Audit of prenatal and postnatal diagnosis of isolated open spina bifida in three university hospitals in The Netherlands

Diagnostic accuracy of ultrasound screening for fetal structural abnormalities during the first and second trimester of pregnancy in low-risk and unselected populations

BACKGROUND

Prenatal ultrasound is widely used to screen for structural anomalies before birth. While this is traditionally done in the second trimester, there is an increasing use of first-trimester ultrasound for early detection of lethal and certain severe structural anomalies.

OBJECTIVES

To evaluate the diagnostic accuracy of ultrasound in detecting fetal structural anomalies before 14 and 24 weeks' gestation in low-risk and unselected pregnant women and to compare the current two main prenatal screening approaches: a single second-trimester scan (single-stage screening) and a first- and second-trimester scan combined (two-stage screening) in terms of anomaly detection before 24 weeks' gestation.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded (Web of Science), Social Sciences Citation Index (Web of Science), Arts & Humanities Citation Index and Emerging Sources Citation Index (Web of Science) from 1 January 1997 to 22 July 2022. We limited our search to studies published after 1997 and excluded animal studies, reviews and case reports. No further restrictions were applied. We also screened reference lists and citing articles of each of the included studies.

SELECTION CRITERIA

Studies were eligible if they included low-risk or unselected pregnant women undergoing a first- and/or second-trimester fetal anomaly scan, conducted at 11 to 14 or 18 to 24 weeks' gestation, respectively. The reference standard was detection of anomalies at birth or postmortem.

DATA COLLECTION AND ANALYSIS

Two review authors independently undertook study selection, quality assessment (QUADAS-2), data extraction and evaluation of the certainty of evidence (GRADE approach). We used univariate random-effects logistic regression models for the meta-analysis of sensitivity and specificity.

MAIN RESULTS

Eighty-seven studies covering 7,057,859 fetuses (including 25,202 with structural anomalies) were included. No study was deemed low risk across all QUADAS-2 domains. Main methodological concerns included risk of bias in the reference standard domain and risk of partial verification. Applicability concerns were common in studies evaluating first-trimester scans and two-stage screening in terms of patient selection due to frequent recruitment from single tertiary centres without exclusion of referrals. We reported ultrasound accuracy for fetal structural anomalies overall, by severity, affected organ system and for 46 specific anomalies. Detection rates varied widely across categories, with the highest estimates of sensitivity for thoracic and abdominal wall anomalies and the lowest for gastrointestinal anomalies across all tests. The summary sensitivity of a first-trimester scan was 37.5% for detection of structural anomalies overall (95% confidence interval (CI) 31.1 to 44.3; low-certainty evidence) and 91.3% for lethal anomalies (95% CI 83.9 to 95.5; moderate-certainty evidence), with an overall specificity of 99.9% (95% CI 99.9 to 100; low-certainty evidence). Two-stage screening had a combined sensitivity of 83.8% (95% CI 74.7 to 90.1; low-certainty evidence), while single-stage screening had a sensitivity of 50.5% (95% CI 38.5 to 62.4; very low-certainty evidence). The specificity of two-stage screening was 99.9% (95% CI 99.7 to 100; low-certainty evidence) and for single-stage screening, it was 99.8% (95% CI 99.2 to 100; moderate-certainty evidence). Indirect comparisons suggested superiority of two-stage screening across all analyses regarding sensitivity, with no significant difference in specificity. However, the certainty of the evidence is very low due to the absence of direct comparisons.

