Visvanathan, D.; (2006) Low power lasers for the treatment of heavy menstrual periods. Doctoral thesis , University of London.

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Abstract

Two of the most frequent causes of excessive menstrual blood loss are dysfunctional uterine bleeding (DUB) and fibroids. Both can be cured by hysterectomy, but no non-surgical treatment for either is entirely satisfactory. This thesis looks at the potential of minimally invasive, low power laser techniques for treating these conditions: photodynamic therapy (PDT) for endometrial ablation for DUB and interstitial laser photocoagulation (ILP) for fibroids. PDT is the local destruction of tissue with light after prior administration of a photosensitising drug. No heat is involved. In pharmacokinetic studies, I instilled the photosensitiser aluminium disulphonated phthalocyanine (AlS2Pc) into the horns of normal rabbit uteri, using fluorescence microscopy of uterine sections to document the drug distribution. The most appropriate drug levels in endometrium and myometrium were seen at 3 hours, at which time a diffuser fibre delivered laser light (670nm) to the endometrium. Histological examination 3-28 days later showed that under optimal conditions, there was close to complete endometrial ablation with minimal myometrial damage. Studies on human hysterectomy specimens compared a range of light delivery devices for PDT. The bifurcator gave the most uniform light distribution. ILP involves inserting one or more thin needles into fibroids at laparoscopy. Laser fibres are passed through the needles to gently heat the target lesion (typically 3W for 10 minutes per fibre site). 21 symptomatic patients with 32 fibroids were treated. At 6 weeks, most lesions were oedematous, but there was a mean shrinkage of 25% at 6 months and 50% at 12 months, with corresponding symptomatic relief. These studies have shown that in the rabbit, PDT with AlS2Pc can produce endometrial ablation safely. The technique is ready for consideration for pilot clinical studies. ILP has been shown to be a safe and relatively simple treatment for moderate sized fibroids, which could be incorporated into gynaecological practice now.

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