Cesarean Delivery Surgical Site
Infection Rate Based on Hospital
Billing Data: Fact or Fiction?
Kelly W. Kline, MD
Mentor: Sharon Keiser, MD
Adam Tyson, MD
Department of Obstetrics & Gynecology
• I have no meaningful conflicts of interest to
disclose.
Background
• Why do we care about surgical site infections
(SSI)?
– Very common delivery method1
– 2-10% complicated by SSI2
– Very costly to patient and healthcare resources3
Background
• What is known about post-cesarean SSI?
– Prophylactic Antibiotics
– Surgical site preparation
Hypothesis
• The hospital-determined rate of post-
cesarean surgical site infection is significantly
lower than the true rate at our institution
Objectives
• Primary:
– Determination of an accurate post-cesarean SSI
rate
• Secondary:
– Identify modifiable risk factors for post-cesarean
SSI
Methods
Study Design
• Retrospective chart review
Participants
• L&D Delivery Log
• OB Teaching Staff cesarean deliveries
• July 1, 2014- June 30, 2015
Billing data participants
• All cesarean deliveries July 1, 2014- June 30, 2015
Methods
• Data Collection
– RedCap software
– 3 abstractors
– Clearly defined variables
• Demographic
• Pregnancy complications
• Intrapartum events
• Surgical Site Infection diagnosis
Methods
• 740 cesarean deliveries performed total
• ExclusionsCase Identifier Reason for Exclusion
A Exploratory laparotomy at time of cesarean delivery
B Exploratory laparotomy at time of cesarean delivery
C Cesarean hysterectomy for placenta accreta
D Cesarean hysterectomy for placenta accreta
E Cesarean hysterectomy for uterine rupture
F Exploratory laparotomy at time of cesarean delivery
G Cesarean hysterectomy for placenta percreta
Methods
• Billing data
– Provided by Infection Prevention department
– Admission log
– OR log
– CPT & ICD-9 codes
Methods: Statistics
• Continuous variables
– T- tests
• Comparison of women diagnosed with SSI
and not diagnosed with SSI
– Fisher’s exact test
Results- Primary Outcome
Information Source Proportion of SSI p-value
Billing Department
(n=1712)
11/ 1712 (0.6%) <0.00001
Charts (n=733) 60/733 (8.3%)
Results- secondary outcome
Demographics Overall (n=733) With SSI (n=60 ) Without SSI
(n=673)
p-value
Age 27.25 (0.22) 27.18 (0.92) 27.58 (0.23) 0.9376
Gravidity 2.75 (0.06) 2.62 (0.21) 2.76 (0.06) 0.4745
Parity 1.05 (0.04) 0.85 (0.12) 1.06 (0.04) 0.0472
Prior C-Section 377 (0.52) 25 (0.41) 352 (0.52) 0.1376
Hypertension 102 (0.14) 10 (0.17) 95 (0.14 0.5585
Ethnicity White 340 (0.47) 31 (0.52) 309 (0.46) 0.3281
Black 239 (0.33) 21 (0.35) 218 (0.32)
Other 152 (0.20) 8 (0.13) 144 (0.21)
Smoker 206 (0.28) 21 (0.35) 185 (0.27) 0.4453
Use of immunosuppressant 7 (0.01) 3 (0.05) 4 (0.01) 0.0145
Pre-pregnancy weight 180.23 (2.29) 190.83 (8.10) 179.4 (2.38) 0.1802
BMI 34.67 (1.00) 36.02 (3.041) 34.54 (1.05) 0.6622
Demographic Information
Results
Pregnancy
Complications
Overall (n=733) With SSI (n=60 ) Without SSI
(n=673)
p-value
Gestational
Diabetes
80 (0.11) 6 (0.10) 74 (0.11) 0.8064
Pre-eclampsia 117 (0.16) 12 (0.10) 105 (0.14) 0.3614
Gestational
Hypertension
51 (0.07) 7 (0.11) 44 (0.07) 0.1780
Systemic Infection
During Pregnancy
10 (0.01) 2 (0.03) 8 (0.01) 0.1941
