In the United States, over one million Cesarean Section deliveries are performed annually. Cesarean delivery accounted for 32% of US births in 2009 while worldwide, the cesarean delivery rate accounts for only 15% of births. While the available evidence suggests there is no difference in maternal mortality when planned c-section is compared to planned vaginal delivery, there is a significant difference between the two routes of delivery when investigating maternal morbidity. In one large study comparing severe morbidity events in planned cesarean vs. planned vaginal deliveries there was a 27.3 to 9.0 per 1000 deliveries rate difference, respectively.
Compared to the planned vaginal delivery group, the planned cesarean group had a significantly higher postpartum risk of:
- cardiac arrest (Odds Ratio 5.1)
- wound hematoma (OR 5.1)
- hysterectomy (OR 3.2)
- major puerperal infection (OR 3.0)
- anesthetic complications (OR 2.3)
- venous thromboembolism (OR 2.2)
- hemorrhage requiring hysterectomy (OR 2.1)
Anesthetic Issues in pregnant patients
- Increased risk of aspiration of gastric contents secondary to increased intraabdominal pressure, relaxed LES, and recumbent position. Cuffed ET mandatory if GA performed.
- Edema of upper airway tissues:, especially in preeclamptic/eclamptic parturients, which may compromise airway and render intubation more difficult.
- Increased basal metabolic rate and decreased FRC which may lead to rapid desaturation upon the induction of general anesthesia.
- Supine position the gravid uterus compresses major blood vessels the vena cava and decreases venous return, cardiac output, and blood pressure. Also regional anesthesia performed with cesarean section can exacerbate this effect by promoting pooling of blood. It is mportant to implement left uterine displacement.
A C-section also increases the risk of complications in future pregnancies. These include :
- Increased risk of placenta previa and accrete: Placenta previa and accreta are significantly more common in pregnancies following one or more cesarean deliveries.
- Increased risk of uterine rupture: Most uterine ruptures are related to a trial of labor after a previous cesarean delivery (TOLAC). Uterine rupture may require hysterectomy and is associated with an increased risk of fetal and maternal morbidity and mortality.
- Complications from multiple abdominal surgeries: Adhesions increase the difficulty of future intraabdominal surgical procedures, and may increase the risk of bladder or bowel injury
In the developing world, the leading cause of maternal death after c-section is hemorrhage. In developed nations, where hemorrhage is more often successfully treated and prevented, thromboembolic disease is more important. Thus, pulmonary embolism is the leading cause of death after a cesarean section in the United States.
Shiliang Liu, Robert M Liston, K S Joseph, Maureen Heaman, Reg Sauve, Michael S Kramer, Maternal Health Study Group of the Canadian Perinatal Surveillance System Maternal mortality and severe morbidity associated with low-risk planned cesarean delivery versus planned vaginal delivery at term. CMAJ: 2007, 176(4);455-60