Management of delivery of woman with prior caesarean section

Management of the woman with a prior caesarean delivery is a controversial issue. 
Previously it was thought that an uterus with scar is a contraindication for  labor because of the chances of rupture of uterus.

In olden days classical vertical uterine incision was used, so at that time the quote by Cragin "Once a cesarean, always a cesarean"  was right. 
Nowadays many changes have come in the technique of caesarean delivery and also the emergencies are being handled successfully, so concept of trail of labor in people with prior caesarean has came.

The effect of prior caesarean delivery on present pregnancy:

Prior caesarean delivery may not significantly alter the course of present pregnancy or labor but it may increase some complications like:

Abortion: as in the uterus with scar when the gestational sac gets implanted over the scar, the implantation may not occur properly leading to abortion.

Preterm labor: when the uterus go on stretching due to the growth of the fetus, the scar tissue may not expand as much as normal myometrium leading to establishment of preterm labor.

Increase in normal pregnancy features:  eg. because of the presence of adhesions in between the abdominal structures the tightening of normal pregnancy may become painful, also frequency of urination in pregnancy may become exaggerated because of adhesions between bladder and uterus.

Increased operative interference: because of recurrent indications again patient may land up in caesarean delivery or because of fear of scar dehiscence in trial of labor second stage may be cut short with instrumental delivery. All these will increase maternal and fetal morbidity.

Retained placenta and postpartum hemorrhage:  if the placenta gets implanted on previous scar the chances of developing placenta accreta etc are common leading to retained placenta which will also lead to postpartum hemorrhage.

The effect of present pregnancy on scar:

The chances of scar dehiscence or rupture are there.

In case of lower segment caesarean section the scar can rupture during delivery usually. The incidence is 1 to 2%. In case of classical caesarean section or in case of hysterectomy the scar can rupture in late pregnancy or during labor. The incidence is 5 to 10%.

 The strength of previous scar:

Uterus with prior cesarean section scar

The success of trail of labor depends mainly on the strength of the previous scar, which depends on the healing of the scar. Healing occurs with muscles and connective tissue. Perfect apposition of the cut margins should be there.

The healing may be affected by following factors:

When the apposition is not perfect: some times because of ragged edges or because of giving incision above the usual site which will lead to thick edges the apposition may not come perfectly affecting the healing.

Presence of infection: in case of chorioamnionitis or any type of sepsis either because of prolonged labor or because of iatrogenic reasons the healing of the scar will be affected.

Haematoma in the layers of the wound: the undiagnosed hematoma in the layers of the wound will lead to improper apposition and also hamper the healing of the wound.

General condition of the patient: in case of poor general condition of the patient like with severe anaemia or with severe infection etc will affect the healing of the scar.

Previous labor to delivery interval: in case of previous prolonged labor to delivery time there will be excessive stretching of lower uterine segment leading to diminished vascularity  to the muscles also prolonged labor can lead to development of infection these will affect the strength of the scar.

Type of the scar: the type of the scar also influence the healing and strength of the scar.

The lower segment scar can be taken as sound scar because thin margins will lead to good approximation, during healing process the lower uterine segment will remain inert, during pregnancy and labor the stretching will occur along the line of scar, placental attachment on scar at lower uterine segment is less,  rupture may occur only during labor with less maternal and perinatal mortality.

 In case of the classical or hysterectomy scar thick margins containing blood and retained deciduas may  lead to improper approximation, during healing process the upper uterine segment will contract and retract  disturbing the sutures, during pregnancy and labor the stretching will occur at right angles to the scar, placental attachment on scar is more likely leading to weakness of scar,  rupture may occur both during pregnancy and  during labor with high maternal and perinatal mortality.

So, either  elective section to be done  or can be allowed for vaginal birth after caesarean section (VBAC) is decided after considering following factors:

As classical caesarean section scar or hysterectomy scar are not considered to be sound in these cases better to go for elective caesarean section.

In case of lower segment caesarean section VBAC can be allowed if the scar is expected to be sound but elective caesarean section to be considered if,

In case the previous section was done by a surgeon with low technical skill the chances of good approximation of edges are doubtful.

If prior section was done for the indication of placenta praevia as the surgery to be completed quickly to prevent blood loss the approximation may not be good, placental sinuses may prone to thrombosis and further sepsis because of being close to vagina.

In case of prolonged labor in previous pregnancy can lead to development of sepsis and weakening of scar.

If the previous caesarean section was difficult section with extension of edges either laterally or involving blood vessels or ending in colporrhexis the scar may not be sound and chances of rupture are there.

 In women who undergone caesarean section with having uterine malformations like unicornuate, bicornuate, didelphic or septate uteru the chances of rupture are more.

The risk of uterine rupture in women with a prior vertical incision that did not extend into the fundus is controversial. Women with a prior vertical incision in the lower uterine segment without fundal extension may be taken for VBAC. This is in contrast to prior classical or T-shaped uterine incisions, which are considered contraindications to VBAC.

In case of prior section was done in preterm with a poorly developed lower uterine segment the incision may almost invariably extended into the active upper segment. So, better to go fore elective section this time.

If the present pregnancy occurred soon that is within 6 months of prior section, the chances of weakening of scar are there. Ideally at least 2 years of gap should be there between two pregnancies.

If present pregnancy is associated with obstetric complications like multiple gestation or polyhydromnios etc which will lead to stretching of the scar and also if conditions loke placenta praevia, severe pre eclampsia or malpresentations exit elective section to be considered.

Prior cesarean pregnancy with placenta previa

Vaginal delivery after caesarean section may lead to weakening of scar.

If placenta in present pregnancy is present in the lower anterior segment attached to prior scar there may be abnormal adherence of placenta which will make operative interference necessary.

If there are more than one prior section before this pregnancy better to choose elective section.

If the estimated weight of the baby is more than 4 kg or appears to be big to that particular pelvis trail of labor may not become successful.

If hysterography finding in the interconceptional period shows wedge depression of more than 5 mm in the scar the chances of rupture are more.

If previous indication was recurrent indication like contracted pelvis or cephlo pelvic disproportion this time elective section to be opted.

Management of prior caesarean cases:

These cases to be considered high risk cases and frequent antenatal checkups to be taken.

In every visit have to ask for any pain over the scar or bleeding per vaginum, in examination any tenderness over the scar to be elicited.

In case of prior classical caesarean section or patients expected to have weak scars to be admitted at 36 weeks as chances of rupture are more during last weeks of pregnancy. The repeat section can be performed after 38 completed weeks.

In case of prior lower uterine segment caesarean section the patients can be admitted at 38 weeks, so that patient can be examined thoroughly and mode of delivery can be planned.

In case vaginal delivery is planned it should be done under strict supervision with preparation to shift to operation theatre if needed. Impending signs of dehiscence to be monitored. Epidural ananlgesia is better avoided as it will mask the signs of scar dehiscence. Second stage can be curtailed with prophylactic forceps. Exploration of scar can be done in only selective cases like continued bleeding inspite of well contracted uterus.if performed under ideal circumstances the results of VBAC and repeat caesarean section are identical. If good observation cannot be maintained better to go for elective section.

If any symptoms of the scar dehiscence like supra pubic dull aching pain even in between contractions, slight vaginal bleeding, frequent desire to pass urine etc along with signs like tachycardia with falling blood pressure, fetal heart rate fluctuations, tenderness over the uterine scar, labour not progressing without any reason, ballooning of lower uterine segment, taking up of cervix etc, the patient to be immediately shifted to operation theatre and caesarean section to be done.

If the patient is undergoing third caesarean section sterilization to be considered strictly unless there is very strong indication to not to do.