Successful first vaginal birth after cesarean section: a predictor of reduced risk for uterine rupture in subsequent deliveries.
BACKGROUND
Uterine rupture is a catastrophic obstetric complication, most often associated with a preexisting cesarean section scar. Although a vaginal birth after a cesarean is considered safe in modern obstetrics, it is not known whether repeated VBACs increase the risk of rupture, or whether the first VBAC proves the strength and durability of the scar, predicting further successful and less risky vaginal deliveries.


OBJECTIVE
To evaluate the effect of repeated vaginal deliveries on the risk of uterine rupture in women who have previously delivered by cesarean section.


METHODS
In this retrospective study, 26 VBAC deliveries complicated by uterine rupture were matched for age, parity, and gravidity with 66 controls who achieved VBAC without rupture. The histories, demography, pregnancy, labor and delivery records, as well as neonatal outcome were compared.


RESULTS
We found that the risk of rupture decreases dramatically in subsequent VBACs. Of the 40 cases of uterine rupture recorded during the 18 year study period, 26 occurred during VBAC deliveries. Of these, 21 were complicated first VBACs. We also found that the use of prostaglandin-estradiol, instrumental deliveries, and oxytocin had been used significantly more often during deliveries complicated with rupture than in VBAC controls.


CONCLUSIONS
Once a woman has achieved VBAC the risk of rupture falls dramatically. The use of oxytocin, PGE2 and instrumental deliveries are additional risk factors for rupture, therefore caution should be exerted regarding their application in the presence of a uterine scar, particularly in the first vaginal birth after cesarean.
Shimonovitz
S
S
Department of Obstetrics and Gynecology, Hadassah University Hospital, Mt. Scopus, Jerusalem, Israel.
Botosneano
A
A
Hochner-Celnikier
D
D
D000328:Adult; D005113:Extraction, Obstetrical; D005260:Female; D006801:Humans; D010121:Oxytocin; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D014597:Uterine Rupture / Q000209:etiology* / Q000517:prevention & control; D016064:Vaginal Birth after Cesarean / Q000009:adverse effects*
D010121:Oxytocin