Endometrial cell counts in recurrent miscarriage: a comparison of counting methods

Area of Science:

• Reproductive immunology
• Cell biology
• Medical imaging analysis

Background:

• Accurate quantification of uterine natural killer (uNK) cells is crucial for understanding endometrial function and reproductive health.
• Manual cell counting methods for uNK cells can be subjective and lack reproducibility.
• Diverse endometrial tissue presents challenges for consistent cell density measurements.

Purpose of the Study:

• To compare the reproducibility of manual cell counting with two computer-aided methods using ImageJ software.
• To evaluate the reliability of ImageJ's 'point picker' and 'particle analysis' tools for quantifying uNK cells.
• To determine the optimal method for assessing uNK cell density in endometrial immunohistochemistry.

Main Methods:

• Immunohistochemistry for CD56(+) uNK cells on human endometrium.
• Manual counting using a tally counter and graticule.
• Computer-aided counting using ImageJ 'point picker' and 'particle analysis' tools.
• Statistical analysis including coefficients of variation (CV) and Bland-Altman plots for interobserver variability.

Main Results:

• Computer-aided methods (ImageJ point picker and particle analysis) showed significantly lower interobserver CVs than manual counting.
• Interobserver CVs for manual counting were 8.2% (6.5%), while ImageJ methods yielded 6.1% (3.3%) and 4.7% (3.9%).
• Mean inter- and intra-observer CVs for %uNK were improved with ImageJ analysis, ranging from 6.8% (4.3%) to 10.3% (6.6%).
• Bland-Altman analysis confirmed no systematic differences in cell counts across methods relative to cell numbers.

Conclusions:

• Computer-aided image analysis with ImageJ offers superior reproducibility for assessing uNK cell density compared to manual counting.
• ImageJ tools provide a more reliable and objective method for quantifying uNK cells in immunohistochemistry.
• This improved methodology enhances the accuracy of research involving uNK cell density in diverse endometrial tissues.