WordNet

relating to or associated with the neck
of or relating to the cervix of the uterus; "cervical cancer"
inability of a part or organ to function properly
lack of physical or intellectual ability or qualifications (同)incompetency

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(子宮などの)頚(けい)部の(にできた)
無能,無力;不適当,無答格

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/10/09 10:50:46」(JST)

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Cervical incompetence (or cervical insufficiency) is a medical condition of pregnancy in which the cervix begins to dilate (widen) and efface (thin) before the pregnancy has reached term. Definitions of cervical incompetence vary, but one that is frequently used is the inability of the uterine cervix to retain a pregnancy in the absence of the signs and symptoms of clinical contractions, or labor, or both in the second trimester.^[1] Cervical incompetence may cause miscarriage or preterm birth during the second and third trimesters. Another sign of cervical incompetence is funneling at the internal orifice of the uterus, which is a dilation of the cervical canal at this location.^[2]

In cases of cervical incompetence, dilation and effacement of the cervix may occur without pain or uterine contractions. In a normal pregnancy, dilation and effacement occurs in response to uterine contractions. Cervical incompetence occurs because of weakness of the cervix, which is made to open by the growing pressure in the uterus as pregnancy progresses. If the responses are not halted, rupture of the membranes and birth of a premature baby can result.

According to statistics provided by the Mayo Clinic, cervical incompetence is relatively rare in the United States, occurring in only 1–2% of all pregnancies, but it is thought to cause as many as 20—25% of miscarriages in the second trimester.

Diagnosis

Diagnosis of cervical incompetence can be challenging and is based on a history of painless cervical dilation usually after the first trimester without contractions or labor and in the absence of other clear pathology. In addition to history, some providers use assessment of cervical length in second trimester to identify cervical shortening using ultrasound.^[3] However, short cervical length has actually been shown to be a marker of preterm birth rather than cervical incompetence. Other diagnostic tests that have been suggested which have not been validated include hysterosalpingography and radiographic imaging of balloon traction on the cervix, assessment of the patulous cervix with Hegar or Pratt dilators, the use of a balloon elastance test, and use of graduated cervical dilators to calculate a cervical resistance index.^[1]

Normally, the cervix should be at least 30 mm in length. Cervical incompetence is variably defined. However, a common definition is a cervical length of less than 25 mm at or before 24 weeks of gestational age. The risk of preterm birth is inversely proportional to cervical length:^[4]

Less than 25 mm; 18% risk of preterm birth
Less than 20 mm; 25% risk of preterm birth
Less than 15 mm; 50% risk of preterm birth

Risk factors

Risk factors for premature birth or stillbirth due to cervical incompetence include:^[5]

diagnosis of cervical incompetence in a previous pregnancy,
previous preterm premature rupture of membranes,
history of conization (cervical biopsy),
diethylstilbestrol exposure, which can cause anatomical defects, and
uterine anomalies.

Repeated procedures (such as mechanical dilation, especially during late pregnancy) appear to create a risk.^[6] Additionally, any significant trauma to the cervix can weaken the tissues involved.

Treatment

Cervical incompetence is not generally treated except when it appears to threaten a pregnancy. Cervical incompetence can be treated using cervical cerclage, a surgical technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal.

Cerclage procedures usually entail closing the cervix through the vagina with the aid of a speculum. Another approach involves performing the cerclage through an abdominal incision. Transabdominal cerclage of the cervix makes it possible to place the stitch exactly at the level that is needed. It can be carried out when the cervix is very short, effaced or totally distorted. Cerclages are usually performed between weeks 14 and 16 of the pregnancy. The sutures are removed between weeks 36 and 38 to avoid problems during labor. The complications described in the literature have been rare: hemorrhage from damage to the veins at the time of the procedure; and fetal death due to uterine vessels occlusion.

No significant differences in pregnancy outcomes were found in a study evaluating pregnancy outcomes after cervical conization. This study suggests for women with cervical insufficiency due to prior cone biopsy, cerclage is not superior to no intervention.^[7] As cerclage can induce preterm contractions without preventing premature delivery,^[8] makes the recommendation that it be used sparingly in women with a history of conization.

A cervical pessary is being studied as an alternative to cervical cerclage since there are fewer potential complications. A silicone ring is placed at the opening to the cervix early in the pregnancy, and removed later in the pregnancy prior to the time of expected delivery. Further study is needed to determine whether a cervical pessary is equal or superiour to current management.^[9]

