Division of Urology, The Hospital for Sick Children (SickKids), Toronto, Ontario, Canada.
Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
Prenat Diagn. 2021 Aug;41(9):1039-1048. doi: 10.1002/pd.6025. Epub 2021 Aug 5.
Lower urinary tract obstruction (LUTO) is a rare but critical fetal diagnosis. Different ultrasound markers have been reported with varying sensitivity and specificity.
The objective of this systematic review and meta-analysis was to identify the diagnostic accuracy of ultrasound markers for LUTO.
We performed a systematic literature review of studies reporting on fetuses with hydronephrosis or a prenatally suspected and/or postnatally confirmed diagnosis of LUTO. Bayesian bivariate random effects meta-analytic models were fitted, and we calculated posterior means and 95% credible intervals for the pooled diagnostic odds ratio (DOR).
A total of 36,189 studies were identified; 636 studies were available for full text review and a total of 42 studies were included in the Bayesian meta-analysis. Among the ultrasound signs assessed, megacystis (DOR 49.15, [15.28, 177.44]), bilateral hydroureteronephrosis (DOR 41.33, [13.36,164.83]), bladder thickening (DOR 13.73, [1.23, 115.20]), bilateral hydronephrosis (DOR 8.36 [3.17, 21.91]), male sex (DOR 8.08 [3.05, 22.82]), oligo- or anhydramnios (DOR 7.75 [4.23, 14.46]), and urinoma (DOR 7.47 [1.14, 33.18]) were found to be predictive of LUTO (Table 1). The predictive sensitivities and specificities however are low and wide study heterogeneity existed.
Classically, LUTO is suspected in the presence of prenatally detected megacystis with a dilated posterior urethra (i.e., the keyhole sign), and bilateral hydroureteronephrosis. However, keyhole sign has been found to have modest diagnostic performance in predicting the presence of LUTO in the literature which we confirmed in our analysis. The surprisingly low specificity may be influenced by several factors, including the degree of obstruction, and the diligence of the sonographer at searching for and documenting it during the scan. As a result, providers should consider this when establishing the differential for a fetus with hydronephrosis as the presence or absence of keyhole sign does not reliably rule in or rule out LUTO.
Megacystis, bilateral hydroureteronephrosis and bladder wall thickening are the most accurate predictors of LUTO. Given the significant consequences of a missed LUTO diagnosis, clinicians providing counselling for prenatal hydronephrosis should maintain a low threshold for considering LUTO as part of the differential diagnosis.
下尿路梗阻（LUTO）是一种罕见但严重的胎儿诊断。已有不同的超声标志物被报道，其灵敏度和特异性各不相同。
本系统评价和荟萃分析的目的是确定用于 LUTO 的超声标志物的诊断准确性。
我们对报告胎儿存在肾积水或产前疑似和/或产后证实 LUTO 的研究进行了系统文献检索。拟合了贝叶斯双变量随机效应荟萃分析模型，并计算了汇总诊断优势比（DOR）的后验均值和 95%可信区间。
共确定了 36189 项研究；636 项研究可进行全文审查，共有 42 项研究纳入了贝叶斯荟萃分析。在所评估的超声征象中，巨膀胱（DOR 49.15 [15.28, 177.44]）、双侧输尿管积水（DOR 41.33 [13.36,164.83]）、膀胱壁增厚（DOR 13.73 [1.23, 115.20]）、双侧肾积水（DOR 8.36 [3.17, 21.91]）、男性（DOR 8.08 [3.05, 22.82]）、少/无羊水（DOR 7.75 [4.23, 14.46]）和尿囊肿（DOR 7.47 [1.14, 33.18]）被发现可预测 LUTO（表 1）。然而，预测的敏感性和特异性较低，且研究存在很大的异质性。
经典情况下，产前发现巨膀胱伴后尿道扩张（即钥匙孔征）和双侧输尿管积水时怀疑存在 LUTO。然而，我们的分析证实，文献中发现钥匙孔征在预测 LUTO 存在方面的诊断性能中等。较低的特异性可能受到多种因素的影响，包括梗阻程度以及超声医师在扫描过程中搜索和记录它的认真程度。因此，提供者在为肾积水胎儿建立鉴别诊断时应考虑到这一点，因为钥匙孔征的存在与否并不能可靠地确定或排除 LUTO。
巨膀胱、双侧输尿管积水和膀胱壁增厚是 LUTO 最准确的预测指标。鉴于漏诊 LUTO 的严重后果，为产前肾积水提供咨询的临床医生应保持较低的 LUTO 鉴别诊断阈值。
