1. Williams ch.26 Prior Cesarean Delivery
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2. For many decades, a scarred uterus was believed to contraindicate labor out of fear of uterine rupture
Cragin (1916)
Once a cesarean, always a cesarean
When this statement was made, the classical vertical uterine incision was used almost universally
The ACOG (1998)
In the absence of a contraindication, a woman with one previous low-transverse cesarean delivery be counseled to attempt labor in a subsequent pregnancy
VBAC
Vaginal birth after cesarean
Pronounced : Vee back

3. Trial of labor versus repeat cesarean delivery
Candidates for a trial of labor
Labor and delivery considerations
Uterine rupture

4. Trial of labor versus repeat cesarean delivery

5. Risks and benefits Beginning in 1989, VBAC increased,
: A number of reports that suggested that
VBAC might be riskier than anticipated
Scott (1991) : 12 uterine rupture
Two women : hysterectomy
Three : perinatal death
Two infants : long-term neurological impairment
Porter and colleages (1998) : 26 uterine rupture
23% of the infants were dead or damaged (intrapartum asphyxia)
Fewer women with a prior cesarean incision attempting vaginal delivery
-> increased cesarean delivery rate

6. Magnitude of risk
Although uterine rupture and its complications clearly are increased with a trial of labor,
-> The absolute risk of complications is quite low
These factors should weigh only minimally in the decision to attempt VBAC
The absolute risk of uterine rupture resulting in death or injury to the fetus : about 1 per 1000
The major controversy surrounding the management thus stems from the question
: Is a 1 per 1000 risk of having an otherwise healthy
fetus die or be damaged as a result of a trial of
labor acceptable ?

7. Maternal morbidity
Maternal mortality : not appear to differ significantly compared with an elective repeat cesarean
Maternal morbidity : conflicting result
In 2000, Mozurkewich and Hutton
: about half required a blood transfusion or hysterectomy
compared with an elective repeat cesarean
In 2004, Landon
: the risks of transfusion and infection were significantly
greater for a trial of labor
In 1996, McMahon
: the major complication (hysterectomy, uterine rupture,
operative injury) were twice as common in a trial of labor
: fivefold greater at a vaginal delivery failed

8. Costs Grobman (2000), cohort of 100,000 DiMaio (2002) Clark (2000)
The safety of VBAC as well as cost effectiveness
Routine repeat cesarean for a second birth was calculated to result in an increased cost of $179million
DiMaio (2002)
Nearly $1100 higher for each elective repeat cesarean
Clark (2000)
The cost of long-term care for neurologically injured infants is taken into account, trial of labor is unlikely to be associated with a significant cost saving for the health care system

9. Elective repeat cesarean delivery
Preference
In spite of increased risks (anesthesia, hemorrhage, damage to the bladder and other organs, pelvic infection, scarring), an elective repeat cesarean is considered to be preferable to attempting a trial of labor
Frequent reasons
① the convenience of a scheduled delivery
② the fear of a prolonged and potentially dangerous labor
Abitbol (1993)
312 women studied, 125(40%) opted for a repeat cesarean
No complications in the elective cesarean group
Two unanticipated fetal deaths in the VBAC group
① Scheduled cesarean : 93% were satisfied with their choice
② Elected a trial of labor : only 53%
③ Uncomplicated trial of labor : 80%

10. Elective repeat cesarean delivery
Fetal maturity
If elective repeat cesarean delivery is planned, it is essential that the fetus be mature

11. Candidates for a trial of labor

13. Type of prior uterine incision

14. Type of prior uterine incision
The lowest risk of scar separation
: the lower uterine segment transverse scar
The highest rates of rupture
: the classical incision (extending into the fundus)
In about one third classical incision, the scar will rupture before the on set of labor
Not infrequently, rupture may take place several weeks before term
With uterine malformations, the risks for uterine rupture : as high as with a classical incision
In 1999, Ravasia
: 8% rupture with unicornuate, bicornuate, didelphic, septate uterus

15. Type of prior uterine incision
A prior vertical incision that did not extend into the fundus : the risk of uterine rupture is controversial
Martin and Shipp (1997)
: low-vertical uterine incision did not have an increased risk for rupture
The ACOG (2004)
: low-vertical incision without fundal extension may be candidates for VBAC
Previously sustained a uterine rupture are at increased risk for recurrence
A rupture confined to the lower segment : 6% recurrence risk
Prior rupture included the upper uterus : 32% recurrence risk

