Cervical lacerations are more frequently observed in nulliparas with obstetric anal sphincter injuries: evidence from a large cohort.

PURPOSE: Cervical lacerations, though infrequent, can lead to significant postpartum bleeding and maternal morbidity if undiagnosed. Obstetric anal sphincter injuries (OASIS) represent a more widely studied complication of vaginal delivery. However, the potential co-occurrence of OASIS and cervical lacerations has not been examined.

METHODS

A retrospective cohort study was conducted at a single university-affiliated medical center from January 2018 to July 2024. The study included term singleton cephalic pregnancies that reached full cervical dilatation, including vaginal deliveries and intrapartum cesarean deliveries performed after full dilatation. Deliveries involving preterm birth, multiple gestation, non-cephalic presentation, elective cesarean delivery, cesarean delivery before full dilatation, or incomplete records were excluded.

RESULTS

Among 22,220 term singleton cephalic deliveries reaching full cervical dilatation, 102 cases (0.46%) were complicated by OASIS. Cervical lacerations were significantly more frequent in women with OASIS compared to those without (4.0% vs. 0.4%, p < 0.001). When stratified by parity, this association was only evident among nulliparous women: 6.1% of nulliparas with OASIS had cervical lacerations versus 0.7% without OASIS (p = 0.001). No significant difference was found among multiparous women. Nulliparas with OASIS also experienced higher rates of vacuum-assisted delivery and postpartum haemorrhage (PPH).

CONCLUSION

Cervical lacerations were more frequently observed among nulliparous women with OASIS, suggesting a pattern of concurrent birth canal trauma. Incorporating routine cervical inspection during OASIS repair, particularly when performed in the operating theatre, may help reduce underdiagnosis of concurrent injury in this population.