1.1. BASIC CONCEPTS OF CERVICAL INSUFFICIENCY
Definition. Cervical insufficiency (CI) is failure of obturative function of the uterine isthmus and cervix, resulting in violated integrity of fetal membranes, leakage of amniotic fluid or rupture of membranes, premature termination of pregnancy. Typical signs of CI include: sudden rupture of membranes, prolapse of the amniotic sac into the vagina, rapid and almost painless expulsion of the fetus from the uterus.
Main causes of CI:
1. Anatomical incompetence of the internal os (as a result of artificial dilation, cervical tears after an abortion or delivery; connective tissue dys-plasia, malformations, post-traumatic injuries, and other causes).
2. Functional incompetence of the internal os due to existing hormonal disorders (hyperandrogenism, genital infantilism, neuroendocrine disease).
Pathogenesis. The mechanisms of premature termination of pregnancy in CI consist in cervical shortening, softening, dilation of the internal os and cervical canal. The gestational sac loses physiological support in the lower pole of uterus. Fetal membranes prolapse into the dilated cervical canal. An increase of intrauterine, intra-abdominal pressure (physical stress), infection of the birth canal disrupt the membrane integrity, membranes rupture, and rapid expulsion of fetus occurs.
In this case, termination of pregnancy can be rapid without prior significant clinical symptoms.
Clinical presentations. Dilation of the cervix and prolapse of amniotic sac occur without increased excitability or hypertone, increased uterine contractile activity. The first symptoms felt by the patient are the sensation of pressure in the vagina, which is exerted by a prolapsing amniotic sac, or rupture of