AUTHORS' CONCLUSIONS

A first-trimester scan has the potential to detect lethal and certain severe anomalies with high accuracy before 14 weeks' gestation, despite its limited overall sensitivity. Conversely, two-stage screening shows high accuracy in detecting most fetal structural anomalies before 24 weeks' gestation with high sensitivity and specificity. In a hypothetical cohort of 100,000 fetuses, the first-trimester scan is expected to correctly identify 113 out of 124 fetuses with lethal anomalies (91.3%) and 665 out of 1776 fetuses with any anomaly (37.5%). However, 79 false-positive diagnoses are anticipated among 98,224 fetuses (0.08%). Two-stage screening is expected to correctly identify 1448 out of 1776 cases of structural anomalies overall (83.8%), with 118 false positives (0.1%). In contrast, single-stage screening is expected to correctly identify 896 out of 1776 cases before 24 weeks' gestation (50.5%), with 205 false-positive diagnoses (0.2%). This represents a difference of 592 fewer correct identifications and 88 more false positives compared to two-stage screening. However, it is crucial to acknowledge the uncertainty surrounding the additional benefits of two-stage versus single-stage screening, as there are no studies directly comparing them. Moreover, the evidence supporting the accuracy of first-trimester ultrasound and two-stage screening approaches primarily originates from studies conducted in single tertiary care facilities, which restricts the generalisability of the results of this meta-analysis to the broader population.

Diagnostic accuracy of ultrasound screening for fetal structural abnormalities during the first and second trimester of pregnancy in low‐risk and unselected populations

This is a protocol for a Cochrane Review (diagnostic). The objectives are as follows:

The main objectives of this review are to assess the diagnostic accuracy of first‐ and second‐trimester fetal anomaly screening in low‐risk pregnant women, and to compare overall performance of single‐ and two‐stage screening approaches with regards to the number of cases detected before birth, as well as the proportion of false positive diagnoses.

Prenatal Diagnosis and Patient Preferences in Patients with Neural Tube Defects around the Advent of Fetal Surgery in Belgium and Holland

Introduction: We review the characteristics and prenatal choices of patients recently evaluated for neural tube defects (NTD) at two tertiary units. The prenatal diagnosis of NTD allows parents to consider all prenatal options. In selected cases of spina bifida aperta this also includes fetal surgery, which we started offering after combined ‘in-house' and ‘exported' training. Material and Methods: This is a retrospective review of prospectively collected data on NTD diagnosed over the last 8 years and recent fetal surgery referrals. Results: A total of 167 patients were referred for assessment at a median of 19 weeks. Cranial lesions were diagnosed significantly earlier than spinal lesions. Of the open spinal lesions, 77% were isolated. Of these, 22% were managed expectantly and 1 (1%) had fetal surgery. There was no correlation between parental decisions on prenatal management with disease-specific severity markers. We had 14 fetal surgery referrals, all but 1 from beyond our typical referral area; 6 of the assessed patients were operated on, 4 were expectantly managed and 4 requested termination of pregnancy (TOP). These pregnancy outcomes were in the expected range. Discussion: Open spina bifida is mainly diagnosed in the second trimester and 76% of subjects request TOP, irrespective of the severity indicators. The number of local patients considering fetal surgery is low.

Impact of introduction of mid-trimester scan on pregnancy outcome of open spina bifida in The Netherlands

OBJECTIVE

To examine the impact of introduction of the mid-trimester scan on pregnancy outcome in cases of open spina bifida in two regions of The Netherlands.

METHODS

This was a retrospective cohort study of 190 cases of open spina bifida diagnosed pre- or postnatally, with an estimated date of delivery between 2003 and 2011.

RESULTS

With implementation of the mid-trimester scan the percentage of cases of open spina bifida detected before the 24(th) week of pregnancy increased from 43% to 88%. The rise in prenatal detection rate was associated with a significant increase in the number of terminated pregnancies and a decrease in the rate of perinatal loss; the percentage of children born alive did not change significantly. In the subgroup that underwent a scan between 18 and 24 weeks of pregnancy, cranial signs were present in 94.4% of cases.

CONCLUSION

Introduction of the mid-trimester scan has led to an increase in early identification of pregnancies complicated by open spina bifida. Pregnancies previously destined to end in perinatal loss are now terminated whilst pregnancies with a relatively good prognosis are frequently continued; the number of children with open spina bifida who are born alive has not changed significantly. Our study confirms that prenatal diagnosis is usually triggered by visualization of a lemon-shaped skull or a banana-shaped cerebellum.

Pregnancy termination following prenatal diagnosis of anencephaly or spina bifida: a systematic review of the literature

BACKGROUND

In regions where prenatal screening for anencephaly and spina bifida is widespread, many cases of these defects are diagnosed prenatally. The purpose of this study was to estimate the frequency of termination of pregnancy (TOP) following prenatal diagnosis of anencephaly or spina bifida and to investigate factors associated with TOP that might lead to selection bias in epidemiologic studies.

