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Updated: Feb 4, 2026

Long-term High-Resolution Intravital Microscopy in the Lung with a Vacuum Stabilized Imaging Window
Published on: October 6, 2016
[Obstetrical anal sphincter injuries and vacuum-assisted delivery at term in primiparas]
N Bourgon1, N Mottet1, A Bourtembourg1
1Pôle Mère-Femme, CHRU Besançon, 3, boulevard Fleming, 25000 Besançon, France.
Objectives:
Operative Vaginal Delivery (OVD) is subject to a risk of perineal tears especially of Obstetrical Anal Sphincter Injuries (OASIS) that are associated with more complications and impaired quality of life. The main objective of this study was to compare the rate of OASIS in primipara at term with fetus in cephalic presentation depending on the type of delivery: OVD using vacuum extractor and spontaneous delivery.
Methods:
This is a single-center retrospective study between 01/01/2010 and 12/31/2014 including all primipara who delivered vaginally at term, a single and living fetus in cephalic presentation. Perineal lesions were classified according to the WHO classification. The primary endpoint was the proportion of OASIS.
Results:
3552 patients were included: 2496 spontaneous deliveries (SD) and 1056 OVD (29.72 %). There were twenty sphincter tears (0.56 %): 7 in SD group (0.28 %) and 13 in OVD (1.23 %), P<0.0001, OR=5.10 [2.00; 12.99]. Other risk factors associated with OASIS in univariable analysis were: maternal age (≥30 years), duration of expulsive efforts (≥20min) and a birth weight≥4000g.
Conclusion:
In these patients, the risk of OASIS in case of AI increases by a factor of 5;10. The high rate of AI in these patients exposes them to a real risk of OASIS. However, the proportion of OASIS in this group remains lower than those reported in the literature and is barely higher than the national overall rate, despite a very restrictive policy of the use of episiotomy.
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