Berks County Medical Society Medical Record Fall 2018 - 22

Reading Hospital/Tower Health

Student Sum mer Research Projects
TOLAC: Should They Be
Managed on A Different
Set of Rules?
A Prospective Study of TOLAC
Patients with a Modern
Definition of Labor Arrest

METHODS:

The objective of the study is to examine the effects of a modified
definition of labor arrest on successful delivery in Trial of Labor
After Cesarean (TOLAC) patients, and to determine whether this
definition should be implemented in clinical practice.

A prospective observational study was conducted. Multiparous
women of any age attempting TOLAC with singleton pregnancies
between gestational ages of 37 weeks 0 days and 41 weeks 6 days
with the spontaneous onset of labor were included in the study.
Patients were recruited from Women's Health Center at Reading
Hospital - Tower Health. Patients' medical charts were accessed
electronically via Epic. Comparisons were made between the route
of delivery, vaginal deliveries vs. cesarean sections, potential risk
factors of failed TOLAC and adverse maternal or neonatal events.
TOLAC success rates were calculated and compared to national
success rates of TOLAC, average 70%, as reported by ACOG.
Data on labor outcomes were reported and self-compared through
a Chi-square/Fisher's Exact test to a predicted C-section rate based
on restrictive labor curves defined by Friedman. Demographics,
time to each vaginal examination, cervical dilation and station at
each examination were extracted from the labor charts. Further
information regarding the type of delivery, the reason for delivery
route if other than routine vaginal delivery, and maternal morbidity
was analyzed. Information on the neonates included birth weight,
Apgar scores, delivery room treatment, neonatal morbidity
and mortality, NICU admission, diagnostic tests, therapeutic
interventions, and length of hospital stay. Only information relevant
to initial hospitalization was considered for both the neonate and the
mother.

BACKGROUND:

RESULTS:

In the 1950s, Dr. Emanuel Friedman defined labor arrest as
no cervical change over 2 hours with adequate contractions (> 200
Montevideo units) during the active phase of labor. This definition
of labor arrest has recently been challenged by the data showing
increased vaginal deliveries while applying less restrictive criteria for
labor arrest. Further retrospective data indicates the labor curves of
TOLAC patients, with or without previous vaginal deliveries, may
be similar to patients without a previous C-section. However, due
to a weaker lower uterine segment in TOLAC patients compared
with non-TOLAC laboring patients with an unscarred uterus, the
question becomes, should we manage TOLAC patients based on the
historical definition or based on emerging evidence. This new data
allows a maximum of 4 hours of sustained uterine contractions with
> 200 MVUs or a maximum of 6 hours of oxytocin augmentation if
the contraction pattern is not achieved. This study will observe the
labor curve in TOLAC patients and assess the risk factors for failed
TOLAC. The expectation is that applying less restrictive criteria for
labor arrest will increase the success of TOLAC, compared to the
national average of 70% as reported by ACOG, without increasing
the rate of complications, such as uterine rupture or poor neonatal
outcomes.

The results discussed are preliminary as the power analysis
calculated the adequate sample size to be 50 subjects. There were
41 eligible women attempting TOLAC. Study population included
32(78%) Hispanic/Latina subjects and 9 non-Hispanic/Latina
subjects, but missing detailed ethnicity data. Of these 41 women,
31(75.6%) had successful TOLAC while 10 (24.4%) failed followed
by C-section with indications of fetal intolerance of labor 60%,
arrest of decent 20%, failure to progress 20%. According to the
traditional 2-hour rule, 4 successful TOLAC patients could have
required C-section with 10% reduction in C-section rate after
applying less restrictive definition for labor arrest. Labor progresses
slowly from initial cervical dilatation (mean 2.8cm) to 5 cm with
mean (SD, median) duration of 514.8 (256.3, 483.5) min. The
longest duration from admission (mean cervical dilatation of 2.8cm)
to 5 cm was 1054 min or 17.6 hours, the shortest was 202 min
or 3.4 hours. After cervical dilatation reaches 7cm, labor typically
accelerates; it takes mean (SD, median) duration of 120.38 (91.61,
80.5) min from 7 to 10 cm. The longest duration from 7-10cm was
270 min or 4.5 hours, the shortest duration was 49 min. Of the 31
subjects with successful TOLAC, 13 (42%) were induced. No uterus
rupture occurred during the study. Mean (SD, median, min-max)
cervical dilatation at the first examination 2.8cm (1.64, 3, 0-6).
Mean (SD, median, min-max) length of first stage 12.2 h (5.1, 13,

by Cassandra Mitchell, Nathalia Arias-Alzate, Brandon
M. Lingenfelter, Jonathan Saperstein, Robert Squiers,
Peter F. Schnatz, John Dougherty, Gerald Ferry, MD,
Xuezhi (Daniel) Jiang

OBJECTIVE:

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Berks County Medical Society Medical Record Fall 2018

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