Should every unit have a 24-hour transvaginal ultrasound available?

The purpose of this debate is to argue the merits of whether the availability of 24-hour transvaginal ultrasound service in every unit will help predict and, subsequently, prevent preterm birth. Any new test introduced will need to fulfil certain criteria. It must be acceptable in terms of risk, cost and patient convenience. It must be an improvement over existing alternatives, and it must aid clinicians to improve care. While the 24-hour availability of transvaginal ultrasound to every maternity unit may be useful to research and teaching, there is, as yet, little evidence that a 24-hour transvaginal ultrasound service improves perinatal and maternal morbidity and mortality. Results from our own centre suggest that experienced clinicians can make an acceptable diagnosis of spontaneous preterm labour (PTL) using only history and digital examination. Based on these findings, the availability of 24-hour vaginal ultrasound in every unit cannot be justified for the diagnosis of spontaneous PTL.