Cerebrospinal fluid cytology in patients undergoing combined spinal epidural versus spinal anaesthesia without an introducer.

The problem of tissue coring exists despite the availability of smaller gauge spinal needles with special tip designs. The aim of the study was to test the hypotheses that a) subarachnoid block given as a part of a combined spinal epidural intervention by needle-through-needle technique introduces a lesser number of epithelial cells into the subarachnoid space compared to isolated subarachnoid block, and b) after lumbar puncture, the initial few drops of cerebrospinal fluid from the spinal needle will have a higher number of epithelial cells than the subsequent sample. One hundred and seven patients of American Society of Anesthesiologists physical status I to III undergoing infra-umbilical surgery were enrolled. Seven patients were excluded from the study and the rest divided into two groups to receive either combined spinal epidural anaesthesia (group A) or isolated subarachnoid anaesthesia, unaided by an introducer (group B). The two groups were compared for the presence of epithelial cells in cerebrospinal fluid. The initial four to six drops of cerebrospinal fluid (sample 1) were collected, the next four to six drops discarded and the following four to six drops (sample 2) collected. The incidence of coring was 96% in group A and 88% in group B (P = 0.142). The median (interquartile range) number of cells in group A, for samples 1 and 2 was 6 (3 to 12.5) and 6 (3 to 10); and in group B, 3.5 (1 to 10) and 4 (1 to 8) respectively. Significant tissue coring was observed with both techniques. Discarding eight to 12 drops of cerebrospinal fluid did not help in reducing the epithelial cell load.