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INTRODUCTION

KEY QUESTIONS

  • What are the diagnostic criteria for cervical insufficiency?

  • What are the indications for history-indicated, ultrasound-indicated, and exam-indicated cerclage?

  • Is an amniocentesis necessary before performing a cerclage?

  • Can cerclages be used in pregnancies with multiple gestations?

CASE 23-1

A 23-year-old gravida 3 para 0020 at 15 weeks and 4 days gestation. Prior pregnancy complicated by a 20-week loss and preterm deliveries at both 28 and 36 weeks gestation. The patient had cerclages placed for 28 and 36 weeks delivery. What is your plan of care?

DEFINITION OF CERVICAL INSUFFICIENCY

Cervical insufficiency (also known as cervical incompetence) is the presumed weakness of the cervix that leads to loss of an otherwise healthy pregnancy, usually in the second trimester. It is classically described as painful cervical dilation in the absence of vaginal bleeding, uterine contractions, or rupture of membranes.

PATHOPHYSIOLOGY

The cause of cervical insufficiency is poorly understood. Risk factors include prior trauma to the cervix, including excisional procedures, mechanical dilation during dilation and curettage, and obstetrical lacerations.14 Other risk factors include uterine anomalies,5,6 in utero exposure to diethylstilbesterol (DES),7 and congenital anomalies including genetic disorders affecting collagen such as Ehler-Danlos syndrome.8,9

DIFFERENTIAL DIAGNOSIS

The differential diagnosis for cervical insufficiency includes:

  • Preterm labor

  • Maternal or fetal infection

  • Placental abruption

  • Uterine distension (i.e. polyhydramnios, multiple fetal gestation)

EVALUATION

Patients suffering from cervical insufficiency typically have mild symptoms such as pelvic pressure, menstrual cramping, backache, and increased vaginal discharge. Evaluation should include a detailed history to elicit symptoms and risk factors as well as a physical exam. The speculum exam should include evaluation of the cervical os, the presence or absence of prolapse fetal parts and membranes, and visualization of debris in the amniotic sac (Fig. 23-1) or overt purulent discharge. A number of studies have demonstrated that intraamniotic debris is associated with an underlying infection.3,10 In addition, a digital exam to assess cervical dilation will be important to evaluate candidacy for an exam-indicated cerclage or the presence of active labor.

FIGURE 23-1.

Amniotic Fluid Sludge. (Reproduced with permission from Fleischer AC, Abramowicz JS, Gonçalves LF, et al: Fleischer’s Sonography in Obstetrics and Gynecology: Textbook and Teaching Cases, 8th ed. New York, NY: McGraw-Hill Education, Inc; 2018.)

Laboratory evaluation is of limited use with the diagnosis, screening, or management of cervical insufficiency. Pregnancy is associated with a slight increase in the white blood cell (WBC) count, so unless this number is markedly elevated to the suggested infectious etiology, it is of limited value. Cervicovaginal fetal fibronectin is not indicated in this setting for diagnosis or management. When overt signs of ...

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