To the Editor:—

We read with interest the two cases of retroperitoneal hematoma following lumbar plexus block reported by Weller et al.  1These cases and the authors’ conclusions prompt a number of comments. In the first case, it is clear that the introduction of the catheter was associated with significant vascular trauma, because “blood could be steadily aspirated.” Those who perform continuous lumbar plexus blocks on a regular basis are certainly familiar with this complication. Although there is little doubt that the administration of enoxaparin contributed to the development of the observed retroperitoneal hematoma, it is surprising that the authors did not consider the initial vascular trauma as a major risk factor, and furthermore, that they did not at that time abort the placement of the perineural catheter. As far as the second case is concerned, the authors describe a patient who had been grossly overdosed on heparin therapy (activated partial thromboplastin time > 100) and had developed a “moderate-sized retroperitoneal hematoma.” Although the authors acknowledge that spontaneous retroperitoneal bleeds are possible in anticoagulated patients, it is the introduction of a 21-gauge needle 3 days earlier that is primarily incriminated in the etiology of the hematoma.

What is particularly unfortunate is that, on the basis of these two cases, the authors go on to recommend that we apply the same guidelines for continuous lumbar plexus blocks as those proposed for neuraxial blocks, thus insinuating that performing lumbar plexus blocks in patients scheduled to be anticoagulated might be considered malpractice. Although no quantitative information is available, our group performs many of these blocks; to date, none of us has any recollection of the development of a retroperitoneal hematoma in any of our patients. We acknowledge that a perineural or retroperitoneal hematoma is a potential and rare complication, but it is also important to remember that the guidelines for neuraxial blocks in the presence of thromboprophylactic therapy were developed because a large number of patients (> 50 and, to date, probably around 80 patients) developed epidural hematoma while receiving therapeutic doses of low molecular weight heparin. The majority of those patients suffered serious neurologic injury. 2Of note, neither of the two patients reported by Weller et al.  suffered neurologic injury, despite one being massively overdosed with intravenous heparin.

To conclude, there is no doubt that caution should be exercised when placing a perineural catheter, especially a lumbar plexus catheter. In any patient for whom one has evidence of significant bleeding at the time of insertion of a perineural lumber plexus catheter, we recommend removal of the catheter at the time of insertion and the use of an alternative approach. This practice seems more measured and reasonable than offering the radical suggestion that continuous lumbar plexus block should be banned in patients receiving anticoagulant postoperatively.

Weller RS, Gerancher JC, Crews JC, Wade KL: Extensive retroperitoneal hematoma without neurologic deficit in two patients who underwent lumbar plexus block and were later anticoagulated. A nesthesiology 2003; 98: 581–5
Horlocker TT, Wedel DJ: Anticoagulation and neuraxial block: Historical perspective, anesthetic implications, and risk management. Reg Anesth Pain Med 1998; 23: 129–34