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Caesarean section or caesarean delivery refers to the delivery of a fetus, placenta, and membranes through an abdominal and uterine incision. The first documented caesarean section on a living person was performed in 1610. The patient died 25 days later. Since that time, numerous advances have made caesarean section a safe procedure. In the past 35 years, the rate of caesarean section has steadily increased from 5% to approximately 30%. Over this time, the maternal mortality ratio (maternal deaths per 100,000 births) has decreased from almost 300 to <10. The following factors are often cited as contributing to the increasing caesarean section rate: (1) lower operative vaginal delivery rates, (2) lower rates of vaginal births after caesarean section (VBAC), and (3) fewer vaginal breech deliveries. In order for the practitioner to perform this common operation safely, he or she must be aware of the indications, risks, operative technique, and potential complications of this procedure.
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Caesarean section is used in cases where vaginal delivery either is not feasible or would impose undue risks to the mother or baby. Some of the indications for caesarean section are clear and straightforward, whereas others are relative. In some cases, fine judgment is necessary to determine whether caesarean section or vaginal delivery would be better. It is not practical to list all possible indications; however, hardly any obstetric complication has not been dealt with by caesarean section. The following indications are currently the most common.
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Repeat Caesarean Section
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A prior uterine incision from a myomectomy or previous caesarean section may weaken the uterine wall or predispose to rupture if labor is permitted. The initial dictum of “once a caesarean, always a caesarean” was held for many years. However, as multiple publications documenting the safety of VBAC began appearing in the literature, many physicians moved away from this long-held belief. In 2000, a national goal was set to lower the rate of repeat caesarean sections to 3% while increasing the VBAC rate to 35%. The major incentives that led to this change in philosophy were fewer delivery risks with vaginal delivery, less need for anesthesia, less postpartum morbidity, shorter hospital stay, lower costs, and the encouragement of earlier and often smoother interaction and bonding between mother and infant. As more and more VBACs were performed in less than ideal settings, more complications arose. There may be no greater obstetric catastrophe than a uterine rupture resulting in maternal and/or fetal death. In fact, there appears to be a trend back toward the belief of “once a caesarean, always a caesarean.” Suffice it to say, “once a caesarean, always a controversy.”
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In general, patients who are the most suitable candidates for trial of labor after caesarean section (TOLAC) are those (1) with 1 prior low-transverse caesarean section, (2) who present in labor, (3) with nonrecurring conditions (eg, breech, abnormal fetal heart rate patterns, placenta previa in prior pregnancy), and (4) with a prior vaginal delivery. Patients who are not candidates for a TOLAC include women with a prior classical (vertical) uterine incision or prior myomectomy. If a trial of labor is to be conducted, the patient must be placed on continuous fetal heart rate and uterine activity monitoring, and a dedicated obstetrician and anesthesiologist must be immediately available to intervene in case uterine rupture is suspected. Prostaglandins for cervical ripening must be avoided, and oxytocin must be used in a judicious and conservative fashion, if at all. Current studies cite a maternal mortality rate of close to 1% in cases of uterine rupture and a perinatal mortality rate of approximately 50% in association with uterine rupture. Therefore, it is of utmost importance that equipment for both maternal and electronic fetal monitoring and appropriate obstetric and neonatal facilities are available. A large-bore intravenous catheter must be used, and blood for possible maternal transfusion must be available. Appropriate anesthesia, a fully equipped operating room, and obstetric and neonatal staff experienced in emergency care must all be immediately available.
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Cephalopelvic Disproportion/Dystocia
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Cases in which the fetal head is too large to traverse the pelvis should be managed by caesarean section. As discussed earlier, if the head does not engage during labor, operative vaginal delivery should not be attempted. Rather, caesarean section must be performed. Inlet disproportion should be suspected in the primigravida if the patient begins labor with the fetal head unengaged. In a significant number of these patients, the fetal head fails to engage, and caesarean section is indicated. Midpelvic disproportion may be suspected if the anteroposterior diameter is short, the ischial spines are prominent, the sacrospinous ligament is short, and the fetus is large. Outlet disproportion usually requires a trial of forceps or vacuum before a safe vaginal delivery is determined to be impossible.
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Dystocia literally means “difficult labor.” This occurs when a patient's labor progresses and then either stops completely (arrests) or becomes prolonged (protracted). When either of these situations occurs during labor, the patient warrants careful reassessment, including evaluation of the labor pattern, contraction pattern, estimated fetal weight and fetal presentation, and evaluation of the pelvis. In other words, the 3 P's (power, passenger, and pelvis) must be adequate in order for a vaginal delivery to occur.
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Abnormal Fetal Lie & Malpresentation
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Transverse lie and breech presentations are common indications for caesarean section. The trend toward caesarean delivery for breech deliveries has been hastened by a large randomized trial comparing breech infants born vaginally versus those born by caesarean section; better outcomes were achieved after caesarean section. Although some still consider vaginal breech delivery to be an acceptable option, experience with the technique is largely disappearing from practice. External cephalic version is a reasonable alternative for some patients and can be attempted to convert the fetus to cephalic presentation. However, this procedure is successful in allowing vaginal birth in only 50% of cases.