Preterm Premature
Rupture of
membranes
(PPROM)
44 (0.06) 5 (0.08) 39 (0.06) 0.3959
Cerclage Placed 24 (0.03) 3 (0.05) 21 (0.03) 0.4378
Pregnancy Complications
Results
Intrapartum Overall (n=733) With SSI (n=60) Without SSI (n=673) p-value
Indication for
cesarean
section*
Previous C-section 342 (0.48) 19 (0.32) 323 (0.48) 0.0130
Arrest of Descent 27 (3.69) 6 (0.1) 31 (0.03) 0.0217
Arrest of Dilation 52 (0.07) 4 (0.07) 48 (0.07) 0.8882
Multiple Gestation 23 (0.03) 3 (0.05) 20 (0.03) 0.3906
Non-cephalic
Presentation
101 (0.14) 4 (0.07) 97 (0.15) 0.0939
Previous
Myomectomy
4 (0.006) 1 (0.016) 3 (0.005) 0.2199
Non-reassuring
fetal heart tracing
175 (0.24) 13 (0.22) 162 (0.24) 0.6637
Preterm Labor 8 (0.02) 0 8 (0.01) 0.3951
Failed Induction of
labor
57 (0.08) 9 (0.15) 48 (0.07) 0.0489
Other 61 (0.08) 5 (0.08) 56 (0.08) 0.9973
Skin Incision Pfannenstiel 713 (0.98) 59 (0.98) 654 (0.98) 0.6781
Vertical Midline or
High Transverse
18 (0.02) 1 (0.02) 17 (0.02)
Uterine
Incision
Low Transverse 672 (0.92) 52 (0.87) 620 (0.92) 0.1452
Classical 41 (0.06) 4 (0.07) 37 (0.06) 0.7668
High Transverse 20 (0.03) 4 (0.07) 16 (0.02) 0.0734
Type of
Fascial Suture
Vicryl 363 (0.50) 34 (0.57) 329 (0.50) 0.5089
PDS 341 (0.50) 26 (0.43) 341 (0.50) 0.2834
Other 1 (0.001) 0 1 (0.001)
Intrapartum and Delivery Characteristics
Results
Intrapartum Overall (n=733) With SSI (n=60) Without SSI
(n=673)
p-value
Labor 300 (0.41) 35 (0.58) 265 (0.40) 0.0045
Surgeon PGY 2.23 (0.02) 2.18 (0.47) 2.23 (0.57) 0.4482
Attending Scrubbed 237 (0.32) 18 (0.30) 219 (0.33) 0.0773
Diagnosed with Chorioamnionitis 58 (0.08) 5 (0.08) 53 (0.08) 0.8056
Maternal Tmax 99.07 100.01 (0.19) 98.99 (0.03) <0.0001
Maternal HR 106.63 (0.62) 112.52 (2.23) 106.10 (0.65) 0.0037
Hours of Rupture of Membranes 14.75 (3.25) 28.54 (10.92) 13.53 (3.43) 0.1935
Fetal HR*** 137.00 138.73 (3.05) 136.84 (0.71) 0.5476
Urgency of C-
Section
Scheduled 332 (0.46) 17 (0.29) 315 (0.48) 0.0077
Priority 241 (0.33) 26 (0.44) 215 (0.32) 0.0549
Urgent 92 (0.13) 8 (0.13) 84 (0.13) 0.8077
Emergency 56 (0.08) 4 (0.12) 49 (0.07) 0.2018
Type of Prep Chlorhexidine 637 (0.88) 46 (0.81) 591 (0.89) 0.0836
Povidone/ Iodine 82 (0.011) 10 (0.18) 72 (0.11) 0.1290
Other 3 (0.004) 1 (0.001) 2 (0.003) 0.2189
Intrapartum and Delivery Characteristics
Conclusions
• The hospital billing data at Greenville
Memorial Hospital are not an accurate
representation of our true surgical site
infection rate
Discussion
Superficial30%
Deep Incisional25%
Organ Space45%
Type of Wound Infection
Discussion
During Postpartum Stay, 24
OB Triage, 24
OBGYN Center, 9
Emergency Department, 1 Other Facility, 2
Location of Diagnosis
Discussion
During Postpartum Stay, 24
OB Triage, 24
OBGYN Center, 9
Emergency Department, 1
Other Facility, 2
Figure 3. Location of Diagnosis
Strengths
• Single primary abstractor
• Use of RedCap
• Did not rely on CPT codes for chart review
data
Weaknesses
• Multiple abstractors
• Billing data cases’ charts not reviewed
• Descriptive study
Future Research
• Vaginal Prep
• Identifying highest risk patients
• Prophylactic interventions
References
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