A caesarean section (C/S) is an operation performed to deliver a baby when vaginal delivery (normal birth) is impossible or unsafe. The doctor makes a cut in the mother's abdomen and uterus (womb) to remove the baby.
When is it used?
A caesarean section may be performed before labour begins if there are medical reasons for not going through labour and vaginal delivery. The health of the mother or baby may be in danger, or vaginal delivery may be impossible. A C/S may also be performed during labour if certain problems arise.
The following are some of the medical circumstances in which a C/S may be performed:
- Incomplete dilatation of the cervix. Sometimes during labour, the cervix (the cylindrical lower part of the uterus that leads into the vagina) does not dilate fully, making vaginal delivery difficult or impossible.
- A woman may have full cervical dilatation, but be unable to push the baby through the birth canal. This may occur because the baby is too large for the birth canal. For example, with cephalo-pelvic disproportion (CPD), the baby's head is too large to fit through the pelvis, or the pelvis is too small for even a normal size baby. Disproportion can also develop if the baby´s head is positioned wrongly.
- Prolapsed cord: the umbilical cord descends before the baby does. (The umbilical cord connects the fetus with the placenta (afterbirth), the blood-rich structure in the uterus that provides the fetus with nourishment.
- Placental abruption: the placenta separates before birth.
- Placenta praevia: the placenta is situated in front of the baby in the lower segment of the uterus and partially or completely covers the cervix.
- Fetal malpresentation or malposition: at the time of delivery the baby is not correctly positioned for normal vaginal birth. For example, if the baby's face or forehead (malposition) or the baby´s shoulder or buttocks (malpresentation) are located lowest instead of the baby´s back of the head, a C/S may be necessary.
- Maternal medical conditions, such as pre-eclampsia, severe hypertension or diabetes. However, having these conditions does not imply that a C/S is always necessary.
- Fetal distress: a baby may become distressed during labour, usually due to insufficient oxygen supply from the placenta, that causes its heartbeat to slow down. This may indicate that the baby cannot tolerate further labour.
- Maternal exhaustion, often from prolonged labour.
- Uterine scar: a woman who has had a C/S previously or a scar in her uterus from a previous operation (for example: removal of fibroids). However, recent studies have shown that a large percentage of women have a good chance for vaginal birth after a caesarean (VBAC). One of the main concerns about going through labour and vaginal birth after having previously had a C/S is that the scar could tear causing a ruptured uterus. This is why an attempt for VBAC is always performed at a hospital where the labour process with the “trial of scar” can be interrupted anytime and a C/S proceeded with if there is inadequate progress of labour or signs of threatening uterine rupture.
An expecting mother with a previous C/S will be advised by her obstetrician whether or not she can undergo a trial of scar. This depends on the obstetrical circumstances which have led to the previous C/S and whether the indication is repetitive. If, for example, the previous C/S was due to a placenta praevia or an umbilical cord prolapse, which are unlikely to recur, a VBAC can be attempted. On the other hand, if the C/S was done for CPD because of a narrow pelvis, the obstetrician may decide to perform an “elective” C/S, which means the C/S will be done at 38 weeks´ gestation without the woman going into labour.
(Reviewed by Prof Bert Schaetzing, University of Stellenbosch)