Management of Cervical Insufficiency

Normal Cervix Anatomical Components: -histologically contains Fibrocollagenousstromal tissue -Endocervix -Ectocervix- portion projecting into the vagina. On average, its 3 cm long and 2.5 cm wide, has a convex, elliptical surface and is divided into anterior and posterior lips. -Internal os -External os – its size and shape varies widely with age, hormonal state, and whether the woman has had a vaginal birth. In nonparous women it appears as a small, circular opening. Versus being fish mouthed--meaning wider, more slit-like and gaping in parous women. In pregnancy the normal cervical length measured from internal to external os is 4 +/- 1cm.

Definition of cervical insufficiency (aka cervical incompetence) A condition in pregnancy where the cervix begins to dilate (and not by initiation of contractions but) due to structural weakness in the cervix itself there is an inability to hold the weight of the pregnancy -- resulting in bulging of the amniotic membranes into the vaginal canalrupturepreterm labor/fetal loss. (Usually occuring in the 2nd trimester)

Risk Factors-causes of cervical incomptence 1--Recurrent 2nd trimester losses 2--History of incompetent cervix with a previous pregnancy 3-Cervical injury -multiple D&C -Repeated surgical trauma - repeated pregnancy termination, -cone biopsy - cervical cautery (to remove growths or stop bleeding) 4-Anatomic abnormalities of the cervix -congenital cervical hypoplasia or aplasia 5-DES (diethylstilbestrol) exposure 6-Connective tissue disorders (Ehlers-Danlos syndrome)

Incidence -Cervical incompetence affects 1 % of the obstetric population. -15-20 percent of miscarriages that occur between 16 and 24 weeks of pregnancy are believed to stem from this etiology

Diagnosis based on an obstetric history of recurrent second- or early third-trimester fetal loss with the above criteria mentioned (painless cervical dilation). However in the absence of recurrence the term cervical insufficiency is used as a working diagnosis based on a single event with the same clinical history, after exclusion of other causes of preterm delivery. Without a prior history of fetal loss, using this term in connection with a short or traumatized cervix alone is not sufficient. Digital exam is very subjective. And diagnosis by transvaginal ultrasonography is more of a repoducible method of measuring the cervix.

Transvaginal ultrasound -Clinically useful to identify signs of effacement (funnelling) and cervical length. -Assessment of the cervix can be done at rest and with application of transfundal/abdominal pressure. TFP is more effective than standing in eliciting cervical changes.

-Funnelling specifically refers to the separation of the internal os from the two sidewalls of the upper end of the cervical canal. - A normal sagittal view of the cervix shows a “T” shaped endocervical canal vs. deviations such as Y, V, U. Y= initial effacement and subsequent V, U visualized on progressive endocervial change and cervical shortening.

Sonographic findings -funneling (mneumonic: Trust Your Vaginal Ultrasound ) -cervical length <25mm -protrusion of membranes -presence of fetal parts in cervix or vagina

Symptoms -If a patient presents with significant cervical dilation (2 cm or more) she may have minimal symptoms. (ie. Pelvic pressure, minimal contractions) -When the cervix reaches 4 cm or more, active uterine contractions or rupture of membranes may occur

Management

Management -Serial TVS assessments in low-risk women to screen for CI are of low yield and should not be done routinely. Management should be determined by prior history. -Serial ultrasound exams every 2 weeks should be considered in a patient with historical risk factors and should be initiated between 16 and 20 weeks of gestation or later. If initiated earlier and the patient appears to have a short cervix then the exam needs to be repeated because usually the upper portion of the cervix is not easily distinquished from the lower uterine segment. -An elective cerclage can be considered in a patient with a history of 3 or more unexplained midtrimester pregnancy losses or preterm deliveries. -Women exposed to diethylstilbestrol (DES) in utero may be evaluated for cervical insufficiency using the same clinical criteria as nonexposed individuals

-The evaluation of a patient with cervical shortening or funneling should include a comprehensive ultrasonographic assessment of the fetus to rule out anomalies, tocometry and lab assessments to rule out labor and chorioamnionitis. –short cervix considered <25mm ( <10th percentile). So if labortocolytics, steroids for fetal lung maturity infection delivery, abx or conservative management limit activity, expectant management -Given the advances in neonatal care and the potential maternal and fetal morbidity associated with cerclage, surgical correction of cervical insufficiency should be limited to pregnancies before fetal viability has been achieved.

Treatments -Bed rest and reduced physical activity--common practice but not medically proven to be effective -Pelvic rest -limit sexual intercourse -cerclage-surgical purse string type suture used to reinforce cervix.

Cerclage Indications for elective cerclage: 1-congenital or acquired visible defects in the ectocervix 2-classic features of cervical incompetencehistory of 2 or more 2nd trimester losses (excluding those resulting from preterm labor or abruption) 3- history of losing each pregnancy at an earlier gestational age 4- history of painless cervical dilation of up to 4 to 6 cm 5-history of cervical trauma caused by cone biopsy, intrapartum cervical lacerations 6-excessive, forced cervical dilation during pregnancy termination.

Cerclage -indicated for placement at 13-16 weeks GA after fetal viability established on ultrasound -urgent/therapeutic cerclage indicated for patients that have serial ultrasound changes consistent with short cervix or funneling. Management of this group remains speculative because of the limited number of well-designed randomized trials. The decision to proceed with cerclage should be made with caution.

Macdonald cerclage procedure (1963) -Running suture placed in the body of the cervix near the internal os to encircle the cervix . Its tightened to reduce the cervical canal to 5-10mm

Modified Shirodkar procedure (1955) -More complicated and involving an anterior incision, placement and tying of special Mersiline tape with suturing of the cervical mucosa back in place. -reserved for patients that have had failure with the Macdonald procedure .

Contraindications/complications/when to remove Contraindications: bleeding, ruptured membranes, uterine contractions Complications: Suture disruption, rupture of membranes, and chorioamnionitis are the most common association with cerclage placement. The correct time for removal is unclear , but removal should be an appropriate time before labor. at 37 weeks.