Cervical Insufficiency (Insufficientia cervicis)

Cervical Incompetence (Insufficientia cervicis), is an obstetric pathology characterized by painless dilation and effacement of the cervix without uterine contractions during the second trimester or early third trimester of pregnancy. This clinical condition leads to prolapse and rupture of the fetal membranes into the vagina, resulting in expulsion of a fetus that has not yet reached viability. Cervical incompetence is responsible for approximately 16–20% of second-trimester pregnancy losses.^【1】

The concept of cervical incompetence has a long history in medical literature. It was first described by Riverius in 1658; approximately 200 years later, Gream suggested that cervical dilation performed for dysmenorrhea or infertility could lead to this condition.^【2】 The first steps toward surgical treatment were taken in 1902 by Herman, who applied trachelorrhaphy in cases of Emmet tears. The first modern report on isthmic repair of cervical incompetence was published by Palmer and Lacomme in 1948; in 1950, Lash proposed pre-pregnancy surgical intervention. Vaginal cerclage techniques still in use today were described by Shirodkar in 1955 and McDonald in 1957; abdominal cerclage was first defined by Benson and Durfee in 1965.^【3】

The incidence of the condition is not precisely known due to diagnostic complexities, but it is reported to occur in 0.1–1% of all pregnancies, or at a rate of 1 in 200 to 1 in 2000 births. This condition is observed in approximately 8% of women with recurrent second-trimester pregnancy loss. According to U.S. data, cervical incompetence is responsible for approximately 10% of preterm births (ACOG data).^【4】

The anatomical structure of the cervix is richer in connective tissue than smooth muscle, in contrast to the uterine corpus. Disruptions in this structure predispose to incompetence.

• Biological and Structural Factors: Increased water content in hyaluronic acid within cervical connective tissue prior to term, relatively reduced connective tissue in the proximal cervix, or alterations in elastin and collagen components may lead to incompetence.
• Traumatic Causes: Among the most common causes. Difficult deliveries, forceps applications, and excessive or rapid cervical dilation during pregnancy termination can cause cervical trauma and increase the risk of incompetence.
• Surgical Interventions: Excisional procedures such as conization and LEEP, performed to treat cervical intraepithelial neoplasia, can result in structural and functional cervical damage. In particular, conization in nulliparous women has been associated with increased risk of preterm birth.^【5】
• Congenital Factors: Uterine anomalies, in utero diethylstilbestrol exposure, and congenital cervical shortening are among the risk factors.
• Other Factors: Multiple pregnancies and cervical myomas are additional contributing factors.

The fundamental mechanism underlying cervical incompetence is the premature initiation of cervical maturation. In a normal pregnancy, the cervix maintains its firmness and retains the pregnancy product within the uterus through a sphincter mechanism, due to its high collagen content. In cases of incompetence, changes occur in the cervical extracellular matrix without activation of proinflammatory cytokines or onset of uterine contractions. The organization of collagen fibers is disrupted, water content increases, and the cervix loses its biomechanical resistance, becoming unable to withstand intrauterine pressure. This process results in cervical shortening and dilation.

Cervical incompetence typically follows a silent course. However, careful questioning may reveal the following symptoms:

• A sensation of fullness or pressure in the pelvic region.
• Mild cramp-like pain in the back and lower back.
• Increase or change in vaginal discharge (mucoid, watery, or slight bloody spotting).
• Changes in urinary habits (due to bladder pressure). These symptoms are often nonspecific, leading to delayed diagnosis.

There is no single laboratory test universally accepted for diagnosing cervical incompetence. Diagnosis is typically established through a combination of the following methods:

1. Obstetric History: The most important diagnostic tool. A typical history includes recurrent, painless cervical dilation leading to pregnancy loss or spontaneous preterm birth during the second or early third trimester.
2. Ultrasonography: The gold standard for diagnosis and monitoring. Transvaginal approach is preferred over transabdominal measurement because the latter can be affected by bladder distension. Scans are typically performed serially between 16 and 24 weeks of gestation.
3. Short Cervix: A cervical length of less than 25 mm is a risk indicator. Measurements of 15 mm or less indicate high risk.
4. Funneling: The funnel-shaped opening of the internal os. It can be classified as T, Y, V, or U shapes; the U shape is associated with the highest risk.
5. Physical Examination and Other Tests:
6. 1. Hegar Burette Test: In pre-pregnancy examination, the painless passage of a size 8 Hegar bougie through the cervical canal is a diagnostic criterion.
   2. Hysterosalpingography: A cervical canal wider than 10 mm or a cervical length shorter than 2.5 cm are diagnostic criteria.

