Rebeccah B. Baucom

Prospective Evaluation of Surgeon Physical Examination for Detection of Incisional Hernias

BACKGROUND Surgeon physical examination is often used to monitor for hernia recurrence in clinical and research settings, despite a lack of information on its effectiveness. This study aims to compare surgeon-reviewed CT with surgeon physical examination for the detection of incisional hernia. STUDY DESIGN General surgery patients with an earlier abdominal operation and a recent viewable CT scan of the abdomen and pelvis were enrolled prospectively. Patients with a stoma, fistula, or soft-tissue infection were excluded. Surgeon-reviewed CT was treated as the gold standard. Patients were stratified by body mass index into nonobese (body mass index <30) and obese groups. Testing characteristics and real-world performance, including positive predictive value and negative predictive value, were calculated. RESULTS One hundred and eighty-one patients (mean age 54 years, 68% female) were enrolled. Hernia prevalence was 55%. Mean area of hernias was 44.6 cm(2). Surgeon physical examination had a low sensitivity (77%) and negative predictive value (77%). This difference was more pronounced in obese patients, with sensitivity of 73% and negative predictive value 69%. CONCLUSIONS Surgeon physical examination is inferior to CT for detection of incisional hernia, and fails to detect approximately 23% of hernias. In obese patients, 31% of hernias are missed by surgeon physical examination. This has important implications for clinical follow-up and design of studies evaluating hernia recurrence, as ascertainment of this result must be reliable and accurate.

Efficient multi-atlas abdominal segmentation on clinically acquired CT with SIMPLE context learning

Abdominal segmentation on clinically acquired computed tomography (CT) has been a challenging problem given the inter-subject variance of human abdomens and complex 3-D relationships among organs. Multi-atlas segmentation (MAS) provides a potentially robust solution by leveraging label atlases via image registration and statistical fusion. We posit that the efficiency of atlas selection requires further exploration in the context of substantial registration errors. The selective and iterative method for performance level estimation (SIMPLE) method is a MAS technique integrating atlas selection and label fusion that has proven effective for prostate radiotherapy planning. Herein, we revisit atlas selection and fusion techniques for segmenting 12 abdominal structures using clinically acquired CT. Using a re-derived SIMPLE algorithm, we show that performance on multi-organ classification can be improved by accounting for exogenous information through Bayesian priors (so called context learning). These innovations are integrated with the joint label fusion (JLF) approach to reduce the impact of correlated errors among selected atlases for each organ, and a graph cut technique is used to regularize the combined segmentation. In a study of 100 subjects, the proposed method outperformed other comparable MAS approaches, including majority vote, SIMPLE, JLF, and the Wolz locally weighted vote technique. The proposed technique provides consistent improvement over state-of-the-art approaches (median improvement of 7.0% and 16.2% in DSC over JLF and Wolz, respectively) and moves toward efficient segmentation of large-scale clinically acquired CT data for biomarker screening, surgical navigation, and data mining.

Postoperative Care Using a Secure Online Patient Portal: Changing the (Inter)Face of General Surgery

BACKGROUND Many patients seek greater accessibility to health care. Meanwhile, surgeons face increasing time constraints due to workforce shortages and elevated performance demands. Online postoperative care may improve patient access while increasing surgeon efficiency. We aimed to evaluate patient and surgeon acceptance of online postoperative care after elective general surgical operations. STUDY DESIGN A prospective pilot study within an academic general surgery service compared online and in-person postoperative visits from May to December 2014. Included patients underwent elective laparoscopic cholecystectomy, laparoscopic ventral hernia repair, umbilical hernia repair, or inguinal hernia repair by 1 of 5 surgeons. Patients submitted symptom surveys and wound pictures, then corresponded with their surgeons using an online patient portal. The primary outcome was patient-reported acceptance of online visits in lieu of in-person visits. Secondary outcomes included detection of complications via online visits, surgeon-reported effectiveness, and visit times. RESULTS Fifty patients completed both online and in-person visits. Online visits were acceptable to most patients as their only follow-up (76%). For 68% of patients, surgeons reported that both visit types were equally effective, while clinic visits were more effective in 24% and online visits in 8%. No complications were missed via online visits, which took significantly less time for patients (15 vs 103 minutes, p < 0.01) and surgeons (5 vs 10 minutes, p < 0.01). CONCLUSIONS In this population, online postoperative visits were accepted by patients and surgeons, took less time, and effectively identified patients who required further care. Further evaluation is needed to establish the safety and potential benefit of online postoperative visits in specific populations.

