Compared with planned repeat low-transverse cesarean section, vaginal birth after cesarean section (VBAC) is not associated with increased risk of maternal or neonatal mortality (strength of recommendation [SOR]: B). Morbidity is slightly increased, as evidenced by higher uterine rupture rates and some neonatal outcome measures (SOR: B)

Crawford, Paul

Kaufmann, Leonora

University of Missouri: MOspace

VOL 55, NO 2 / FEBRUARY 2006 149w w w. j f p o n l i n e . c o mCLINICAL INQUIRIESThe most recent Cochrane Reviewfound that both VBAC and repeat low-transverse cesarean section have benefitsand risks associated with them; however,after reviewing the limited data, theyconcluded that no trial exists to ade-quately help women and their caregiversmake an informed decision between thetwo.2 A strong theme in the CochraneReview, echoed in most reviews, was the■ Evidence summaryContrary to the goals of Healthy People2010, the rate of cesarean sections isincreasing.1 The repeat cesarean rate forlow-risk women of all ages and racialgroups is now 88.7%, the highest ratesince the Centers for Disease Control andPrevention (CDC) began tracking the sta-tistic in 1989. Is VBAC safe, or is a trial oflabor no longer supported by the data? How safe is vaginal birth after cesareansection for the mother and fetus?Compared with planned repeat low-transversecesarean section, vaginal birth after cesarean section (VBAC) is not associated with increasedrisk of maternal or neonatal mortality (strength ofrecommendation [SOR]: B). Morbidity is slightlyincreased, as evidenced by higher uterine rupture rates and some neonatal outcome measures (SOR: B). E V I D E N C E - B A S E D A N S W E RRisks of C-section and labor must be considered when counseling regarding route of deliveryAnother question to pose is: how safe is repeatcesarean section for the mother and fetus? Howmuch do morbidity and mortality increase witheach new intra-abdominal procedure? Each timethe belly is opened there is new scar, withincreased likelihood of adhesions and potential forfuture bowel obstruction. Consider these riskswhen counseling regarding route of delivery. Riskof uterine rupture appears to be higher in trials oflabor (and confers a statistically significant butsmall increase in morbidity but not mortality).However, the uterine scar can silently fail withoutlabor—as is sometimes discovered at a scheduledrepeat section, usually without untoward effects onmother or fetus.Remember that you are sending a youngwoman home with a new baby to care for (alongwith other children) and a major abdominal procedure (through an old scar) to recover from,which one could certainly define as morbidity.Cesarean section is an important tool, but we must be careful to practice best possible care andconsider all patient factors and preferences. Anddata are still lacking to support the notion thatVBAC is unsafe.Lynda DeArmond, MDWaco Family Practice Residency Program, Waco, TexasC L I N I C A L C O M M E N T A R YPaul Crawford, MDEglin Air Force Base Family Medicine Residency, Eglin AFB, FloridaLeonora Kaufmann, MLISCarolinas Health Care System, Charlotte, NC150 VOL 55, NO 2 / FEBRUARY 2006  THE JOURNAL OF FAMILY PRACTICECLINICAL INQUIRIESabsence of high-quality prospective ran-domized data.In an attempt to quantify the risks ofVBAC, a systematic review determinedthat attempted VBAC, compared withrepeat low-transverse cesarean section,increased the risk of uterine rupture by 2.7per 1000 cases (95% confidence interval[CI], 0.73–4.73).3 This additional risk rateis often quoted in VBAC reviews and wascited in the Agency for HealthcareResearch and Quality evidence report; it isbased on 1 prospective, nonrandomizedcohort trial and 1 retrospective cohortstudy.4,5No randomized controlled trials existfor determining maternal safety of VBAC,although another recent systematic reviewfound 2 