Definition
Delivery of a fetus via the abdominal route (laparotomy) requiring an incision into the uterus (hysterotomy).
Cesarean is needed or not?
Absolute Indications for Cesarean section delivery
Maternal
• Failed induction of labor
• Failure to progress (labor dystocia)
• Cephalopelvic disproportion
Uteroplacental
• Previous uterine surgery (classical cesarean)
• Prior uterine rupture
• Outlet obstruction (fibroids)
• Placenta previa, large placental abruption
Fetal
• “Fetal distress”/non-reassuring fetal testing
• Cord prolapse
• Fetal malpresentation (transverse lie)
Relative Indications for Cesarean section delivery
Maternal
• Elective repeat cesarean section
• Maternal disease (severe pre-eclampsia, cardiac disease, diabetes, cervical cancer)
Uteroplacental
• Prior uterine surgery (full-thickness myomectomy)
• Funic (cord) presentation in labor
Fetal
• Fetal malpresentation (breech, brow, compound presentation)
• Macrosomia
• Fetal anomaly (hydrocephalus)
• Most indications for cesarean section are relative and rely on the judgment of the obstetric care provider.
• The most common indication for a primary (first) cesarean section is the failure to progress in labor.
• Absolute cephalopelvic disproportion (CPD) refers to the clinical setting in which the fetus is too large relative to the bony pelvis to allow for vaginal delivery even under optimal circumstances. Relative CPD is where the fetus is too large for the bony pelvis because of malpresentation (brow, compound presentation).
Technical considerations
• Elective cesarean section can be performed after 39 weeks’ gestation without documenting fetal lung maturity.
• Regional is preferred over general analgesia.
• Routine use of prophylactic antibiotics will decrease the incidence of postoperative febrile morbidity.
• Skin incision may be Pfannenstiel (low transverse incision, muscle separating, strong, but limited exposure), midline vertical (offers the best exposure, but is weak), or paramedian (vertical incision lateral to rectus muscles, rarely used). Pfannenstiel incisions may rarely be modified to improve exposure by dividing the rectus muscles horizontally (Maylard incision) or lifting the rectus of the pubic bone (Cherney incision).
• Elective surgery (such as myomectomy) should not be performed at the time of cesarean section, because of the risk of bleeding. Puerperal (cesarean section) hysterectomy
Indications
• Performed primarily as an emergency procedure when the mother’s life is at risk due to uncontrolled hemorrhage (30–40%).
• Other indications include abnormal placentation (see Chapter 56), severe cervical dysplasia, and cervical cancer.
• Permanent sterilization is not an acceptable indication for puerperal hysterectomy.
Technical considerations
• A highly morbid procedure usually requiring general anesthesia. As such, it should be performed only as a last resort.
• Warming blanket, three-way Foley catheter, and blood products should be available.
• Emergency puerperal hysterectomies are associated with a fourfold increased risk of complications compared with elective procedures. Blood loss is often excessive (2–4 L) and blood transfusions are usually required (90%). Despite a high morbidity, overall maternal mortality rate is low (0.3%).
• It may be possible to leave the cervix behind (subtotal or supracervical hysterectomy), thereby minimizing complications, especially blood loss. This may not be possible if the cervix is the source of the excessive bleeding, such as with placenta previa.
• Although women will be amenorrheic and sterile, menopausal symptoms will not develop if the ovaries are left in place.
VERTICAL HYSTEROTOMY
• Used only in selected instances
• Blood loss, twofold risk of blood transfusion
• Possible indications include:
(i) no access to lower segment (adhesions, pelvic mass such as fibroids)
(ii) poorly developed or no lower segment (such as very preterm infants, preterm breech)
(iii) impacted transverse lie
(iv) placenta previa
(v) large abnormal fetus (e.g. hydrocephalus, large sacrococcygeal teratoma)
(vi) planned hysterectomy (e.g. cancer)
TRANSVERSE HYSTEROTOMY
• Most commonly used
• Lower blood loss (because the lower uterine segment is thin and poorly vascularized)
• Heals strongest
Vaginal birth after cesarean section
Background
• Of cesarean section deliveries, 30% are elective repeat procedures.
• Maternal mortality rate from cesarean section delivery is <0.1%, but is 2- to 10-fold higher than that associated with vaginal birth.
• Maternal morbidity (infection, thromboembolic events, wound dehiscence) is markedly higher with cesarean section.
Results
• Successful vaginal birth after cesarean section (VBAC) can be achieved in 65–80% of women.
• Factors associated with successful VBAC include prior vaginal delivery, estimated fetal weight <4,000 g, and a non-recurrent indication for the previous cesarean section (breech, placenta previa) rather than a potential recurrent indication (such as CPD).
Contraindications
• Absolute contraindications include a prior classic (high vertical) cesarean section, “fetal distress,” transverse lie, and placenta previa.
• Relative contraindications include breech presentation, prior full thickness uterine myomectomy, prior uterine rupture, and (possibly) multiple gestations.
Complications
• Uterine dehiscence (subclinical separation of the prior uterine incision) occurs in 2–3% of cases. It is often detected only by manual exploration of the scar after vaginal delivery. In the absence of vaginal bleeding, no further treatment is necessary.
• Uterine rupture may be life-threatening. Symptoms and signs include acute onset of fetal bradycardia (70%), abdominal pain (10%), vaginal bleeding (5%), hemodynamic instability (5–10%), and/or loss of the presenting part (<5%). Epidural anesthesia may mask some of these features.
Risk factors include:
1 type of prior uterine incision (<1% for lower segment transverse incision, 2–3% for lower segment vertical, and 4–8% for high vertical);
2 two or more prior cesarean sections (4%)
3 prior uterine rupture
4 “excessive” use of oxytocin (although “excessive” is poorly defined)
5 dysfunctional labor pattern (especially prolonged second stage or arrest of dilation)
6 induction of labor using prostaglandins.
Factors NOT associated with an increased risk for rupture include epidural anesthesia, unknown uterine scar, fetal macrosomia, and indication for prior cesarean section.
Clinical Considerations
• Continuous intrapartum fetal monitoring is recommended.
• Follow the labor curve carefully for evidence of labor dystocia.
• The capacity to perform an emergency cesarean section should be at hand.