Panniculus Retractor Use for Visualization of Fetal Anatomy: A Randomized Controlled Trial.

Objective: To evaluate whether use of a panniculus retractor device for pregnant patients with body mass index (BMI) 40 or higher and a panniculus improves the completion rate of the fetal anatomic examination.

Methods: This was a randomized trial in which eligible patients with BMI 40 or higher and a panniculus were randomized to undergo their detailed fetal anatomic examination with a panniculus retractor device in place compared with usual care. The primary outcome was the completion rate of 16 prespecified views from the anatomic examination. Secondary outcomes included completion rate of all 64 views from our institution's detailed anatomic examination, duration of examination, major fetal anomaly detection rate, depth from the skin to amniotic cavity before and after retractor placement, patient and ultrasonographer satisfaction, and prespecified adverse events. We assumed a baseline completion rate of 23% for the primary outcome and targeted a twofold improvement with 80% power and two-sided α of 0.05, which resulted in a sample size of 132 participants. The goal enrollment was increased to 150 participants to account for potential dropout. Statistical tests included the Student's t test, χ 2 , and relative risks (RRs) as appropriate.

Results: From March to July of 2023, 150 participants completed the study: 74 in the retractor group and 76 in the usual care group. Baseline characteristics were similar between groups except for panniculus grade. The completion rate of 16 prespecified views was 25.7% (19/74) in the retractor group and 31.6% (24/76) in the control group (RR 0.81, 95% CI, 0.49-1.35). There were no significant differences between groups for any of the secondary outcomes. Patient satisfaction and ultrasonographer satisfaction were similar between groups.

Conclusion: Use of a panniculus retractor device during the fetal anatomic examination for patients with BMI 40 or higher and a panniculus was well tolerated by patients and ultrasonographers but did not improve the completion rate of 16 prespecified fetal anatomic views.

Clinical trial registration: ClinicalTrials.gov , NCT05764408.