16. Closure of prior incision
Whether the risk of subsequent uterine rupture is related to the number of layers is controversial
Chapman (1997), Tucker (1993)
: no relationship between a one-and two-layer closure and risk of subsequent uterine rupture
Durnwald and Mercer (2003)
: single layer closure -> no increased risk of rupture, uterine dehiscence
Bujold (2002)
: single layer closure -> a fourfold increased risk of rupture compared with a double layer closure
Videaff and Lucas (2003)
: double layer closure -> wound healing have not demonstrated any advantages

17. Closure of prior incision
Healing of the cesarean incision
Willians (1921)
: By regeneration of the muscular fibers and
not by development of scar tissue
: Inspection of the unopened uterus at repeat c/sec
-> no trace of the former incision
-> almost invisible linear scar
Schwarz (1938)
: By fibroblast proliferation
: the proliferation of connective tissue is minimal,
-> the normal relation of smooth muscle to
connective tissue gradually is reestablished

18. Interdelivery interval
If the hysterotomy scar did not have sufficient time to heal
-> The risk of uterine rupture would be increased
Completer uterine involution and restoration of anatomy (by studies using MRI)
-> At least 6 months
Shipp (2001)
: Interdelivery intervals of 18months or less
-> threefold increased risk of symptomatic uterine
rupture

19. Number of prior cesarean incision
The risk of uterine rupture increases with the number of previous cesarean deliveries
Landon (2004)
: twice as high in women with multiple prior cesareans compared with only one (1.4% versus 0.7%)
Caughey (1999)
: five fold in two previous cesareans compared with only one (3.7% versus 0.8%)
Any previous vaginal delivery (before or after c/sec)
-> significantly improves the prognosis for a
subsequent successful VBAC
-> lowers the risk of subsequent uterine rupture
ACOG (2004)
: two prior low-transverse c/sec with a prior vaginal delivery
should be considered for VBAC

20. Indication for prior cesarean delivery
The success rate for a trial of labor depends to the indication for the previous c/sec
Wing and Paul (1999), O’Herlihy(1998)
: breech presentation -> 91% successful VBAC
: fetal distress -> 84% successful VBAC
: dystocia -> 68% successful VBAC
Hoskins and Gomez (1997)
(relation to cervical dilation)
: cervix 5cm or less -> 67% successful VBAC
: cervix 6 to 9cm -> 73% successful VBAC

21. Fetal macrosomia
Increasing fetal size would increase the risk of uterine rupture with VBAC
Zelop (2001)
: weighed less than 4000g -> 1.0% rupture
: Infants weighed at least 4000g -> 1.6% rupture
: birth weight exceeded 4250g -> 2.4% ruptuer
Elkousy (2003)
: no previous vaginal deliveries, the birthweight at
least 4000g
-> the doubled risk of uterine rupture

22. Maternal obesity Carroll (2003)
: As maternal weight increased, the rate of
VBAC success decreased
Edward (2003)
: Puerperal infection was higher in obese
women attempting a trial of labor

23. Labor and Delivery Considerations

24. Guidelines for women with a prior cesarean who have chosen a trial of labor (the ACOG,2002)
⑴ Prompt evaluation of the laboring patient must be
performed
⑵ Continuous electronic monitoring of fetal heart rate and
uterine contractions should be considered
⑶ Personnel familiar with the potential complications of a trial of
labor should be vigilant for nonreassuring fetal heart rate
patterns and inadequate progress of labor
⑷ Attempts should be limited to institutions with physicians
immediately available to provide emergency care

25. The ACOG (2002) recommend that the following issues be addressed before the ultimate decision to attempt a vaginal delivery
⑴ Advantages of a successful vaginal delivery, for
example, shorter postpartum hospital stay; less
painful, more rapid recovery; and others
⑵ Contraindications to a trial of labor, for example,
prior classical cesarean, placenta previa, and others
⑶ Risk of uterine rupture (approximately 1%)

