Tubal sterilization by means of selective catheterization: comparison of a hydrogel and a collagen glue

Use of n-Butyl-2-Cyanoacrylate for Fallopian Tube Embolization via Selective Catheterization in a Rabbit Model: Feasibility Study for Potential Nonsurgical Sterilization

PURPOSE

To determine whether fallopian tube embolization with n-butyl-2-cyanoacrylate (nBCA) administered via a microcatheter in a rabbit model was technically feasible and resulted in short-term tubal occlusion.

MATERIALS AND METHODS

In 10 female New Zealand white rabbits, the 2 cervices were cannulated using a 5-F catheter and hydrophilic guide wire transvaginally. Salpingography confirmed tubal patency bilaterally. A 2.4-F microcatheter was advanced to the distal fallopian tube, and nBCA/ethiodized oil was administered as the microcatheter was withdrawn to fill the length of the tube. A metallic coil was deployed prior to nBCA administration in half of the fallopian tubes. Rabbits were evaluated for tubal occlusion with salpingography at 1 month, followed by euthanasia and histopathologic analysis. Inflammation and fibrosis were graded from 0 (normal) to 3 (severe).

RESULTS

Fallopian tube embolization was technically successful in 17 (85%) of 20 fallopian tubes. Thirteen (76%) of 17 embolized fallopian tubes were occluded at 1 month on salpingography (nBCA only, 7/9; nBCA and coil, 6/8). On histopathologic analysis, direct or indirect evidence of occlusion was observed in 14 (82%) of 17 fallopian tubes. Mild or early fibrosis was observed in 65% of the tubes. The mean inflammation and fibrosis scores for the embolized tubes were 0.62 and 0.94, respectively.

CONCLUSIONS

This pilot study demonstrated that embolization of rabbit fallopian tubes using nBCA administered via a microcatheter is technically feasible and results in occlusion of most fallopian tubes in the short term with minimal inflammation. Investigation of efficacy in preventing pregnancy over the long term is warranted.

Placement of the Essure Permanent Birth Control Device with Fluoroscopic Guidance: A Novel Method for Tubal Sterilization

An effective transcervical method for fluoroscopically guided fallopian tube occlusion has long been sought for female sterilization. The Essure permanent birth control device was approved by the Food and Drug Administration in November 2002 and is currently indicated for hysteroscopic placement. In a series of eight patients, bilateral Essure microcoils were placed with fluoroscopic guidance in seven patients for a success rate of 87.5%. One patient described peri- and postprocedure pelvic pain, otherwise no complications were identified. All patients returned to normal activities within 24 hours. Fluoroscopically guided transcervical tubal sterilization with the Essure microcoil device (Conceptus, San Carlos, CA) is a viable outpatient procedure.

Tubal sterilization with a waterborne polyethylene glycol in situ cross-linking material: a minimally invasive approach

OBJECTIVE

To assess the effectiveness and compatibility of an in situ-gelling polymeric device when implanted in the fallopian tube to prevent pregnancy.

DESIGN

Controlled laboratory study.

SETTING

Animals in a controlled laboratory environment.

ANIMAL(S)

Ten white New Zealand rabbits (nine female and one male).

INTERVENTION(S)

The material was implanted through a small incision into one of each rabbit's twin fallopian tubes. The rabbits then were allowed to heal. After a healing period of 6 to 10 weeks, the rabbits were bred. After breeding, the animals were killed, and samples were collected from their fallopian tubes for histology.

MAIN OUTCOME MEASURE(S)

Pregnancy of the specimens.

RESULT(S)

Four specimens showed unilateral pregnancy (pregnancy in only one uterus). Because rabbits have the capacity to be pregnant in both uteri simultaneously, this suggests strong potential of the material for use as a contraceptive.

CONCLUSION(S)

Although concerns remain concerning distension and potential injury resulting from use of the system, enough data have been gathered to warrant further study of this material for use in humans.

Fallopian Tube Occlusion with Use of a Small Intestine Submucosa Device: Evaluation in a Rabbit Model

PURPOSE

The present study evaluates the short- and midterm efficacy of a small intestinal submucosa (SIS) device for fallopian tube occlusion in rabbits.

MATERIALS AND METHODS

In a pilot study, several SIS device designs were tested for positional stability (absence of migration). The design selected for further testing consisted of a center of spongy SIS surrounded by an SIS sheet and held together by a 0.006-inch wire helix with two barbs. It was delivered on the tip of a short coaxial 3-F/5-F catheter set. Using this design, bilateral transuterine fallopian tube occlusion was performed in eight New Zealand White rabbits. Follow-up consisted of plain radiography at 2 weeks and hysterosalpingography at 6 weeks (n = 4 animals; eight tubes), 12 weeks (n = 2 animals; four tubes), or 24 weeks (n = 2 animals; four tubes). Thereafter, the animals were killed and the fallopian tubes were harvested for histologic evaluation.

