Delivery after previous Caesarean section
|Vaginal birth after caesarean|
- Vaginal birth after Caesarean section (VBAC)
- Elective repeat Caesarean section (ERCS)
Both have higher risks than a vaginal birth with no previous Caesarean section. Criteria for making VBAC include that the previous Caesarean section should be a low transverse one. VBAC confers a higher risk for mainly uterine rupture and perinatal death of the child than ERCS. Furthermore, opting for VBAC results in 20-40% of times in that Caesarean section is performed eventually anyway, with greater risks for complications in an emergent repeat Caesarean section than in an ERCS. On the other hand, VBAC confers less maternal morbidity and a decreased risk of complications in future pregnancies than ERCS.
- 1 Technique
- 2 Selection criteria
- 3 VBAC versus no previous Caesarean section
- 4 Outcomes in VBAC versus ERCS
- 5 Society and culture
- 6 See also
- 7 References
- 8 External links
For a VBAC, depending on the provider, special precautions may be encouraged during a trial of labor following a Caesarean section, including IV or IV port placement, continuous or intermittent fetal monitoring, and conservative or absent labor induction and augmentation using chemical stimulants. Other intrapartum management options, including analgesia/anesthesia, are identical to those of any labor and vaginal delivery.
For ERCS, the choice of skin incision should determined by what seems to be most beneficial for the present operation, regardless of the choice of the previous location as seen by its scar. Hypertrophic scars are best excised because it gives a better cosmetic result and is associated with improved wound healing. On the other hand, keloid scars should have there margins left without any incision because of risk of tissue reaction in the subsequent scar.
According to the American Pregnancy Association, 90% of women who have undergone Caesarean deliveries are candidates for VBAC.
Factors favoring VBAC
- If the previous caesarean(s) involved a low transverse incision there is less risk of uterine rupture than if there was a low vertical incision, classical incision, T-shaped, inverted T-shaped, or J-shaped incision.
- A previous successful vaginal delivery (before or after the caesarean section) increases the chances of a successful VBAC.
- The reason for the previous caesarean section should not be present in the current pregnancy.
- Location at an institution equipped to respond to emergencies with physicians immediately available to provide emergency care.
Factors favoring ERCS
- The more caesarean sections that a woman has had, the less likely she will be eligible for VBAC.
- The presence of twins will decrease the likelihood of VBAC. Some doctors will still allow VBAC if the twins are positioned properly for birth.
- VBAC may be discouraged if there are other medical complications (such as diabetes), if the mother is over 40, if the pregnancy is post due date, or if the baby is malpositioned.
- VBAC after two or more prior lower uterine segment transverse CS is controversial. The Royal College of Obstetricians and Gynaecologists recommends that women with a prior history of even two previous uncomplicated low transverse Caesarean sections, in an otherwise uncomplicated pregnancy at term, with no contraindication for vaginal birth, may be considered suitable for planned VBAC.
According to ACOG guidelines, the following criteria may reduce the likelihood of VBAC success but should NOT preclude a trial of labor: having two prior caesarean sections, suspected fetal macrosomia (fetus greater than 4000-4500 grams in weight), gestation beyond 40 weeks, twin gestation, and previous low vertical or unknown previous incision type, provided a classical incision is not suspected.
Criteria definitely meaning ERCS
The presence of any of the following practically always mean that ERCS will be performed:
- Maternal request for elective repeat CS after counselling
- Maternal or fetal reasons to avoid vaginal birth in current pregnancy
- Previous uterine incision other than transverse segment including classical (longitudinal). The Royal College of Obstetricians and Gynaecologists recommends that women with a prior history of one classical (longitudinal) Caesarean section should give birth by elective repeat Caesarean section (ERCS).
- Previous complicated lower uterine segment transverse incision
- Unknown previous uterine incision
- Previous uterine rupture
- Previous hysterotomy or myomectomy entering the uterine cavity
VBAC versus no previous Caesarean section
VBAC, compared to vaginal birth without a history of Caesarean section, confers an increased risks for malpresentation, placenta previa, placenta accreta, prolonged labor, antepartum hemorrhage, uterine rupture, preterm birth, low birth weight, and stillbirth. However, some risks may be due to confounding factors related to the indication for the first Caesarean, rather than due to the procedure itself.
Outcomes in VBAC versus ERCS
VBAC and ERCS differ in outcomes on many end-points.
The American Congress of Obstetricians and Gynecologists (ACOG) states that VBAC is associated with decreased maternal morbidity and a decreased risk of complications in future pregnancies than ERCS.
