Topic: Cauda Equina Syndrome Subject: Medicine A 65-year-old male presents with a 1-month history of problems passing urine. He says that his bladder will feel full when he needs to urinate, but the urine stream is weak and his bladder does not feel as if it has emptied completely. The symptoms have become increasingly severe over the past week. Other symptoms include upper respiratory congestion for 3 days which he has treated with an over-thecounter decongestant with some relief, constipation with no passage of stool in the past 9 days, and increasing low back pain incompletely relieved with ibuprofen, with associated weakness in both legs. Examination shows a healthy-appearing male who is moderately overweight. He is afebrile and vital signs are normal. There is no abdominal tenderness and no masses are detected. A rectal examination reveals a large amount of hard stool in the rectum; a markedly enlarged (4+), boggy, tender prostate gland; laxity of the anal sphincter; and numbness in the perianal area. Urinalysis shows trace protein and 10-20 WBCs/hpf. Ultrasonography shows a post-void residual volume of 250 mL (normal for age <100). Which one of the following must be done urgently in this patient?
A. Foley catheterization
B. Hospitalization for intravenous antibiotics
C. Digital disimpaction of the rectum, and Fleet enemas until clear
D. MRI of the lumbosacral spine
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Correct Answer : D.
The differential diagnosis of urinary retention in the elderly is broad. While most causes are benign and readily treated, the physician must be vigilant in looking for conditions that require urgent intervention. This patient presents with many possible causes of urinary retention, with the most common being benign prostatic hyperplasia. Acute prostatitis, especially in a male with an enlarged prostate, is another relatively common reason for obstructive symptoms. This patients physical examination and abnormal urinalysis support this diagnosis, but his normal vital signs and lack of fever suggest he can be treated with an oral fluroquinolone and does not require hospital admission for intravenous therapy. Medications such as oral decongestants can contribute to urinary retention in men with enlarged prostate glands, and should be used with caution and discontinued if obstructive symptoms occur. Obstipation (severe constipation caused by intestinal obstruction) with stool impaction is another relatively common reason for urinary retention in the elderly and can be treated with manual disimpaction and enemas. In this patient, the presence of increasing low back pain and leg weakness, and the findings of anal sphincter laxity and numbness in the perianal area on examination, suggest the presence of a serious neurologic etiology such as cauda equina syndrome. Urgent diagnosis and treatment are necessary to reduce morbidity, and MRI should be performed immediately. The presence of a mildly elevated post-void residual is not an indication for urgent decompression with a Foley catheter.