下面是美国最新的有关宫颈机能不全的诊疗常规： 

The diagnosis of cervical insufficiency is either based on historic factors or on a combination of historic factors and transvaginal ultrasound (TVU) measurement of cervical length. 

子宫颈机能不全的诊断是基于既往病史和/或孕期经阴道超声测量子宫颈长度的检查  苏州大学附属第一医院妇产科韩冰

Using historic factors alone, cervical insufficiency is defined as painless cervical dilatation leading to recurrent second trimester pregnancy losses/births. 

如果单独仅靠既往病史诊断，无痛性子宫颈扩张导致复发的孕中期流产 

A preferable definition allows the diagnosis of cervical insufficiency during any pregnancy. Using this definition, cervical insufficiency is defined by TVU cervical length<25 mm and/or advanced cervical changes on physical examination before 24 weeks of gestation in women with either: One or more prior pregnancy losses/births at 14 to 36 weeks, and/or Other significant risk factors for cervical insufficiency. 

孕期诊断：经阴道超声子宫颈管长度小于25mm，和/或妇科检查（24周前）宫颈进行性缩短（既往有一次或者多次14-36周的流产/早产史，其他引起子宫颈功能不全的危险因素） 

●  For women with two or more consecutive prior second trimester pregnancy losses or three or more early preterm births who have risk factors for cervical insufficiency and in whom other causes of preterm birth have been excluded, we recommend history-indicated cerclage (Grade 1B). 

对于那些有过2次孕中期流产或早早产的子宫颈机能不全的患者，排除其他因素后，建议预防性环扎 

●  For women with suspected cervical insufficiency and prior early preterm birth who do not meet criteria for history-indicated cerclage, sonographic surveillance should be started early in pregnancy (eg, 14 to 16 weeks). We suggest cerclage for women who develop a short cervix (<25 mm) before 24 weeks (Grade 2B). 

对于那些达不到上述要求的患者，可以在孕期动态监测子宫颈管长度，（14-16周），如果在24周前子宫颈管长度小于25mm，建议环扎。 

Vaginal progesterone administration or placement of a pessary are alternative approaches. 也可以选用阴道用孕激素 ●  We recommend progesterone supplementation for women with singleton gestations and a history of spontaneous preterm birth (Grade 1B). 对于那些单胎既往有自发早产病史的患者，推荐使用孕激素