Laparoscopic Sterilization: Prevention of Failures
Richard M. Soderstrom
Table Of Contents
Richard M. Soderstrom, MD
PREVENTING LAPAROSCOPIC STERILIZATION FAILURES
WHEN STERILIZATION FAILS
Unfortunately for patient and physician, sterilization failures occur. Each technique has inherent problems, and Mother Nature has a remarkable propensity to reconstitute the integrity of the normal Fallopian tube. Statistical reports on the success and failure of techniques are usually flawed because of anecdotal experience, retrospective review, and short-term follow up. Too frequently, different techniques are “modified” by the individual surgeon, who in essence “invents another method” without the luxury of adequate statistics. Laparoscopy for sterilization became popular in the early 1970s. Of the laparoscopic procedures first described, unipolar electrocoagulation without transection has boasted the lowest failure rate of all laparoscopic techniques to date. When unipolar failures occur, a fistula is always the culprit.1 By the middle 1970s, presumed risks of unipolar electrocoagulation moved the laparoscopist to other techniques thought to be safer, and bipolar methods becoming the most popular.
However, in recent years, problems with bipolar failure have become apparent in the literature. Incompatible equipment and inadequate coagulation appear to play a major role in these disturbing reports. Bipolar techniques that coagulate less than 2 cm of tube and in which the energy delivered to the tube and delivered below 25 watts of power appear to have an unacceptable failure rate. As with unipolar methods, a cutting wave form is preferred with the power setting at between 25 and 35 watts.
When bipolar failures are examined, a healthy endosalpinx is usually found with scarred muscular tissue surrounding the patient's salpinx. These findings are consistent with incomplete electrocoagulation suggesting that the visual end point of electrocoagulation is not sufficient information to declare the tube coagulated. Use of an ammeter or current flow meter as provided by several manufacturers appears to reduce the risk of incomplete coagulation.
Failures associated with mechanical occlusive devices frequently follow improper placement of the device, usually too distally on the tube. Clips that are placed at oblique angles to the axis of the tube or misapplied to other structures can lead to incomplete closure of the tubal lumen. When any mechanical device in medicine are used, occasional flaws in the individual device may render the operation unsuccessful.
In general, when Silastic ring failures occur, they are secondary to spontaneous reanastomosis. In these cases, after the loop contained above the applied area has atrophied, the tube may not separate, as is the usual case, and spontaneous reanastomosis occurs. In such cases, the ring is frequently found perched on top of the anastomosis or adjacent to the anastomosis on the mesosalpinx.
By 1996, the world's first prospective study of all female sterilization techniques was completed.2 During 14 years with a 10-year follow-up period, over 10,000 cases of sterilization procedures were analyzed by the US Centers for Disease Control and Prevention (CDC). All these methods were found to have a higher risk of failure than previously stated from retrospective studies. Each of the laparoscopic methods evaluated studied a sufficient number of patients to claim statistical validity. Of the nine study centers, six were teaching institutions that may slightly influence the higher than expected failure rate. Of particular concern is the finding of a 1 in 20 failure rate in patients less than 28 years old who had a bipolar method. A bipolar failure frequently resulted in an ectopic pregnancy, a life-threatening event. Fortunately, in 1999, further review of the bipolar method failures found that when at least three burns of the tube were completed, the failure rate dropped to 3.2 in 1000, supporting the recommendations of those who developed the bipolar methods.3
Table 1 reveals the risk of each method resulting in a failure.
|PREVENTING LAPAROSCOPIC STERILIZATION FAILURES|
Unipolar methods by the electrical properties inherent in monopolar generators supply an adequate amount of energy to destroy the endosalpinx in only a few seconds provided about 25 watts are used. Because the energy pathway seeking ground spreads out laterally, the recommended 3-cm coagulated tube is frequently accomplished with only two applications of the forceps' electrode. Because of the physics of power or current density, a 3-mm forceps is more efficient than one with a 5-mm diameter. However, using a smaller forceps may require an additional application to achieve the recommended 3-cm area of coagulation. There is no publication to date that demonstrates any increased success with coagulation plus transection or resection.
