Neostigmine Linked to Rapid Bladder Emptying in Single Case of Postoperative Urinary Retention

A 73-year-old man with a long history of prostate disease avoided a urinary catheter after a single intravenous dose of neostigmine appeared to reverse postoperative urinary retention within minutes, according to a case report published in Discover Medicine on 21 October 2026. The report, authored by Mitch Daniel, Victoria Martin, John Hodgson, Tanjina Jalil and Enrico Camporesi, describes a temporal association between the drug and bladder emptying, but the authors are explicit that a single case without a comparator cannot establish causation or efficacy.

Postoperative urinary retention, commonly abbreviated POUR, is a frequent complication of surgery and anesthesia. The authors cite an incidence of roughly 4 to 5 percent in elective procedures when retention is defined as requiring catheterization or an overnight admission. The condition matters clinically because a bladder that cannot empty risks overdistension injury, discomfort, urinary tract infection and delayed discharge. The standard treatment is bladder catheterization, which reliably decompresses the bladder but carries its own burden: postoperative catheter-associated urinary tract infections are typically reported at rates between 1 and 3.6 percent, with higher rates in certain subgroups and with prolonged catheterization.

Pharmacologic alternatives to the catheter have been explored for decades. Alpha-adrenergic antagonists such as tamsulosin have been used prophylactically, particularly in men, with mixed results in reducing retention. Cholinergic agents such as bethanechol, which aim to stimulate contraction of the detrusor muscle that empties the bladder, have shown variable efficacy and are used less commonly. Neostigmine, a reversible acetylcholinesterase inhibitor, enhances parasympathetic activity and thereby promotes detrusor contraction, making it biologically plausible as a treatment for retention. Its use specifically as a rescue treatment for established POUR, however, is rarely reported in the literature.

The patient in this case arrived with a dense cluster of risk factors. He had benign prostatic hyperplasia diagnosed three years earlier, managed for more than ten years with daily finasteride and tamsulosin. He had bladder cancer treated with transurethral resection of a bladder tumor twenty years before. He also carried a diagnosis of interstitial pulmonary fibrosis. Rising prostate-specific antigen levels and worsening nocturia had prompted a prostate MRI and a subsequent MRI-guided transperineal prostate biopsy, the procedure that brought him to the operating room. He also reported a single prior episode of urinary retention of unknown cause.

The biopsy was performed under general anesthesia with sevoflurane and completed without complication in under thirty minutes.

Thirty minutes after arrival in the post-anesthesia care unit, the patient could not void, and a bladder scan showed 300 mL of retained urine. Over the next several hours he drank fluids, ambulated continuously, tried caffeine and took an additional dose of tamsulosin, yet a follow-up scan showed the retained volume had grown to 565 mL. He described a dry mouth and a muted sense of bladder fullness. Five hours into the retention, still wanting to avoid self-catheterization, he asked to try neostigmine after a discussion of risks, benefits and alternatives.

With the patient connected to standard five-lead electrocardiogram, blood pressure and pulse oximetry monitors, the team administered 0.5 mg of intravenous neostigmine. The anesthesiologist observed only a minimal, temporary reduction in heart rate, with no other hemodynamic or pulmonary changes. Fifteen minutes later the patient voided completely, leaving a postvoid residual of 65 mL, which satisfied the final discharge criterion. He went home promptly and reported no voiding difficulties at urological follow-up one week later. The case was reported in line with the SCARE criteria for surgical case reports.

The authors are careful about what this sequence does and does not show. Complete bladder emptying occurred within fifteen to twenty minutes of the injection, a striking temporal association, but they note that the temporal sequence alone does not establish that neostigmine caused the outcome. Before the drug was given, the patient had already spent five hours under observation with prolonged ambulation, hydration, caffeine intake and tamsulosin on board, so spontaneous resolution of the retention cannot be excluded. As a single case without a comparator, the report cannot establish causality, efficacy or generalizability, and unmeasured factors may have contributed to the resolution. Long-term outcomes beyond the immediate postoperative period were not systematically assessed.

Broader evidence offers context but not confirmation. A 2024 meta-analysis by Chen and colleagues, covering 14 studies and 4,196 postoperative patients, found that neostigmine significantly improved POUR resolution compared with control or standard therapies. Yet the effect is not consistent across all perioperative settings: although neostigmine has been observed to accelerate bladder emptying after spinal anesthesia, it did not reduce the overall incidence of retention or the need for catheterization in patients undergoing lower abdominal and lower-extremity surgery. The authors also point out that sugammadex, a newer reversal agent, may perform better than neostigmine in reducing the risk of iatrogenically induced retention, though their case concerns neostigmine given after retention had already developed, a scenario for which reports after transperineal prostate biopsy remain limited.

The authors position the observation as hypothesis-generating rather than practice-changing. They caution that it should not be interpreted as evidence that neostigmine can routinely replace catheterization when catheterization is clinically indicated, since an undrained, overdistended bladder carries real risks. What the case does provide is a detailed, monitored example of a patient with multiple retention risk factors in whom a single low-dose injection was followed by complete emptying without adverse hemodynamic effects. The authors call for prospective studies to define neostigmine’s safety, efficacy, patient-selection criteria and potential role in perioperative urinary retention protocols, ideally in appropriately monitored settings where the drug’s effect can be separated from the passage of time.

Subject of Research: Resolution of postoperative urinary retention after neostigmine administration in a single patient case report

Article Title: Case report of postoperative urinary retention resolution following neostigmine administration in a patient with multiple risk factors for POUR

Article References: Daniel, M., Martin, V., Hodgson, J., Jalil, T., & Camporesi, E. (2026). Case report of postoperative urinary retention resolution following neostigmine administration in a patient with multiple risk factors for POUR. Discover Medicine, 3(1), Article 162. https://doi.org/10.1007/s44337-026-00729-y

Image Credits: AI Generated

DOI: 10.1007/s44337-026-00729-y

Keywords: postoperative urinary retention, neostigmine, case report, prostate biopsy, bladder catheterization, benign prostatic hyperplasia, acetylcholinesterase inhibitor, detrusor contraction, anesthesia complications, urinary tract infection, tamsulosin, Discover Medicine