Association of Perioperative Hypothermia During Colectomy With Surgical Site Infection

IMPORTANCE Maintaining perioperative normothermia has been shown to decrease the rate of surgical site infection (SSI) after segmental colectomy and is part of the World Health Organizations Guidelines for Safe Surgery. However, strong evidence supporting this association is lacking, and an exact definition of normothermia has not been described. OBJECTIVE To determine whether intraoperative hypothermia in patients who undergo segmental colectomy is associated with postoperative SSI. DESIGN, SETTING, AND PARTICIPANTS In a retrospective cohort study at a single tertiary-referral hospital, 296 adult patients who underwent elective segmental colectomy from January 1, 2005, through December 31, 2009, were included. Exclusion criteria included postoperative stoma, emergent or urgent operation, and diagnosis of inflammatory bowel disease. EXPOSURES Perioperative temperature was measured continuously, and 4 possible definitions of hypothermia were explored, including temperature nadir, mean intraoperative temperature, percentage of time at the temperature nadir, and percentage of time with a temperature of less than 36.0°C. MAIN OUTCOMES AND MEASURES The primary outcome measure was 30-day SSI. Secondary outcome measures included clinical leak, return to the operating room, and nasogastric tube placement (a surrogate for ileus). RESULTS The mean (SD) findings were as follows: intraoperative temperature, 35.9°C (0.6°C); temperature nadir, 34.3°C (2.8°C); percentage of time at the nadir, 4.7% (10.8%); and percentage of time with a temperature of less than 36.0°C, 49.9% (42.0%). The rate of SSI was 12.2% (n = 36). There was no statistically significant difference in temperature measurements between the patients who developed an SSI and those who did not. Logistic regression models evaluated each exposure measure and its effect on SSI, adjusting for body mass index, smoking status, and sex. The adjusted analyses revealed no association between intraoperative hypothermia and 30-day SSI (odds ratio, 1.17; 95% CI, 0.76-1.81; P = .48). Increased body mass index (odds ratio, 1.39; 95% CI, 1.10-1.76; P = .007) was significantly associated with SSI in all 4 logistic regression models. CONCLUSIONS AND RELEVANCE Patients who underwent segmental colectomy and sustained a period of intraoperative hypothermia were no more likely to develop an SSI than those who were normothermic.

Comparative Evaluation of Dynamic Abdominal Sonography for Hernia and Computed Tomography for Characterization of Incisional Hernia

IMPORTANCE Previous work has demonstrated that dynamic abdominal sonography for hernia (DASH) is accurate for the diagnosis of incisional hernia. The usefulness of DASH for characterization of incisional hernia is unknown. OBJECTIVE To determine whether DASH can be objectively used to characterize incisional hernias by measurement of mean surface area (MSA). DESIGN, SETTING, AND PARTICIPANTS A prospective cohort study was conducted. A total of 109 adults with incisional hernia were enrolled between July 1, 2010, and March 1, 2012. Patients with a stoma, fistula, or soft-tissue infection were excluded. INTERVENTIONS DASH was performed by a surgeon to determine the maximal transverse and craniocaudal dimensions of the incisional hernia. A separate surgeon, blinded to the DASH results, performed the same measurements using computed tomography (CT). MAIN OUTCOMES AND MEASURES The MSA was calculated, and the difference in MSA by DASH and CT was compared using the Wilcoxon signed rank test. Subset analysis was performed with patients stratified into nonobese, obese, and morbidly obese groups. We hypothesized that there was no significant difference between MSA as measured by DASH compared with CT. RESULTS A total of 109 patients were enrolled (mean age, 56 years; mean body mass index, 32.2 [calculated as weight in kilograms divided by height in meters squared]; and 67.0% women). The mean (SD) MSA measurements were similar between the modalities: DASH, 41.8 (67.5) cm2 and CT, 44.6 (78.4) cm2 (P = .82). The MSA measurements determined by DASH and CT were also similar for all groups when stratified by body mass index. There were 15 patients who had a hernia 10 cm or larger in transverse dimension. The mean body mass index of this group was 39.2, and the MSA measurements by DASH and CT were similar (P = .26). CONCLUSIONS AND RELEVANCE DASH can be used to objectively characterize hernias by MSA, with accuracy demonstrated in the obese population and in patients whose hernias were very large (≥10 cm in diameter). DASH offers the advantages of real-time imaging and no ionizing radiation and may obviate the need for the patient to schedule additional imaging appointments.