RESULTS

A single device was placed successfully in each fallopian tube. Fifteen of 16 devices (94%) remained in place throughout follow-up. One device migrated into the vagina at 2-week follow-up. Hysterosalpingography of the 15 tubes with occluders in place showed occlusion in seven of seven (100%) at 6 weeks, three of four (75%) at 12 weeks, and two of four (50%) at 24 weeks. Histologic evaluation revealed luminal occlusion by reorganized SIS containing macrophages, fibrocytes, and scant foreign-body giant cells. Only a mild inflammatory reaction was observed around the tube. In the animals with recanalization at 12 and 24 weeks, new channels were found alongside the original still-occluded fallopian tube lumen.

CONCLUSIONS

The original lumen of the fallopian tube was effectively occluded by the SIS occluder, which was remodeled within the fallopian tubes of rabbits. Partial peripheral recanalization was observed over time.

Partition-controlled progesterone release from waterborne, in situ-gelling materials

The primary goal of this work was to evaluate the long-term constant zero-order release of progesterone from a waterborne, in situ-gelling, injectable material. The motivation for this is to develop an intrafallopian tube embolization system for contraception. Poly(ethylene glycol) diacrylate (PEGDA, 575 g/mol) or poly(propylene glycol) diacrylate (PPODA, 540 g/mol) as a Michael-type addition acceptor was combined with pentaerythritol-tetrakis (3-mercaptopropionate; a Michael-type addition donor) to create a 75 wt.% emulsion solution in 0.1M PBS (pH 7.4 for PEGDA and pH 12 for PPODA) that gels in minutes by the Michael-type reaction to form a hydrophobic solid. Samples, with approximately 5.5 or 25 wt.% progesterone, were formed in Tygon tubing. Samples (1.6 mm x 1.0 cm cylinders) showed constant, partition-controlled release of progesterone for a prolonged period (time dependent on the mass of progesterone). Cylinders with approximately 25 wt.% load of progesterone exhibited constant release (approximately 40 microg per day) for more than 50 days in both the PEGDA and PPODA systems. This type of release is normally associated with preformed hydrophobic matrix systems. In contrast, these in situ-gelling materials reported here can be used to provide zero-order, partition-controlled release of progesterone and enhance the efficiency of an intrafallopian tube embolization system through progesterone release in an injectable, in situ-forming system.

Use of ethylene vinyl alcohol copolymer for tubal sterilization by selective catheterization in rabbits

PURPOSE

To assess the efficacy of ethylene vinyl alcohol copolymer (Uryx) in nonsurgically occluding the fallopian tube and achieving tubal sterilization in the rabbit model.

MATERIALS AND METHODS

Ten mature virgin female New England rabbits underwent transvaginal selective bilateral fallopian tube cannulation with use of a coaxial catheter system under general anesthesia. Selective salpingography was performed bilaterally to assess patency of the fallopian tubes. Ethylene vinyl alcohol copolymer was injected unilaterally through a microcatheter to completely fill the middle portion of the tube. Three to seven days after injection, each animal was bred. Conception was determined by ultrasonography (US) 7-19 days after effective breeding. If pregnant, the rabbit was killed. Otherwise, it was permitted to rebreed until pregnancy was achieved. Histologic specimens of the fallopian tubes were prepared and analyzed.

RESULTS

Patency of the fallopian tubes was demonstrated bilaterally in all animals by the free spillage of contrast material into the peritoneum. The delivery of ethylene vinyl alcohol copolymer into the fallopian tubes was successful in all animals but one, in which most of the plug almost immediately extruded into the uterus. Pregnancy was detected by US in the untreated fallopian tube in the nine rabbits that were receptive to breeding. No pregnancies were detected in the injected side. Histologic analysis demonstrated variable degrees of occlusion, fibrosis, and inflammation, with the majority of specimens demonstrating mild to moderate inflammation and moderate to marked fibrosis.

CONCLUSION

Ethylene vinyl alcohol copolymer can reliably be placed nonsurgically via the transvaginal approach into the fallopian tubes with use of a coaxial catheter system. Ethylene vinyl alcohol copolymer appears to result in less fibrosis than previously investigated agents and demonstrates a 100% early sterilization rate in the rabbit model.

A review of selective salpingography and fallopian tube catheterization

Use of selective salpingography and fallopian tube recanalization has revolutionized the diagnosis and treatment of infertility. Selective salpingography, a diagnostic procedure in which the fallopian tube is directly opacified through a catheter placed in the tubal ostium, has been used since the late 1980s to differentiate spasm from true obstruction and to clarify discrepant findings from other tests. In fallopian tube recanalization, a catheter and guide wire system is used to clear proximal tubal obstructions. The recanalization procedure is simple for interventional radiologists to perform and is successfully completed in most patients (71%-92%). Pregnancy rates after the procedure have been variable, with an average rate of 30%. The combination of selective salpingography with fallopian tube recanalization has improved the overall management of infertility caused by tubal obstruction. The same catheterization technique used in fallopian tube recanalization is currently being explored for use in tubal sterilization.