Lukes A S, Thorp J M, Eucker B, Pahel-Short L
Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, USA.
Am J Obstet Gynecol. 1997 Mar;176(3):639-41. doi: 10.1016/s0002-9378(97)70561-1.
Identifying patients at risk for preterm delivery continues to be difficult. We analyzed fetal fibronectin immunoassays in 763 subjects with threatened preterm delivery from 10 clinical sites.
Symptomatic women between 24 weeks 0 days and 34 weeks 6 days with intact amniotic membranes and cervical dilatation <3 cm were included. Specimens were obtained from the posterior vaginal fornix and concentrations of fetal fibronectin were measured by enzyme-linked immunosorbent assay. A total of 150 (20%) patients had positive results for the fetal fibronectin immunoassay. The simultaneous effects of multiple variables on predicting positive fetal fibronectin immunoassay results were analyzed with use of logistic regression models. Variables included were patient age (mean 24.2 years), race (40% white), gravidity (29% primigravid), history of previous premature infants (15%), sexual activity within 24 hours of sample collection (66/763 or 9%), cervical examination within 24 hours of sample collection (107/763 or 14%), vaginal bleeding (118/759 or 16%), uterine contractions (192/750 or 26% with three or more in 1 hour), cervical dilatation (94/763 or 12% with dilatation between 1 and 3 cm), estimated gestational age at sampling (mean 30 weeks 2 days).
Regardless of the variable selection process (e.g., forward, backward, or stepwise), the reduced model showed five significant variables in predicting positive fetal fibronectin: cervical dilatation (chi2 33.5, p = 0.0006), sexual activity within 24 hours of sample collection (chi2 22.9, p < 0.0001), presence of vaginal bleeding (chi2 17.0, p < 0.0001), cervical examination within 24 hours of sample collection (chi2 11.6, p < 0.0006), and uterine contractions (chi2 6.8, p = 0.01). Deletion of the true positive subset did not change these variables or the magnitude of risk.
Cervical dilation or manipulation predicts positive fetal fibronectin assays and may serve to explain some of the false-positive results generated by the test.
识别有早产风险的患者仍然具有挑战性。我们分析了来自10个临床地点的763例有早产迹象的受试者的胎儿纤连蛋白免疫测定结果。
纳入孕周在24周0天至34周6天之间、胎膜完整且宫颈扩张<3 cm的有症状女性。从阴道后穹窿获取标本，采用酶联免疫吸附测定法测量胎儿纤连蛋白浓度。共有150例（20%）患者的胎儿纤连蛋白免疫测定结果为阳性。使用逻辑回归模型分析多个变量对预测胎儿纤连蛋白免疫测定阳性结果的同时影响。纳入的变量包括患者年龄（平均24.2岁）、种族（40%为白人）、孕次（29%为初产妇）、既往有早产史（15%）、样本采集前24小时内有性行为（66/763或9%）、样本采集前24小时内进行过宫颈检查（107/763或14%）、阴道出血（118/759或16%）、子宫收缩（192/750或26%，1小时内有3次或更多宫缩）、宫颈扩张（94/763或12%，扩张1至3 cm）、采样时的估计孕周（平均30周2天）。
无论变量选择过程如何（例如向前、向后或逐步选择），简化模型显示在预测胎儿纤连蛋白阳性方面有五个显著变量：宫颈扩张（卡方值33.5，p = 0.0006）、样本采集前24小时内有性行为（卡方值22.9，p < 0.0001）、存在阴道出血（卡方值17.0，p < 0.0001）、样本采集前24小时内进行过宫颈检查（卡方值11.6，p < 0.0006）和子宫收缩（卡方值6.8，p = 0.01）。剔除真阳性亚组并未改变这些变量或风险程度。
宫颈扩张或操作可预测胎儿纤连蛋白测定阳性，这可能有助于解释该检测产生的一些假阳性结果。
