What is the most common cause of a classical cesarean (C-) section?

Most Common Causes of Classical Cesarean Section

The most common indication for classical cesarean section is difficulty accessing the lower uterine segment, particularly in preterm deliveries, followed by dense adhesions and abnormal placentation such as placenta previa or accreta. 1

Primary Indications for Classical Cesarean Section

Preterm Labor and Difficult Lower Segment Access

• Classical cesarean section is most frequently performed when the lower uterine segment is poorly developed or inaccessible, which occurs predominantly in preterm deliveries. 1
• The vertical incision through the contractile corpus allows smooth and gentle fetal delivery when the lower segment cannot accommodate safe transverse incision. 1
• This technique provides the critical advantage of being easily extended when needed for safe fetal extraction. 2

Dense Adhesions

• Prior cesarean sections create scar tissue that can make lower segment access technically impossible, necessitating a classical approach. 1
• The prevalence of cesarean scar defects ranges from 24-88% in women with prior cesarean sections, which can complicate subsequent surgical access. 3

Abnormal Placentation

• Placenta previa and placenta accreta spectrum are major indications for classical cesarean section when the placenta overlies or invades the lower uterine segment. 1
• The risk of placenta accreta increases dramatically with each prior cesarean: 12.9 per 10,000 after one cesarean, 41.3 per 10,000 after two, and 78.3 per 10,000 after three cesarean sections. 3
• When placenta accreta is present with placenta previa, the incidence ranges from 11% with one prior cesarean to 67% with five or more prior cesarean deliveries. 3

Technical Considerations

When Classical Incision is Necessary

• The vertical hysterotomy through the upper uterine segment is indicated when transverse lower segment incision would result in inadequate exposure or risk fetal or maternal injury. 2
• Operative complications including fetal injury and uterine lacerations result from inadequate uterine incisions, making the classical approach safer in specific scenarios. 2

Surgical Challenges

• Uterine closure after classical cesarean is technically more difficult than lower segment closure. 1
• The procedure requires speedy and skillful technique to minimize risks of hemorrhage and adhesion formation. 1

Critical Long-Term Implications

Subsequent Pregnancy Risks

• The most serious risk of classical cesarean section is uterine rupture in subsequent pregnancies, with an incidence of approximately 1% even without trial of labor. 4
• Prior classical cesarean section is an absolute contraindication for trial of labor after cesarean (TOLAC). 1
• The overall uterine rupture prevalence in women with any prior cesarean is 22 per 10,000 births (0.22%), increasing to 35 per 10,000 (0.35%) when labor occurs. 5

Maternal Morbidity Considerations

• While preterm classical cesarean is not associated with significantly increased short-term maternal mortality or ICU admission compared to low transverse cesarean (OR 2.38; 95% CI 0.15-38.07 for mortality), data remain limited. 4
• Subgroup analysis from 28-31 weeks gestation shows increased risks of endometritis, transfusion requirements, and ICU admission with classical incision. 4

Common Clinical Pitfalls

• Failure to anticipate the need for classical cesarean in preterm deliveries can lead to inadequate surgical planning and increased complications. 1
• Attempting forced placental removal in cases of placenta accreta during classical cesarean results in profuse hemorrhage and should be avoided; the placenta should be left in situ. 6
• Underestimating the technical complexity of classical cesarean closure increases risk of hemorrhage and future uterine rupture. 1