Background: Our objective was to determine the accuracy of in-vitro sperm penetration into cervical mucus or substitutes in evaluating sperm motility in semen.
Methods: This was a systematic quantitative review of test accuracy studies. The Cochrane library (2000:4), Medline (1966-2001), Embase (1988-2001) and SciSearch (1981-2001) were searched, in addition to manual searches of conference papers and bibliographies of known primary and review articles. Primary studies measuring in-vitro sperm penetration into cervical mucus, or substitutes (i.e. sperm-mucus penetration test, SMPT) and comparing results with sperm motility in semen were included.
Results: There were 18 primary diagnostic studies published in 17 papers, involving a total of 2580 samples. Fourteen primary diagnostic tests used vanguard distance as diagnostic criteria (SMPT(vd)) and the pooled likelihood ratio (LR) for positive (LR+) and negative (LR-) tests were 2.29 (1.82-2.87) and 0.52 (0.44-0.63) respectively. Four studies used diagnostic criteria based directly or indirectly on swim-up sperm count per high power field (SMPT(sc)) instead. Their pooled LR+ and LR- were 5.24 (3.36-8.18) and 0.15 (0.06-0.39) respectively.
Conclusions: SMPT(vd) has a low accuracy in the evaluation of sperm motility in semen. However, SMPT(sc) was found to be more accurate. This method of using sperm concentration, instead of vanguard distance, as diagnostic criteria of in-vitro SMPT has potential as a useful laboratory-based sperm function test.