Notes

^ ^a ^b American College of Obstetricians and, Gynecologists (Feb 2014). "ACOG Practice Bulletin No.142: Cerclage for the management of cervical insufficiency.". Obstetrics and gynecology. 123 (2 Pt 1): 372–9. PMID 24451674. doi:10.1097/01.AOG.0000443276.68274.cc.
^ Cervical assessment from Fetal Medicine Foundation. Retrieved Feb 2014.
^ Macdonald, R; Smith, P; Vyas, S (Sep 2001). "Cervical incompetence: the use of transvaginal sonography to provide an objective diagnosis.". Ultrasound in Obstetrics & Gynecology. 18 (3): 211–6. PMID 11555448. doi:10.1046/j.1469-0705.2001.00459.x.
^ Cervical incompetence at Radiopedia. By Dr Praveen Jha and Dr Laughlin Dawes et al. Retrieved June 2014
^ Althuisius SM; Dekker GA; Hummel P; Bekedam DJ; van Geijn HP (Nov 2001). "Final results of the Cervical Incompetence Prevention Randomized Cerclage Trial (CIPRACT): therapeutic cerclage with bed rest versus bed rest alone.". American Journal of Obstetrics & Gynecology. Academic Press. 185 (5): 1106–1112. PMID 11717642. doi:10.1067/mob.2001.118655.
^ "Cervical Incompetence – Protocol for Management" (PDF). PROTOCOL #40. Maternal Fetal Medicine, University of New Mexico. 2012-03-03. Archived from the original (PDF) on 2012-06-17.
^ Armarnik, S; Sheiner, E; Piura, B; Meirovitz, M; Zlotnik, A; Levy, A (April 2011). "Obstetric outcome following cervical conization.". Archives of gynecology and obstetrics. 283 (4): 765–9. PMID 21327802. doi:10.1007/s00404-011-1848-3.
^ Zeisler, H; Joura, EA; Bancher-Todesca, D; Hanzal, E; Gitsch, G (July 1997). "Prophylactic cerclage in pregnancy. Effect in women with a history of conization.". The Journal of reproductive medicine. 42 (7): 390–2. PMID 9252928.
^ Abdel-Aleem, H; Shaaban, OM; Abdel-Aleem, MA (May 31, 2013). "Cervical pessary for preventing preterm birth.". The Cochrane database of systematic reviews. 5: CD007873. PMID 23728668. doi:10.1002/14651858.CD007873.pub3.

References

The first revision of this article was adapted from material from the public domain source "Summary Report: ICD-9-CM coordination and maintenance committee", published at http://www.cms.hhs.gov/paymentsystems/icd9/icd111700.pdf.

UpToDate Contents

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1. 頸管無力症 cervical insufficiency
2. Second-trimester pregnancy termination: Dilation and evacuation
3. 妊婦における腟出血の病因および評価の概要 overview of the etiology and evaluation of vaginal bleeding in pregnant women
4. 単胎妊娠した女性の自然早産予測のための妊娠第2三半期の子宮頚管長測定 second trimester evaluation of cervical length for prediction of spontaneous preterm birth in singleton gestations
5. 経膣的子宮頸管縫縮術 transvaginal cervical cerclage

English Journal

Robotic Cerclage in Advanced-stage Endometriosis.

Moawad GN1, Abi Khalil ED2, Samuel D3.
Journal of minimally invasive gynecology.J Minim Invasive Gynecol.2016 Nov - Dec;23(7):1026-1027. doi: 10.1016/j.jmig.2016.04.010. Epub 2016 Apr 27.
STUDY OBJECTIVE: To show a stepwise surgical technique of robotic-assisted transabdominal cerclage placement in a patient with deeply infiltrative endometriosis.DESIGN: A step-by-step surgical tutorial using narrated video.SETTING: The George Washington University Hospital. Local institutional revie
PMID 27131398

Co-morbidity of cervical incompetence with polycystic ovarian syndrome (PCOS) negatively impacts prognosis: A retrospective analysis of 178 patients.

Wang Y1, Gu X1, Tao L2, Zhao Y3.
BMC pregnancy and childbirth.BMC Pregnancy Childbirth.2016 Oct 12;16(1):308.
BACKGROUND: Cervical incompetence is an important cause of miscarriage and premature birth and polycystic ovary syndrome is a heterogeneous endocrine disorder that is the most common cause of anovulatory infertility and eugonadotrophic hypogonadism. By now, it is still debated whether women with PCO
PMID 27733131

Deficiency in memory B cell compartment in a patient with infertility and recurrent pregnancy losses.

Sung N1, Byeon HJ2, Garcia MD1, Skariah A1, Wu L1, Dambaeva S3, Beaman K3, Gilman-Sachs A3, Kwak-Kim J4.
Journal of reproductive immunology.J Reprod Immunol.2016 Sep 28;118:70-75. doi: 10.1016/j.jri.2016.09.003. [Epub ahead of print]
Alterations in normal balance of B cell subsets have been reported in various rheumatic diseases. In this study, we report a woman with a history of recurrent pregnancy losses (RPL) and infertility who had low levels of memory B cells. A 35-year-old woman with a history of RPL and infertility was de
PMID 27716543

Japanese Journal

IS-48 A Significance of emergency total cervical occlusion (double cerclage) in advanced cervical incompetence(Group7 Perinatology1,International Session)

Kim Yun-sook,Mun Seong-Taek,Sunwoo Jae-Gun,Bae Dong-han
日本産科婦人科學會雜誌 63(2), 929, 2011-02-01
NAID 110008510201

正常妊婦と子宮頸管無力症妊婦の骨盤と骨盤底筋機能の変化の比較

名取初美,平田良江,島田啓子 [他]
金沢大学つるま保健学会誌 35(1), 27-35, 2011
… Aim : To compare the changes in the pelvis and pelvic floor muscle function innormal pregnant women and pregnant women with cervical incompetence.【目的】正常妊婦と子宮頸管無力症妊婦の妊娠中の骨盤と骨盤底筋機能の変化を比較することである。 … Methods : The subjects consisted of 14 normal pregnant women and 10 pregnantwomen with cervical incompetence. …
NAID 40018947601