Case Presentation:
A 60 year‐old man presented with 5‐days of nausea, vomiting, and abdominal pain. His family described him as having increased fatigue, decreased mental status, and poor urinary output over the past week. He had a cervical spinal fusion one month prior. He had orthostatic hypotension, was somnolent and oriented only to person and “hospital”, and had no focal neurologic deficits. His abdomen was diffusely tender, especially in the lower quadrants, with no rebound tenderness or guarding and normal bowel sounds. His serum creatinine was 14.2‐mg/dL, blood urea nitrogen was 108‐mg/dL, and his leukocyte count 2100‐cells/ml with 41% neutrophils and an absolute neutrophil count 861‐cells/mL. The serum hemoglobin and platelet levels were normal. The patient was aggressively hydrated with 3 liters of 0.9% saline without any urination. An indwelling bladder catheter was placed and drained 600‐mL of urine. Over subsequent days, his neutrophil count increased to normal and the creatinine decreased to his baseline with resolution of the delirium. Once the delirium resolved, the patient revealed that following cervical spinal fusion, he was placed on a two‐week course of trimethoprim‐sulfamethoxazole.
Discussion:
Acute renal failure is a common problem encountered by the general internist and is often divided into pre‐renal, intrinsic renal, and post‐renal causes. Post‐renal azotemia can be understood anatomically from urethra, to the prostate, to internal urinary sphincter, to the bladder. Obstruction due to one of these areas can be overcome with a urethral or suprapubic catheter, which leads to an increased post‐void residual. Abnormalities superior to the bladder require obstruction of both ureters, and unilateral obstruction typically requires a solitary kidney to present with pathology.
The control of urination requires intact neurologic connections between the pons through the cauda equina and sacral plexus to innervate the bladder and sphincter. Owing to its role in micturation, cervical injury typically results in detrusor hyperreflexia and detrusor sphincter dyssynergia, and presents as hesitancy, weak stream, and incomplete voiding. Similarly, postoperative urinary retention (POUR) is very common following neurosurgical procedures, affecting 36% of patients. Cervical spinal surgery patients have an 11.1% chance of developing POUR with increased risks seen in advancing age, benign prostatic hypertrophy, diabetes mellitus, and beta‐blocker usage. Due to his urinary retention, the patient developed trimethoprim‐sulfamethoxazole toxicity including agranulocytosis and diarrhea. Following the correction of urinary retention, the medication and its metabolites were rapidly cleared with resolution of his symptoms.
Conclusions:
With the incidence of internists managing post‐surgical patients on the rise, internists should be adept at managing common complications associated with surgery such as urinary retention.