METHODS

We included articles indexed in Medline or Embase between 1990 and May 2012 reporting the frequency of TOP following prenatal diagnosis of anencephaly or spina bifida with English-language abstracts, 20 or more prenatally diagnosed cases, and at least half of the study years in 1990 or later. We summarized the frequency of TOP across studies using random-effects metaanalysis and stratified results by fetal and study characteristics.

RESULTS

Among the 17 studies identified, 9 included anencephaly and 15 included spina bifida. Nine were from Europe, six were from North America, and one each was from South America and Asia. The overall frequency of TOP following prenatal diagnosis was 83% for anencephaly (range, 59-100%) and 63% for spina bifida (range, 31-97%). There were insufficient data to stratify the results for anencephaly; TOP for spina bifida was more common when the prenatal diagnosis occurred at less than 24 weeks' gestation, with defects of greater severity, and in Europe versus North America.

CONCLUSIONS

Because underascertainment of birth defects might be more likely when the pregnancy ends in TOP and TOP is associated with fetal characteristics, selection bias is possible in epidemiologic studies of anencephaly or spina bifida.

Role of prenatal ultrasound in predicting survival and mental and motor functioning in children with spina bifida

OBJECTIVE

To determine which prenatal ultrasound findings can predict survival and mental and motor functioning in children with spina bifida.

METHODS

Prenatal ultrasound examinations of all liveborn children who were prenatally diagnosed with spina bifida between 1997 and 2002 at the University Medical Centre, Utrecht (n = 41) were retrospectively reviewed for lesion level, head circumference, ventriculomegaly, scoliosis and talipes. These measures were correlated with postnatal anatomical (as assessed by magnetic resonance imaging (MRI)) and functional lesion levels, survival and motor and mental outcome at 5 years of age. The capacity of prenatal ultrasonography to determine lesion level was also assessed in all fetuses diagnosed with spina bifida from 2006-2007 (n = 18).

RESULTS

Nineteen infants died before the age of 5 years. Multivariate regression analysis showed that higher lesion level and head circumference > or = the 90th percentile on prenatal ultrasound examination were independent predictors of demise (P < 0.05 and P = 0.01, respectively). None of the ultrasound features was a predictor of motor or mental functioning. Ultrasound predicted anatomical lesion level within one level of the postnatal findings in 50% of the first cohort and 89% of the second cohort (P < 0.01). The level of the anatomical lesion as assessed by postnatal MRI differed from the functional lesion by as many as six vertebral levels.

CONCLUSIONS

Lesion level and head circumference on prenatal ultrasound are predictive of survival in children with spina bifida. No predictors were found for mental or motor function at the age of 5 years.

Deliberate termination of life of newborns with spina bifida, a critical reappraisal

OBJECTS

Deliberate termination of life of newborns (involuntary euthanasia) with meningomyelocele (MMC) is practiced openly only in The Netherlands. 'Unbearable and hopeless suffering' is the single most cited criterion for this termination, together with the notion that 'there are no other proper medical means to alleviate this suffering'. In this paper, both (and other) statements are questioned, also by putting them in a broader perspective.

METHODS

First, a historical overview of the treatment of newborns with MMC is presented, concentrating on the question of selection for treatment. Second, a thorough analysis is made of the criteria used for life termination. Third, a case of a newborn with a very severe MMC is presented as a 'reference case'.

CONCLUSION

'Unbearable and hopeless suffering' cannot be applied to newborns with MMC. They are not 'terminally ill' and do have 'prospects of a future'. In these end-of-life decisions, 'quality of life judgments' should not be applied. When such a newborn is not treated, modern palliative care always will suffice in eliminating possible discomfort. There is no reason whatsoever for active life-termination of these newborns.

