Objectives
To determine the relationship between intra‐amniotic pressure and cervical length (CL) in patients with twin–twin transfusion syndrome (TTTS) undergoing fetoscopic laser photocoagulation (FLP), and to identify pre‐ or intraoperative factors associated with increased intra‐amniotic pressure in this population.
Methods
This was a prospective cohort study of patients undergoing FLP for TTTS. Exclusion criteria were triplet or higher‐order gestation and prior cervical cerclage, amnioreduction or FLP procedure. CL was assessed using preprocedure transvaginal ultrasound. Intra‐amniotic pressure measurements were obtained on initial placement of the trocar into the amniotic cavity, using a direct hydrostatic pressure gauge. The relationship between intra‐amniotic pressure and CL was assessed using multivariate linear regression analysis, including relevant preoperative and intraoperative variables.
Results
In total, 283 pregnancies met the inclusion criteria. Quintero stage of TTTS was I in 33 pregnancies, II in 88, III in 150 and IV in 12. Mean gestational age (GA) at FLP was 20.7 ± 3 weeks. Mean intra‐amniotic pressure was 23.1 ± 9 mmHg. On unadjusted linear regression analysis, there was no significant association between intra‐amniotic pressure and preoperative CL (P = 0.24) or GA at delivery (P = 0.22). On multivariate analysis, the factors associated significantly with intra‐amniotic pressure were: number of prior term deliveries (P = 0.03), recipient maximum vertical pocket (P < 0.0001), Quintero stage IV (P = 0.01) and type of anesthesia (sedation vs general anesthesia; P = 0.01).
Conclusion
In pregnancies with TTTS, intra‐amniotic pressure is not associated with CL or GA at delivery. This novel finding suggests that cervical shortening in this population is not mechanically driven. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.