Original Article

International Urogynecology Journal

, Volume 24, Issue 5, pp 769-774

First online:

Obstetric anal sphincter injuries in vaginal delivery of twins: associated risk factors and comparison with singletons

  • Shay PoratAffiliated withDepartment of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto Email author 
  • , David BaudAffiliated withDepartment of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto
  • , Dan FarineAffiliated withDepartment of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Introduction and hypothesis

Risk factors related to obstetric anal sphincter injuries (OASIS) are known for singleton deliveries. No study to date has described the rate and risk factors involved in twin deliveries.

Methods

We conducted a retrospective cohort study (1985–2010) of all vaginal twin and singleton deliveries in a single tertiary center. The adjusted odds ratio (OR) for OASIS at delivery was estimated using the logistic regression model.

Results

The study comprised 1,538 and 91,312 patients with vaginal twin and singleton delivery, respectively. Twenty twin (1.27 %) and 2,331 (2.55 %) singleton deliveries were complicated with OASIS. The following OASIS-associated risk factors were shared by both populations: nulliparity [twins adjusted OR 5.9, 95 % confidence interval (CI) 1.7–20.9; singletons adjusted OR 3.9, 95 % CI 3.5–4.4), occipitoposterior (OP) position (twins adjusted OR 3.00, 95 % CI 1.1–8.0; singletons adjusted OR 1.6, 95 % CI 1.3–2.00), birthweight (for each 100 g) (twin adjusted OR 1.1, 95 % CI 1.0–1.2; singletons adjusted OR 1.07, 95 % CI 1.06–1.08), and instrumental delivery (twins adjusted OR 4.3, 95 % CI 1.2–15.4, singletons adjusted OR 2.4, 95 % CI 2.2–2.6).

Conclusions

Risk factors of nulliparity, OP position, large fetal size, and instrumental delivery were shared by both twin and singleton deliveries. These data will be useful in counselling women carrying twins who intend to deliver vaginally.

Keywords

Anal sphincter OASIS Singleton Twin Vaginal delivery