though rare , it can lead to neurological sequelae such as bowel and bladder dysfunction , sexual dysfunction , saddle anesthesia , sciatica , and motor weakness .
hematoma is a good culture medium for bacteria ; therefore , reducing hematoma is advantageous in reducing infection .
many surgeons consider that a surgical drain increases the postoperative infection rate2561821 ) . as a foreign body
is inserted into a patient , it can lead to local inflammatory responses and can activate host defense system ; alternatively , it can act as an inlet of infection .
therefore , there is a controversy about usefulness of surgical drain in single - level lumbar disc surgery and that bleeding is not much . in this study
we studied 70 patients who had undergone single - level lumbar discectomy from april 2011 to march 2012 .
the patients who had undergone multilevel surgery , fusion surgery , and/or previous lumbar surgery were not included in this study .
this study was based on retrospective analysis of the patients ' medical records that included their age , sex , diagnosis , level of surgery , mean operation time , length of stay after surgery , past history ( hypertension and diabetes ) , and smoking or not , levels of c - reactive protein ( crp ) , and scores of visual analogue scale ( vas ) .
the patients were divided into 2 groups : one that received the surgical drain and the other that did not .
there were 42 patients who received the drain that included 21 men and 21 women with mean age of 49.93 years , and there were 28 patients who did not receive the drain that included 13 men and 15 women with mean age of 43.86 years .
both groups received prophylactic antibiotics ( 1st generation cephalosporin ) intravenously for 7 to 8 days .
we checked the levels of crp on postoperative days 1 , 3 , and 5 .
the amounts of surgical drainage collected for 24 hours were checked daily at the same time . in drainage group ,
proximal tip culture of surgical drain was conducted when removed . between postoperative days 7 and 8 ,
we compared the rates of infection , the levels of crp , and the scores of vas in preoperative , postoperative , and the first postoperative follow - up phases at the outpatients department .
the demographics of the 2 groups were compared using t - test and fisher exact test .
the mean duration of the surgical drain and the mean of total amounts of drainage were 2.88 days and 71.57ml , respectively .
the daily amounts of drainage on the postoperative days 1 , 2 , and 3 were 35.4 , 20.8 , and 14.27ml , respectively ( fig .
the differences in the levels of crp between the 2 groups were not significant ( p>0.05 ) ( fig .
2 ) . the mean level of crp in drainage group on postoperative days 1 , 2 , and 3 were 4.17 , 3.76 , and 2.41mg / l and in nondrainage groups mean level of crp were 4.89 , 5.2 , and
the differences in the scores of vas in preoperative , postoperative , and follow - up phases were not significant between the 2 groups ( p>0.05 ) ( fig .
3 ) . the mean scores of vas in the drainage group in preoperative , postoperative , and follow - up phase were 7.5 , 2.64 , and 0.64 and mean scores of vas in the nondrainage groups were 7.28 , 2.1 , and 0.76 .
the mean length of hospital stay after surgery was 9.68 days ; further , it was 8.68 days in the drainage group and 9.87 days in the nondrainage group .
the mean operation time of the drainage group was longer than the nondrainage group ( 150.2 minutes vs. 130.8 minutes ) .
but there was no significant difference between the 2 groups ( p>0.05 ) . in the group that did not receive surgical drain ,
the mean operation time of infected patients was 100 minutes and that of no infection patients was 144.5 minutes .
the operation time of infected patients was shorter than no infection patients , but there was no significance ( p>0.05 ) .
there was no statistically significant difference between the 2 groups ( p=0.157 ) ( tables 1 , 2 ) .
one of the 2 infected patients in the group that did not receive surgical drain was a 39-year - old woman who had undergone left l5-s1discectomy .
after 13 days of operation , she had fever and pus - like discharge at the operated site .
she underwent a repeated surgery on postoperative day 14 and received antibiotics treatment for 6 weeks ( fig .
the other patient was a 53-year - old woman who had undergone right l4-l5 discectomy .
the lumbar magnetic resonance imaging ( mri ) revealed fluid collection with rim enhancement at the operated site and adjacent soft tissue enhancement was also observed .
she underwent a repeated surgery on postoperative day 13 and received antibiotics treatment for 6 weeks .
the intraoperative pus culture grew methicillin - resistant and coagulase - negative staphylococcus ( fig .
