Access techniques in endoscopic fetal surgery

Endoscopic surgery may in the future become an attractive alternative to open fetal surgery. Herein, we present our evolving experience with minimal access techniques in sheep and nonhuman primate models. Fifty-two pregnant sheep (term = 145 d) were used. All underwent laparotomy. Cannulas were 5 mm diameter with balloon fixation device. In group I (95-105 d, n = 22, and 70-74 d, n = 19), a total of 119 cannulas were placed by open hysterotomy and pursestring suture through myometrium and membranes. In group II (n = 11), access was obtained by Seldinger guidewire technique. Eight cannulas were introduced over a dilator and 7 were radially expanding endoscopic cannulas. Fifteen cannulas were also placed in 5 pregnant Rhesus monkeys using Seldinger and radially expanding techniques. Cannula removal was followed by insertion of a collagen sponge plug and oversewing of the myometrium. Mini-hysterotomies with purse-stringing provided excellent access to the amniotic cavity, without dissection of the membranes. Classic Seldinger technique with forward dilatation was equally effective, but caused stretching of membranes. In sheep and in primates, Seldinger technique with radial dilatation allowed safe access without membrane separation. Leak-proof removal of the cannulas was achieved in all primates. Open hysterotomy with purse-string and balloon-tipped cannula provides efficient and safe access to the gravid sheep uterus. Seldinger technique allows equally secure access, and alleviates the need for hysterotomies. Radial dilatation of the porthole eliminates forward dissection of the membranes, both in sheep and primate models. This method, and collagen plug insertion upon completion of the endoscopic procedure, may provide a truly minimally invasive approach to in-utero surgery.

Amnioinfusion with Hartmann's solution: a safe distention medium for endoscopic fetal surgery in the ovine model

In this study, we have investigated the maternal effects of distending the uterine cavity with Hartmann's solution in 2nd trimester equivalent pregnant sheep. In 7 pregnant ewes, double endoscopic cannulation of the amniotic cavity was performed under general anesthesia, and 1 liter of Hartmann's solution at 38 degrees C, radiolabeled with 99mTc-red blood cells, was infused. Maternal central venous pressure, hematocrit, serum and amniotic fluid osmolarity, and amniotic fluid volume were measured at nine time points within a 2-hour period. Over this time interval, no significant fluid shift to the maternal compartment was observed. We detected no adsorption of radioactivity to the fetus or membranes, and no diffusion of radioactivity to maternal or fetal tissues was noticed. We conclude from these experiments that following double cannulation and intra-amniotic infusion of Hartmann's solution into the 2nd-trimester pregnant ovine uterus, no significant shift of fluid to the maternal compartment was observed over a 2-hour time period.

Enterocele as a consequence of laparoscopic resection of deeply infiltrating endometriosis

Laparoscopic excision of deeply infiltrating endometriosis in the cul-de-sac or the rectovaginal septum by means of electrosurgery or laser is performed frequently. Little is known about the long-term results or complications of this surgery. We suggest that enterocele could be a complication of the procedure. A patient developed a large enterocele 3 years after a laparoscopic excision of a deep endometriotic nodule with resection of the uterosacral ligaments. We question whether routine preventive measures should not be taken after excision of a deep endometriotic nodule from the rectovaginal septum.

Underwater Nd:YAG laser coagulation of blood vessels in a rat model

Endoscopic coagulation of placental and umbilical cord vessels has been suggested as a treatment for selected cases of twin-twin transfusion syndrome and of acardiac twin. The feasibility, safety and hemostatic effect of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser in an underwater environment were experimentally studied in an in vivo model, mimicking the in utero situation and fetoplacental vessels. In 10 male Wistar rats, immersed in normal saline at 38 degrees C, femoral vessels, carotid artery, abdominal aorta and vena cava were coagulated under endoscopic control. A 100-Watt Nd:YAG laser was used in continuous mode with a 600-micron fiber. Outcome measurements were vascular diameter, total energy (joules) used to obtain visual coagulation and subsequent vascular obliteration. Overall failure rate was 32% and perforation of the vessel occurred in 7.7% of cases.

