Measurement of cervical length with vaginal ultrasound in midgestation in asymptomatic women with a singleton pregnancy to predict preterm delivery

• Register: ISRCTN
• Last refreshed on: 23 October 2023
• Main ID: ISRCTN18093885
• Date of registration: 28/09/2016
• Prospective Registration: No
• Primary sponsor: Region Västra Götaland
• Public title: Measurement of cervical length with vaginal ultrasound in midgestation in asymptomatic women with a singleton pregnancy to predict preterm delivery
• Scientific title: Measurement of cervical length with vaginal ultrasound in the second trimester in asymptomatic women with a singleton pregnancy to predict preterm delivery: a Swedish multi-center observational study
• Date of first enrolment: 01/05/2014
• Target sample size: 11000
• Recruitment status: Completed
• URL: https://www.isrctn.com/ISRCTN18093885
• Study type: Observational
• Study design: Multicentre prospective observational study (Screening)
• Phase: Not Applicable

Countries of recruitment

Sweden

Contacts

• Name: Ulla-Britt Wennerholm

Key inclusion & exclusion criteria

Inclusion criteria:
1. Asymptomatic women > 18 years old
2. With a live healthy singleton pregnancy in gestational week 18+0-20+6
3. Able to understand oral and written information

Exclusion criteria:
1. Fetal malformation
2. Rupture of membranes
3. Current vaginal bleeding
4. Ongoing miscarriage
5. Cerclage in situ
6. Current progesterone treatment at the time of recruitment


Age minimum:
Age maximum:
Gender: Female

Health Condition(s) or Problem(s) studied

Pregnancy
Pregnancy and Childbirth

Intervention(s)

This is a Swedish multicentre prospective observational study. where healthy asymptomatic women with a singleton pregnancy will be examined with transvaginal ultrasound and measurement of cervical length during midtgestation.

Ultrasound examinations of the cervix are carried out by specially trained midwives, who have undergone standardized theoretical education and practical training. A certification system specially designed for this project is in place. The ultrasound examinations are performed vaginally with the woman in the lithotomy position with an empty urinary bladder. The vaginal ultrasound probe is slowly introduced into the vagina until the cervix becomes visible. Care is taken not to exert undue pressure on the cervix: the anterior and posterior lips of the cervix should appear equally thick. Ideally, the cervical canal should be horizontal in the image. The length of the closed cervical canal ( the line made by the interface of the mucosal surfaces) is measured as a straight line between the internal and external cervical os. If the isthmus is present its length is measured separately. Each measurement is taken three times, and all three are recorded. Images are stored for quality assessment.
These measurements are taken at 18+0-20+6 gestational weeks and 21+0-23+6 gestational weeks.

The women themselves and all medical staff are blinded to the results of the cervical length measurements. However, an ultrasound finding of bulging amniotic membranes is disclosed.

Primary Outcome(s)

Ability of sonographic cervical length to predict preterm birth < 33 weeks, expressed as the area under the receiver operating characteristic curve (ROC) sensitivity, specificity, positive and negative likelhood ratio.

Secondary Outcome(s)

Ability of sonographic cervical length to predict spontaneous PTB <33 + 0 gestational weeks and for total and spontaneous PTB <28 + 0, <29 + 0, <30 + 0, <31 + 0, <32 + 0, <34 + 0 and< 35 + 0 gestational weeks.

All calculations will be made for:
1. the length of the closed cervical canal
2. if the isthmus is present its length is measured separately
3. from the external cervical os to the apparent (virtual) inner cervical os (if isthmus is present)
4. the length of the closed cervical canal + the isthmus.

Each measurement is taken three times and all three are recorded. Calculations will be made for the minimum, maximum and mean value and separately for measurements taken at 18 + 0 - 20 + 6 gestational weeks and 21+ 0 - 23 + 6 gestational weeks. using the ROC curves, the optimal method for measuring cervical length (which week, which measurement) and the optimal cervical length cutoff of the optimal method to predict PTB will be identified. The ability of a change in cervical length between the first (at 18 + 0 - 20 + 6) and the second (at 21 + 0 - 23 + 6) cervical length measurement to predict PTB. The prevalence of "short cervix" (using different definitions) will be calculated.

Secondary ID(s)

2014-10104-117089-114 The Swedish Research Council

Source(s) of Monetary Support

Swedish Research Council, Vetenskapsrådet, Regional R & D Council, Uppsala / Örebro (Regionala FOU rådet Uppsala/Örebro), Centrum fÖr Klinisk Forskning Dalarna, Southern Älvsborg Hospital (SÄS, Forskningsenhet), Regional R & D funds Västra Götaland (VGR Regionala FOU medel), Hjalmar Svensson Research Fund (Handlanden Hjalmar Svensson, Göteborg), Löf (County Councils' Mutual Insurance)

Ethics review

Status:
Approval date:
Contact:

Old ethics approval format; Ethical committee at University of Gothenburg, Sweden, 13/11/2013 (ref: 825-13), 17/01/2014 (ref: T053-14), 08/12/2015 (ref: T972-15) and 25/02/2016 (ref: T122-16)

Results

• Results available: Yes
• Date Completed: 01/11/2017