Risk factors for explantation due to infection after sacral neuromodulation: a multicenter retrospective case-control study.

BACKGROUND: Sacral neuromodulation is an effective therapy for overactive bladder, urinary retention, and fecal incontinence. Infection after sacral neurostimulation is costly and burdensome. Determining optimal perioperative management strategies to reduce the risk of infection is important to reduce this burden. OBJECTIVE: We sought to identify risk factors associated with sacral neurostimulator infection requiring explantation, to estimate the incidence of infection requiring explantation, and identify associated microbial pathogens. STUDY DESIGN: This is a multicenter retrospective case-control study of sacral neuromodulation procedures completed from Jan. 1, 2004, through Dec. 31, 2014. We identified all sacral neuromodulation implantable pulse generator implants as well as explants due to infection at 8 participating institutions. Cases were patients who required implantable pulse generator explantation for infection during the review period. Cases were included if age ≥18 years old, follow-up data were available ≥30 days after implantable pulse generator implant, and the implant was performed at the institution performing the explant. Two controls were matched to each case. These controls were the patients who had an implantable pulse generator implanted by the same surgeon immediately preceding and immediately following the identified case who met inclusion criteria. Controls were included if age ≥18 years old, no infection after implantable pulse generator implant, follow-up data were available ≥180 days after implant, and no explant for any reason <180 days from implant. Controls may have had an explant for reasons other than infection at >180 days after implant. Fisher exact test (for categorical variables) and Student t test (for continuous variables) were used to test the strength of the association between infection and patient and surgery characteristics. Significant variables were then considered in a multivariable logistic regression model to determine risk factors independently associated with infection. RESULTS: Over a 10-year period at 8 academic institutions, 1930 sacral neuromodulator implants were performed by 17 surgeons. In all, 38 cases requiring device explant for infection and 72 corresponding controls were identified. The incidence of infection requiring explant was 1.97%. Hematoma formation (13% cases, 0% controls; P = .004) and pocket depth of ≥3 cm (21% cases, 0% controls; P = .031) were independently associated with an increased risk of infection requiring explant. On multivariable regression analysis controlling for significant variables, both hematoma formation (P = .006) and pocket depth ≥3 cm (P = .020, odds ratio 3.26; 95% confidence interval, 1.20-8.89) remained significantly associated with infection requiring explant. Of the 38 cases requiring explant, 32 had cultures collected and 24 had positive cultures. All 5 cases with a hematoma had a positive culture (100%). Of the 4 cases with a pocket depth ≥3 cm, 2 had positive cultures, 1 had negative cultures, and 1 had a missing culture result. The most common organism identified was methicillin-resistant Staphylococcus aureus (38%). CONCLUSION: Infection after sacral neuromodulation requiring device explant is low. The most common infectious pathogen identified was methicillin-resistant S aureus. Demographic and health characteristics did not predict risk of explant due to infection, however, having a postoperative hematoma or a deep pocket ≥3 cm significantly increased the risk of explant due to infection. These findings highlight the importance of meticulous hemostasis as well as ensuring the pocket depth is <3 cm at the time of device implant.

Anatomic relationships of psoas muscle: clinical applications to psoas hitch ureteral reimplantation.

OBJECTIVE: The objective of the study was to examine the anatomic relationship of the genitofemoral and femoral nerves to the psoas major muscle. STUDY DESIGN: Dissections were performed in 17 unembalmed female cadavers. Point A was used as the approximate location for placement of psoas hitch sutures and as the reference point from which all measurements were taken. Measurements included the width of the psoas major muscle, psoas minor tendon, genitofemoral nerve branches, and femoral nerve. The relative location of the genitofemoral and femoral nerves to point A and the presence or absence of a psoas minor tendon were documented. RESULTS: The psoas minor tendon was absent on at least 1 side in 11 specimens (64.7%). The median width of the psoas minor tendon was 7 mm (range, 3-11.5 mm). The median width and depth of the psoas major muscle was 21.5 mm (range, 10-35 mm) and 20.0 mm (range, 11.5-32 mm), respectively. The median width of the genitofemoral nerve was 2 mm (range, 1-4.5 mm) and that of the femoral nerve was 6.3 mm (range, 5-10.5 mm). Overall, 54 genitofemoral nerve branches were identified in 17 cadavers, 30 medial (55.5%), 22 lateral (40.7%), and 2 directly overlying point A (3.7%). CONCLUSION: The exact location for the placement of the psoas hitch sutures will vary, depending on the location of the ureteral injury and the anatomy of the psoas muscle and surrounding structures. A thorough understanding of this regional anatomy should optimize the placement of psoas hitch sutures during ureteral reimplantation procedures and help avoid nerve and vessel injury.