[Laser therapy for benign prostate hyperplasia]

Various procedures operating with different laser systems and application techniques are available for laser treatment of benign prostate hyperplasia (BPH). They generate differing qualitative and quantitative effects in tissue such as coagulation, vaporisation or, respectively, ablation as well as incisions leading according to technique to a resection or enucleation. Since these procedures are considered as alternatives to transurethral resection of the prostate (TURP), the objective of laser therapy is not only to achieve, in comparison to TURP, an equivalent improvement of the symptoms and quality of life but also a maximal urinary flow strength or, respectively, a reduction of obstruction to bladder emptying with lower accompanying morbidity and shorter hospitalisation. Most of the published case control and randomised studies on laser therapy for BPH show heterogeneous results both with regard to the improvement of subjective and objective urination parameters as well to complications. This is due, on the one hand, to the laser or its qualitative action and, on the other hand, to the operator and the resulting specific quantitative effect. The biophysical relationships between the laser parameters and the tissue effects are a topic of current discussion. The biological effect depends not only on the depth of penetration and the scattering but also on other parameters of the laser. For the generation of voluminous coagulation necrosis with a laser in the ca. 800 to 1100 nm wavelength region, a carbonisation of the surface must be avoided. For thermal vaporisation, for example, the Nd:YAG laser with contract-free application or contact tips as well as diode lasers of varying wavelengths are suitable. Especially suitable are the potassium titanyl phosphate (KTP) laser and the lithium triboride (LBO) laser. Ablation is also possible with the Ho:YAG laser. An incision and thus resection or enucleation is also possible with various laser systems including thermal ones, but is more effective with a continuous beam laser of ca. 2000 nm. The Ho:YAG laser achieves an athermal incision the quality of which depends on the pulse energy and the time behaviour of the laser impulse.