A Caesarean section leaves a scar in the wall of the uterus which is considered weaker than the normal uterine wall. A VBAC carries a risk of uterine rupture of 22–74/10,000. There is virtually no risk of uterine rupture in women undergoing ERCS. If a uterine rupture does occur, the risk of perinatal death is approximately 6%. Mothers with a previous lower uterine segment cesarean are considered the best candidates, as that region of the uterus is under less physical stress during labor and delivery.
Risks to the child
A VBAC carries a 2–3/10,000 additional risk of birth-related perinatal death when compared with ERCS. The absolute risk of such birth-related perinatal loss is comparable to the risk for women having their first birth. Planned VBAC carries an 8/10,000 risk of the child developing hypoxic ischaemic encephalopathy, but the effect on the long-term outcome of the infant upon experiencing HIE is unknown.
On the other hand, attempting VBAC probably reduces the risk that the child will have respiratory problems after birth such as infant respiratory distress syndrome (IRDS), as rates are estimated at 2–3% with planned VBAC and 3–4% with ERCS.
Conversion from planned VBAC to Caesarean
The chance of having a successful VBAC is decreased by the following factors:
- Labor induction
- No previous vaginal birth
- Body mass index greater than 30
- Previous Caesarean for obstructed labour such as shoulder dystocia
- No epidural anaesthesia
- Previous preterm caesarean birth
- Cervical dilation at admission less than 4 cm
- Less than 2 years from previous Caesarean birth
- Advanced maternal age
- Non-white ethnicity
- Short stature
- Male infant
When the first four factors are present, successful VBAC is achieved in only 40% of cases. In contrast, in women with a previous Caesarean section who have had a subsequent vaginal birth, the chance of a successful vaginal birth again is estimated at 87–90%.
Risks in future pregnancies
ERCS, as compared to VBAC, further increases the risks of complications in future pregnancies. Complications whose risks significantly increase with increasing number of repeated Caesarean sections include:
- Placenta accreta, estimated to be present in 0.2%, 0.3%, 0.6%, 2.1%, 2.3% and 6.7% of women undergoing their first, second, third, fourth, fifth, and sixth or more Caesarean sections, respectively. According to the United States Agency for Healthcare Research and Quality, "Abnormal placentation has been associated with both maternal and neonatal morbidity including need for antepartum hospitalization, preterm delivery, emergent caesarean delivery, hysterectomy, blood transfusion, surgical injury, intensive care unit (ICU) stay, and fetal and maternal death and may be life-threatening for mother and baby."
- Hysterectomy, estimated to be performed in 0.7%, 0.4%, 0.9%, 2.4%, 3.5% and 9.0% of women undergoing their first, second, third, fourth, fifth, and sixth or more Caesarean sections, respectively
- Injury to bladder, bowel or ureter
- The need for postoperative ventilation
- Intensive care unit admission
- Blood transfusion requirement, estimated at 7%, 8% and 14% with a history of two, three and five Caesarean births, respectively.
- Duration of operative time and hospital stay.
Aside from uterine rupture risk, the drawbacks of VBAC are usually minor and identical to those of any vaginal delivery, including the risk of perineal tearing. Maternal morbidity, NICU admissions, length of hospital stay, and medical costs are typically reduced following a VBAC rather than a repeat caesarean delivery.
Society and culture
While vaginal births after Caesarean (VBAC) are not uncommon today, the rate of VBAC has declined to include less than 10% of births after previous Cesarean. Although Caesarean deliveries made up only 5% of births overall in the USA until the mid-1970s, it was commonly believed that for women with previous Caesarean sections, "Once a Caesarean, always a Caesarean". A consumer-driven movement supporting VBAC changed medical practice and led to soaring rates of VBAC in the 1980s and early 1990s, but rates of VBAC dramatically dropped after the publication of a highly publicized scientific study showing worse outcomes for VBACs as compared to repeat Caesarean and the resulting medicolegal changes within obstetrics. In 2010, the National Institutes of Health, U.S. Department of Health and Human Services, and American Congress of Obstetrics and Gynecology all released statements in support of increasing VBAC access and rates.
Trends in the United States
Although caesarean sections made up only 5% of all deliveries in the early 1970s, among women who did have primary caesarean sections, the century-old opinion held, "Once a caesarean, always a caesarean." Overall, cesarean sections became so commonplace that the cesarean delivery rate climbed to over 31% in 2006. A mother-driven movement supporting VBAC changed standard medical practice, and rates of VBAC rose in the 1980s and early 1990s. However, a major turning point occurred in 1996 when one well publicized study in The New England Journal of Medicine reported that vaginal delivery after previous caesarean section resulted in more maternal complications than a repeat caesarean delivery. The American Congress of Obstetrics and Gynecology subsequently issued guidelines which identified VBAC as a high-risk delivery requiring the availability of an anesthesiologist, an obstetrician, and an operating room on standby. Logistical and legal (professional liability) concerns led many hospitals to enact overt or de facto VBAC bans. As a result, the rate at which VBAC was attempted fell from 26% in the early 1990s to 8.5% in 2006.
