Twin-to-Twin Transfusion Syndrome (TTTS)

What you're actually anesthetizing for - Fetoscopic laser photocoagulation of the placental anastomoses, typically performed between 15 and 26 weeks under ultrasound guidance. You have two patients and no direct benefit to the one you are anesthetizing.

Sedation plus local is the usual plan - Local anesthetic infiltration of the maternal abdominal wall with maternal sedation is the most common anesthetic for minimally invasive fetal surgery. Opioids, a low-dose propofol infusion, or a remifentanil infusion keep airway reflexes intact and keep her able to follow commands for position changes or to hold still when the surgeon asks.

When sedation won't work - The number and size of port sites, an anterior placenta requiring lateral decubitus positioning, surgeon preference, or high aspiration risk push you to neuraxial or general anesthesia. Volatile agents have the added benefit of titratable uterine relaxation.

Aspiration prophylaxis regardless of technique - She stays NPO and gets metoclopramide and sodium citrate whether the plan is sedation, neuraxial, or general.

Fetal analgesia versus fetal immobility - The cord and placenta are noninnervated, so laser on the anastomoses needs no fetal analgesia. Fetal immobility is still often requested — movement can dislodge the needle and damage the umbilical vein, and paralysis cuts fetal heart rate variation by about 80%.

Fetal paralysis dosing - Rocuronium 2-3 mg/kg IM or 1 mg/kg IV, drawn up sterilely by you and handed to the obstetrician for fetal IM or direct umbilical vein administration. Onset is 2-5 minutes and duration 2-3 hours. Adding atropine 10-20 mcg/kg with the relaxant reduces the risk of fetal bradycardia.

Left uterine displacement - 15-degree pelvic tilt with a wedge under the right hip. Aortocaval compression drops maternal pressure and cardiac output, which impairs uteroplacental flow and compromises both patients at once.

Be stingy with fluid - Maintain maternal pressure with ephedrine or phenylephrine rather than volume. Irrigation fluid absorbed from the surgical site and amnioinfusion both add up, and pulmonary edema is a real risk.

Postoperative tocolysis - Preterm premature rupture of membranes remains the main complication. Indomethacin tocolysis is continued in the immediate postoperative period.

Postoperative monitoring - The obstetric team follows the fetus by ultrasound until it regains regular movement. She may stay overnight for uterine activity and fetal heart rate monitoring; if stable, she goes home to continue the pregnancy. Unlike open fetal surgery and EXIT, a later vaginal delivery is not contraindicated.

Twin-to-twin transfusion syndrome (TTTS) complicates monochorionic twin gestations, where both fetuses share one placenta. Unbalanced arteriovenous anastomoses deep in the placenta shunt blood one direction, making one twin the donor and the other the recipient. The donor becomes hypovolemic, renal perfusion drops, the renin-angiotensin-aldosterone system fires, and it develops oliguria and oligohydramnios plus anemia. The recipient becomes hypervolemic, cardiac stretch releases ANP and BNP, and it develops polyuria, polyhydramnios, polycythemia, and — in severe disease — AV valve insufficiency, diastolic dysfunction, pulmonary stenosis or atresia, and hydrops.

Diagnosis is sonographic: one placenta, maximum vertical pocket under 2 cm in one sac and over 8 cm in the other. It affects roughly 8-10% of monochorionic diamniotic twins, usually appearing between 16 and 26 weeks. Untreated before 26 weeks, fetal mortality runs 60-80%.