Endoscopic fetal surgery by excimer laser. An experimental study in premature lambs

Fetal malformations are detected early in pregnancy by means of ultrasound challenging fetal therapy. While open fetal surgery has been preformed during preliminary clinical trials we evaluated fetoscopic therapy avoiding laparotomy and uterotomy. We used a laser fibre (900 mu) which was introduced into the uterus by an endoscope. During animal experiments in five fetal lambs with a gestational age of 120-122 days we used an excimer laser (Technolas, x) with a wave-length of 308 nm. Laser incisions were compared with the conventional cutting technique using a scapel. During histological evaluation the tissue effect was morphometricly analysed. The zone of devitalisation was characterized by pycnosis of the nuclei and in a change of cytoplasma volume. The excimer laser incisions using a frequency of 40 HZ had a mean zone of devitalisation of 50.3 +/- 4.5 mu. Using the excimer laser with a frequency of 10 HZ we found a tissue alteration of only 11.2 +/- 3.4 mu. The incisions by scapel showed a extended traumatisation with a mean tissue effect of 153.2 +/- 16.3 mu. From these results we conclude, that endoscopic surgery may be come a usefull additional tool for fetal therapy.