nonrandomized prospective trialsof sufficient quality to analyze. Theauthors concluded there were “no statisti-cally significant differences betweenplanned elective repeat cesarean sectionand planned VBAC.”6 Upon closer reviewin PubMed, one of the cited studies did notstudy 312 patients for VBAC outcomes asalleged; rather, it investigated patient atti-tudes towards VBAC.7Since publication of that review, alarge, multicenter, prospective, nonran-domized trial involving 33,699 patientsfound no significant difference betweenVBAC and planned cesarean for hyster-ectomy (0.2% vs 0.3%; odds ratio[OR]=0.77; 95% CI, 0.51–1.17), maternaldeath (0.02% vs 0.04%; OR=0.38; 95%CI, 0.1–1.46), and neonatal death (0.08%vs 0.05%; OR=1.82; 95% CI, 0.73–4.57).8Significant associations were found foruterine rupture rates in spontaneous labor(24/6685 [0.4%] vs no cases; numberneeded to harm [NNH]=279) and neona-tal hypoxic-ischemic encephalopathy (0.46cases per 1000 vs no cases; NNH=2174).8A retrospective Canadian cohort trialof 308,755 women also demonstrated anassociation of VBAC with uterine rupture(0.65% of trial-of-labor cases; OR=2.38;95% CI, 2.12–2.67), and a trend towardshigher maternal mortality in the cesareangroup (1.6 per 100,000 for VBAC vs 5.6per 100,000 for planned cesarean;OR=0.32; 95% CI, 0.07–1.47).9The effect of VBAC on neonatal mor-bidity and mortality is unclear. In contrastto the negative larger trial,8 a smaller retro-spective cohort of 24,529 births found ahigher association of perinatal death fortrial of labor (adjusted OR=11.7; 95% CI,1.4–101.6).10 The perinatal death rate wassimilar to rates in nulliparous women.Regarding morbidity, one retrospectivecohort trial showed VBAC was associatedwith an increase in neonatal sepsis (1% vs0%; CI not given) compared with plannedcesarean, but VBAC resulted in less tran-sient tachypnea (5% vs 7%) and hyper-bilirubinemia (2% vs 6%).11Recommendations from othersBoth the American College of Obstetriciansand Gynecologists and the Society ofObstetricians and Gynecologists ofCanada state that women with 1 previouslow-transverse cesarean section should beoffered a trial of labor after appropriatecounseling of the risks and benefits.12,13Furthermore, induction with oxytocin isallowed, but the use of prostaglandins isnot recommended. Based on expert opin-ion, both organizations encourage VBAConly in institutions staffed with surgeonsand anesthesiologists immediately avail-able to provide emergent cesarean.R E F E R E N C E S1. Menacker F. Trends in cesarean rates for first birthsand repeat cesarean rates for low-risk women: UnitedStates, 1990–2003. Natl Vital Stat Rep 2005; 54:1–8.2. Dodd J, Crowther C, Huertas E. Guise J, Horey D.Planned elective repeat caesarean section versusplanned vaginal birth for women with a previous cae-sarean birth. Cochrane Database Syst Rev 2005;(4):CD004224.3. Guise J, McDonagh M, Osterweil P, Nygren P, Chan B,Helfand M. Systematic review of the incidence andconsequences of uterine rupture in women with previ-ous caesarean section. BMJ 2004; 329:19–25.4. Vaginal Birth After Cesarean (VBAC). Summary.Evidence Report/Technology Assessment, No. 71.AHRQ publication 03-E017. Rockville, Md: Agency forHealthcare Research and Quality; 2003. Available at:www.ahrq.gov/clinic/epcsums/vbacsum.htm.Accessed on January 9, 2006. 