Endoscopic In Utero Tracheal Plugging in the Fetal Lamb to Treat Congenital Diaphragmatic Hernia

A case control surgical trial was performed in 13 time-dated pregnant ewes to evaluate the feasibility and pulmonary effects of intratracheal obstruction by an endoscopically positioned balloon. Fifteen fetuses were subjected to tracheoscopic balloon obstruction for progressively longer periods (range 2-18 days). In case of multiple pregnancies, 10 other fetuses were used as negative controls. A 1.2-mm miniscope with a double-lumen sheath and a detachable balloon were used. Feasibility of the technique was assessed in all animals based on operating time, intraoperative complications, and tracheal obstruction. Pulmonary effects were assessed by lung-to-body weight ratio (LBWR) and morphometric terminal brachial density (MTBD). In 14 animals the trachea was successfully obstructed until delivery. Tracheoscopic manipulation time ranged from 3 to 14 minutes. One intraoperative death occurred, but the contralateral control fetus also died during the procedure. When obstruction lasted for more than 7 days, the mean LBWR was 0.060 &plusmn; 0.01 (range 0.051-0.075) and in controls 0.031 &plusmn; 0.01 (range 0.017-0.039, p <0.0005). The MTBD was 0.65 &plusmn; 0.59, compared with 1.30 &plusmn; 0.80 for controls. Using a simple and fast technique of fetoscopic tracheoscopy, the trachea can be obstructed, leading to pulmonary hyperplasia, which is of potential value when treating congenital diaphragmatic hernia.

Fetoscopic Nd:YAG Laser Coagulation for Twin-Twin Transfusion Syndrome in Cases of Anterior Placenta

Laser coagulation of anastomosing placental chorionic plate vessels was suggested as a treatment of severe twin-twin transfusion syndrome in midtrimester. An anteriorly located placenta may hamper access and visualization of the vessels involved. We treated six women with completely anterior placenta at 18 to 22 weeks' gestation. Through a 2- to 3-cm minilaparotomy the uterus was accessed after retraction of the viscera. A flexible cannula was inserted through the uterine fundus, and a 35-degree, 0.20-mm minifibroscope and 400-mm fiber were introduced. All vessels crossing the intertwining membrane were coagulated in a continuous mode and a maximum output of 45 W. All fetuses survived the operation. One fetus died in utero 6 weeks postoperatively from cardiac failure, and its receptor twin was born alive. All other pregnancies are either continuing, or the women delivered two healthy babies. Thus far, total fetal survival is 91.6%, compared with results with posterior-sided placentas. Neodymium:yttrium-aluminum-garnet laser coagulation is also possible in case of anterior placenta, but requires a minimal maternal incision and general anesthesia to allow safe cannula placement. A bent scope allows for a larger placental surface to be treated.

The effect of open and endoscopic fetal surgery on uteroplacental oxygen delivery in the sheep

Open fetal surgery predictably results in postoperative uterine contractions and often in premature labor, but its intraoperative effects on the uterus are not known. In 10 pregnant ewes (108 to 115 days' gestation), uterine artery flow, uterine venous oxygen saturation, arterial saturation, and uterine electromyography were recorded simultaneously (control). Six ewes underwent a stapled hysterotomy, and four underwent placement of three endoscopic surgery cannulas and amnioinfusion. Uterine contractions were present 52% of the time (range, 34% to 72%), and there was no significant difference between control, hysterotomy, and endoscopic access. Uterine artery blood flow and uteroplacental oxygen delivery at rest decreased (to 73% of control) after hysterotomy (P < .05), but not after endoscopy. Fetal + uteroplacental oxygen consumption did not differ significantly between the groups. In conclusion, (1) uteroplacental oxygen delivery after hysterotomy alone decreased to levels critical for adequate fetal oxygenation; (2) endoscopy did not alter uteroplacental oxygen delivery; and (3) during open fetal surgery, further oxygen demand/delivery mismatch is likely, by traction on uterine and umbilical vessels and fetal stress.

Gasless laparoscopy in infants: the rabbit model

Laparoscopic operations can be performed in neonates and infants, but carbon dioxide pneumoperitoneum may be more dangerous than in adults. Therefore the concept of gasless laparoscopy is especially attractive for small children. The authors have developed an animal training model of gasless infant laparoscopy using the rabbit. Eleven New Zealand white rabbits (mean weight, 2.2 kg) were premedicated with fentanyl (10 micrograms intramuscularly) and maintained under inhalation anesthesia by mask, with halothane (1.0 to 2.5%) in oxygen and nitrous oxide (1:1). The animals were neither intubated nor mechanically ventilated. Heart rate and oxygen saturation were monitored by pulse oximetry. A supraumbilical incision was made through the peritoneum, and an abdominal wall elevator was inserted. A 4-mm-diameter 30 degrees endoscope was introduced at the same site, allowing excellent visualization of the abdominal cavity. Three additional 5-mm cannulas were placed, and a standard Nissen fundoplication was performed in all 11 animals. In seven of these, a left nephrectomy was also performed. Five-millimeter pediatric instruments and 1.7- and 2.7-mm laryngoscopic instruments were used. The rabbit can serve as a training model for laparoscopy in the infant. Gasless laparoscopy, using abdominal wall elevation, may be particularly useful in very small patients.

