P < 0.01) and SGA <5th centile (aOR 0.78, 95% CI 0.66-0.91, P < 0.01). This result was reproduced when the data were pooled with other studies in the systematic review, showing a significant reduction in SGA (<5th centile) births with preconception commencement of FA (aOR 0.75, 95% CI 0.61-0.92, P < 0.006). In contrast, postconception folate had no significant effect on SGA rates.

CONCLUSION

Supplementation with FA significantly reduces the risk of SGA at birth but only if commenced preconceptually independent of other risk factors.

SYSTEMATIC REVIEW REGISTRATION

This systematic review was prospectively registered with PROSPERO number CRD42013004895.

The Percutaneous shunting in Lower Urinary Tract Obstruction (PLUTO) study and randomised controlled trial: evaluation of the effectiveness, cost-effectiveness and acceptability of percutaneous vesicoamniotic shunting for lower urinary tract obstruction

BACKGROUND

Congenital lower urinary tract obstruction (LUTO) is a disease associated with high perinatal mortality and childhood morbidity. Fetal vesicoamniotic shunting (VAS) bypasses the obstruction with the potential to improve outcome.

OBJECTIVE

To determine the effectiveness, cost-effectiveness and patient acceptability of VAS for fetal LUTO.

DESIGN

A multicentre, randomised controlled trial incorporating a prospective registry, decision-analytic health economic model and preplanned Bayesian analysis using elicited opinions. Patient acceptability was evaluated by interview in a qualitative study.

SETTING

Fetal medicine departments in the UK, Ireland and the Netherlands.

PARTICIPANTS

Pregnant women with a male singleton fetus with LUTO.

INTERVENTIONS

In utero percutaneous VAS compared with conservative care.

MAIN OUTCOME MEASURES

The primary outcome was survival to 28 days. Secondary outcome measures were survival and renal function at 1 year of age, cost of care and cost per additional life-year and per disability-free survival at the end of 1 year.

RESULTS

The trial stopped early with 31 women randomised because of difficulties in recruitment. Of those randomised to VAS and conservative management, 3/16 (19%) and 2/15 (13%), respectively, did not receive their allocated intervention. Based on intention-to-treat analysis, survival at 28 days was higher if allocated VAS (50%) than conservative management (27%) [relative risk (RR) 1.88, 95% confidence interval (CI) 0.71 to 4.96, p = 0.27]. At 12 months survival was 44% in the VAS arm and 20% in the conservative arm (RR 2.19, 95% CI 0.69 to 6.94, p = 0.25). Neither difference was statistically significant. Of survivors at 1 year, two in the VAS arm had no evidence of renal impairment and four in the VAS arm and two in the conservative arm required medical management. One baby in the conservative arm had end-stage renal failure at 1 year. VAS was more expensive because of additional surgery and intensive care. VAS cost £15,500 per survivor at 1 year and £43,900 per disability-free year. Elicited expert opinions showed uncertainty in the effect of VAS at 28 days. In a Bayesian analysis combining elicited opinion with the results, uncertainty of the benefit of VAS remained (RR 1.31, 95% credible interval 0.84 to 2.18). The acceptability study identified visualisation of the fetus during ultrasound scanning, perceiving a personal benefit, and altruism as positive influences on recruitment. Fear of the VAS procedure and the perceived severity of LUTO influenced non-participation. The need for more detailed information about the condition and its implications during pregnancy and following delivery was a further important finding of this research. Recruitment was hampered by logistical and regulatory difficulties, a lower incidence of LUTO and lower antenatal diagnosis rate [estimated to be 3.34 (95% CI 2.95 to 3.72) per 10,000 total births and 47%, respectively, in an associated epidemiological study] and high termination of pregnancy rates. In the registry women also demonstrated a clear preference for conservative management.

CONCLUSIONS

Survival to 28 days and 1 year appears to be higher with VAS than with conservative management, but it is not possible to prove benefit beyond reasonable doubt. Notably, prognosis in both arms for survival and renal function is poor. VAS was substantially more costly and unlikely to be regarded as cost-effective based on the 1-year data. Parents should be counselled about the risks of pregnancy loss with or without VAS insertion. The National Institute for Health and Care Excellence interventional procedures guidance (IPG 202) should be updated to reflect this new evidence. Babies in the PLUTO trial should be followed up long term for the different outcomes.

TRIAL REGISTRATION

ISRCTN53328556.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 17, No. 59. See the NIHR Journals Library website for further project information.

Association and prediction of amniotic fluid measurements for adverse pregnancy outcome: systematic review and meta-analysis

BACKGROUND

Measurements of amniotic fluid volume are used for pregnancy surveillance despite a lack of evidence for their predictive ability.

OBJECTIVE

To evaluate the association and predictive value of ultrasound measurements of amniotic fluid volume for adverse pregnancy outcome.

SEARCH STRATEGY

Electronic databases (inception to October 2011), reference lists, hand searching of journals, contact with experts.

SELECTION CRITERIA

Studies comparing measurements of amniotic fluid volume with adverse outcome, excluding pre-labour ruptured membranes or congenital/structural anomalies.

