John Guillebaud

Bio: John Guillebaud is an academic researcher from Churchill Hospital. The author has contributed to research in topics: Vasectomy & Muscle contraction. The author has an hindex of 12, co-authored 16 publications receiving 511 citations.

Complications of Vasectomy: Review of 16,000 Patients

Abstract: Sixteen thousand, seven hundred and ninety-six men underwent vasectomy between 1970 and December 1983 and have been reviewed. Post-operative side effects were few and significant complications were reported in 0.9%. Failure to achieve sterility occurred in 72 men, 69 of whom have been analysed. The early recanalisation rate was 0.36%. This rate was not influenced by the operative technique used, but varied markedly between individual surgeons. Experience and care with technique should result in a failure rate of 0.2% or better. There were six cases of late recanalisation in men previously thought sterile by two consecutive azoospermic analyses 4 months after vasectomy.

Late failure of vasectomy after two documented analyses showing azoospermic semen.

Abstract: From April 1970 to December 1980, 14 047 men underwent vasectomy for sterilisation under local anaesthetic at this clinic. In each man sterility was confirmed by two analyses of semen showing azoospermia. Allowing for a minimum follow up of three years, the wives of six of these men subsequently became pregnant between 16 months and three years after vasectomy. Analyses of semen confirmed recanalisation of the vasa deferentia in all six men. Only five similar cases initially fulfilling the same criteria for sterility have previously been reported. Full account of the rare possibility of recanalisation should be taken both when couples are counselled preoperatively and when pregnancy occurs after the male partner has been confirmed to be sterile.

The incidence of chronic scrotal pain after vasectomy: a prospective audit

Abstract: OBJECTIVE To assess the extent of scrotal pain in men before and after vasectomy, to produce accurate data for the benefit of men considering this procedure, and hence improved informed consent about the outcomes, as chronic scrotal pain after vasectomy is a poorly quantified clinical problem. PATIENTS AND METHODS Between November 2004 and January 2006 nine surgeons carried out vasectomies in 625 men (mean age 39.9 years, sd 5.6) under local anaesthesia. A questionnaire was devised to establish the presence of any scrotal or testicular pain, and to characterize this discomfort; 6 months after the procedure a modified version of the same questionnaire was administered. RESULTS In all, 593 (94.7%) men returned the preoperative questionnaires and were entered into the study; 488 (82.2%) of these completed the follow-up questionnaire, giving a mean (sd) follow-up of 6.8 (1.6) months. In all, 65 men reported new-onset scrotal pain at 7 months (14.7%). The mean visual analogue score for this pain was 3.4/10. Four men (0.9%) in the responding group described pain after vasectomy as ‘quite severe and noticeably affecting their quality of life’. CONCLUSION At 7 months after vasectomy about 15% of previously asymptomatic men have some degree of scrotal discomfort. These early data indicate that chronic scrotal pain after vasectomy is a genuine entity, but a longer-term follow-up in this group will be important to allow further evaluation of how this pain develops with time.

Temporary reappearance of sperm 12 months after vasectomy clearance

Abstract: Objectives To determine the incidence of positive semen analysis 12 months after vasectomy clearance. Subjects and methods A prospective study was undertaken, starting in 1990, of men undergoing vasectomy. Azoospermia was confirmed by two successive semen analyses 16 weeks after vasectomy. One year later a further sample was analysed for the presence of sperm. Results Of 1000 men who provided a sample for analysis, six men (0.6%) have had positive semen analyses 1 year after the initial tests showed azoospermia. In all six the sperm count was < 10 000 per mL. Five of the six men produced a repeat sample 1 month later which, in all five cases, showed azoospermia. No pregnancies have been reported to date. Conclusion Transitory reappearance of sperm following successful vasectomy occurs in about 0.6% of men. This incidence is 18 times greater than the reported pregnancy rate following successful vasectomy.

Advances in male contraception.

Abstract: Despite significant advances in contraceptive options for women over the last 50 yr, world population continues to grow rapidly. Scientists and activists alike point to the devastating environmental impacts that population pressures have caused, including global warming from the developed world and hunger and disease in less developed areas. Moreover, almost half of all pregnancies are still unwanted or unplanned. Clearly, there is a need for expanded, reversible, contraceptive options. Multicultural surveys demonstrate the willingness of men to participate in contraception and their female partners to trust them to do so. Notwithstanding their paucity of options, male methods including vasectomy and condoms account for almost one third of contraceptive use in the United States and other countries. Recent international clinical research efforts have demonstrated high efficacy rates (90-95%) for hormonally based male contraceptives. Current barriers to expanded use include limited delivery methods and perceived regulatory obstacles, which stymie introduction to the marketplace. However, advances in oral and injectable androgen delivery are cause for optimism that these hurdles may be overcome. Nonhormonal methods, such as compounds that target sperm motility, are attractive in their theoretical promise of specificity for the reproductive tract. Gene and protein array technologies continue to identify potential targets for this approach. Such nonhormonal agents will likely reach clinical trials in the near future. Great strides have been made in understanding male reproductive physiology; the combined efforts of scientists, clinicians, industry and governmental funding agencies could make an effective, reversible, male contraceptive an option for family planning over the next decade.

Chronic post-surgical pain: 10 years on

Abstract: In the past ten years there has been recognition that chronic post-surgical pain is a significant problem. This is a complex area of research and although the quality of studies has improved many difficulties remain. Several recent publications have examined risk factors. Severe acute postoperative pain emerges as a factor that we may be able to influence. There is a need for education of the medical profession and the general public, so that effective measures are introduced and unnecessary and inappropriate operations minimized.

When does acute pain become chronic

Abstract: The transition from acute to chronic pain appears to occur in discrete pathophysiological and histopathological steps. Stimuli initiating a nociceptive response vary, but receptors and endogenous defence mechanisms in the periphery interact in a similar manner regardless of the insult. Chemical, mechanical, and thermal receptors, along with leucocytes and macrophages, determine the intensity, location, and duration of noxious events. Noxious stimuli are transduced to the dorsal horn of the spinal cord, where amino acid and peptide transmitters activate second-order neurones. Spinal neurones then transmit signals to the brain. The resultant actions by the individual involve sensory-discriminative, motivational-affective, and modulatory processes in an attempt to limit or stop the painful process. Under normal conditions, noxious stimuli diminish as healing progresses and pain sensation lessens until minimal or no pain is detected. Persistent, intense pain, however, activates secondary mechanisms both at the periphery and within the central nervous system that cause allodynia, hyperalgesia, and hyperpathia that can diminish normal functioning. These changes begin in the periphery with upregulation of cyclo-oxygenase-2 and interleukin-1β-sensitizing first-order neurones, which eventually sensitize second-order spinal neurones by activating N-methyl-d-aspartic acid channels and signalling microglia to alter neuronal cytoarchitecture. Throughout these processes, prostaglandins, endocannabinoids, ion-specific channels, and scavenger cells all play a key role in the transformation of acute to chronic pain. A better understanding of the interplay among these substances will assist in the development of agents designed to ameliorate or reverse chronic pain.