Beaver Heidi, Lanzarone Valeria, Low Gary Kk
Christopher Kohlenberg Department of Perinatal Ultrasound Nepean Hospital, Nepean Blue Mountain Local Health District Kingswood New South Wales Australia.
Research Operations Nepean Hospital, Nepean Blue Mountain Local Health District Kingswood New South Wales Australia.
Australas J Ultrasound Med. 2024 Aug 29;27(4):218-228. doi: 10.1002/ajum.12409. eCollection 2024 Nov.
To assess the effects of bladder fullness and lower uterine contractions ultrasound on transabdominal and transvaginal cervical length measurements at the mid-trimester fetal anomaly scan (FAS).
Transabdominal and transvaginal cervical length measurements from 925 mid-trimester FAS examinations were retrospectively analysed. Images were assessed for lower uterine contraction and bladder fullness using a novel qualitative assessment. Bland-Altman plots and single-score interclass correlation (ICC) were used to determine correlation between transabdominal and transvaginal measurements. Sensitivity and specificity of transabdominal cut-offs were calculated.
Transabdominal and transvaginal measurements of the cervix correlated poorly (ICC 0.306). An overfilled bladder and lower uterine contractions on average increased the length of transabdominal cervical length measurements. Removing these variables did not significantly improve correlation between transabdominal and transvaginal measurements of the cervix but resulted in an improved sensitivity of transabdominal assessment to detect a clinically relevant short cervix.
Resolving the confounding factors of an overfilled bladder and lower uterine contractions can help improve the our ability to detect a short cervix on transabdominal ultrasound. Our data set supported a two-stage approach to cervical length screening which would allow 100% sensitivity when a cut-off of ≤35 mm is used on transabdominal ultrasound and would limit the need for transvaginal scanning to approximately 39% of patients. This cut-off is in line with the findings of other studies. The low prevalence of short cervix in our study did however make it difficult to extrapolate reliable calculations.
Although transabdominal measurements correlate poorly with transvaginal measurements of the cervix, we demonstrated an improved sensitivity for detecting a short cervix using a transabdominal approach when no contractions or overfilled bladder is present. This potential could be explored in a future study with a larger sample size.
评估孕中期胎儿结构超声检查（FAS）时膀胱充盈及子宫下段收缩对经腹和经阴道测量宫颈长度的影响。
回顾性分析925例孕中期FAS检查的经腹和经阴道宫颈长度测量值。采用一种新的定性评估方法评估图像中的子宫下段收缩和膀胱充盈情况。使用Bland-Altman图和单评分组内相关系数（ICC）来确定经腹和经阴道测量值之间的相关性。计算经腹测量值的敏感度和特异度。
经腹和经阴道测量宫颈长度的相关性较差（ICC 0.306）。膀胱过度充盈和子宫下段收缩平均会增加经腹测量的宫颈长度。去除这些变量并不能显著改善经腹和经阴道测量宫颈长度之间的相关性，但会提高经腹评估检测临床相关短宫颈的敏感度。
解决膀胱过度充盈和子宫下段收缩这些混杂因素有助于提高我们经腹超声检测短宫颈的能力。我们的数据集支持采用两阶段宫颈长度筛查方法，即经腹超声使用≤35 mm的临界值时可实现100%的敏感度，并将经阴道扫描的需求限制在约39%的患者。该临界值与其他研究结果一致。然而，我们研究中短宫颈的低患病率使得难以得出可靠的计算结果。
尽管经腹测量与经阴道测量宫颈长度的相关性较差，但我们证明在无宫缩或膀胱未过度充盈时，经腹方法检测短宫颈的敏感度有所提高。这一潜力可在未来更大样本量的研究中进行探索。
