Author(s): Bethanechol Chloride for the Prevention of Postoperative Urinary Retention After Anal Surgery Under Spinal Anesthesia
Postoperative urinary retention is a commonly encountered problem after anal surgery particularly under spinal anesthesia. Bethanechol chloride, a muscarinic cholinergic receptor agonist was used to determine whether it could prevent this problem.
One hundred six patients with mean age of 37 ± 9 who underwent anal surgery under spinal anesthesia from January to August 2007 were included in this nonblinded randomized prospective experimental study. Forty-six patients were given bethanechol chloride 25mg/tab 1 hour post-op then another dose after 4-6 hours. Intravenous fluid was limited to <750 ml perioperatively and patients were asked to void within 6-8 hours post-op. Those with the urge to void but unable to do so within the hour or had hypogastric pain (VAS > 8) were immediately catheterized and the amount drained recorded.
The study showed that the number of patients catheterized in the bethanechol group was significantly lower (6.52% vs 23.33%, P=0.038) and the mean amount of urine drained was less than the control (<400cc, P=0.001). Using Z test, the proportion of patients catheterized in the bethanechol group was significantly lower than the control (P=0.0097). No significant relationship was noted between the patient's age (<50 or >50) and gender with regards to urinary retention (P=0.254 and P=0.187, respectively). The number needed to treat (NNT) showed that six patients treated with bethanechol are needed to prevent one patient from experiencing urinary retention.
Although bethanechol chloride did not completely prevent the development of postoperative urinary retention, its use was associated with reduced need for catheterization.
Key words: Bethanechol chloride, postoperative urinary retention, spinal anesthesia