Cervical Length Screening in Obstetrics

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Guideline for Cervical Length Screening for Prevention of Preterm Birth

Purpose: To establish guidelines for screening for cervical length (CL) to prevent preterm birth (PTB) in singleton gestations without PTB

Patient Eligibility for Screening

  • Singleton, viable pregnancy
  • Gestational age 18 0/7 – 23 6/7 weeks
  • Non-Eligible: multiple gestation, presence of cerclage in current pregnancy, prior PTB

Cervical length (CL) will be evaluated once in pregnancies meeting criteria above. The preferred screening method is transvaginal ultrasound (TVU) CL.

Technical Aspects of TVU Screening

  • Post-void transvaginal ultrasound to anterior fornix
  • Sagittal view of cervix with echogenic endocervix along length of canal
  • Withdraw probe until blurred, then reinsert making sure to avoid excessive pressure
  • Enlarge image to occupy 2/3 of screen
  • Obtain three measurements to use the best, shortest image
  • Measure from internal to external os along entire endocervical canal
  • Transfundal pressure for 15 seconds, then 3 more measurements
  • Report only shortest best CL

Definition of Short Cervix, and Treatment

  • Patients such as those above with CL ≤ 20mm are identified to have clinically significant cervical length shortening warranting consideration for available therapy.
  • Currently, vaginal progesterone daily is suggested for singleton gestations identified before 24weeks to have a short TVU CL ≤ 20mm
  • Patients with CL ≥ 25mm are identified to have a normal cervical length

1. Iams JD, Goldenberg RL, Meis PJ, Mercer BM, Moawad A, Das A, Thom E, McNellis D, Copper RL, Johnson F, Roberts JM. The length of the cervix and the risk of spontaneous premature delivery. NEJM 1996; 334: 567-72.

2. Hassan SS, Romero R, Berry S et al. Patients with ultrasonographic cervical length

3. Fonseca EB, Celik E, Parra M, Singh M, Nicolaides KH. Progesterone and the risk of preterm birth among women with a short cervix. NEJM 2007;357:462-9.

4. Hassan SS, Romero R, Vidyadhari D et al. Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double blind, placebo controlled trial. Ultras Obstet Gynecol, ePub ahead of print.

5. Owen J, Hankins G, Iams J, Berghella V, Sheffield JS, Perez-Delboy A, Egerman RS, Wing DA, Tomlinson M, Silver R, Ramin SM, Guzman ER, Gordon M, How HY, Knudtson EJ, Szychowski JM, Cliver S, Hauth JC. Multicenter randomized controlled trial of cerclage for preterm birth prevention in high-risk women with shortened midtrimester cervical length. AJOG 2009; 201: 375e.1-e.8.

6. Cahill AG, Odibo AO, Caughey AB, Stamilio DM, Hassan SH, Macones GA, Romero R. Universal cervical length screening and treatment with vaginal progesterone to prevent preterm birth: a decision and economic analysis. AJOG 2010;115:548e.1-8.

7. Berghella V. Novel developments on cervical length screening and progesterone for preventing preterm birth. BJOG 2009;116:182-7.

8. Progesterone and preterm birth prevention: translating clinical trials data into clinical practice. Society for Maternal-Fetal Medicine Publications Committee, with assistance of Vincenzo Berghella. Am J Obstet Gynecol. 2012 May;206(5):376-86

Cervical Length Screening Diagram 1

PTB, preterm birth; TVU, transvaginal ultrasound; CL, cervical length; ^250 mg IM every week from 16-20 weeks to 36 weeks; *e.g. daily 200 mg suppository or 90mg gel from time of diagnosis of short CL to 36 weeks


Cervical Length Screening Flow Diagram

 Cervical Length Screening Flow Diagram

One Response to “Cervical Length Screening in Obstetrics”

  1. I love the efforts you have put in this, thanks for all the great blog posts.