To the Editor:

We read with great interest the recent article by Li et al. [1], “Prophylactic diphenhydramine attenuates postoperative catheter‑related bladder discomfort in patients undergoing gynecologic laparoscopic surgery.” However, we have some concerns with regards to their study conclusion. The authors recommended that administration of prophylactic diphenhydramine, 30 mg, at induction of general anesthesia reduced the incidence and severity of postoperative bladder discomfort without significant side effects in patients receiving gynecologic laparoscopic surgery.

Earlier lots of studies have shown that postoperative nausea and vomiting(PONV) is one of the most common adverse events after laparoscopic surgery with a reported incidence of 40–75%, which may delay postoperative recovery and discharge [2, 3]. In addition, PONV is the leading cause of discontinuation of intravenous patient-controlled analgesia (PCA), leading to decrease in the patient satisfaction and increase in the adverse effects (including the postoperative catheter-related bladder discomfort) [3, 4]. So, PONV in patients scheduled for laparoscopic surgery has been prevented and treated with a variety of antiemetics [4].

In the article by Li et al. although there were no significant differences between diphenhydramine and control groups in patient characteristics, PONV or analgesic requirement (p > 0.05), it was not clear whether the preventive treatments of PONV were used in both groups. Under such a setting, an important question will be raised: in the control group, the high PONV rate (21.7%) may lead to the high rate of postoperative catheter-related bladder discomfort.

From the discussion above, the current study by Li did not provide convincing evidence that prophylactic diphenhydramine at the induction of general anesthesia reduced the incidence and severity of postoperative bladder discomfort.