DATA COLLECTION

Data on study characteristics, design, quality. Random effects meta-analysis to estimate summary odds ratios (prognostic association) and summary sensitivity, specificity and likelihood ratios (predictive ability).

MAIN RESULTS

Forty-three studies (244,493 fetuses) were included demonstrating a strong association between oligohydramnios (varying definitions) and birthweight <10th centile (summary odds ratio [OR] 6.31, 95% confidence interval [95% CI] 4.15-9.58; high-risk population [author definition] n = 6 studies, 28,510 fetuses), and mortality (neonatal death any population summary OR 8.72, 95% CI 2.43-31.26; n = 6 studies, 55,735 fetuses; and perinatal mortality high-risk population summary OR 11.54, 95% CI 4.05-32.9; n = 2 studies, 27;891 fetuses). There was a strong association between polyhydramnios (maximum pool depth >8 cm or amniotic fluid index ≥25 cm) and birthweight >90th centile (OR 11.41, 95% CI 7.09-18.36; n = 1 study, 3960 fetuses). Despite strong associations, predictive accuracy for perinatal outcome was poor.

AUTHOR'S CONCLUSION

Current evidence suggests that oligohydramnios is strongly associated with being small for gestational age and mortality, and polyhydramnios with birthweight >90th centile. Despite strong associations with poor outcome, they do not accurately predict outcome risk for individuals.

When is birthweight at term abnormally low? A systematic review and meta-analysis of the association and predictive ability of current birthweight standards for neonatal outcomes

Background

Intrauterine growth restriction is a cause of neonatal morbidity and mortality. A variety of definitions of low birthweight are used in clinical practice, with a lack of consensus regarding which definitions best predict adverse outcomes.

Objectives

To evaluate the relationship between birthweight standards and neonatal outcome in term-born infants (at ≥ 37 weeks of gestation).

Search strategy

MEDLINE (1966–January 2011), EMBASE (1980–January 2011), and the Cochrane Library (2011:1) and MEDION were included in our search.

Selection criteria

Studies comprising live term-born infants (gestation ≥ 37 completed weeks), with weight or other anthropometric measurements recorded at birth along with neonatal outcomes.

Data collection and analysis

Data were extracted to populate 2 × 2 tables relating birthweight standard with outcome, and meta-analysis was performed where possible.

Main results

Twenty-nine studies including 21 034 114 neonates were selected. Absolute birthweight was strongly associated with mortality, with birthweight < 1.5 kg giving the largest association (OR 48.6, 95% CI 28.62–82.53). When using centile charts, regardless of threshold, the summary odds ratios were significant but closer to 1 than when using absolute birthweight. For all tests, summary predictive ability comprised high specificity and positive likelihood ratio for neonatal death, but low sensitivity and a negative likelihood ratio close to 1.

Author's conclusions

Absolute birthweight is a prognostic factor for neonatal mortality. The indirect evidence suggests that centile charts or other definitions of low birthweight are not as strongly associated with mortality as the absolute birthweight. Further research is required to improve predictive accuracy.

Diagnostic accuracy of spot urinary protein and albumin to creatinine ratios for detection of significant proteinuria or adverse pregnancy outcome in patients with suspected pre-eclampsia: systematic review and meta-analysis

OBJECTIVE

To determine the diagnostic accuracy of two "spot urine" tests for significant proteinuria or adverse pregnancy outcome in pregnant women with suspected pre-eclampsia.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Searches of electronic databases 1980 to January 2011, reference list checking, hand searching of journals, and contact with experts.

INCLUSION CRITERIA

Diagnostic studies, in pregnant women with hypertension, that compared the urinary spot protein to creatinine ratio or albumin to creatinine ratio with urinary protein excretion over 24 hours or adverse pregnancy outcome. Study characteristics, design, and methodological and reporting quality were objectively assessed.

DATA EXTRACTION

Study results relating to diagnostic accuracy were extracted and synthesised using multivariate random effects meta-analysis methods.

RESULTS

Twenty studies, testing 2978 women (pregnancies), were included. Thirteen studies examining protein to creatinine ratio for the detection of significant proteinuria were included in the multivariate analysis. Threshold values for protein to creatinine ratio ranged between 0.13 and 0.5, with estimates of sensitivity ranging from 0.65 to 0.89 and estimates of specificity from 0.63 to 0.87; the area under the summary receiver operating characteristics curve was 0.69. On average, across all studies, the optimum threshold (that optimises sensitivity and specificity combined) seems to be between 0.30 and 0.35 inclusive. However, no threshold gave a summary estimate above 80% for both sensitivity and specificity, and considerable heterogeneity existed in diagnostic accuracy across studies at most thresholds. No studies looked at protein to creatinine ratio and adverse pregnancy outcome. For albumin to creatinine ratio, meta-analysis was not possible. Results from a single study suggested that the most predictive result, for significant proteinuria, was with the DCA 2000 quantitative analyser (>2 mg/mmol) with a summary sensitivity of 0.94 (95% confidence interval 0.86 to 0.98) and a specificity of 0.94 (0.87 to 0.98). In a single study of adverse pregnancy outcome, results for perinatal death were a sensitivity of 0.82 (0.48 to 0.98) and a specificity of 0.59 (0.51 to 0.67).