In March 2010, the National Institutes of Health met to consolidate and discuss the overall up-to-date body of VBAC scientific data and concluded, "Given the available evidence, trial of labor is a reasonable option for many pregnant women with one prior low transverse uterine incision.". Simultaneously, the U.S. Department of Health and Human Services Agency for Healthcare Research and Quality reported that VBAC is a reasonable and safe choice for the majority of women with prior caesarean and that there is emerging evidence of serious harms relating to multiple caesareans. In July 2010, The American Congress of Obstetricians and Gynecologists (ACOG) similarly revised their own guidelines to be less restrictive of VBAC, stating, "Attempting a vaginal birth after cesarean (VBAC) is a safe and appropriate choice for most women who have had a prior cesarean delivery, including for some women who have had two previous cesareans."
Enhanced access to VBAC has been recommended based on the most recent scientific data on the safety of VBAC as compared to repeat caesarean section, including the following recommendation emerging from the NIH VBAC conference panel in March 2010, "We recommend that hospitals, maternity care providers, health care and professional liability insurers, consumers, and policymakers collaborate on the development of integrated services that could mitigate or even eliminate current barriers to trial of labor." The U.S Department of Health and Human Services' Healthy People 2020 initiative includes objectives to reduce the primary caesarean rate and to increase the VBAC rate by at least 10% each.
The American Congress of Obstetricians and Gynecologists (ACOG) modified the guidelines on vaginal birth after previous Caesarean delivery in 1999, 2004, and again in 2010. In 2004, this modification to the guideline included the addition of the following recommendation:
Because uterine rupture may be catastrophic, VBAC should be attempted in institutions equipped to respond to emergencies with physicians immediately available to provide emergency care.
In 2010, ACOG modified these guidelines again to express more encouragement of VBAC, but maintained it should still be undertaken at facilities capable of emergency care, though patient autonomy in assuming increased levels of risk should be respected (ACOG Practice Bulletin Number 115, August 2010).
The recommendation for access to emergency care during trial of labor has, in some cases, had a major impact on the availability of VBACs to birthing mothers in the US. For example, a study of the change in frequency of VBAC deliveries in California after the change in guidelines, published in 2006, found the VBAC rate fell to 13.5% after the change, compared with 24% VBAC rate before the change. The new recommendation has been interpreted by many hospitals as indicating a full surgical team must be standing by to perform a Caesarean section for the full duration of a VBAC woman's labor. Hospitals that prohibit VBACs entirely are said to have a 'VBAC ban'. In these situations, birthing mothers are forced to choose between having a repeat Caesarean section, finding an alternate hospital in which to deliver their babies or attempting delivery outside the hospital setting.
Most recently, enhanced access to VBAC has been recommended based on updated scientific data on the safety of VBAC as compared to repeat Caesarean section, including the following recommendation emerging from the NIH VBAC conference panel in March 2010, "We recommend that hospitals, maternity care providers, health care and professional liability insurers, consumers, and policymakers collaborate on the development of integrated services that could mitigate or even eliminate current barriers to trial of labor." The U.S Department of Health and Human Services' Healthy People 2020 initiative includes objectives to reduce the primary cesarean rate and to increase the VBAC rate by at least 10% each.
ACOG recommends that obstetricians offer most women with one prior cesarean section with a low-transverse incision a trial of labor (TOLAC) and that obstetricians should discuss the risks and benefits of VBAC with these patients.
This VBAC success calculator https://mfmu.bsc.gwu.edu/PublicBSC/MFMU/VGBirthCalc/vagbirth.html is a useful educational tool (noted by the US Agency for Healthcare Research and Quality) for clinicians who are discussing the risks and benefits of VBAC with their patients.
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- www.caesarean.org.uk: Independent UK website providing information and support on caesarean and VBAC issues.
- med/3434 at eMedicine this is a good summary of the current knowledge and opinion on this subject.
- http://consensus.nih.gov/2010/vbacstatement.htm: Statement from panel of medical experts regarding VBAC safety.
- http://www.ahrq.gov/clinic/tp/vbacuptp.htm: Detailed summary of scientific research regarding the safety of VBAC and repeated Caesarean section is included in an evidence report pdf at the bottom of the page.
- http://www.acog.org/About_ACOG/News_Room/News_Releases/2010/Ob_Gyns_Issue_Less_Restrictive_VBAC_Guidelines: Updated ACOG guidelines regarding VBAC.
- http://www.guideline.gov/syntheses/printView.aspx?id=25231 : Comparison of the current ACOG (USA) and RCOG (UK) guidelines related to VBAC management.