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Fetal Heart Rate Tracing Abnormalities
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Fetal monitoring before and during labor may disclose fetal problems that otherwise would not be evident. As a result of continuous fetal monitoring, the number of caesarean sections performed for a “nonreassuring fetal status” has increased. Best estimates demonstrate that approximately 10% of caesarean sections are performed for this indication.
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In addition to the indications discussed earlier, other conditions that may lead to caesarean section are placenta previa, preeclampsia–eclampsia if remote from term, placental abruption, multiple gestations, fetal abnormalities (eg, hydrocephalus), cervical cancer, and active genital herpes infection. One other indication that is becoming more prevalent is patient choice. The idea of primary elective caesarean section continues to increase in popularity and generate controversy.
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Preoperative Preparation for Caesarean Section
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The following steps are generally taken before caesarean section is performed. The patient is made aware of the indications for the caesarean section, the alternatives, and the potential risks, benefits, and complications. She then signs a form indicating that she has received the appropriate information and consents to the procedure (“informed consent”). An intravenous 18-gauge needle should be in place with an appropriate intravenous solution running before the operation begins. The patient is given an antacid to minimize the likelihood of aspiration during anesthesia. A Foley catheter is placed to allow for continuous bladder drainage before, during, and after surgery. Anesthesia is administered, and the abdomen is prepped. The patient is covered with sterile drapes. Tilting the patient slightly to the left moves the uterus to the left of the midline and minimizes pressure on the inferior vena cava.
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Opinions differ regarding the type of abdominal incision that should be performed. Most obstetricians use the transverse (Pfannenstiel) incision with or without transection of the rectus muscles because wound dehiscence is rare and because the cosmetic result is usually better. In cases in which the caesarean section must be performed urgently or emergently, especially in patients with prior abdominal surgery or marked obesity, the midline vertical suprapubic incision is preferred because it is much quicker and the exposure for expeditious delivery and resolving uterine bleeding (by hysterectomy, if needed) usually is better. In the presence of a prior lower abdominal scar, it is important to enter the peritoneal cavity at the upper end of the incision to avoid entering the bladder, which may have been pulled upward on the abdominal wall at the time of closure of the previous incision.
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Before the uterine incision is made, laparotomy pads that have been soaked in warm saline and wrung out can be placed on either side of the uterus to catch the spill of amniotic fluid. The degree of dextrorotation should also be determined by noting the position of the round ligaments so that the uterine incision will be centered. Torsion should not be corrected; instead, access to the midline should be obtained by retracting the abdominal wall to the patient's right. The different types of uterine incisions will be discussed later.
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Encountering the Placenta
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If the placenta is encountered beneath the uterine incision, the operator should avoid cutting through it; otherwise serious fetal bleeding may result. If the placenta cannot be avoided, an incision can be made through it. However, the baby must be delivered as quickly as possible and the cord clamped immediately to prevent significant blood loss.
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The operator delivers the baby, and then the placenta delivers. Recent evidence has demonstrated that blood loss can be minimized by massaging the uterus to allow for spontaneous placental expulsion rather than by manually separating and extracting the placenta. After delivery of the placenta, the uterus should be massaged and oxytocin administered in a dilute intravenous solution at a rate sufficient to maintain a firm contraction. The uterine cavity is wiped clean with a sponge so as to remove any retained membranes. The uterus is exteriorized, and active bleeding sinuses are clamped with either Pennington clamps or ring forceps.
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Closure of the Uterine Incision
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The closure of the uterine incision is dependent on the type of incision that is made. In general, the entire thickness of the myometrium should be closed. In order to potentially decrease the likelihood of uterine rupture during a subsequent pregnancy, the uterine incision should be closed in 2 layers. The 2 types of uterine incisions used most often and discussed here are the classical uterine incision and the low-transverse uterine incision.
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Classical Caesarean Section
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This is the simplest to perform. However, it is associated with the greatest loss of blood and with a greater risk of uterine rupture with subsequent pregnancies when compared with low-transverse incisions. The currently accepted indications for classical caesarean section are placenta previa, transverse lie (especially back down), and preterm delivery in which the lower uterine segment is poorly developed. A classical caesarean section may be preferred if extremely rapid delivery is needed, because this type of incision may offer the fastest means of delivering the baby. Nonetheless, the hazards of this procedure must be weighed against the additional minute or so needed to dissect the bladder away from the lower uterine segment and make the transverse semilunar low-transverse uterine incision.
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In performing a classical procedure, a vertical incision is made in the body of the uterus. A scalpel is used to enter the uterine activity, and the incision is enlarged with bandage scissors. The fetus is delivered through the incision. After the placenta and membranes are removed, the uterine defect is repaired with 3 layers of running, interlocking absorbable suture. Number 0 suture is recommended for the 2 deeper layers, and 2-0 suture is used for the superficial layer to reapproximate the serosal edges.
