Clinical meaning
A cesarean section (C-section) is a surgical procedure in which the fetus is delivered through an incision in the abdominal wall (laparotomy) and the uterine wall (hysterotomy). The procedure involves incision through multiple tissue layers: skin, subcutaneous fat, rectus fascia, rectus abdominis muscle (separated, not cut), peritoneum, and finally the uterine myometrium. The most common uterine incision is the low transverse (Kerr) incision, made in the thinner lower uterine segment, which results in less blood loss, easier repair, and lower risk of uterine rupture in future pregnancies compared to the classical vertical incision. The uterine myometrium is composed of three smooth muscle layers: the outer longitudinal layer, the middle interlacing layer (which contains the major blood vessels and is responsible for the 'living ligature' effect that controls postpartum hemorrhage through contraction), and the inner circular layer. After delivery, the uterus must contract firmly to compress the spiral arteries at the former placental attachment site. The placental site covers approximately 200 square centimeters of endometrial surface and contains between 150 and 200 spiral arteries. Failure of the myometrium to contract (uterine...