Intrauterine endoscopic creation of urinary tract obstruction in the fetal lamb: a model for fetal surgery

OBJECTIVE

Our purpose was to evaluate the feasibility of intrauterine endoscopic fetal surgery in a fetal lamb model by creating a urinary tract obstruction.

STUDY DESIGN

Lower urinary tract obstruction was created by ligation of the urethra and urachus in 21 fetal lambs, eight at 95 to 105 days' gestation (term 145 days) and 13 at 70 to 75 days. The endoscopic approach consisted of a 0-degree 5 mm telescope, three 5 mm cannulas, uterine distention by amnioinfusion, and adapted instrumentation. Intrauterine fetal monitoring included temperature and pulse oximetry registration.

RESULTS

In 20 cases the urachus could be identified and ligated inside the umbilical cord. The urethra was ligated in the anterior abdominal wall (n = 7) or obstructed at the level of the penis (n = 13). Mean fetal heart rate was 147 +/- 35 beats/min, and fetal temperature at the end of intervention was 38.14 degrees +/- 2.1 degrees C. The overall postoperative survival rate was 76%.

CONCLUSION

Urinary tract obstruction can be created endoscopically in the fetal lamb. This operation can serve as a model for endoscopic fetal surgery.

Infrared fetoscopy in the sheep

The strong light sources used in fetoscopy and embryoscopy may cause eye injuries to the fetus. To circumvent this potential hazard, we have successfully used an infrared light source and infrared video camera to perform 'night vision' fetoscopy in a fetal lamb model.

A model for fetal surgery through intrauterine endoscopy

Video-endoscopic technology may offer new hope for the future of fetal surgery. Ten time-dated pregnant ewes (95 to 105 days; term, 145 days) were used to develop a model of fetal surgery through intrauterine endoscopy. Special 5-mm ports were designed with short, flexible, balloon-tipped shafts. The cannulas were inserted through purse-stringed hysterostomies. Amnioinfusion of warmed physiological fluid (Hartmann) was used as the work medium. Fetal heart rate and oxygen saturation (pulse oximetry), temperature, and amniotic pressure were monitored continuously through endoscopically placed sensors. Surgical procedures included subcutaneous dissection of the abdominal wall and ligation of the urethra in the male fetus (n = 7), ligation of the urachus within the umbilical cord (n = 8), and endoscopy of the fetal esophagus and trachea (n = 6). Bloodless surgery was achieved with a novel coagulation device that allows bipolar cutting and coagulation in an electrolyte-rich fluid medium. The mean fetal operative time was 147 minutes (range, 130 to 195). The intraamniotic temperature was maintained between 38.0 +/- 0.9 degrees C and 41.7 +/- 1.7 degrees C throughout the procedure. Oxygen saturation ranged from 51 +/- 20% to 72 +/- 14%, and fetal heart rate from 120 to 140 beats per minute. In conclusion, intrauterine endoscopy in a fluid medium allows fully monitored surgical procedures, lasting more than 2 hours, to be performed on the fetal lamb.

Fetoscopy-guided fetal endoscopy in a sheep model

Video-endoscopic surgical treatment of the fetus may, in the future, become an alternative to open fetal operation. Six 95-day-old fetal lambs were examined through intrauterine endoscopy using amnioinfusion and specially designed balloon-tipped cannulas. The fetuses were monitored endoscopically for oxygen saturation, heart rate and temperature throughout the procedure. With a rigid 5 millimeter telescope and a flexible 3 millimeter endoscope, the respiratory and upper gastrointestinal tracts could be examined. No mucosal or other trauma was noted upon completion of the endoscopy; all lambs survived the procedure. While the applications of fetal endosurgery are likely to be similar to those of open fetal operation, fetal endoscopy (looking in the fetus) is a new entity for which clinical relevance (rather than mere feasibility) remains to be demonstrated. This technique, however, could become a valuable research tool to study fetal gastrointestinal and pulmonary physiologic factors in situ.