^{Hegar Burette}

^{(Generated by Artificial Intelligence)}

Treatment is divided into surgical and nonsurgical approaches.

Nonsurgical Methods

In addition to bed rest, activity restriction, and pessary use, pharmacological support is administered.

• Progesterone Therapy: Vaginal progesterone is recommended for patients with a prior history of spontaneous preterm birth and a cervical length less than 25 mm on transvaginal ultrasound (in singleton pregnancies, typically before 24 weeks).

Cervical cerclage is the primary and well-established surgical treatment.

• Prophylactic Cerclage: Performed before any cervical changes occur, typically between 12 and 16 weeks of gestation, in women with a history of cervical incompetence. Success rate is approximately 85–90%.^【6】
• Therapeutic Cerclage: Performed upon detection of cervical shortening or funneling during routine monitoring.
• Emergency Cerclage: A procedure performed in cases of advanced cervical dilation, effacement, or prolapsed membranes, up to 24–28 weeks of gestation. It may extend pregnancy by an average of 4–13 weeks and improve fetal survival chances.

Cerclage should not be performed in the following conditions:

• Active uterine bleeding.
• Active preterm labor (uncontrollable contractions).
• Chorioamnionitis (intra-amniotic infection).
• Preterm Premature Rupture of Membranes (PPROM).
• Fetal demise or nonviable fetal anomaly.

1. Vaginal Cerclage: The most commonly performed approach.
2. 1. McDonald Technique: Involves placing a purse-string suture at the cervicovaginal junction. It is popular due to its simplicity and lack of need for bladder dissection. Nonabsorbable suture materials are typically used.
   2. Shirodkar Technique: Involves placing the suture closer to the internal os and covering it with mucosa. It is preferred when the McDonald technique has failed or when structural abnormalities are present.
2. Transabdominal Cerclage: Performed when vaginal cerclage has failed or when anatomical defects or deep traumatic lacerations are present. A suture is placed at the cervicocervical junction via laparotomy or laparoscopy. A disadvantage is that it necessitates cesarean delivery for pregnancy termination; however, fetal survival rates range from 85–95%.^【7】

^{Cervical Cerclage}

^{(Generated by Artificial Intelligence)}

In emergency cerclage cases, the following maneuvers are used to prevent membrane damage and elevate the presenting parts:

• Trendelenburg Position: The patient is placed in a head-down position to utilize gravity.
• Foley Balloon Use: A filled Foley catheter balloon is gently used to push the membranes upward.
• Amniocentesis: Amniotic fluid may be aspirated to reduce intra-amniotic pressure and exclude infection.

Cerclage is effective in reducing preterm birth rates. However, success rates decline as cervical dilation increases in emergency cases.^【8】Fetal survival rates are 85–95% in appropriately selected cases.^【9】

• Preterm labor and uterine contractions.
• Premature rupture of membranes.
• Chorioamnionitis.
• Cervical trauma, laceration, or rupture.
• Suture displacement, cervical stenosis, and fistula formation.

Postoperative management typically includes bed rest, hydration, prophylactic antibiotics, and tocolytic therapy. Sutures are removed at 37 weeks of gestation or upon onset of labor.

Warning: The content in this article is provided solely for general encyclopedic informational purposes. The information herein should not be used for diagnosis, treatment, or medical guidance. Always consult a physician or qualified healthcare professional before making any health-related decisions. The author and KÜRE Encyclopedia assume no responsibility for any consequences arising from the use of this information for diagnostic or therapeutic purposes.