Cervical insufficiency is a clinical diagnostic term that is synonymous with cervical incompetence and is classically defined as recurrent second-trimester pregnancy loss following painless cervical dilatation, attributed to the inability of the cervix to retain the gestation [1]. Cervical insufficiency occurs in the absence of uterine contractions or labour (painless cervical dilatation) and is usually due to a functional or structural defect.
Incidence
It occurs in approximately 1% of all pregnant women, but rises to 8% in those who suffered a second or third trimester pregnancy loss.[2] In a study done in Rivers state Nigeria the prevalence of cervical incompetence in Rivers State University Teaching Hospital is 0.69% or 6.9 per 1000 deliveries[3].
Aetiology
Cervical insufficiency usually occurs during the middle of the second or early third trimester, depending upon the severity of insufficiency. The retentive power of the cervix (internal os) may be impaired functionally and/or anatomically due to the following conditions:
(a) Congenital Uterine anomalies: such as those resulting from diethylstilbesterol (DES) exposure, or intrinsic deficiencies in cervical collagen and elastin.
(b) Acquired (iatrogenic) following:
(i) Dilatation and curettage operation,
(ii) Prior induced or spontaneous first- and second-trimester abortions
(iii) Operative vaginal delivery through an undilated cervix and
(iv) Amputation of the cervix or cone biopsy of trachelectomy.
(c) Others—multiple gestations, prior preterm birth.
Pathophysiology
The cervix plays a critical role in protecting the intrauterine environment. Before parturition, the cervix is firm, composed predominantly of collagen. Any conÂdition that degrades collagen enhances cervical softening and pliability, which sets the stage for dilatation. As previously mentioned, this process involves several mediators, including prostaglandins and cytokines; thus, it is not surprising that inflammation is frequently seen in the setting of preterm labor.[1]
The cervical canal normally contains mucus with antibacterial properties. With cervical dilatation, these antibacterial properties are impaired, increasing the risk of ascending infection, which subsequently stimulates progressive cervical dilatation. As a result, the cervix becomes incompetent to retain intrauterine contents, and preterm delivery ensues.[1]
Diagnosis
This involves taking a detailed history, performing clinical examination and then investigations.
History
History of repeated mid-trimester painless cervical dilatation (without apparent cause) and escape of amniotic fluid followed by painless expulsion of the products of conception are very much suggestive.
Clinical examination
(i) Bimanual examination reveals presence of unilateral or bilateral tear and/or gaping of the cervix up to the internal os. However, this can only be done during the Inter-conceptional period (that is in a non- pregnant woman)
(ii) vaginal speculum examination would reveal painless cervical shortening and dilatation. Also there could be detection of dilatation of internal os with herniation of the membranes. This examination can be done in a pregnant woman.
Investigations
Tests done during the inter-conceptional period are:
(i) Passage number 6-8 Hegar dilator beyond the internal os without any resistance and pain and absence of internal os snap on its withdrawal specially in premenstrual period indicate incompetence.
(ii) Premenstrual hysterocervicography shows funnel-shaped shadow. The internal os is supposed to be tight due to action of progesterone during this phase of cycle. Similar funnel-shaped shadow may be found if hysterography is done in the proliferative phase even with a competent cervix.
Tests that can be done during pregnancy are:
Sonography: Short cervix < 25 mm and funnelling of the internal os > 1 cm would be noted.
Management
The management could be surgical or non-surgical. The non-surgical methods include:
- Bed rest
- Pelvic rest
- Use of vaginal pessary
Surgical method is cervical cerclage which could either be done via a transabdominal or transvaginal approach. The two commonly used vaginal procedures include: McDonald and modified Shirodkar.
References
- Gestational Diseases and the Placenta, Emily E. Meserve, Theonia K. Boyd, in Diagnostic Gynecologic and Obstetric Pathology (Third Edition), 2018 Cervical Incompetence – an overview | ScienceDirect Topics
- Romero R, Espinoza J, Erez O, Hassan S. The role of cervical cerclage in obstetric practice: Can the patient who could benefit from this procedure be identified? Am J Obstet Gynecol 2006;194:1-9. Back to cited text no. 1 [PUBMED]
- Wekere FCC, Clement-Wekere GAF, Nonye-Enyidah EI. Cervical incompetence: prevalence, socio-demographic and clinical characteristics in Rivers State University Teaching Hospital, Port Harcourt, South-South Nigeria. Yen Med J. 2020;2(1):127-134. Cervical incompetence: prevalence, socio-demographic and clinical characteristics in Rivers State University Teaching Hospital, Port Harcourt, South-South Nigeria. – Yenagoa Medical Journal