BACKGROUND AND PURPOSE:

• Currently, there are 3 methods to assess cervical length
  • Transvaginal (TVU)
  • Transabdominal (TAU)
  • Transperineal (TPU, also called translabial)
• Berghella and Saccone (Cochrane Reviews, 2019) follow up on previous review (2013) to analyze the effectiveness of cervical length measurement to prevent preterm birth (PTB)

METHODS:

• Systematic review and meta-analysis
• Sources
  • Cochrane Pregnancy and Childbirth’s Trials Register | ClinicalTrials.gov | WHO International Clinical Trials Registry Platform (ICTRP)
  • Contacted experts in the field for additional and ongoing trials
  • 2 new studies included since previous review
• Inclusion criteria
  • Published and unpublished RCTs
  • Studies that screened women for risk of PTB by cervical length with TVU, TAU, or TPU
    • Knowledge vs no knowledge of cervical length results
    • Ultrasound vs no ultrasound for cervical length
  • Exclusion: Studies focused on effectiveness of interventions based on short cervical length (e.g., progesterone, cerclage or pessary)
• Participants
  • All pregnant women, between 14 to 32 weeks gestational age
• Study design
  • Standard Cochrane methodology

RESULTS:

• 7 RCTs (N = 923) were included, all using TVU
• Quality of evidence for primary outcome
  • Very low for all population due to limitations in study design, inconsistency between the trials, and imprecision, due to small sample size

Asymptomatic Women with Twin Pregnancies

• Uncertain whether knowledge of TVU-measured cervical length vs no knowledge reduces PTB <34 weeks (very low quality evidence)
  • Risk ratio (RR) 0.62 (95% CI, 0.30 to 1.25; 1 study, 125 participants)
  • Also inconclusive for PTB <36, <32, or <30 weeks as well as other maternal and perinatal outcomes

Singletons with Symptoms Of PTL

• Uncertain whether knowledge of TVU-measured cervical length vs no knowledge reduces PTB <37 weeks’ (very low quality evidence)
  • RR 0.59 (95% CI 0.26 to 1.32; 2 studies, 242 participants)
• Birth occurred approximately four days later in the knowledge groups
  • Mean difference (MD) 0.64 weeks (95% CI, 0.03 to 1.25; 3 trials, 290 women)
• Also inconclusive for PTB <34 or <28 weeks | Birthweight <2500 g | Perinatal death | Maternal hospitalization | Tocolysis | Steroids for fetal lung maturity

For Singletons with Symptoms Of PPROM

• Inconclusive for incidence of maternal and neonatal infections between the TVU and no ultrasound groups

For Asymptomatic Singletons

• Inconclusive for PTB <37 weeks
  • RR 1.27 (95% CI, 0.61 to 2.61; 296 participants)
• Also inconclusive for gestational age at birth, and other perinatal and maternal outcomes

CONCLUSION:

• Due to limited data, the authors conclude that that cannot derive

…any conclusions for women with asymptomatic twin or singleton pregnancies, singleton pregnancies with PPROM, or other populations and clinical scenarios

• Authors propose that future studies should include clear protocols for managing pregnancies based on TVU-measured CLs

Learn More – Primary Sources:

Cervical assessment by ultrasound for preventing preterm delivery

Related ObG Topics:

Cervical Cerclage – Professional Recommendations

The Role of Routine Cervical Length Screening For Preterm Birth Prevention

Does Shortened Midtrimester Cervical Length Predict Preterm Birth?

Does Cervical Pessary Benefit Women at risk for Preterm Birth due to Short Cervix?