R. Siddiqui and S.P. Luby

Department of Community Health Sciences, The Aga Khan University, Karachi.

Prolapsed intervertebral disc is a common cause of back pain and sciatica for which selected patients undergo surgical laminectomy. Infection of the intervertebral disc may arise as a result of direct introduction of organisms during disc excision (discitis). A patient with post operative discitis typically gains temporary relief of pain after surgery, but within one to eight weeks severe pain recurs which is aggravated by motion. There is little or no fever and the surgical wound site is benign. The leukocyte count is normal but the erythrocyte sedimentation rate is elevated. The incidence of discitis following laminectomy is reported to range between .75 - 2.8% . The Community Health Sciences Department, The Aga Khan University was invited to investigate an outbreak of post operative infections associated with laminectomies and to formulate recommendations to reduce them.

We reviewed the medical records of all patients admitted for prolapsed intervertebral disc at one surgical unit of Hospital A from January 1, 1993 to December 31,1993. We defined a case of discitis as one who developed fever or persistent pain and limitations of leg and back movements, postoperatively with an erythrocyte sedimentation rate of >50 mm, with no other apparent cause of their illness or fever. We compared the post operative infection rates by epidemiological and environmental related risk factors. We interviewed personnel, examined the premises and after analyzing the data issued recommendations. At the request of Hospital officials we returned to Hospital A 6 months later and reviewed medical records from January 1,1994 to July 31,1994 to see if the infection rate had changed.

There were 73 admissions for prolapsed intervertebral disc in 1993. We were able to locate 59 records; 18 were excluded because either they did not under go surgery, their admitting diagnosis was changed or they left against medical advice. Of the 41 patients reviewed 6 (15%) developed post operative infection. Persons operated upon by a single surgeon, Surgeon A, were 9 times more likely to develop post operative infection than those who were not (Relative Risk [RR] =9, 95% CI= 2.7 - 31.4, p=.007). Potential contributing environmental factors included poor preparation of patients, inadequate records & care to maintain sterile theater and leaking sewage around the ward. In the follow up period of January to July 1994, 43 patients were admitted with the diagnosis of prolapsed intervertebral disc. We located and reviewed 30 records. Two persons (6.6% ), both women, developed discitis. Combining both the 1993 and 1994 patients women were 4.4 times more likely to develop discitis than men (31% versus 7%, RR=4.4, CI= 1.3 - 15.6, p= .032).

Operative procedure and poor infection control contributed to the high postoperative infection rate. Adequate preparation of patients and sterility in the operating room are essential. Moreover, criteria for selection of patients for surgical treatment of prolapsed intervertebral discs developed in settings where the risk of post operative infection is high should be different from those in settings with lower complication rates.

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