333 Prediction of preterm birth by transvaginal-ultrasound and MRI cervical length measurement in pregnancies treated SFLP

Abstract

Transvaginal ultrasound measurement (TVUS) of cervical length (CL) is one of the most powerful predictors of preterm birth (PTB). Cervical length may also be measured by MRI, but its predictive accuracy for PTB has not been well established. We sought to quantify the predictive accuracy of pre-op TVUS CL and MRI CL as well as post-up TVUS CL measurements for preterm birth outcomes among pregnancies complicated by TTTS that underwent laser surgery Retrospective cohort study to quantify the rate, risk and predictive accuracy of TVUS and MRI for preterm birth <28 and <32 weeks in 626 pregnancies with TTTS that had laser therapy at a single center (2010-2019). Data on pre-operative TVUS (n=579), MRI (n=424), and post-op TVUS (n=596) CL measures were available for analysis. Generalized linear models estimated relative risk and receiver operator characteristic curves generated area under the curve (AUC) to estimate predictive accuracy of CL for PTB outcomes The highest rate and risk of PTB were associated with the shortest CLs measured post-operatively from SFLP in TTTS patients. Over half of pregnancies with perioperative CL ≤2.5cm delivered by 28 weeks of gestation age, regardless of imaging modality. However, TVUS was superior to MRI CL measurement to predict PTB. Pre-op TVUS CL <2.0 cm was the best predictor of PTB <32 wks (AUC 0.8194), and the best predictor of PTB <28 wks was post-op CL <1.5 cm (AUC 0.8148), see Figure. MRI was a poor predictor of PTB at all CL cut-offs Both pre-op and post-op SFLP TVUS measures of CL are good predictors of preterm birth in pregnancies complicated by TTTS, but MRI CL is not. Pre-operative TVUS CL <2cm and post-operative CL <1.5 were the best predictors of PTB <32wks and PTB <28wks, respectively. These data demonstrate that TVUS is the optimal screening modality for cervical length in pregnancies with TTTS undergoing SFLP. This information may assist to counsel patients perioperatively on PTB risk.View Large Image Figure ViewerDownload Hi-res image Download (PPT)