Table 1.

Advantages and disadvantages of direct measurement of ROS in semen.

Assays	Advantages	Disadvantages
Chemiluminescence [7]	Robust, high sensitivity and specificity	Time-consuming, large and expensive equipment Interfering variables Requires high sample volume
Nitroblue tetrazolium (NBT) [8], [9]	Cost-effective, user friendly Detect neutrophils at a concentration of 0.5 × 106/mL or higher	Subjective interpretation of a positive vs negative neutrophils
Cytochrome c reduction test [10]	Quantify O2•− released during the respiratory burst of neutrophils or by isolated enzymes Good for high level of ROS production	Relatively insensitive to detect NADPH oxidase activity, if enzymatic activity is low Cannot detect intracellular O2•−
Fluorescein isothiocyanate (FITC)-labelled lectins [11], [12]	Detect acrosome status	Difficult to distinguish true and false acrosomal reactions Impossible to detect sperm viability and acrosomal status in one picture Fluorescent signal fades at times
Electron spin resonance [10], [13]	Broad usages such as observations of free radicals, analysis of free radical characteristics, quantitative analysis of free radicals, and kinetic analysis Good for high level of ROS production	Limitation if a free radical reacts immediately with a molecule other than the spin-trapping agent Inference factors such as possible neutralisation