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Low-Transverse Caesarean Section
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Because the low-transverse uterine incision (Figs. 20–10 through 20–17) is associated with less blood loss and the risk of subsequent uterine rupture is less than with a classical caesarean section, this type of caesarean delivery is performed more frequently. After the peritoneal cavity is opened and the uterus identified, the bladder fold of peritoneum is picked up with tissue forceps and incised transversely. The bladder is bluntly separated from the anterior aspect of the uterus inferiorly for a distance of 3–4 cm. The bladder is held away from this area by a specially designed bladder retractor. A transverse incision is made through the anterior uterine wall with the scalpel. Using either bandage scissors or fingers, the transverse incision is extended in a semilunar fashion and extended superiorly at the lateral edges in order to avoid the uterine vessels.
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If the maneuver can be easily done, the fetal presenting part is elevated with the hand, making sure not to flex the wrist, thereby increasing the possibility of extension of the incision inferiorly toward the cervix. If the head is located deep in the pelvis, the head can safely be pushed up by an assistant inserting a hand into the vagina to elevate the fetal head for ease of delivery. After the baby and placenta are delivered, the uterus is exteriorized and clamps are placed on the cut edges of the uterus in areas of significant bleeding from the uterine sinuses. The uterine incision is generally closed in 2 layers using number 0 chromic catgut or other absorbable suture. After adequate hemostasis has been achieved, the bladder peritoneum either is reapproximated with suture or is left in place. Before the uterus is returned to the peritoneal cavity, the adnexa should be inspected for the presence of any pathology, such as ovarian cysts. Some practitioners prefer to close the anterior peritoneum with absorbable suture, whereas others prefer to leave it alone. The fascia, subcutaneous tissue, and skin are reapproximated in standard fashion.
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The most common complications that result from caesarean section are postpartum hemorrhage, endometritis, and wound infection. Administering prophylactic antibiotics and ensuring hemostasis prior to closure of the abdomen have helped decrease the incidence of these complications. New data are emerging that demonstrate a lower risk of endometritis when antibiotics are given prior to the skin incision when compared to after clamping of the umbilical cord. The major factors affecting healing of the uterine incision are hemostasis, accuracy of apposition, quality and amount of suture material, and avoidance of infection and tissue strangulation. It can generally be stated that the longer the operative procedure, the greater is the likelihood of postoperative complications. Disasters following caesarean section are rare. Some clearly are not preventable. Others are the direct result of faulty surgical technique, especially lack of attention to hemostasis, inept or ill-chosen anesthesia, inadequate blood product replacement or transfusion of mismatched blood, and delayed diagnosis or mismanagement of infection.
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Unfortunately, little information about the integrity of a particular scar in a subsequent pregnancy is gained by inquiry into the presence or absence of postoperative infection and location of the incision. In a later pregnancy, pain in the area of the scar may suggest dehiscence. Approximately 50% of all ruptures of classical uterine scars occur before the onset of labor. The incidence of uterine rupture is approximately 4–9% of classical scars and 0.7–1.5% of low-transverse scars. Rupture of a classical scar usually is catastrophic, occurring suddenly, totally, and with partial or total extrusion of the fetus into the abdominal cavity. Shock due to internal hemorrhage is a prominent sign. Rupture of the low-transverse scar usually is more subtle and almost always occurs during active labor. The most common presenting sign (present in more than 80% of cases) is a change in the fetal heart rate pattern. A newly recognized finding of variable or late decelerations should alert the obstetrician. Additional findings that might signal uterine rupture include vaginal bleeding, abdominal pain (especially over the prior incision site), and loss of fetal station. A scalp electrode to ensure a continuous fetal heart rate tracing should be utilized as soon as possible in patients who are undergoing TOLAC. If uterine rupture is suspected, the patient must undergo surgery as soon as possible.
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Perinatal Morbidity & Mortality
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Although it may appear on the surface that caesarean delivery is the safest for the baby, this may not be entirely true. Although usually benign, transient tachypnea of the newborn is more common with caesarean section than with vaginal delivery. The risk of fetal hemorrhage and hypoxia is present when the placenta is encountered below the uterine incision and is inadvertently or purposely transected. There is also the potential risk for laceration of the baby at the time that the uterine incision is made. Fetal laceration is reported to occur on an infrequent basis at a rate of approximately 0.2–0.4% of all caesarean sections. The usual site is on the face, in the area of the cheek, but it may also occur on the buttock, ear, head, or any other body site under the incision. Therefore, it is of great importance that care is taken when incising the layers of the uterus. This is especially true in a prolonged labor, in which the uterus may be very thin. Because of the potential complications to the baby inherent with each caesarean section, each infant should be examined by a trained professional as soon as possible after delivery.
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