eMedicine Specialties > Urology > Surgery

Lasers in Urology: Follow-up

Author: Michael Grasso, MD, Chairman, Department of Urology, Saint Vincent's Medical Center; Professor and Vice Chairman, Department of Urology, New York Medical College
Coauthor(s): David A Green, MD, Staff Physician, Department of Urology, New York Medical College
Contributor Information and Disclosures

Updated: Jan 15, 2008

Outcome and Prognosis

The outcomes are specific to the various forms of treatment used, which range from lithotripsy to the ablation of tumors or prostate tissue and are mentioned in the above sections.

Future and Controversies

Tissue welding

Laser energy is applied in a constructive manner to reapproximate tissues. The results are very promising thus far, with good tensile strength, watertight seals, and minimal scar formation. Tissue solders (albumin solutions) and chromophores added to tissue edges before reapproximation speed the welding process, increase tensile strength, and minimize collateral injury.

This technology may be particularly helpful in laparoscopic surgery, in which current methods of reapproximation are clumsy and time consuming. Vasovasotomy for vasectomy reversal using a tissue welding technique has a reported patency rate near 95% and a subsequent pregnancy rate of 35%. This is comparable to current microsurgical techniques, yet the required technical skills are less, operating time is decreased, and, so far, reported complications are fewer. Hypospadias repair is another technically tedious operation that is lending itself, mostly in the laboratory, to tissue-welding repair. Other reported applications of tissue welding in urology include pyeloplasty, augmentation cystoplasty, and continent urinary diversion.

Proposed future laparoscopic applications include ureteroureterostomy, pyeloplasty, ureteroneocystostomy, and bladder and bowel anastomoses.

Local temperature control of tissue to be reapproximated is the main parameter that affects the quality of a tissue weld. This has been difficult to control, and the end-point is too subjective for consistent results. One group overcame this using a dual-chamber optical fiber that delivers laser energy and senses surface temperature simultaneously. The optimal temperature for lasers to denature and weld tissue proteins is 70-80°C.

Because urine lacks the clotting ability of blood, tight anastomoses of urothelial structures are even more important than in vascular surgery. Laser welding can provide the urologist and patient an immediate watertight seal with a tensile strength that exceeds conventional closures. This application is in its clinical infancy; however, the future may bring a ubiquitous, mature technology.

Autofluorescence

The ability to ablate and weld increases the laser's use as a diagnostic tool. In this capacity, light of a specific wavelength is used to differentiate healthy from dysplastic or malignant tissue. This may involve the use of dyes that are metabolized differentially by normal and abnormal tissues. With bladder tumors, the sensitivity of this method is near 100%; however, false-positive results secondary to inflammatory lesions make the specificity only 60-70%. This can lead to too many unnecessary biopsies. Koenig et al (1996) developed a novel approach using the innate fluorescing ability of tissues without the addition of dyes, a process called autofluorescence.14

Light of 337 nm emitted by a nitrogen laser and applied to bladder tissue was absorbed then re-emitted at 385 nm and 455 nm by tissue collagen and nicotinamide adenine dinucleotide (NADH), respectively. Because of the blood supply, thickness, and relative lack of collagen in tumors, they can be distinguished from healthy tissue. By using a pulsed beam for delivery, the same optical fiber may be used to detect the return of fluorescence and then obtain absorption spectra. Healthy tissue fluoresces with greater intensity than malignant tissue and, more importantly, has 2 absorption peaks at 385 and 455 nm. Malignant tissue, on the other hand, usually has only 1 absorption peak at 455 nm.

Inflammatory tissue, which can mimic malignancy in appearance, almost always emits at both the 385- and 455-nm peaks, the same as healthy tissue. This method of detection has yielded a very high sensitivity, specificity, and positive and negative predictive values, (97, 98, 93, and 99% respectively), making it a potentially useful diagnostic tool.

Conclusion

The future of lasers in urology will be based on developing new wavelengths that are more precise and applicable to evolving treatment schemes. Er:YAG is a great example; it is much more precise than holmium, with less than a millimeter of collateral tissue effect. This could make an excellent endoscopic scalpel; however, at this time, no user-friendly delivery system for this laser that allows for endoscopic use exists. Further developments are anticipated eagerly.

