TITLE:
Transvaginal Ultrasonographic Measurement of Lower Uterine Segment in Term Pregnant Patients with Previous Cesarean Section
AUTHORS:
Anitha Thomas, Grace Rebekah, Reeta Vijayaselvi, Ruby Jose
KEYWORDS:
TOLAC, Transvaginal Ultrasonography, Scar Thickness
JOURNAL NAME:
Open Journal of Obstetrics and Gynecology,
Vol.5 No.11,
September
24,
2015
ABSTRACT: Background: With an aim to reduce the rates of repeat cesarean section in
women with a previous scar, prediction of scar rupture or dehiscence is
important. If we could predict the risk of rupture by measuring the scar
thickness closer to term, we could pursue a trial of scar safely. Aims: To
evaluate the use of ultrasound measured thickness of lower uterine segment as
one of the predictors of scar rupture or dehiscence in labour and establish a
cut off beyond which trial of labour can be attempted safely. Methodology: 187
randomly selected pregnant women with history of one previous cesarean section
in the past who satisfied the inclusion criteria, attending the outpatient
clinic over a period of six months, at a tertiary level teaching institution in
southern India were selected and counseled to undergo a transvaginal
measurement of the scar region. These women were then followed up until
delivery and the outcome of trial of scar, successful vaginal delivery, rupture
or dehiscence of uterus was analysed in relation to the scar thickness and
various other contributing factors. Results: 187 women with history of previous
cesarean section, attending the outpatient clinic were randomly chosen to
undergo trans vaginal scan at term. 52 underwent elective cesarean section and
135 went through trial of scar. The median cut-off of the lower uterine segment
in this study population of 135 was 2.4 mm. The sensitivity was 90.9%,
specificity was 43.5%, positive predictive value was 12.5%, and negative
predictive value was 98.3% at this cut-off for scar rupture or dehiscence. Conclusions:
The lower uterine scar thickness could be a useful tool to predict scar
rupture. This could aid in making decisions regarding induction of labour with
oxytocin in women with previous cesarean section.