1. Perinatal Quality Foundation (www.perinatalquality.org)
Why Measure Cervical Length
Lecture 1
Perinatal Quality Foundation (

2. Lecture 1
Spontaneous Pre-term Birth (sPTB) Preventing sPTBS Screening test requirements Cervical Length Screening for sPTB Interventions for Short Cervix Society Statements

3. Little Babies Create Big Problems
Preterm birth
1400 premature babies born daily in US
1 of 8 births
Costs exceed $26 billion annually in US
Even higher rates worldwide
Complications
Neonatal: respiratory morbidity, necrotizing entercolitis, intraventricular hemorrhage
Childhood: 20% of mental retardation, 30% of vision impairment, and 50% of cerebral palsy is due to PTB
Lifelong: risks increased for heart disease, diabetes, cancer, etc.

4. How do we Prevent Disease?
Primary
Protect healthy people from developing the disease
Education, lifestyle changes, nutrition, etc
Secondary
Early detection to slow or halt disease
Screening useful only if specific requirements met
Tertiary
Manage when disease occurs
Typical allopathic medicine approach, but often too late

5. Preventing spontaneous PTB
Primary Nutritional supplements Dental care Secondary Selection of high risk patients for treatment Cervical length screening Tertiary Tocolytics (drugs to suppress contractions) Antibiotics Anti-inflammatory agents

6. No Primary or Tertiary approaches have been proven effective
Preventing sPTB
No Primary or Tertiary approaches have been proven effective

7. Preventing sPTB
Some secondary strategies are effective Selection of high-risk patients (intramuscular progesterone for patients with a history of sPTB) Cervical length screening

8. What Defines a Good Screening Test?
Disease
Clinically important, clearly defined, with a well known prevalence and recognizable early asymptomatic phase
Technique
Well described, safe and acceptable, has a reasonable cutoff identified, reproducible results (reliable), and accurate results (valid)
Intervention, cost-effectiveness and feasibility
Early intervention is effective, screening and treating abnormals is cost-effective, facilities for screening and treatment are readily available

9. Cervical Length is a Good Screening Test
Criterion: Disease
Comments
Disease is clinically important
PTB is leading cause of perinatal morbidity/mortality, with more than 1 million deaths annually worldwide
Disease is clearly defined
Birth <37weeks
Disease prevalence is well known
12% in US, about 10% worldwide
Disease natural history is known / Recognizable early asymptomatic phase
Cervical length inversely related to sPTB risk, and early cervical changes occur at the internal os
TVU of the cervix is a screening test, NOT a DIAGNOSTIC test (I totally disagree with TVU being a diagnostic test: just because a cervix is short, it’s not insufficient/incompetent – many other reasons, as will see later). CI cannot be diagnosed with this test alone.

10. Cervical Length is a Good Screening Test
Criterion: Technique
Comments
Screening technique well described
Several articles document technique
Screening is safe and acceptable
RCT on PPROM showing safety*
99% would have it again; <2% have severe pain
Screening has a reasonable cutoff identified
20mm is the 5th percentile, 25mm is the 10% percentile in the general US population**
Results are reliable (reproducible)
<10% intra- and inter-observer variability
Results are accurate (valid)
Better than manual exam; predictive in all populations studied (hundreds of studies)
*Carlan, Obstet Gynecol 1993; 81: **Iams, N Engl J Med 1996; 334:567

11. Cervical Length is a Good Screening Test
Criteria: Intervention, cost-effectiveness, feasibility
Comments
‘Early’ intervention is effective
2 RCTs showed benefit of vaginal progesterone
Screening and treating abnormals is cost-effective
2 manuscripts support cost-effectiveness
Facilities for screening are readily available
All pregnancies offered USN for fetal anatomy screening at weeks
Facilities for treatment are readily available
Vaginal progesterone is easy to obtain and administer as outpatient

12. Intervention for Short Cervix is Effective
Vaginal progesterone (90mg gel) reduces risk by 45% in high and low risk women with CL mm
RCT, n=32,091 screened and n=458 randomized
Hassan, Ultrasound Obstet Gynecol 2011;38:18

13. Intervention for Short Cervix is Effective
Vaginal progesterone (200mg suppository) reduces risk by 44% in high and low risk women with CL <15mm
RCT (n=24,620 screened, n=250 randomized)
Fonseca, N Engl J Med 2007;357:462

14. Intervention for Short Cervix is Effective
Cerclage reduces sPTB by 30% in women with a history of sPTB and a cervix <25mm before 24 weeks gestation
Berghella, Obstet Gynecol 2011;117:663
Owen, Am J Obstet Gynecol 2009; 201:375

15. Intervention for Short Cervix is Effective
Cerclage in women using 17OHPC who develop a short cervix <25mm shows a trend toward benefit (study not powered for this result)
PTB <28w (%)
Similarly, women with a prior PTB and a short CL<25mm had a 34% risk of PTB<32w if they received neither 17P or cerclage, 25% if they received cerclage, 21% if they received 17P, and 17% if they received both.
Berghella, Am J Obstet Gynecol 2010;202:351

16. ACOG on CL screening
Cervical length measured by transvaginal ultrasound examination is a useful screening test for predicting spontaneous preterm birth. Cervical length screening by transvaginal ultrasound examination is safe, highly reproducible, and more useful in predicting preterm birth than transabdominal ultrasound examination. Cervical length screening is most useful for predicting preterm birth in women who have had a prior preterm birth and have a singleton gestation.
ACOG Committee Opinion 522, Obstet Gynecol 2012:119:879

17. SMFM on CL screening
There is level I evidence of prevention of PTB and neonatal benefits based on treating with vaginal progesterone low-risk singleton gestations identified with TVU screening to have a short CL. This strategy is not only beneficial in terms of improvement in health in a condition (PTB) of utmost importance to society, but also cost-effective, and in fact cost-saving. TVU CL is a safe, acceptable, reproducible and accurate screening test, with potentially widespread availability.
Berghella, SMFM Publication Committee, Am J Obstet Gynecol 2012:10:1016

18. Summary
ACOG: The utility of universal cervical length screening for the prevention of preterm birth is controversial and being debated. SMFM: Cervical length screening in singleton gestations without prior preterm birth cannot yet be mandated universally. Nonetheless, implementation of such a screening strategy should be viewed as reasonable, and can be considered by individual practitioners
ACOG Committee Opinion 522, Obstet Gynecol 2012:119:879
Berghella, SMFM Publication Committee, Am J Obstet Gynecol 2012:10:1016

19. Summary: Twins
ACOG: There are insufficient data on the efficacy of interventions for the prevention of preterm birth in women with multiple gestations with both a prior preterm birth and a short cervical length. Cerclage may increase preterm birth in women with a twin pregnancy and a cervical length of less than 25mm is not recommended at this time. SMFM: The evidence does not support the use of any type of progestogen for prevention of PTB in multiple gestations with unknown CL. There is insufficient evidence to assess the effect of progestogens in women with both multiple gestation and short CL.
ACOG Committee Opinion 522, Obstet Gynecol 2012:119:879
Berghella, SMFM Publication Committee, Am J Obstet Gynecol 2012:10:1016

20. Training/Quality Control
Regardless of whether practitioners choose to screen universally or selectively, correct technique is critical to avoiding incorrect diagnosis and treatment. SMFM: TVU CL needs to be performed with proper technique in order to yield accurate results, with quality control and monitoring
Berghella, SMFM Publication Committee, Am J Obstet Gynecol 2012:10:1016

21. Training/Quality Control
Elements of effective training: Didactic education Image review with standardized criteria