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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
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Williams ch.26Prior 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
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 • 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
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
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
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