5. McMahon MJ, Luther ER, Bowes WA, Olshan AF.Comparison of a trial of labor with an elective secondcesarean section. N Engl J Med 1996; 335:689–695. Vaginal birth aftercesarean does notincrease risk of mortality to themother or infant;morbidity may beslightly increasedFAST TRACKHow safe is vaginal birth after cesarean? ▲VOL 55, NO 2 / FEBRUARY 2006 1516. Dodd J, Crowther C. Vaginal birth after Caesarean ver-sus elective repeat Caesarean for women with a singleprior Caesarean birth: a systematic review of the liter-ature. Aust N Z J Obstet Gynaecol 2004; 44:387–391.7. Abitbol MM, Castillo I, Taylor UB, Rochelson BL,Shmoys S, Monheit AG. Vaginal birth after cesareansection: the patient’s point of view. Am Fam Physician1993; 47:129–134.8. Landon M, Hauth J, Leveno K, et al, for the NationalInstitute of Child Health and Human DevelopmentMaternal-Fetal Medicine Units Network. Maternal andperinatal outcomes associated with a trial of labor afterprior cesarean delivery. N Engl J Med 2004;351:2581–2589.9. Wen S, Rusen I, Walker M, et al, for the MaternalHealth Study Group, Canadian Perinatal SurveillanceSystem. Comparison of maternal mortality and mor-bidity between trial of labor and elective cesarean sec-tion among women with previous cesarean delivery.Am J Obstet Gynecol 2004; 191:1263–1269. 10. Smith G, Pell J, Cameron A, Dobbie R. Risk of perina-tal death associated with labor after previous cesareandelivery in uncomplicated term pregnancies. JAMA2002; 287:2684–2690.11. Hook B, Kiwi R, Amini S, Fanaroff A, Hack M. Neonatalmorbidity after elective repeat cesarean section andtrial of labor. Pediatrics 1997; 100:348–353.12. American College of Obstetricians and GynecologistsCommittee on Practice Bulletins—Obstetrics. ACOGPractice Bulletin. Vaginal Birth After Cesarean Delivery.Obstet Gynecol 2004; 104:203–212. 13. Martel M, MacKinnon C, and the Clinical PracticeObstetrics Committee, Society of Obstetricians andGynaecologists of Canada. Guidelines for vaginal birthafter previous Caesarean birth. J Obstet Gynaecol Can2005; 27:164–188.A C K N O W L E D G M E N T SThe opinions and assertions contained herein are the pri-vate views of the author and are not to be construed as offi-cial, or as reflecting the views of the US Air Force medicaldepartment or the US Air Force at large. FAMILYPRACTICETHE JOURNAL OFTHE JOURNAL OF FAMILY PRACTICE uses a simplified rating system called the Strength of Recommendation Taxonomy(SORT). More detailed information can be found in the February 2003 issue,“Simplifying the language of patient care,”pages 111–120.Strength of Recommendation (SOR) ratingsare given for key recommendations for readers.SORs should be based on the highest-quality evidence available.A Recommendation based on consistent and good-quality patient–oriented evidence.B Recommendation based on inconsistent or limited-quality patient-oriented evidence.C Recommendation based on consensus, usual practice,opinion, disease-oriented evidence, or case series for studies of diagnosis, treatment, prevention, or screeningLevels of evidence determine whether a studymeasuring patient-oriented outcomes is ofgood or limited quality, and whether the resultsare consistent or inconsistent between studies.STUDY QUALITY1—Good-quality, patient-oriented evidence (eg, validated clinical decision rules, systematic reviews and meta-analyses of randomized controlled trials[RCTs] with consistent results, high-quality RCTs, ordiagnostic cohort studies)2—Lower-quality patient-oriented evidence (eg, unvalidated clinical decision rules, lower-quality clinical trials, retrospective cohort studies, case controlstudies, case series)3—Other evidence (eg, consensus guidelines, usual practice, opinion, case series for studies of diagnosis,treatment, prevention, or screening)Consistency across studies Consistent—Most studies found similar or at least coherent conclusions (coherence means that differencesare explainable); or If high-quality and up-to-date systematic reviews or meta-analyses exist, they supportthe recommendationInconsistent—Considerable variation among study findingsand lack of coherence; or If high-quality and up-to-date systematic reviews or meta-analyses exist, they do not find consistent evidence in favor of the recommendationEvidence-based medicine ratings

How safe is vaginal birth after cesarean section for the mother and fetus?

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