Ultrasound-guided High-Intensity Focused Ultrasound to treat Twin-Twin Transfusion Syndrome (USgHIFU-TTTS study)
Twin-twin transfusion syndrome
Design: Phase 1a safety/efficacy (Bryant Day model). Recruitment: Potential participants will be identified from: 1. Women booked for obstetric care at Queen Charlotte's and Chelsea Hospital (QCCH), or referred to QCCH from other UK NHS maternity centres. These women will need to enroll in the Twin Placental Mapping study. 2. Women enrolled in the clinical research study "Investigating the feasibility of using Doppler ultrasound imaging to map placental vasculature and anastomoses in monochorionic diamniotic (MCDA) twin pregnancies, IRAS 242564" (the Twin Placental Mapping study) Study Design: To address the primary research objective the study is designed as a phase 1a safety/efficacy study using the Bryant and Day model. Bryant and Day's Two-Stage design will be used to incorporate a formal check of the number of positive responses as well as the number of patients experiencing significant iatrogenic harm in each successive participant before recruiting further patients into the study. The researchers will require five participants to be recruited into Stage 1, with 13 patients being the maximum number of patients to be accrued for the study in Stage 1 and Stage 2 combined. Study methodology: Prior to entry into the USgHIFU-TTTS study, the following procedures need to have been completed: 1. Twin Placental Mapping study (separate study) 2. Assessment of fetal wellbeing (staging of TTTS) 3. Assessment of maternal medical and obstetric history Time from Placental Mapping study to USgHIFU-TTTS study The window of opportunity for any type of treatment for TTTS can be very small. Potential participants will be allowed 24-72 hours to decide whether or not they want to take part in the study, unless there is an urgent clinical need to proceed, when 12-24 hours of consideration will be allowable if the woman feels this sufficient (i.e. same or next day enrolment). If the USgHIFU treatment is planned for the day following the pre-study procedures described above,
1. Able to understand patient information sheet (with appropriate support/interpretation if required) and give informed consent 2. Women currently pregnant with monochorionic diamniotic twin pregnancies 3. Gestational age between 12+0 and 17+6 weeks at time of USgHIFU treatment 4. Pregnancy diagnosed with TTTS Stage I-IV (Quintero staging) 5. Aged 18 years or more 6. Enrolled in the "Investigating the feasibility of using Doppler ultrasound imaging to map placental vasculature and anastomoses in monochorionic diamniotic (MCDA) twin pregnancies, IRAS 242564" (twin placental mapping) study
1. Maternal age 51 years or more (average age of menopause in the UK) 2. Pregnancy diagnosed with TTTS Stage V (one or both fetuses dead) 3. Chorionicity assigned at > 14+0 weeks 4. Higher-order pregnancy (even if containing MCDA pair) 5. BMI >35 6. Significant abdominal scarring, subject to medical assessment 7. Unable or unwilling to travel to London for treatment and follow-up 8. Placental anastomoses cannot be identified with ultrasound 9. USgHIFU treatment cannot be planned for technical reasons