Department of Obstetrics and Gynecology, Lenox Hill Hospital-Northwell Health, New York, NY.
Department of Obstetrics and Gynecology, Lenox Hill Hospital-Northwell Health, New York, NY.
Am J Obstet Gynecol MFM. 2020 May;2(2):100059. doi: 10.1016/j.ajogmf.2019.100059. Epub 2019 Oct 25.
Asymptomatic short cervical length is an independent risk factor for spontaneous preterm birth. However, most studies have focused on the associated risk of a short cervical length when encountered between 16 and 23 weeks' gestation. The relationship between cervical length and risk of spontaneous preterm birth after 23 weeks is not well known.
To evaluate the risk of spontaneous preterm birth in asymptomatic women with a short cervix (≤25 mm) at 23-28 weeks' gestation.
A retrospective cohort study of women with asymptomatic short cervix (cervical length ≤25 mm) at extreme prematurity, defined as 23-28 weeks' gestation, was performed at a single center from January 2015 to March 2018. Women with symptoms of preterm labor, multiple gestations, fetal or uterine anomalies, cervical cerclage, or those with incomplete data were excluded from the study. Demographic information as well as data on risk factors for spontaneous preterm birth were collected. Patients were divided into 4 groups based on the cervical length measurement (≤10 mm, 11-15 mm, 16-20 mm, and 21-25 mm). The primary outcome was time interval from enrollment to delivery. Secondary outcomes included delivery within 1 and 2 weeks of enrollment, gestational age at delivery, and delivery prior to 32, 34, and 37 weeks, respectively. Continuous variables were compared using Kruskal-Wallis test, whereas categorical variables were compared using the χ or Fisher exact test as appropriate. The Wilcoxon test for difference in survival time was used to compare gestational age at delivery among the 4 cervical length groups, with data stratified based on gestational age at enrollment.
Of the 126 pregnancies that met inclusion criteria, 22 (17.4%) had a cervical length of ≤10 mm, 23 (18.3%) had a cervical length of 11-15 mm, 37 (29.4%) had a cervical length of 16-20 mm, and 44 (34.9%) had a cervical length of 21-25 mm. Baseline characteristics were similar among all 4 groups. The shorter cervical length group was associated with a shorter time interval from enrollment to delivery (cervical length ≤10 mm, 10 weeks; cervical length 11-15 mm, 12.7 weeks; cervical length of 16-20 mm, 13 weeks; cervical length of 21-25 mm, 13.2 weeks; P = .006). Regardless of the cervical length measurement, delivery within 2 weeks was extremely uncommon (1 patient; 0.8%). The prevalence of spontaneous preterm birth at <32 weeks or <34 weeks was higher in women with a cervical length of ≤10 mm compared to those with a longer cervical length (P < .001).
The risk of spontaneous preterm birth in asymptomatic women with a sonographic short cervix increases as cervical length decreases. The risk is substantially higher in women with a cervical length of ≤10 mm. Women with a cervical length of ≤10 mm also had the shortest time interval to delivery. Nevertheless, delivery within 1 or 2 weeks is highly unlikely, regardless of the cervical length at the time of enrollment. Therefore, based on our data, we suggest that management decisions such as timing of administration of antenatal corticosteroids in asymptomatic patients with a cervical length of ≤25 mm at 23-28 weeks' gestation may be delayed until additional indications are present.
无症状的短宫颈长度是自发性早产的独立危险因素。然而，大多数研究都集中在 16 至 23 周妊娠时短宫颈长度相关的风险。23 周后宫颈长度与自发性早产风险之间的关系尚不清楚。
评估 23-28 周妊娠时无症状短颈（≤25mm）妇女自发性早产的风险。
在 2015 年 1 月至 2018 年 3 月，在一家单中心进行了一项回顾性队列研究，纳入了极度早产（定义为 23-28 周妊娠）且无症状短颈（宫颈长度≤25mm）的妇女。研究排除了有早产症状、多胎妊娠、胎儿或子宫异常、宫颈环扎术或资料不全的患者。收集了人口统计学信息以及自发性早产的危险因素数据。根据宫颈长度测量结果（≤10mm、11-15mm、16-20mm 和 21-25mm）将患者分为 4 组。主要结局为从入组到分娩的时间间隔。次要结局包括入组后 1 周和 2 周内分娩、分娩时的孕龄以及分别在 32 周、34 周和 37 周前分娩。连续变量采用 Kruskal-Wallis 检验进行比较，分类变量采用 χ2 或 Fisher 确切检验进行比较。Wilcoxon 检验用于比较 4 个宫颈长度组的分娩时孕龄，数据根据入组时的孕龄进行分层。
在符合纳入标准的 126 例妊娠中，22 例（17.4%）宫颈长度≤10mm，23 例（18.3%）宫颈长度为 11-15mm，37 例（29.4%）宫颈长度为 16-20mm，44 例（34.9%）宫颈长度为 21-25mm。所有 4 组的基线特征相似。宫颈长度较短的组从入组到分娩的时间间隔更短（宫颈长度≤10mm，10 周；宫颈长度 11-15mm，12.7 周；宫颈长度 16-20mm，13 周；宫颈长度 21-25mm，13.2 周；P=0.006）。无论宫颈长度测量如何，在 2 周内分娩的情况都非常罕见（1 例；0.8%）。与宫颈长度较长的患者相比，宫颈长度≤10mm 的患者发生<32 周或<34 周自发性早产的比例更高（P<0.001）。
在无症状的短宫颈超声患者中，宫颈长度越短，自发性早产的风险就越高。宫颈长度≤10mm 的患者风险显著更高。宫颈长度≤10mm 的患者到分娩的时间间隔也最短。然而，无论入组时的宫颈长度如何，1 或 2 周内分娩的可能性都非常低。因此，根据我们的数据，我们建议在 23-28 周妊娠时无症状患者宫颈长度≤25mm 的情况下，可能需要延迟管理决策，例如是否给予产前皮质激素，直到出现其他指征。
