Case 2:Cervical insufficiency

Case report 

A 27-year old woman, G10 P2 A7 presented at 16 weeks and 6 days Gestational Age (GA) with protruding membranes. Her obstetric history included 1 molar pregnancy and 5 early miscarriages. She had an expulsion at 16 weeks GA after painless dilation, most probably due to cervical insufficiency. In the next pregnancy, an elective cerclage was placed by transvaginal approach and vaginal progesterone tablets were used. At 21 weeks GA she presented with pelvic pressure and premature rupture of the membranes. Considering the gestational age and the poor prognosis, the cerclage was removed and she delivered that same day. In the subsequent pregnancy a transvaginal cervical cerclage was performed for the second time. Due to premature contractions, this cerclage had to be removed at 21 weeks GA and the patient delivered one day later.

Definition

 cervical insufficiency as "the inability of the uterine cervix to retain a pregnancy in the second trimester in the absence of clinical contractions, labor, or both" 

Pathogenesis

Structural cervical weakness is the likely cause of many recurrent second-trimester losses/births, but it probably accounts for only a minor proportion of all second-trimester losses/births. The majority of these cases are probably caused by other disorders, such as decidual inflammation/infection, placental bleeding, or uterine overdistension. These other disorders can initiate biochemical changes in the cervix that lead to premature cervical shortening and often a single (ie, nonrecurrent) second-trimester loss/birth. 

Symptoms 

 Women with cervical insufficiency in the current pregnancy may be asymptomatic or may present with mild symptoms, such as pelvic pressure, Braxton-Hicks-like contractions, premenstrual-like cramping, backache, and/or a change in vaginal discharge. Discharge volume may increase; the color may change from clear, white, or light yellow to pink, tan, or red spotting; and the consistency may become thinner. Symptoms, if present, typically begin between 14 and 20 weeks of gestation and may be present for several days or weeks before the diagnosis of cervical insufficiency is made.

The classic obstetric history of women with structural cervical weakness leading to recurrent cervical insufficiency is characterized by recurrent second-trimester pregnancy losses/deliveries that were associated with no or minimal mild symptoms.

cervical insufficiency in women with a classic history of ≥2 consecutive prior second-trimester pregnancy losses/extremely preterm births.

Physical examination

Provocative maneuvers such as suprapubic or fundal pressure or the Valsalva maneuver may reveal fetal membranes in the endocervical canal or vagina; this is always an abnormal finding.

Imaging

The transvaginal ultrasound(TVUS) cervical length is typically short (≤25 mm) before 24 weeks. If serial ultrasound examinations have been performed, a decrease in cervical length over time may be noted.

TVUS screening is discontinued at 24 weeks of gestation, as cerclage is rarely performed after this time.

Diagnosis

We base the diagnosis of cervical insufficiency on either a classic past obstetric history or on a combination of obstetric history and transvaginal ultrasound (TVUS) measurement of cervical length. Physical examination alone is adequate in women with advanced cervical dilation and/or effacement.

The diagnosis is usually limited to singleton gestations because the pathogenesis of second-trimester pregnancy loss/extremely preterm delivery (ie, <28 weeks) in multiple gestations is usually unrelated to a weakened cervix.

 The diagnosis of cervical insufficiency cannot be made or excluded in nonpregnant women by any test.

Candidates for amniocentesis

We perform amniocentesis to look for subclinical infection when the cervix is ≥2 cm dilated on manual or speculum examination, as the incidence of intra-amniotic infection in these women is approximately 20 to 50 percent.

Management

1. Placement of cerclage at 12 to 14 weeks of gestation in women with this diagnosis. 

Cerclage is not indicated in multiple gestations, given that the body of evidence shows no improvement in pregnancy outcome compared with appropriate controls without cerclage.

Most clinicians avoid placing a cerclage after approximately 24 weeks of gestation since the procedure may cause accidental rupture of the fetal membranes leading to early preterm delivery of a viable infant, with its attendant high risk of neonatal morbidity and mortality. 

Contraindications 

Fatal anomaly incompatible with life

Intrauterine infection

Active bleeding

Active preterm labor

Preterm prelabor rupture of membranes (PPROM)

Fetal demise.

Preoperative assessment

Fetal evaluation

Screening for infection

Excluding membrane rupture and preterm labor

Choice of McDonald versus shirodkar procedure

1. Shirodkar

This procedure is more complicated than the McDonald cerclage because it requires incisions and dissection of the paracervical area. The bladder is emptied to facilitate visualization of the cervix.

2. McDonald

The procedure is begun by grasping the anterior and posterior lips of the cervix with one or two ring forceps. We insert a curved needle loaded with large caliber nonabsorbable synthetic suture (at least number 1 or 2 braided or monofilament) at 12 o'clock, at the junction of the rugated vaginal epithelium and the smooth cervix just distal to the vesicocervical reflection and at least 2 cm above the external os, as feasible.

The cerclage is removed electively at 36+0 to 37+0 weeks of gestation or immediately upon onset of preterm labor in order to avoid cervical laceration and/or uterine rupture.

A McDonald cerclage usually can be cut and removed in the office without analgesia. A Shirodkar cerclage often requires a return to the operating room for removal, either because the knot is buried under the vaginal epithelium or the Mersilene tape has been infiltrated by cervical granulation tissue. 

Complication

Membrane rupture

Intraamniotic infection

Suture migration

2. At 16 weeks of gestation, you can begins progesterone supplementation with either hydroxyprogesterone caproate weekly or vaginal progesterone daily and continues it until 36 weeks of gestation 

Mechanism of Action

Progesterone as a natural steroid hormone that induces secretory changes in the endometrium, promotes mammary gland development, relaxes uterine smooth muscle, blocks follicular maturation and ovulation, and maintains pregnancy. When used as part of an ART program in the luteal phase, progesterone supports embryo implantation.

REFERENCES

1. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No.142: Cerclage for the management of cervical insufficiency. Obstet Gynecol 2014; 123:372. Reaffirmed 2019.
2. Vyas NA, Vink JS, Ghidini A, et al. Risk factors for cervical insufficiency after term delivery. Am J Obstet Gynecol 2006; 195:787.