保胎中，请问b超能看出宫颈机能不全吗?　Have had the puerpera of cervix slack to ask: how to see the length of cervix below B ultra?

　　反复自然流产专家陈凤林教授指出：b超能看出宫颈机能不全，尤其是全景彩超，看的非常清楚，但只适用于怀孕后，如果是怀孕前就要采取扩宫试验来明确了!

　　宫颈分解剖学内口与组织学内口，它们之间有一子宫峡部相隔，宫颈管正常长度为2.5-3cm,当做妇科检查时，宫颈内口能顺利通过7号扩宫棒，或妊娠期无明显腹痛而B超测内口宽度>0.5cm,宫颈管长度<2.5cm,有助于诊断。从妊娠第4～5个月易发生。

　　Professor Chen Fenglin pointed out that: under normal circumstances, the normal length of cervical canal is 2.5-3cm. When it is used for gynecological examination, the inner mouth of the cervix can pass the No.7 uterine expanding stick smoothly, or there is no obvious abdominal pain during pregnancy, while the width of the inner mouth measured by B-ultrasound is more than 0.5cm, and the length of the cervical canal is less than 2.5cm, which is helpful for the diagnosis of cervical relaxation.