When selecting the anesthesia method in cesarean operations, attention must be paid to the

urgency of the operation, pre-existing maternal systemic problems, general status of the

fetus,and the surgeon’s and patient’s preference. Although general or regional anaesthesia

can be used in lower segment Caesarean section (LSCS), regional anesthesia is the most

widely preferred anaesthesia method for caesarean sections in developed countries.

Regional anaesthesia offers many advantages to the mother like,awake mother during the

labour, very little or no requirement for airway intervention, protection of airway reflexes,

reduced blood loss, reduced probability of drug-related fetal depression, and the

continuation of analgesia in the postoperative period.

There is a greater tendency of high level of sensory blockade in parturients with spinal

anaesthesia. Pregnant patients display higher sensitivity to local anaesthetics. Neuraxial

blockage forms at low concentration of local anaesthetics. A decreased lumbosacral

subarachnoidal space volume is a major factor in the cephalad intrathecal spread of local

anesthetics in term parturients and their subarachnoidal space is decreased due to the

compressive effect of huge uterus.

There is greater amount of epidural tissue in parturients, the epidural veins are widened and

the epidural space is narrowed, therefore there is a need for 25-30% less local anaesthetics

in spinal and epidural anaesthesia. In circumstances that lead to increased intra abdominal

pressure or widening of epidural veins, generally high levels of blocks are induced.

Abdominal circumference(AC) correlates with intra abdominal volume, maternal AC

increases during pregnancy and it is influenced by fetus size, amniotic fluid, size of the

uterus.

Increased height of block can lead to high spinal anaesthesia, hypotension and respiratory

depression. However, low level of blockade can lead to inadequate anesthesia and patient

discomfort. Although it is considered safe anaesthetic method, nausea and vomiting are

reported after spinal anaesthesia despite prehydration and left displacement of uterus. This

is attributed to greater aortio caval compression and greater cephaloid spread of sensory blockade by an enlarged uterus.