26. ⑷ Increased risk of uterine rupture with more than one
prior cesarean delivery, attempts at cervical ripening
or labor induction, macrosomia, and oxytocin
augmentation
⑸ In the event of rupture, there is a 10 to 25 percent
risk of significant adverse fetal sequelae
⑹ Although catastrophic uterine rupture leading to
perinatal death or permanent neonatal injury is rare,
occurring less often than 1 per 1000 VBAC attempts,
it dose occur despite the best available resources

27. Cervical ripening and labor stimulation
Any attempt to induce cervical ripening or
to induce or augment labor
=> Increases the risk of uterine rupture in
women undergoing a trial of labor

28. Cervical ripening and labor stimulation
Oxytocin
Use of oxytocin to induce or augment labor has been implicated in uterine ruptures in women attempting VBAC
Oxytocin dose and duration correlated directly with uterine rupture
The ACOG (2002)
: Oxytocin may be used for both labor induction
and augmentation with close patient monitoring in
women with a prior cesarean delivery undergoing
a trial of labor

29. Cervical ripening and labor stimulation
Experiences at Parkland Hospital
: Between 1986 and 1990
1482 delivered vaginally,
uterine rupture : 1.5 per 1000
Another 307 women received oxytocin,
uterine rupture : 10 per 1000
=> Our experience with uterine ruptures led us to
the decision to discontinue the use of oxytocin
in women with prior cesarean deliveries

30. Cervical ripening and labor stimulation
Prostaglandins
Prostaglandins use in women attempting VBAC
-> increases the risk of uterine rupture
Ravasia (2000)
: the rate of uterine rupture was significantly
greater in the women treated with prostaglandin
E2 gel than in those having spontaneous labor
(2.9% versus 0.5%)
Lydon-Rochelle (2001)
: The risk of uterine rupture was nearly 16-fold greater for women undergoing induction of labor with prostaglandins compared with that of a repeated cesarean delivery

31. Epidural analgesia
The use of epidural analgesia for labor in women with a prior cesarean delivery was debated in the past
=> masking the pain of uterine rupture
However
Less than 10% of women with scar separation experience pain and bleeding
Fetal heart rate decelerations are the most likely sign of rupture
The ACOG (20020
Epidural analgesia may safely be used during a trial of labor
The anesthesia service be notified whenever a woman with a prior cesarean is admitted in active laobr

32. Uterine scar exploration
Surgical correction of a scar dehiscence is necessary only if significant bleeding is encountered
Asymptomatic separations
=> Do not generally require exploratory
laparotomy and repair

33. Uterine rupture

34. Classification Complete uterine rupture
All layer of the uterine wall separated
Incomplete uterine rupture (= uterine dehiscence)
Uterine muscle separated but visceral peritoneum is intact
Morbidity and mortality are appreciably greater when rupture is complete
The greatest risk factor for either complete or incomplete uterine rupture
=> Prior cesarean delivery

35. Diagnosis
The symptoms and physical findings may appear bizarre unless the possibility of uterine rupture is dept in mind
Hemoperitoneum
: Irritation of the diaphragm with pain referred to the chest
-> pulmonary or amnionic fluid embolism
Intrauterine pressure catheters
: Few women experience cessation of contractions following
uterine rupture
–> not shown to assist reliably in the diagnosis
The most common electronic fetal monitoring finding
: Sudden, severe heart rate decelerations
(late decelerations, bradycardia, undetectable fetal heart action)

36. Diagnosis Remarkably little appreciable pain or tenderness
Most women in labor are treated for discomfort with narcotics, lumbar epidural analgesia
The evident condition
Signs of fetal distress
Maternal hypovolemia from concealed hemorrhage
Pelvic examination
The fetal presenting part has entered the pelvis
-> Loss of station
If the fetus is partly or totally extruded from the site of rupture
-> the presentign part moved away from the pelvic inlet
-> a firm contracted uterus may be felt alongside the fetus

37. Prognosis
Rupture and expulsion of the fetus into the peritoneal cavity
-> the chances for intact fetal survival are dismal
-> mortality rates : 50~75%
Fetal condition depends on how much placenta is intact
-> likely decreases over minutes
If the fetus is alive at the time of rupture
-> immediate delivery, most often by laparotomy
The maternal prognosis
much better and seldom fatal
If untreated -> most women would die from hemorrhage or
later from infection

38. Hysterectomy versus repair
Scar separation without bleeding
: Exploratory laparotomy is not indicated
Frank rupture
: Hysterectomy may be required