Perineal length among Vietnamese women

Vietnamese clinicians routinely perform episiotomies in the belief that 3rd-4th degree tears may be prevented, based partly on the view that Vietnamese women have a short perineal length that puts them at increased risk of tears. However, there is no evidence to suggest Vietnamese women have a short perineum compared with other populations. We aimed to determine the mean perineal length among Vietnamese women in early labor and in the second stage, and to compare this to findings from similar studies in other populations.

We undertook an observational study in a tertiary obstetric hospital in Vietnam from October 2014 to June 2015. Pregnant women who presented in early labor with a live singleton cephalic presentation at ≥37 weeks gestation were eligible. Perineal length was measured early in the 1st stage of labor (≤4 cm dilation) and in 2nd stage of labor (10 cm dilation). Mean perineal length was compared to other populations using t-tests.

Of 395 women, 159 (40.3%) were nulliparous and 236 (59.8%) multiparous. Overall the mean perineal length in early labor was 3.4 cm (±0.4), and did not differ by parity. Mean perineal length among Vietnamese women was significantly shorter (P < 0.001) than other populations (means 3.8-4.6 cm). Among 365 women who reached 2nd stage the mean perineal length was 4.3 cm (±0.6).

The perception that Vietnamese women have a relatively shorter perineal length appears to have some basis and outcomes reported from episiotomy trials may not be generalizable to Vietnamese women.