Trial of Labor After Cesarean Section (TOLAC): Updated Clinical
Recommendations
Desiree Lie, MD, MSEd
Introduction and Background
During the Clinical Update Recommendations Session of the 2005 Annual
American Academy of Family Physicians (AAFP) Scientific Assembly, Eric Wall,
MD, MPh, Clinical Associate Professor, Departments of Family Medicine,
Public Health, and Preventive Medicine, Oregon Health and Sciences
University, Portland, Oregon, discussed evidence for and controversies
surrounding a Trial of labor after cesarean section (TOLAC).[1] Twenty-six
percent of all births in the United States now result in cesarean section,
and this rate has been rising steadily in recent years. However, the rate of
vaginal birth after cesarean section (VBAC) has been declining steadily.
Among women with previous cesarean section, the likelihood of VBAC was 9% in
2003 compared with 19% in 1989.
AAFP Guidelines for TOLAC
Guidelines for TOLAC, based on patient-centered outcomes (morbidity,
mortality, symptoms, cost, and quality of life), were developed by an AAFP
Task Force and published on the AAFP Web site in July 2005.[2] The
guidelines apply to women with a history of 1 cesarean section and low
transverse incision. The grade levels of the evidence used in the guidelines
are as follows:
Grade A -- Good-quality studies with patient-oriented evidence
Grade B -- Inconsistent or limited patient-oriented evidence
Grade C -- Case series, consensus, usual practice or opinion
A Maternity Care Facility is defined as a site with capability for cesarean
section. Labor at home and home deliveries are excluded from the guidelines.
The AAFP guidelines were based on an extension of the Agency for Healthcare
Quality and Research AHRQ Evidence Report Number 71.[3] A total of 1651
studies on the topic were identified. Of these, only 180 studies were
selected as being of sufficient quality to be included in the
recommendations. Studies up to March 2004 were included in the analysis.
The recommendations and grade of evidence are summarized as follows by Dr.
Wall:[2]
Recommendation 1. All women with 1 previous cesarean delivery with a low
transverse incision are candidates for and should be offered TOLAC (grade
A).
Recommendation 2. Patients desiring TOLAC should be counseled that their
chances of a successful VBAC is influenced by several factors. Positive
factors include maternal age less than 40 years; prior vaginal delivery,
particularly prior successful VBAC; favorable cervical factors; and
nonrecurrent indication for cesarean delivery. Negative factors include
increased number of prior cesarean deliveries, gestational age over 40
weeks, birth weight over 4000 g, and induction or augmentation of labor
(grade B).
Recommendation 3. Prostaglandins should not be used for cervical ripening or
induction with TOLAC because they increase the risk for uterine rupture and
reduce the rate of successful vaginal delivery (grade B).
Recommendation 4 (the most controversial). TOLAC should not be restricted to
facilities with surgical teams present throughout labor because there is no
evidence that these additional resources result in improved outcomes. A
management plan for uterine rupture and other potential emergencies
requiring rapid cesarean section should be available and documented for each
woman undergoing TOLAC. This recommendation differs from the current
American College of Obstetrics and Gynecology (ACOG) guidelines and
policy[4] (grade C).
Recommendation 5. All factors that may affect a woman's decision to undergo
TOLAC should be explored, including recovery time and safety. However, the
impact of counseling on maternal decision-making is unclear, as little
evidence is available (grade C).
Summary of the Literature
Results of the AAFP Task Force literature review were summarized by Dr. Wall
and compared with the 2003 AHRQ report, [3] the main outcomes of which
comprised uterine rupture and mortality. Seventy-six percent of women
undergoing TOLAC are likely to succeed. Seven observational studies found a
reduced success rate (63%) when induction with oxytocin or augmentation was
used, and success was reduced even further to 51% if prostaglandins were
used for induction. Risk for uterine rupture increased slightly with TOLAC
when induction or augmentation was used.
Maternal death and infant mortality did not differ between TOLAC and
repeated cesarean section. Infection rates were reported as higher with
failed TOLAC than with repeated cesarean section (8% vs 3.5%). Risk for
uterine rupture was estimated at 4.8 per 10,000 women with or without TOLAC.
Risk for infant death from uterine rupture was reported at 1.5/100,000.
There was no literature on quality-of-life issues related to VBAC.
Risk-assessment tools (2 validated scoring systems were identified)[5, 6]
were only partially useful in predicting successful vaginal delivery.
Individual factors found to be associated with improved outcomes included
demographic (younger than 40 years), delivery (spontaneous labor,
nonrecurrent indication for delivery), medical (absence of diabetes) and
cervical factors. Overall, teaching hospitals had a higher success rate with
TOLAC than did community hospitals. The influence of TOLAC counseling on
patient decision-making was unclear, as reported in 1 recent review.[7] Dr.
