Diagnostic Accuracy of an Initial Azoospermic Reading Compared With Results of Post-Centrifugation Semen Analysis After Vasectomy

Is it possible to apply trial outcomes to a real-world population? A novel approach to External Validity Analysis

BACKGROUND

Translation of findings from randomised controlled trials (RCT), the foundation of evidence-based medicine, into clinical practice requires an understanding of relationships between patient characteristics, treatment practices and outcomes. We propose a novel technique, External Validity Analysis (EVA), to evaluate applicability of findings from a large RCT, comparing baseline characteristics, interventions and outcomes between the RCT and a large clinical database.

AIM

To perform EVA of the findings of a randomised controlled trial (ESTHER-1) to a population in an Australian clinic setting. To demonstrate this method, we evaluated the discordance in first cycle follicle-stimulating hormone (FSH) exposure and outcomes between the two populations, to inform clinical practice.

MATERIALS AND METHODS

In this retrospective, descriptive analysis, we compared practices and outcomes between the follitropin alfa 'conventional' dosing arm of the ESTHER-1 trial and a selected comparable clinic subpopulation of patients who underwent controlled ovarian stimulation using FSH.

RESULTS

Mean FSH exposure was 34% higher in the clinic subpopulation than in the trial subpopulation, resulting in higher average ovarian response without improving the likelihood of clinical pregnancy or live birth.

CONCLUSIONS

EVA allowed for the comparison of a trial population with a selected clinic population with similar characteristics. With respect to FSH consumption, this analysis revealed higher exposure to FSH in the clinic setting without a corresponding benefit. The comparison reveals population differences as well as the potential to improve clinical outcomes through a reappraisal of current practices and objectives in gonadotropin dose selection.

2016 Laboratory guidelines for postvasectomy semen analysis: Association of Biomedical Andrologists, the British Andrology Society and the British Association of Urological Surgeons

Post-vasectomy semen analysis (PVSA) is the procedure used to establish whether sperm are present in the semen following a vasectomy. PVSA is presently carried out by a wide variety of individuals, ranging from doctors and nurses in general practitioner (GP) surgeries to specialist scientists in andrology laboratories, with highly variable results.

Key recommendations are that: (1) PVSA should take place a minimum of 12 weeks after surgery and after a minimum of 20 ejaculations. (2) Laboratories should routinely examine samples within 4 h of production if assessing for the presence of sperm. If non-motile sperm are observed, further samples must be examined within 1 h of production. (3) Assessment of a single sample is acceptable to confirm vasectomy success if all recommendations and laboratory methodology are met and no sperm are observed. Clearance can then be given. (4) The level for special clearance should be <100 000/mL non-motile sperm. Special clearance cannot be provided if any motile sperm are observed and should only be given after assessment of two samples in full accordance with the methods contained within these guidelines. Surgeons are responsible both preoperatively and postoperatively for the counselling of patients and their partners regarding complications and the possibility of late recanalisation after clearance. These 2016 guidelines replace the 2002 British Andrology Society (BAS) laboratory guidelines and should be regarded as definitive for the UK in the provision of a quality PVSA service, accredited to ISO 15189:2012, as overseen by the United Kingdom Accreditation Service (UKAS).

Effectiveness of vasectomy techniques

The effectiveness of various vasectomy techniques is reviewed, with a focus on methods used for vas occlusion. Spontaneous recanalization of the vas is more common than generally recognized and is often transient. Simple ligation and excision has an unacceptably high risk for failure. Techniques that include cautery seem to have a lower risk for failure than techniques that do not include cautery. There is insufficient evidence to recommend a particular standardized cautery technique, but adding fascial interposition to cautery seems to be associated with the lowest risk for failure.