The Classical Caesarean Section in the Management of High-risk Pregnancies
Dr Devendra Kanagalingam, Senior Consultant, Dept of Obstetrics & Gynaecology, Singapore General Hospital
It is a commonly held belief that the caesarean section, one of the most frequently performed operations today, was named after Julius Caesar because the great emperor of ancient Rome was himself delivered by caesarean section. In fact, this is a myth. The caesarean section probably got its name from a law passed in Roman times which required women who died while pregnant to have their dead foetuses removed and buried separately. It is believed that the original operations were performed to fulfil this obligation. In subsequent practice, the caesarean section became an operation which was performed as a desperate measure to save a mother, often when the baby was already dead. This would occur, for instance, in obstructed labour and would only be undertaken after days of labour when it became clear that the fetus could not be delivered vaginally.
It is fascinating to consider how rapidly the caesarean section has evolved into what it is today – a routine operation which is performed for maternal and fetal benefit. These developments are largely a result of asepsis and the development of anaesthesia and surgical techniques. The early operations were termed classical caesarean sections and involved making a vertical, midline incision into the upper segment of the uterus.
In the mid 20th century, the lower segment caesarean section was devised. As the name suggests, this involves making a transverse incision into the lower segment of the uterus. To do this, the obstetrician must first mobilise the bladder away from the lower segment because in its natural state, the lower segment is covered by the bladder. It is now established that the lower segment operation results in less blood loss as the lower segment is thinner and less vascular. It is also established that the risk of uterine rupture in a subsequent pregnancy is higher with a classical caesarean section as compared to the lower segment operation. This resulted in the classical operation quickly falling out of favour. Today, the classical operation is rarely done and many obstetricians have never performed or even observed one.
There remain valid clinical indications to perform a classical caesarean section. Obstetric textbooks often state that the classical section can be considered when there is an anterior low lying placenta (placenta praevia major) with a vascular lower segment or if access to the lower segment is difficult due to pathology like uterine fibroids. It is useful in the case of foetal transverse lie with the foetal back inferior or if a carcinoma of the cervix is diagnosed during pregnancy. Clearly, these conditions are relatively infrequent and many of these indications for a classical section are relative rather than absolute.
Rapid developments in obstetrics and neonatal medicine have resulted in an additional two indications for the classical caesarean section. The first is the increased incidence of placenta accreta, increta and percreta. These conditions, collectively, termed morbidly-adherent placenta, result from invasion of the placenta into the myometrium. In these conditions, placental removal following delivery is not possible. In the most severe variety, placenta percreta, placental invasion through the entire myometrium and into adjacent organs such as the bladder may occur (see figures 1 and 2).
If attempts are made to remove such a placenta at caesarean section, torrential bleeding will occur and maternal death as a result of postpartum is not uncommon. Current management of this condition involves delivery of the baby and leaving the placenta in-utero for it to undergo autolysis. Placenta percreta typically occurs in women who have had a previous lower segment caesarean section in whom the placenta in a subsequent pregnancy attaches to the scarred lower segment. Performing a classical caesarean section is essential in a case of placenta percreta as the obstetrician must avoid cutting through the low lying placenta if it is to be left in-utero.
The other newer indication for performing a classical caesarean section is a direct result of improvements in neonatal salvage for babies who are extremely premature. Frequently delivery is mandated in these pregnancies as a result of medical or obstetric complications such as preterm pre-labour rupture of membranes
(PPROM), pre-eclampsia, systemic lupus erythematosus and intrauterine growth restrictions. We are seeing an increasing number of such pregnancies at the Singapore General Hospital because such women require management by a multi-disciplinary, tertiary level institution. When delivery is undertaken at these early gestations, typically 24 to 27 weeks, the lower segment is not yet formed and access to the fetus through a transverse incision is difficult owing to the small uterus. We have used the classical caesarean section to good effect in these cases and have found that delivery of these small babies is both easier and less traumatic with the classical incision.
A common misconception held not only by lay persons but also by some healthcare workers is that the abdominal incision in a caesarean section reflects the type of uterine incision. The midline vertical incision in a classical caesarean section refers to the incision made on the uterus. The corresponding skin incision can be either a transverse incision or a midline incision. We have found that a classical caesarean section can be done with a lower
transverse skin incision, particularly when we are operating on women with premature foetuses. The common skin incisions used in a caesarean section are shown in figure 3. Of the two transverse incisions shown, it is now more common to perform a Cohen incision than the older Pfannenstiel incision. The Cohen incision is a horizontal skin crease incision while in the Pfannenstiel incision, the edges of the incision curve upwards.
We believe that familiarity with the classical caesarean section is an important obstetric skill as the need for the procedure is increased in modern obstetrics. While only one classical caesarean section was performed in SGH between 2000 and 2004, 24 classical operations have been performed over the last 6 years. Surgeons-in-training are always taught that selection of the appropriate skin incision is an essential step in ensuring a successful operation. In obstetrics and caesarean sections, success must surely depend on both the choice of skin as well as uterine incision.