The transvaginal ultrasound examination for the measurement of the cervix (the neck of the womb) is gradually becoming part of the detailed second trimester anomaly scan. The cervical measurement enables the identification of the small group of women at high risk for preterm delivery.
Large randomized trials have shown that pregnant women with short cervix (usually cervical length less than 20-25mm) benefit from the treatment with vaginal progesterone. The advantage of the progesterone therapy is clear in women with moderate shortening but there is some doubt whether in cases of extreme shortening cervical cerclage might be a better option.
In our study published recently we examined the outcome of 233 singleton low risk pregnancies with very short cervix (equal/less than 15mm) discovered at 20-24 weeks. The analysis showed that in cases with cervical length between 9 and 15mm both therapies (vaginal progesterone and cervical cerclage) perform equally well, whereas in women with extremely short cervix (8mm or less) cervical cerclage is more efficient.
This information helps the clinician customize the treatment according to the individual circumstances.
Souka AP, Papamihail M, Pilalis A. Very short cervix in low-risk asymptomatic singleton pregnancies: Outcome according to treatment and cervical length at diagnosis. Acta Obstet Gynecol Scand. 2020 Apr 25. doi: 10.1111/aogs.13881. Epub ahead of print. PMID: 32333390.