The Primary Investigator for this study has departed this institution. Other investigators at this institution were not interested in proceeding with this study.

In this research study, the investigators want to learn more about the safety and effectiveness of a fetal surgery, known as fetoscopic laser photocoagulation (FLP), for the treatment of a pregnancy condition called vasa previa (VP). Vasa previa is a pregnancy complication that happens when blood vessels from the fetus grow over the entrance to the womb. In a VP pregnancy, natural vaginal birth is deadly for the baby in more than half of cases due to the bursting of VP vessels and severe blood loss. Currently, VP patients are recommended to be closely monitored and often hospitalized once they reach the third trimester of pregnancy. An early delivery by C-section would typically be performed in order to avoid breaking the exposed fetal vessels.

Fetoscopic laser photocoagulation is a minimally invasive surgery in the womb to remove or correct abnormal blood vessels and tissues. In the FLP procedure, the surgeon uses a fetoscope (a tiny telescope) and a laser device to seal off unprotected vessels. While this surgery has been used to treat other pregnancy conditions, it has not yet been proven to be safe and/or effective for the treatment of vasa previa. This treatment aims to eliminate the VP, and, if successful, may have the potential to minimize the risk of bleeding, thereby enabling patients to avoid long hospitalization before delivery. This procedure may enable VP patients to have a vaginal delivery instead of C-section.

Inclusion Criteria:

• Pregnant patient
• Singleton pregnancy
• Confirmed diagnosis of vasa previa, defined as unprotected fetal vessels running through the membranes at or within 5cm of the internal cervical os. Diagnosis must be confirmed after 26w0d, and before 32w5d
• Able to undergo intervention during 30w0d to 32w6d
• Type II vasa previa in which one placental lobe is considered to be accessory, defined as constituting less than 20% of the total placental mass seen on MRI and US imaging
• Type II vasa previa in which multiple bridging vessels connect the two placental lobes (≥4 vessels), and only 1-2 vessel(s) run through or within 5cm of the internal cervical os
• Patient is eligible to undergo anesthesia
• Patient and biological father of the fetus (if available) are able to provide signed informed consent

Exclusion Criteria:

• Gestational age at referral higher than 32w6d
• Multiple pregnancy
• Vasa previa types I and III
• Type II vasa previa in which the accessory lobe constitutes more than 20% of the total placental mass, as determined by the fetal surgeon during diagnostic fetoscopy
• Type II vasa previa in which all of the bridging vessels between placental lobes are running over the internal cervical os
• Fetal growth restriction, defined as estimated fetal weight or abdominal circumference less than the 10th percentile for gestational age
• Abnormal fetal brain MRI, including delayed maturation, hemorrhage, arterial ischemic injury, abnormal ventricular size, or any congenital anomalies
• Allergy or previous adverse reaction to ancillary medications with no available alternative
• Preterm contractions and PPROM before surgery
• Preeclampsia or uterine anomaly during the current pregnancy
• Placenta previa, low-lying placenta, placenta accreta spectrum disorder
• Suspicion of major recognized congenital syndrome on ultrasound or MRI that is not compatible with postnatal life
• Maternal pre-pregnancy BMI >40
• Active hepatitis B, hepatitis C, or HIV infection
• High risk for congenital fetal bleeding disorders
• Unreliable pregnancy dating due to an irregular menstrual cycle/uncertain last menstrual period with no confirmed dating from first trimester ultrasound
• The surgeon determines that the procedure is not feasible for any other reason after diagnostic fetoscopy