The Impact of a Very Short Abstinence Period on Conventional Sperm Parameters and Sperm DNA Fragmentation: A Systematic Review and Meta-Analysis

Purpose: In recent years, a growing number of studies have supported the beneficial effects of a very short abstinence period on sperm parameters, especially in patients with oligoasthenozoospermia. However, the results are controversial and no consensus exists regarding whether to request a second semen collection in clinical practice. Therefore, this systematic review and meta-analysis aimed to evaluate the influence of a very short abstinence period (within 4 h) on conventional sperm parameters and sperm DNA fragmentation (SDF) rate. Materials and Methods: The literature search was performed using Scopus and PubMed databases. The meta-analysis was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol (PRISMA-P) guidelines. All eligible studies were selected according to the Population, Intervention, Comparison/Comparator, Outcomes, and Study design (PICOS) model. The quality of evidence of the included studies was analyzed through the Cambridge Quality Checklists. The standardized mean difference (SMD) was used to analyze the outcomes. Cochran-Q and I(2) statistics were used to evaluate statistical heterogeneity. Results: We assessed for eligibility 1334 abstracts, and 19 studies were finally included. All 19 articles evaluated the effects of a very short abstinence period on sperm parameters and, among these, 5 articles also evaluated the effects on SDF rate. The quantitative analysis showed a significant reduction in semen volume after a very short abstinence period in both normozoospermic men and patients with oligozoospermia, asthenozoospermia, and/or teratozoospermia (OAT) patients. We found a statistically significant increase in sperm concentration and total and progressive motility in the second ejaculation of patients with OAT. In contrast, the SDF rate decreased significantly in the second ejaculate of OAT patients. Conclusions: This is the first systematic review and meta-analysis investigating the impact of a very short abstinence period on sperm parameters and SDF rate. The results suggest that collecting a second consecutive ejaculation after a very short time from the first could represent a simple and useful strategy for obtaining better-quality spermatozoa, especially in patients with abnormal sperm parameters.