An assessment of the accuracy of visual diagnosis of meconium-stained amniotic fluid

Objective: The assessment of meconium content in the amniotic fluid depends on visual observation by clinicians at the bedside. The aim of the present study was to compare visual evaluation of meconium-stained amniotic fluid with spectrophotometer evaluation. Study Design: Ten gram of meconium was added to 100 ml of amniotic fluid and mixed. The solution was serially two-fold diluted with amniotic fluid. The serially diluted tubes' absorbance spectrum was measured at 420 nm and thus a standard scale was established. Ninety five samples of meconium- stained amniotic fluid were collected from labouring women and the grade of meconium was deter- mined visually at the bedside. The samples' absorbance spectrum was measured at 420 nm and recorded. Spectrophotometer was considered gold standard and the ranges of optical density in the standard scale was used to test the accuracy of visual categorization of the samples. In the statistical analysis chi-square test was used and significance was p<0.05. Results: The accuracy rate of visual diagnosis of meconium-stained amniotic fluid were found as statistically significant (accuracy rate=54.74%, p<0.001). Visual evaluation was correct in 19.4% of thin, 53.1 % of moderate and 90.6% of thick meconium samples when examined with spectrophotometer. Conclusion: Visually diagnosed thin meconium can be moderate or thick meconium when examined objectively. The visual diagnosis at bedside is not always reliable and should be replaced with an objective method like spectrophotometry. (author)