CONCLUSION

The maternal "spot urine" estimate of protein to creatinine ratio shows promising diagnostic value for significant proteinuria in suspected pre-eclampsia. The existing evidence is not, however, sufficient to determine how protein to creatinine ratio should be used in clinical practice, owing to the heterogeneity in test accuracy and prevalence across studies. Insufficient evidence is available on the use of albumin to creatinine ratio in this area. Insufficient evidence exists for either test to predict adverse pregnancy outcome.

Long-term renal and neurodevelopmental outcome in infants with LUTO, with and without fetal intervention

Congenital lower urinary tract obstruction (LUTO) is a heterogeneous group of pathologies, the most common being posterior urethral valves (PUV) or urethral atresia. The bladder neck obstruction in utero leads to a spectrum of disease including mild oligohydramnios with normal renal function to a picture of severe oligohydramnios associated with chronic obstructive macro/microcystic renal parenchymal disease leading to chronic renal impairment. These anomalies may be isolated or complex; the latter being associated with other structural or chromosomal abnormalities. If isolated, the congenital bladder neck obstruction may be amenable to in-utero therapy. In a significant proportion of babies affected by LUTO there is severe oligohydramnios (occurring before 20 weeks gestation) and associated with pulmonary hypoplasia, a scenario almost always associated with perinatal death. For those babies that survive the perinatal period there is a significant risk of renal impairment, often necessitating renal dialysis or transplantation in childhood. In addition, there may be other morbidities such as chronic filling anomalies of the bladder that may require treatment.

Effectiveness of fetal cystoscopy as a diagnostic and therapeutic intervention for lower urinary tract obstruction: a systematic review

OBJECTIVE

To determine the effectiveness of fetal cystoscopy in the prenatal diagnosis of and intervention for congenital lower urinary tract obstruction.

METHODS

This study was a literature search using MEDLINE, Embase, Cochrane Library, MEDION, Web of Science reference lists and contact with experts. All studies reporting on fetal cystoscopy in lower urinary tract obstruction with data for a 2 × 2 table were selected for review. No language restrictions were applied. There was independent selection of studies, data extraction and quality assessment by two reviewers. Peto odds ratios were calculated as a summary measure of effect.

RESULTS

A total of 2071 citations were identified and 66 papers selected for detailed evaluation, from which four papers with a total of 63 patients were selected for inclusion. Two papers had results for the use of cystoscopy in diagnosis, showing that fetal cystoscopy altered the ultrasound diagnosis of the underlying pathology in 36.4 and 25.0% of fetuses, respectively. Compared to no treatment, fetal cystoscopic intervention demonstrated an odds ratio for improved perinatal survival of 20.51 (95% CI, 3.87-108.69). However, comparing vesicoamniotic shunt (VAS) with fetal cystoscopy there appeared to be no significant improvement in the perinatal survival odds ratio of 1.49 (95% CI, 0.13-16.97). These results had wide CIs and for cystoscopy vs. VAS, all results crossed the line of no effect.

CONCLUSION

There is little published evidence for the effectiveness of therapeutic fetal cystoscopy as an intervention for congenital lower urinary tract obstruction and the quality of this evidence is poor. It should thus be considered to be an 'experimental intervention' and subjected to further investigation.

The quality of reporting of primary test accuracy studies in obstetrics and gynaecology: application of the STARD criteria

Background

In obstetrics and gynaecology there has been a rapid growth in the development of new tests and primary studies of their accuracy. It is imperative that such studies are reported with transparency allowing the detection of any potential bias that may invalidate the results. The objective of this study was to determine the quality of reporting in diagnostic test accuracy studies in obstetrics and gynaecology using the Standards for Reporting of Diagnostic Accuracy - STARD checklist.

Methods

The included studies of ten systematic reviews were assessed for compliance with each of the reporting criteria. Using appropriate statistical tests we investigated whether there was an improvement in reporting quality since the introduction of the STARD checklist, whether a correlation existed between study sample size, country of origin of study and reporting quality.

Results

A total of 300 studies were included (195 for obstetrics, 105 for gynaecology). The overall reporting quality of included studies to the STARD criteria was poor. Obstetric studies reported adequately > 50% of the time for 62.1% (18/29) of the items while gynaecologic studies did the same 51.7% (15/29). There was a greater mean compliance with STARD criteria in the included obstetric studies than the gynaecological (p < 0.0001). There was a positive correlation, in both obstetrics (p < 0.0001) and gynaecology (p = 0.0123), between study sample size and reporting quality. No correlation between geographical area of publication and compliance with the reporting criteria could be demonstrated.

Conclusions

The reporting quality of papers in obstetrics and gynaecology is improving. This may be due to initiatives such as the STARD checklist as well as historical progress in awareness among authors of the need to accurately report studies. There is however considerable scope for further improvement.