Normal urine output after elective caesarean section: an observational study.

Area of Science:

• Obstetrics
• Anesthesiology
• Nephrology

Background:

• Postoperative urine output monitoring lacks obstetric-specific guidelines.
• Peri-operative oxytocin infusions complicate fluid balance assessment.
• Elective caesarean section under neuraxial anaesthesia presents unique monitoring challenges.

Purpose of the Study:

• To establish a normal range for postoperative urine output following elective caesarean section.
• To investigate the impact of oxytocin infusions on urine output.
• To assess renal function markers and fluid balance in this cohort.

Main Methods:

• Sixty women undergoing elective caesarean section were studied for 24 hours post-catheterization.
• Urine output, fluid input, intra-operative blood loss, and oxytocin use were recorded.
• Renal function markers and urine osmolality were analyzed, with statistical comparisons using Mann-Whitney U and paired t-tests.

Main Results:

• Oxytocin infusions (75% of participants) were associated with significantly lower urine output (0.8 mL/kg/h vs. 1.4 mL/kg/h in the first 6 hours, P=0.02).
• Higher blood loss was observed in women receiving oxytocin (0.4 L vs. 0.3 L, P=0.003).
• Pre-operative urine osmolality was high (622.5 mosm/kg), suggesting pre-existing dehydration.

Conclusions:

• Postoperative urine output exhibits wide inter-individual variation, particularly after 6 hours.
• Oxytocin administration appears to reduce urine output, potentially due to direct effects or increased blood loss.
• Clinical monitoring of postoperative urine output must consider oxytocin use and potential pre-operative dehydration.