Bipolar methods usually fail by inadequate coagulation either by using too low a power setting, the wrong waveform or not coagulating enough of the tube.4,5 Once again, the generator should be set in the cutting or undamped waveform (most generators dedicated to only a bipolar output are set in the cutting waveform); it should be set at about 25 to 35 watts and a current flow meter will reassure the surgeon that all the current that can be delivered has been completed. Three centimeters of contiguous coagulation is the recommendation of the three inventors of bipolar forceps—Rioux, Corson, and Kleppinger. As previously mentioned, in 1999, the authors of the 1996 CDC study evaluated the high failure rate associated with the bipolar method and determined that if the parameters given here were followed, the success of the bipolar methods was similar to the Pomeroy and unipolar methods.
There are two heated or true “cautery” forceps used by a few surgeons in the United States for female sterilization. A Waters hook electrode burns and transects the tube over an area of 80 μm. Using low voltage, the Semm endocoagulator is a paddle-like forceps that can coagulate as much area as desired. Semm recommends transection after coagulation. To date, no studies have been published with enough statistical power to declare a failure rate.
All electrical methods recommend that the isthmic portion of the tube be destroyed. Some clinicians believe that coagulation of the cornua may increase fistula formation.
The Hulka clip is designed to occlude the isthmic portion of the tube slowly over 48 hours. The gold spring that closed the clip's jaw is programmed to occlude that amount of tube trapped in the jaws if the clip is applied at a 90-degree angle to the axis of the tube. However, if an oblique application occurs or the clip is applied to the ampullary portion of the tube, the increased amount of tissue caught in the clip's jaw prevents complete closure.
The Filshie clip should be applied as described for the Hulka clip method. However, the silicon rubber insert that creates the pressure gradient that causes closure may give greater tolerance should an oblique application occur. Current data on its failure rate, approved by the Food and Drug Administration, would support that contention. By design, it is easier to confirm complete inclusion of the tube before application than with the Hulka clip.
The silicone band or Falope ring fails most often when it is misapplied away from the isthmic portion of the tube. As with the clip applicators, the ring applicator requires periodic maintenance to perform properly. Because the silicone rubber must maintain its memory to occlude the tube properly, the ring should be place on the applicator just before it is placed on the tube. To load the ring more than 5 minutes before the application may stretch the rubber permanently. It should be remembered that the knuckle of tube occluded by the ring will atrophy such that months later, the ring will reside on or near the mesosalpinx that supplied that portion of the tube before occlusion.
|WHEN STERILIZATION FAILS|
A word about the management of failed tubal sterilization is appropriate. Too often, the repeat procedure is performed by another physician who may or may not have a keen knowledge of the technique previously employed. At the second sterilization procedure, it is the duty of the surgeon to approach this matter in a scientific fashion. The description of the anatomy should be clear and photographs or videotapes taken. Chromotubation may reveal that the tube that looks sealed is actually open. When a Falope ring sterilization fails, the length of each tube should be measured. By design, the Falope ring applicator draws up 2.6 cm of tube. The length of a normal tube is 10 to 12 cm, so if the ring had been properly applied to the tube, the tubal length would shortened by about 2.6 cm. The suspected patent portion of the tube should be removed, not simply coagulated. In a pathology laboratory, the tube suspected of patency should be instilled by chromotubation to identify the exact point of failure. Clips should be dissected with care to identify any device defect. If necessary, multiple microscopic slides of the area in question should be made for close scrutiny by a trained and informed pathologist. Use of a Mallory or Masson trichrome stain helps to highlight tissue previously destroyed by electrical energy. To casually say “the tube looked normal to me” serves no one well.
Dictate the operative note immediately. Alert the pathologist before the examination about those questions that may or will be asked for it is estimated that at least 50% of sterilization failures will have some kind of legal review.6,7,8,9
Understanding the recognized methods of laparoscopic female sterilization will go a long way to reduce the failure rates. Stay with the recommendations of those who have developed each method and keep accurate and timely records. The following steps, if followed should keep the failure rates as low as possible.
Using modified sterilization techniques that may seem reasonable must be supported by evidence-based medicine.
2. Peterson HB, Xia Z, Wilcox LS et al for the US Collaborative Review of Sterilization Working Group: The risk of pregnancy after tubal sterilization: Findings from the US Collaborative Review of Sterilization. Am J Obstet Gynecol 174: 1161, 1996
6. Soderstrom RM: Legal aspects of female sterilization and sterilization failures. In Phillips JM (ed): Endoscopic Female Sterilization: A Comparison of Methods, p 199. Downey, CA: American Association of Gynecologic Laparoscopists, 1983