Effects of residential distance to hospitals with neonatal surgery care on prenatal management and outcome of pregnancies with severe fetal malformations

OBJECTIVES

To examine the effect of maternal origin and distance between maternal residence and the nearest maternity ward with a neonatal surgical center in the same hospital, on prenatal diagnosis, elective termination of pregnancy, delivery in an adequate place and neonatal mortality for pregnancies with severe malformations requiring neonatal surgery, and to examine the effect of the place of delivery on neonatal mortality.

METHODS

This was a retrospective study, through the France Central-East malformation registry, of 706 fetuses with omphalocele (n = 123), gastroschisis (n = 99), diaphragmatic hernia (n = 222), or spina bifida (n = 262), but without chromosomal anomalies. Maternal origin was classified as Western European and non-Western European. Adequate place for delivery was defined as birth in a Level-III maternity ward with a neonatal surgical center in the same hospital.

RESULTS

The prenatal diagnosis rate was 67.7% in 1990-1995 and 80.2% in 1996-2001 (odds ratio (OR), 2.07 (95% CI, 1.24-3.45)). On multivariate analysis, the rate was significantly lower for women living 11-50 km (adjusted OR, 0.49 (95% CI, 0.25-0.94)), or > 50 km (adjusted OR, 0.39 (0.20-0.74)) from the closest adequate place of delivery, compared with those living < 11 km from it, but there was no difference for maternal origin. Non-Western European women had fewer elective terminations of pregnancy (adjusted OR, 0.34 (95% CI, 0.14-0.81)) and fewer deliveries in an adequate place (adjusted OR, 0.40 (95% CI, 0.18-0.89)). Neonatal mortality was lower in the case of delivery in an adequate place (adjusted OR, 0.22 (95% CI, 0.07-0.72)) and was not associated with maternal origin and distance from nearest maternity ward with a neonatal surgical center.

CONCLUSION

Rate of prenatal diagnosis decreases with increasing distance between parental residence and referral center. Non-Western European women are diagnosed prenatally as often as are Western Europeans, but terminate their pregnancy less often, perhaps for cultural reasons. Non-Western European women with malformed fetuses deliver in adequate centers less often, probably because of the way the perinatal care system is run.

Alpha-fetoprotein detection of neural tube defects and the impact of standard ultrasound

OBJECTIVE

The purpose of this study was to evaluate neural tube defect (NTD) detection according to whether serum alpha-fetoprotein (AFP) screening or standard ultrasound are performed.

STUDY DESIGN

Prenatal and neonatal datasets were reviewed to identify pregnancies with NTDs from 1 institution between January 2000 and December 2003. AFP screening was offered < 21 weeks and considered elevated if > or = 2.50 multiples of the median. Standard ultrasound was performed for specific indications in low-risk pregnancies.

RESULTS

There were 66 NTDs, 1 per 950 deliveries. AFP sensitivity was 65%. If the gestational age used for AFP calculation was confirmed with ultrasound, sensitivity improved to 86%. The sensitivity of standard ultrasound was 100%, P < .001 compared with AFP screening. NTDs detected with standard ultrasound were identified later in gestation, as examinations were performed for other indications.

CONCLUSION

Standard ultrasound improved NTD detection over AFP screening alone, by improving AFP test sensitivity and identifying NTDs in low-risk pregnancies.

Prenatal diagnosis of musculoskeletal anomalies

Musculoskeletal anomalies are not uncommon in prenatal life. They can be either sporadic or part of chromosomal syndromes causing prenatal morbidity and mortality. The prenatal diagnosis of musculoskeletal anomalies is based on information assembled from various imaging modalities and from biochemical and genetic workups. The prenatal diagnosis can serve as a prognostic tool and in counseling the parents. Among the imaging methods, ultrasonography is the most popular and cost effective in observing and following fetal development from the very early stages of gestation. Transvaginal sonography can detect and identify most of the normal and the specific pathologic changes very close to the stage of their embryogenic development. From a practical point of view, early detailed transvaginal sonography screening at 14 to 15 weeks of gestation is very useful while late detection at 20 to 23 weeks of gestation may provide some additional information in low-risk pregnancies. Very early screening, even during the ninth week, may be indicated in high-risk pregnancies. Additional genetic counseling is recommended when abnormal findings are suspected. We summarize the diagnostic approach and the information available for the most common musculoskeletal anomalies.