Baldini et al.  1are to be congratulated for their excellent review of the problem of postoperative urinary retention. It reflects the growing role of the anesthesiologist in perioperative management and enhances our awareness of the impact of our anesthetic techniques on postoperative outcomes. Their description of the anatomy, physiology, and pharmacology of this phenomenon will serve as a reference source for many practitioners.

As an anesthesiologist in the ambulatory setting, however, I have a concern about their generalizations in their concluding page about the requirement for voiding in outpatients after neuraxial blockade. The authors correctly identify in earlier references that the potential for urinary retention is proportional to the duration of the blockade, which they discuss both in their section on the duration of surgery and in their review of spinal anesthetics.2–5They cite our own prospective study that specifically addressed the issue of discharge without a voiding requirement.6These references support the principle that otherwise low-risk outpatients have no greater risk of retention after short duration neuraxial blockade than those receiving general anesthesia, and requiring voiding before discharge may represent an unnecessary delay. Therefore, it is unfortunate that the discussion of outpatient requirements refers only to the policy by Pavlin et al. , that spinal and epidural blockade are inherent risk factors for urinary retention.

That conclusion was based on previous publication from Pavlin's group, which demonstrated delayed discharge after spinal anesthetics performed with bupivacaine and lidocaine plus epinephrine.7In their subsequent study of voiding in outpatients, 26 patients received neuraxial blockade: 22 were given either bupivacaine or lidocaine plus epinephrine.8Therefore, their conclusions are consistent with their experience and data, and previous reports regarding long-duration blockade. The publications mentioned above, however, demonstrate that the use of short-duration local anesthetics for outpatient spinal blockade are not associated with an increased risk of urinary retention for low-risk patients, and thus do not necessarily mandate voiding before discharge. Further work is obviously indicated, but it seems that neuraxial anesthesia alone (with a short-acting drug in a low-risk patient) is not a risk factor for postoperative retention.

Virginia Mason Medical Center, Seattle, Washington. michael.mulroy@vmmc.org

1.
Baldini G, Bagry H, Aprikian A, Carli F: Postoperative urinary retention: Anesthetic and perioperative considerations. Anesthesiology 2009; 110:1139–57
2.
Pawlowski J, Sukhani R, Pappas AL, Kim KM, Lurie J, Gunnerson H, Corsino A, Frey K, Tonino P: The anesthetic and recovery profile of two doses (60 and 80 mg) of plain mepivacaine for ambulatory spinal anesthesia. Anesth Analg 2000; 91:580–4
3.
Gupta A, Axelsson K, Thörn SE, Matthiessen P, Larsson LG, Holmström B, Wattwil M: Low-dose bupivacaine plus fentanyl for spinal anesthesia during ambulatory inguinal herniorrhaphy: A comparison between 6 mg and 7.5 mg of bupivacaine. Acta Anaesthesiol Scand 2003; 47:13–9
4.
Liu SS, Ware PD, Allen HW, Neal JM, Pollock JE: Dose-response characteristics of spinal bupivacaine in volunteers: Clinical implications for ambulatory anesthesia. Anesthesiology 1996; 85:729–36
5.
Ben-David B, Levin H, Solomon E, Admoni H, Vaida S: Spinal bupivacaine in ambulatory surgery: The effect of saline dilution. Anesth Analg 1996; 83:716–20
6.
Mulroy MF, Salinas FV, Larkin KL, Polissar NL: Ambulatory surgery patients may be discharged before voiding after short-acting spinal and epidural anesthesia. Anesthesiology 2002; 97:315–9
7.
Pavlin DJ, Rapp SE, Polissar NL, Malmgren JA, Koerschgen M, Keyes H: Factors affecting discharge time in adult outpatients. Anesth Analg 1998; 87:816–26
8.
Pavlin DJ, Pavlin EG, Gunn HC, Taraday JK, Koerschgen ME: Voiding in patients managed with or without ultrasound monitoring of bladder volume after outpatient surgery. Anesth Analg 1999; 89:90–7