the incidence of symptomatic epidural hematoma is rare ; however , the overall incidence rates of epidural hematomas on the first postoperative day of lumbar decompression surgery were reported using mri to be as frequent as 86%12 ) .
postoperative surgical drain can not only reduce the incidence and severity of hematoma formation but can also reduce the postoperative fibrosis14 ) .
the incidence of postoperative infection can be less than 1% after decompressive operation and more than 10% after fusions15 ) . in this study
, we analyzed the relation between the surgical drainage and postoperative infection in 70 patients who had undergone single - level lumbar disc surgery .
there were 2 cases of postoperative infection and both of them did not receive surgical drains ; however , there was no statistical significance . additionally , there was no significant difference in the outcomes of surgery ( pain and length of hospital stay after surgery ) .
additionally , from the financial perspective , there was no significant increase in the length of hospital stay because of surgical drain .
the difference in the infection rates of the 2 groups ( one that received the surgical drains and the other that did not ) was not statistically significant .
although many surgeons consider that surgical drain insertions increase infection rate , many studies have also shown no increase in the infection rate of surgical drains34816 ) .
kanayama et al.8 ) studied drain use after single - level lumbar decompression surgery and found " wound infection was not influenced by use of a drain . " more recently , poorman et al.17 ) studied drain use in cervical surgery and concluded " no differences in incidence of complications . " ho et al.7 ) reported significant increase the incidence of delayed postoperative infection in patients who did not received surgical drains .
though it may not always be correct , the tip cultures of surgical drains can allow us to detect postoperative infection at an early stage , and it can lead to faster initiation of antibiotics treatment10111920 ) .
positive tip culture predicts wound infection in 50% and a negative culture virtually excludes the possibility of a deep infection .
kobayashi et al.11 ) studied the efficacy of use of drain tip culture and conclude " rain tip culture is useful for early detection of surgical site infection caused by methicillin resistant bacteria . " in their series , there were 34 cases of positive tip culture and there were 19 surgical site infections .
drain tip culture had a sensitivity of 52% , specificity of 92% and the association between positive tip culture and wound infection was significant ( p<0.05 ) . in our study , the patients who underwent postoperative infection may have an opportunity to detect it earlier if they received drain tip culture .
surgical drains can reduce the risk of hematoma formation and can detect postoperative infection early by conducting drain tip culture .
however , even though simple , inserting surgical drain require additional effort of medical worker , time , cost of material , postoperative care and patient 's discomfort .
the decision to use or not a surgical drain is left to the surgeon 's discretion but using surgical drain can be considered in patient who has bleeding tendency and who has susceptibility to infection .
although many surgeons are apprehensive about postoperative infection by surgical drainage , no increase in infection rate and no difference in wound healing or postoperative neurological deficit have been observed .
the tip cultures of surgical drains can be an effective means of detection of the postoperative infection
 objectivesurgical drains are commonly used after the spine surgeries for minimizing hematoma formation , which can delay wound healing and may become a source of fibrosis , infection , and pain . 
 the drain , however , may provide a direct route for infection if it is contaminated . 
 our objective was to survey the relationship between surgical drains and infection.methodsthe 70 patients who had undergone single - level lumbar discectomy from april 2011 to march 2012 were retrospectively analyzed . 
 each patient 's medical chart and magnetic resonance image were thoroughly reviewed after all the patients had been divided into the drainage and the nondrainage groups . 
 the amounts and durations of the surgical drains in the drainage group were analyzed . 
 additionally , the levels of c - reactive protein , rates of infection , scores of preoperative and postoperative visual analog scale ( vas ) , and lengths of hospital stay after operation were compared between the 2 groups.resultsin this study , 70 patients were retrospectively analyzed ; out of which , 42 and 28 patients were included in the drainage and the nondrainage groups , respectively . 
 two of the postoperative infection cases in the nondrainage group required to undergo repeated operations . 
 the frequency of the postoperative infection cases was higher in the nondrainage group than in the drainage group ; however , there was no significant statistical difference between the 2 groups ( p=0.157).conclusionsurgical drains did not elevate postoperative infection . 
 furthermore , drain tip cultures allowed us to detect postoperative infection at an early stage , and it led to faster initiation of antibiotics treatment . 