Wall suggested that additional factors to consider include perceived
recovery time, presence of children at home, partner availability, perceived
breastfeeding success, and safety.
Future Research Agenda
Given the limitations of the existing literature,[8,9] Dr. Wall outlined
issues for a future research agenda:
The definition of uterine rupture should be standardized. Definitions are
currently inconsistent across studies. For example, uterine dehiscence is
included within the definition for some studies, making comparisons across
studies challenging.
Validated instruments for measuring quality of life for mothers (including
ability to care for the family after delivery) are not available. Long-term
issues, such as pelvic floor function and, again, impact on families, are
not considered.
Development of decision support and shared decision-making tools is needed.
Specific management plans appropriate for uterine rupture should be
developed. It is not certain from the literature if more rapid intervention
improves outcomes during labor.
New technologies should be aimed at identifying women at high risk for TOLAC
failure and should increase the ability to predict morbidity and uterine
rupture (eg, locating the placenta with imaging, or examining the thickness
of the lower uterine wall).
Subsequent Data
Dr. Wells concluded by summarizing a recent publication,[10] not included in
the AAFP Task Force review, in which vaginal delivery was attempted by
17,898 women, and 15,801 women has elective repeated cesarean delivery
without labor. Symptomatic uterine rupture occurred in 124 women who
underwent a trial of labor (0.7%). Hypoxic-ischemic encephalopathy occurred
in no infants whose mothers underwent elective repeated cesarean delivery
and in 12 infants born at term whose mothers underwent a trial of labor
(P<.001). Seven of these cases of hypoxic-ischemic encephalopathy followed
uterine rupture (absolute risk, 0.46 per 1000 women at term undergoing a
trial of labor), and 2 involved death of the infant.
The rate of endometritis was higher in women undergoing TOLAC than in women
undergoing repeated elective cesarean delivery (2.9% vs 1.8%), as was the
rate of blood transfusion (1.7% vs 1.0%). The frequency of hysterectomy and
of maternal death did not differ significantly between groups (0.2% vs 0.3%,
and 0.02% vs 0.04%, respectively). The study concluded that TOLAC is
associated with a greater perinatal risk than is elective repeated cesarean
delivery without labor, although absolute risks are low. This information is
relevant for counseling women about their options after cesarean section.
References
Wall EM. Clinical recommendations update: Trial of labor after C-section.
Programs and abstracts of the American Academy of Family Physicians Annual
Scientific Assembly; September 28-October 2, 2005; San Francisco,
California. Program 31.
American Academy of Family Physicians. Trial of labor after cesarean
(TOLAC), formerly trial of labor versus elective repeat cesarean section for
the woman with a previous cesarean section; March 2005. Available at
http://www.aafp.org/x1597.xml. Accessed November 4, 2005.
Guise JM, McDonagh M, Hashima J, et al. Vaginal birth after cesarean section
(VBAC). Evidence Report/Technology Assessment No. 71 (prepared by the Oregon
Health & Science University Evidence-based Practice Center under contract
No. 290-97-0018). AHRQ Publication No. 03-E018. Rockville, MD: Agency for
Healthcare Research and Quality, 2003.
American College of Obstetricians and Gynecologists. ACOG Practice Bulletin
#54: Vaginal birth after previous cesarean delivery. Available at
http://pt.wkhealth.com/pt/re/ajog/abstract.00000447-200511000-00011.htm;jsessionid=DBKZ8BT7CEy89FgnOOeepRojGk8polr17kqEk46UqU1XaInH2Cck!958525354!-949856144!9001!-1.
Accessed November 20, 2005.
Flamm B, Geiger A. Vaginal birth after cesarean delivery: an admission
scoring system. Obstet Gynecol. 1997;90:907-910.
Troyer L, Parisi V. Obstetric parameters affecting success in a trial of
labor: designation of a scoring system. Am J Obstet Gynecol.
1992;167:1099-1104.
Eden KB, Hashima JN, Osterweil P, Nygren P, Guise JM. Childbirth preferences
after cesarean birth: a review of the evidence. Birth. 2004;31:49-60.
Dodd C, Crowther J. Vaginal birth after Caesarean versus elective repeat
Caesarean for women with a single prior Caesarean birth: A systematic review
of the literature. Aust N Z J Obstet Gynaecol. 2004;44:387-391.
Guise JM, Berlin M, McDonagh M, Osterweil P, Chan B, Helfand M. Safety of
vaginal birth after cesarean: a systematic review. Obstet Gynecol.
2004;103:420-429.
Landon MB, Hauth JC, Leveno KJ, et al. Maternal and perinatal outcomes
associated with a trial of labor after prior cesarean delivery. N Engl J
Med. 2004;351:2581-2589.
Leanne Wynne
Midwife in charge of "Women's Business"
Mildura Aboriginal Health Service Mob 0418 371862
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