A comparison of epidural and cerebrospinal fluid glucose in parturients at term: an observational study

Detecting inadvertent dural puncture during labour epidural insertion can be difficult when using a loss of resistance to saline technique. Testing fluid for glucose that leaks from a Tuohy needle may confirm the presence of cerebrospinal fluid and infer inadvertent dural puncture. This study compared the glucose content of intrathecal fluid obtained during spinal anaesthesia for elective caesarean delivery with that of fluid from a Tuohy needle or epidural catheter when establishing epidural analgesia for labour.

Women aged ≥18 years undergoing elective caesarean delivery and labouring parturients who requested epidural analgesia were recruited prospectively in a tertiary referral centre over a three-month period. Fluid was collected into a sterile container either during spinal anaesthesia or from a labour epidural needle. Glucose content was evaluated using a bedside blood glucometer and laboratory colorimetric analyzer.

Of the 118 women approached, 115 participated. All 40 women having spinal anaesthesia and 2/75 (2.7%) women having epidural analgesia, in whom inadvertent dural puncture was subsequently confirmed, had fluid samples testing positive for glucose. Median [range] laboratory glucose readings were 2.9 [1.3-5.1] mmol/L for cerebrospinal fluid and <0.3 mmol/L in fluid that leaked from a Tuohy needle (P=0.0001).

When using a loss of resistance to saline technique for epidural catheter placement, bedside glucometer testing of fluid leaking from the epidural needle may be of value in the early detection of inadvertent dural puncture.