and is thought to be responsible for approximately 15% of habitual immature deliveries between 16 and 28 weeks of gestation
before onset of labour
In most cases, the etiology is unknown
Known causes include Congenital weakness as Mullerian abnormalities (cervical hypoplasia, in utero diethylstilbestrol [DES] exposure), traumatic abnormalities (prior surgical or obstetric trauma), and connective tissue abnormalities (Ehlers-Danlos syndrome).
Embryologically, the body and cervix of the uterus are derived from fusion and recanalization of the paramesonephric (Mullerian) ducts, a process that is complete by the 5th month of pregnancy.
Histologically, the cervix consists of fibrous connective tissue, muscle, and blood vessels. Muscular connective tissue constitutes approximately 15% of the cervical stroma, but is not uniformly distributed throughout the cervix, constituting approximately 30%, 18%, and 7% of the upper, mid, and lower thirds of the cervix, respectively (2).
Conversely, the fibrous connective tissue content of the cervical stroma increases as one moves from the external os to the uterine corpus, and it this component that is believed to confer tensile strength to the cervix. Defects in tensile strength are thought to lead to premature cervical dilatation and pregnancy loss.
Despite many advances in modern obstetrics ,there remains much controversy regarding the diagnosis and treatment of cervical incompetence
There is no precise method for diagnosing CI
Strongest evidence for diagnosis of CI is lack of any other causes for reccurrent pregnancy loss eg : chromosomal abnormalities,infection,endocrine disorders,immunologic disease)
With history of consistent with condition. - Or + Pre-pregnancy physical findings
Ultrasonography is useful as adjunct to other diagnostic measures
History of consistent with condition
Painless premature cervical diltation during pregnancy and before onset of labour
a sudden unexpected rupture of the membranes followed by painless expulsion of the fetus
Resulting in repeated mid trimester spontaneous miscarriage or premature delivery
Ultrasonography is useful
Before cerclage – length of cervical canal , width of isthmus , funneling of upper part of cervical canal with protrusion of the membranes(when the cervical os (opening) is greater than 2.5 cm, or the length has shortened to less than 20 mm. Sometimes funneling is also seen )
After cerclage – determine exact site of cerclage,proximal cervical canal segment length above cerclage ,distal cervical canal segment length below cerclage,internal os diameter ,funneling if present , and protrusion of membranes)
CERCLAGE or encerclage
Suspected cervical incompetence remains the only acceptable indication for cervical cerclage. Indications can be classified as follows:
(1) Prophylactic (elective) cervical cerclage
(2) Asymptomatic women with sonographic evidence of cervical shortening and/or funneling may also benefit from cervical cerclage (often called urgent cerclage)
(3) Emergency (salvage) cervical cerclage
Cerclage should be delayed until after 14 weeks so that early miscarriage caused by other factors is possible. There is no consensus about how late in pregnancy