New lasing mediums are the subject of intense research and development worldwide. Plastic conjugated polymers are one of the most promising mediums under study. With these mediums, scientists have generated emissions across the entire visible spectrum. They have been proven to amplify light, even through microscopic blocks of polymer. The hope for the future is a widely tunable, highly cost-effective laser using thin films of conjugated polymers and packaged in an ultracompact device.

 


More on Lasers in Urology

Overview: Lasers in Urology
Workup: Lasers in Urology
Treatment: Lasers in Urology
Follow-up: Lasers in Urology
Multimedia: Lasers in Urology
References
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Further Reading

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Keywords

lasers in urology, urologic lasers, urological lasers, laser, laser lithotripsy, laser ablation of prostate, laser prostatectomy, laser surgery, tissue welding, photodynamic therapy, autofluorescence, neodymium:yttrium-aluminum-garnet laser, Nd:YAG laser, holmium:yttrium-aluminum-garnet laser, Ho:YAG laser, holmium:YAG laser, ruby laser, CO2 laser, carbon dioxide laser, frequency-doubled double-pulse Nd:YAG laser, FREDDY laser, potassium-titanyl phosphate crystal laser, KTP laser, potassium-titanyl phosphate laser, dye lasers, coumarin laser, alexandrite laser, semiconductor diode laser, tissue coagulation, thermal treatment, nitrogen laser, erbium:yttrium-aluminum-garnet laser, Er:YAG laser, thulium:yttrium-aluminum-garnet laser, thulium:YAG laser, endoscopic intracorporeal laser lithotripsy, laser coagulation, laser vaporization, Greenlight laser, visual laser ablation of the prostate, VLAP, Ho:YAG prostate enucleation, HoLEP

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Contributor Information and Disclosures

Author

Michael Grasso, MD, Chairman, Department of Urology, Saint Vincent's Medical Center; Professor and Vice Chairman, Department of Urology, New York Medical College
Michael Grasso, MD is a member of the following medical societies: American Medical Association, American Urological Association, California Medical Association, and Endourological Society
Disclosure: Nothing to disclose.

Coauthor(s)

David A Green, MD, Staff Physician, Department of Urology, New York Medical College
Disclosure: Nothing to disclose.

Medical Editor

Raymond Rackley, MD, Professor of Surgery, Cleveland Clinic Lerner College of Medicine at CWRU; Co-Section Head, Section of Voiding Dysfunction and Female Urology, Glickman Urological Institute, Cleveland Clinic Foundation
Raymond Rackley, MD is a member of the following medical societies: American Urological Association
Disclosure: Pfizer, Novartis, Proctor & Gamble, Allergan Honoraria None; Pfizer, Novartis, Proctor & Gamble, Allergan Consulting fee Other

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Mark Jeffrey Noble, MD, Consulting Staff, Urologic Institute, Cleveland Clinic Foundation
Mark Jeffrey Noble, MD is a member of the following medical societies: American College of Surgeons, American Medical Association, American Urological Association, Kansas Medical Society, Sigma Xi, Society of University Urologists, and Southwestern Oncology Group
Disclosure: Nothing to disclose.

CME Editor

J Stuart Wolf, Jr, MD, FACS, David A Bloom Professor of Urology, Director, Division of Minimally Invasive Urology, Department of Urology, University of Michigan Medical Center
J Stuart Wolf, Jr, MD, FACS is a member of the following medical societies: American College of Surgeons, American Medical Association, American Urological Association, Catholic Medical Association, Endourological Society, Society for Urology and Engineering, Society of Laparoendoscopic Surgeons, and Society of University Urologists
Disclosure: Terumo Corporation Consulting fee Consulting; Omeros Corporation Consulting fee Consulting

Chief Editor

Bradley Fields Schwartz, DO, FACS, Associate Professor of Urology, Director, Center for Laparoscopy and Endourology, Department of Surgery, Southern Illinois University School of Medicine
Bradley Fields Schwartz, DO, FACS is a member of the following medical societies: American College of Surgeons, American Urological Association, Association of Military Osteopathic Physicians and Surgeons, Endourological Society, Society of Laparoendoscopic Surgeons, and Society of University Urologists
Disclosure: Nothing to disclose.

 
 
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