Why This Procedure Exists
Congenital diaphragmatic hernia allows abdominal contents to herniate into the chest during fetal development, compressing the lungs and preventing normal growth. The resulting pulmonary hypoplasia — not the hernia itself — drives mortality in severe cases 0:53. Fetoscopic endoluminal tracheal occlusion (FETO) addresses this by temporarily trapping lung fluid in utero, using hydrostatic pressure to expand the compressed lung and stimulate growth before birth 0:47.
The Core Problem
The fetal lung secretes fluid continuously. In normal development, this fluid drains through the trachea and is swallowed. In CDH, the herniated viscera occupy thoracic space that the lung needs to expand into. FETO reverses the usual physiology: by occluding the trachea with a balloon, the procedure converts the lung's own secretions into an expansion force 0:47 0:53.
How the Approach Works
FETO is a single-trocar percutaneous procedure performed on the mother 0:33. A trocar is placed through the maternal abdominal wall into the uterus, and a standard fetoscope — equipped with a side channel for instrument passage — is advanced through it 0:42. The entire procedure hinges on navigating fetal anatomy at a scale where a few millimeters of misalignment matters.
Anatomical Navigation
The fetoscope enters through the fetal mouth. The tongue serves as the first reliable landmark — its bumpy surface is unmistakable on the scope 1:21. Intermittent fluid flow through the scope pushes tissue away and clears the visual field 1:29. If the fetal head is not aligned with the scope axis, the operator must twist and turn the instrument to advance 1:38.
The critical distinction is between trachea and esophagus. The epiglottis, once identified, guides the scope toward the airway 1:58. Even experienced operators occasionally enter the esophagus first; the maneuver is to back out and reorient [q2]. The scope is then advanced through the vocal cords.
Once past the cords, the operator always advances to the carina — the bifurcation of the mainstem bronchi 2:36. Visualizing the carina serves two purposes: it confirms tracheal (not esophageal) position, and it establishes where in the trachea the scope sits [q4]. This is not optional; it is the only way to be certain of location.
Scope Manipulation Constraints
The fetoscope traverses the maternal abdominal wall, the uterine wall, and the amniotic space before entering the fetus. Excessive torque on the scope can damage the membranes 2:23. "You also don't want to be torquing the membranes too much, right? Because remember this is going through the abdominal wall through the uterine wall, and we don't want it to cause any membrane damage from excessive turning of the scope" [q3]. The operator must balance the need for precise positioning against the mechanical limits of the access route.
Balloon Positioning and Deployment
After confirming position at the carina, the scope is withdrawn slightly. The balloon must sit in the main trachea, not be driven into one mainstem bronchus 2:56. As the balloon is inflated, the scope is backed up further to allow visualization of the deployment 3:03. The balloon is filled with water — typically 0.65 to 0.8 mL, adjusted for tracheal diameter 3:08. It contains a small metal ball, visible both endoscopically and on subsequent imaging 3:29.
Final confirmation requires seeing the balloon below the vocal cords and positioned in the main trachea 3:48. The scope is then withdrawn. The balloon remains in place, occluding the trachea and allowing lung fluid to accumulate.
What Remains Uncertain
This discussion focused on procedural technique rather than patient selection or outcomes. The episode did not address which CDH cases benefit most from FETO, at what gestational age the procedure is performed, when the balloon is removed, or how lung growth is monitored after placement. These are separate clinical questions.
When to Involve This Team
FETO is performed by specialized fetal surgery centers. The discussion did not specify referral criteria, but the procedure targets severe CDH cases where pulmonary hypoplasia is the limiting factor 0:53. Referral would occur prenatally, after CDH is diagnosed on fetal imaging and severity is assessed. The window for intervention is narrow — the balloon must be placed early enough to allow lung growth but late enough that the fetus can tolerate the procedure, and it must be removed before delivery to allow the infant to breathe.
For obstetricians managing a fetus with CDH, the relevant question is whether the predicted lung volume and liver position suggest severe hypoplasia. If so, contact with a fetal surgery center should occur as soon as the diagnosis is made, not after waiting to see if the lung grows on its own.
Takeaways from this story
- FETO uses trapped lung fluid as an expansion force to counter pulmonary hypoplasia in severe CDH.
- Visualizing the carina is mandatory—it confirms tracheal position and prevents esophageal misplacement.
- Scope torque must be minimized because the instrument traverses maternal abdominal and uterine walls.
- Balloon volume (0.65-0.8 mL) is adjusted to tracheal size and must sit in the main trachea, not a bronchus.