OBJECTIVES:

To estimate the prevalence of perineal tears in patients which delivery was instrumented by vacuum and to identify the risk factors that lead to a tear in the anal sphincter.

MATERIAL AND METHOD:

Descriptive, cross-sectional, retrospective and observational study. All vacuum deliveries were selected among the instrumental deliveries of the population in a secondary care hospital in Mexico City. The inclusion criteria were women who delivered vaginally at term with sole and normoevolutive pregnancies. The perineal tears were classified according to WHO. The statistical analysis included the estimation of prevalences with their corresponding confidence intervals. Variables were described by means and standard deviations or absolute and relative frequencies. Tears were compared using χ2 tests considering a statistical significance of p < 0.05.

RESULTS:

The number of instrumented deliveries was 74 out of 708 cases of total deliveries, those with vacuum were 70 out of 74. Considering the instrumented deliveries with vacuum, the most prevalent tears were those of first and second degree with values of 40.0% (CI 29-51) and 38.6% (CI 27-50) respectively. There were not associated risk factors to severe perineal tears.

CONCLUSIONS:

Prevalence in the studied population was similar to developed countries and moderate tears are the most prevalent.

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