Cesarean sections, often referred to as C-sections, represent a common surgical method for childbirth. This procedure involves delivering a baby through incisions made in the mother’s abdomen and uterus. While C-sections are widely performed, various techniques exist, each distinguished by the type and location of the incision made on the uterus. Understanding these different approaches helps clarify why a particular method might be chosen for delivery.
Understanding the Classical Incision
A classical C-section is characterized by a specific type of incision made on the uterus. Unlike the more common low transverse incision, which is a horizontal cut across the lower, thinner part of the uterus, a classical incision involves a vertical cut in the upper, muscular, and contractile portion of the uterus, known as the fundus. The physical characteristics of this incision mean it extends through the thicker muscle of the uterine body.
Historically, the classical incision was the original method for C-sections, but its use declined with the development of the low transverse technique due to associated risks. While the skin incision on the abdomen may still be horizontal, it is the uterine incision that determines whether the C-section is classified as classical. This method provides a larger opening for delivery, which can be advantageous in certain situations.
When a Classical C-Section is Necessary
Classical C-sections are not routinely performed today due to higher risks but are reserved for specific, medically necessary situations. One primary indication is extreme prematurity, particularly before 30 weeks of gestation, when the lower uterine segment is not yet fully formed or developed enough to allow for a safe low transverse incision. In such cases, the upper uterine segment provides better access for fetal delivery.
Other circumstances requiring a classical incision include certain fetal presentations, such as a transverse lie where the baby is positioned horizontally, or specific fetal anomalies like conjoined twins or macrocrania, which necessitate a larger opening for delivery. When the placenta blocks the lower uterus (placenta previa) or is abnormally implanted, a classical incision may be used to avoid cutting through the placenta. Difficult access to the lower uterine segment due to dense adhesions from previous surgeries or severe morbid obesity can also make a classical incision necessary. In emergency situations where rapid delivery is paramount, and there is insufficient time for the lower uterine segment to thin out or for a careful dissection, a classical incision can facilitate a quicker extraction of the baby. This procedure is also considered when there are uterine abnormalities, such as large fibroids in the lower segment or certain anomalous uterine structures, that prevent a low transverse cut.
Considerations for Subsequent Pregnancies
A classical C-section carries important implications for any future pregnancies due to the nature of the uterine incision. The primary concern is a significantly increased risk of uterine rupture in subsequent labors compared to a low transverse incision. This elevated risk exists because the vertical incision is made in the upper, contractile part of the uterus. This region of the uterus experiences strong contractions during labor, placing considerable stress on the scar.
The scar tissue from a classical incision is considered weaker and more prone to separating or rupturing under the forces of labor. The risk of uterine rupture after a classical C-section can range from 4% to 12%, which is substantially higher than the 0.2% to 1.5% risk associated with a low transverse incision. Due to this heightened risk, medical guidelines strongly recommend against a trial of labor after a classical C-section (VBAC).
For individuals who have undergone a classical C-section, repeat C-sections are generally advised for all subsequent deliveries, often scheduled before the onset of labor. This approach aims to prevent the uterus from experiencing the contractions that could lead to rupture, thereby minimizing risks to both the mother and the baby. The timing of such repeat C-sections is carefully considered, often between 36 and 37 weeks of gestation, to balance the risk of uterine rupture with fetal maturity.