Routine Transvaginal Ultrasound at the Time of the Anatomy Scan: To Do or Not To Do?

Objective:  There are no universal guidelines for transvaginal ultrasound (TVUS) at the time of the anatomy scan. TVUS can provide information on placental location and cervical length (CL) but may lead to more interventions. As a quality assurance initiative, a universal TVUS (UTVUS) protocol at the time of the anatomy scan was started at our institution. This study was conducted to assess whether there was a decrease in preterm birth (PTB), postpartum hemorrhage (PPH), and neonatal intensive care unit (NICU) admission once UTVUS was implemented.

Study design:  This was a retrospective cohort study performed on singleton gestations from February 2021 to January 2022. In the first 6 months of the study period, patients only had TVUS based on risk factors (pre group). In the second half of the study period, UTVUS was implemented at the time of the anatomy scan (post group).

Results:  A total of 2,118 patients were included in the study. There were 1,037 patients in the pre group, of which 161 underwent TVUS based on high-risk factors (history of the cervical procedure, history of prior PTB, and placenta appearing low lying or cervix appearing short on abdominal ultrasound). The post group/UTVUS included 1,081 patients. Patients in the pre group had statistically significantly earlier gestational age at first TVUS (p < 0.0001), were less likely to have had a prior PTB <36 weeks (p = 0.03), and were more likely to have a history of cervical procedure (p = 0.0006) than patients in the post group. There was an increased use of vaginal progesterone in the UTVUS with 33 patients (as opposed to 10 patients in the pre group; p = 0.0007). The proportion of patients with PTB, PPH, or NICU admission did not significantly differ between the two groups even after adjusting for cofounders (p > 0.05).

Conclusion:  Our data show that UTVUS did not decrease the adverse pregnancy outcomes. In addition, the implementation of UTVUS adds more discomfort for a patient, more time to the patient's scan, and is an additional cost. Therefore, surveillance by abdominal ultrasound and adding TVUS based on risk factors may be a reasonable alternative.

Key points: · UTVUS showed no difference between CLs.. · There is not sufficient evidence to conclude a difference between PTB or PPH in the two groups.. · There was significantly more placenta previa diagnosed in the post group, yet most resolved..