Williams ch.26 Prior Cesarean Delivery 부산백병원 산부인과 R3 박영미

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

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

Trial of labor versus repeat cesarean delivery

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

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 ?

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

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

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%

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

Candidates for a trial of labor

Type of prior uterine incision

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

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

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

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

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

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

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

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

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

Labor and Delivery Considerations

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

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%)

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

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

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

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

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

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

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

Uterine rupture

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

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)

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

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

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