Antenatal Anovaginal Distance, a Potential Indicator of Perineal Damage during Pregnancy

Abstract

Background/objectives: Perineal injuries, including episiotomies and spontaneous tears, are common complications during childbirth, often leading to significant discomfort and prolonged recovery for women. This retrospective observational cohort study aimed to explore the relationship between antenatal anovaginal distance (AVD) and the incidence of perineal injuries in a cohort of pregnant women evaluated for pelvic floor health at 28 to 32 weeks of gestation.

Methods: Conducted at the University Hospital of Padua over 18 months, the study included 416 women who underwent vaginal delivery at term. Based on AVD, the study participants were divided into two groups: AVD-N group, which included 252 patients with AVD ≥ 2 cm, and the AVD-R group, which included 164 with AVD < 2 cm. The results of the pelvic floor assessment and those related to childbirth were then examined in relation to AVD (reduced vs. normal).

Results: The study found that women with reduced AVD were more likely to experience perineal injuries. Specifically, the incidence of episiotomy and severe perineal tears (3rd and 4th degree) was significantly higher in the reduced AVD group (p < 0.05). Furthermore, a lower AVD was associated with increased perineal muscle hypertonicity and a higher likelihood of operative delivery with episiotomy. Logistic regression analysis confirmed that reduced AVD was an independent risk factor for perineal injuries, regardless of other maternal or neonatal characteristics.

Conclusions: These results suggest that AVD measurement during pregnancy may help identify women at higher risk of perineal trauma, enabling more personalized obstetric care to mitigate these outcomes.

Keywords: anovaginal distance; episiotomy; perineal health; perineal tear; pregnancy; vaginal delivery.

Figure 1

The distribution of AVD: (a)—by perineal tonicity, (b)—by type of delivery, (c)—by tear degree, (d)—by episiotomy.