Spina bifida screening in the first trimester using ultrasound biparietal diameter measurement adjusted for crown‐rump length or abdominal circumference

Abstract

Objective Compare the performance of first trimester ultrasound biparietal diameter (BPD) screening for open spina bifida (OSB) when BPD is adjusted for crown‐rump length (CRL) or abdominal circumference (AC). Methods For 63 OSB and 24 265 unaffected pregnancies, BPD was expressed as multiple of the normal median (MoM) based on CRL and on AC, and as the ratio BPD/AC. Screening performance was assessed by the Mahalanobis distance, the observed detection rate with normal fifth and 10th percentile cut‐offs and the area under the receiver‐operator characteristic curve (AUC). Results Mahalanobis distance for BPD MoM was considerably higher when based on AC than on CRL: 1.69 versus 1.14. Screening performance was also higher: using a fifth percentile cut‐off, the detection rate was 59% compared with 41%; using a 10th percentile cut‐off, the rates were 63% and 51%. Whilst the false‐positives rates were slightly higher too—5.3% versus 5.1% and 10.8% versus 9.9%—the AUC was statistically significantly higher: 0.872 (95% CI, 0.816‐0.928) compared with 0.735 (95% CI, 0.664‐0.806). BPD/AC had intermediate performance. Conclusion The best results are obtained when AC, rather than CRL, is used to express BPD values in MoMs. First trimester OSB screening can detect half to two‐thirds of cases.

Fetal open spinal dysraphism repair through a mini‐hysterotomy: Influence of gestational age at surgery on the perinatal outcomes and postnatal shunt rates

“…This strengthens previous findings about the influence of fetal lateral ventricle size before surgery on postnatal shunt rates and reinforces the notion that there is no reason to delay fetal surgery . Currently, accurate screening of an OSD is possible at the 11 to 13 +6 week anomaly scan, allowing for better planning for the early treatment or, in some cases, termination of the pregnancy.…”

Ratio of fetal choroid plexus to head size: simple sonographic marker of open spina bifida at 11–13 weeks' gestation

“…Interestingly, only few data have been published on OSB ultrasound markers in the axial plane of the head. Some groups focused on the small head size [12][13][14]17 , relative either to CRL or to abdominal size 14,27 . Other studies reported on changes at the level of the cerebral peduncles 28 , which become parallel and posteriorly shifted, resulting in compression of the aqueduct of Sylvius 10,15,16,19,28 .…”

Cranial sonographic markers of fetal open spina bifida at 11 to 13 weeks of gestation

“…The DR of 66.7% for BPD < 5th percentile was marginally superior to that previously reported. In previous studies, the DR for this marker ranged from 26% to 55.6% . The use of BPD/AC ratio marginally improved the detection of open spina bifida, identifying 70.4% of the cases.…”

“…The use of BPD/AC ratio marginally improved the detection of open spina bifida, identifying 70.4% of the cases. DRs of 54% using BPD/AC and 69.2% using BPD/transverse abdominal diameter < 1 have been reported …”

“…Also in the sagittal view, the junction between the midbrain and the BS below the maxillo‐occipital (MO) line was reported as a sign of open spina bifida . In the axial view, a smaller biparietal diameter (BPD) has been suggested as a useful marker, either alone or after adjustment for the crown‐rump length (CRL) or abdominal circumference (AC) . In the same section, subjective posterior displacement of the midbrain against the occipital bone was first observed and then objectively quantified via measurement of the distance between the occipital bone and the aqueduct of Sylvius (AoS) .…”