Previous Methicillin-Resistant Staphylococcus aureus Infection Independent of Body Site Increases Odds of Surgical Site Infection after Ventral Hernia Repair.

BACKGROUND Methicillin-resistant Staphylococcus aureus infections can be difficult to manage in ventral hernia repair (VHR). We aimed to determine whether a history of preoperative MRSA infection, regardless of site, confers increased odds of 30-day surgical site infection (SSI) after VHR. STUDY DESIGN A retrospective cohort study of patients undergoing VHR with class I to III wounds between 2005 and 2012 was performed using Vanderbilt University Medical Centers Perioperative Data Warehouse. Preoperative MRSA status, site of infection, and 30-day SSI were determined. Univariate and multivariate analyses adjusting for confounding factors were performed to determine whether a history of MRSA infection was independently associated with SSIs. RESULTS A total of 768 VHR patients met inclusion criteria, of which 46% were women. There were 54 (7%) preoperative MRSA infections (MRSA positive); 15 (28%) soft tissue, 9 (17%) bloodstream, 4 (7%) pulmonary, 3 (6%) urinary, and 5 (9%) other. Overall SSI rate was 10% (n = 80), SSI rate in the MRSA-positive group was 33% (n = 18), compared with 9% (n = 62) in controls (p < 0.001). Multivariate analysis demonstrated that a history of MRSA infection significantly increased odds of 30-day SSI after VHR by 2.3 times (95% CI, 1.1-4.8; p = 0.035). Other factors associated with postoperative SSI were performance of myofascial release, increasing BMI, length of operation, open repair, and clean-contaminated wound classification. CONCLUSIONS A history of site-independent MRSA infection confers significantly increased odds of 30-day SSI after VHR. Additional investigation is needed to determine perioperative treatment regimens that might decrease odds of SSI in VHR, and optimal prosthetic types and techniques for this population.

Immersive Virtual Reality for Visualization of Abdominal CT.

Immersive virtual environments use a stereoscopic head-mounted display and data glove to create high fidelity virtual experiences in which users can interact with three-dimensional models and perceive relationships at their true scale. This stands in stark contrast to traditional PACS-based infrastructure in which images are viewed as stacks of two dimensional slices, or, at best, disembodied renderings. Although there has substantial innovation in immersive virtual environments for entertainment and consumer media, these technologies have not been widely applied in clinical applications. Here, we consider potential applications of immersive virtual environments for ventral hernia patients with abdominal computed tomography imaging data. Nearly a half million ventral hernias occur in the United States each year, and hernia repair is the most commonly performed general surgery operation worldwide. A significant problem in these conditions is communicating the urgency, degree of severity, and impact of a hernia (and potential repair) on patient quality of life. Hernias are defined by ruptures in the abdominal wall (i.e., the absence of healthy tissues) rather than a growth (e.g., cancer); therefore, understanding a hernia necessitates understanding the entire abdomen. Our environment allows surgeons and patients to view body scans at scale and interact with these virtual models using a data glove. This visualization and interaction allows users to perceive the relationship between physical structures and medical imaging data. The system provides close integration of PACS-based CT data with immersive virtual environments and creates opportunities to study and optimize interfaces for patient communication, operative planning, and medical education.

Endoscopic and Surgical Management of Hereditary Nonpolyposis Colorectal Cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome is a disease characterized by autosomal dominant clustering of colorectal cancer (CRC) as well as other cancers. It is critical for clinicians and surgeons caring for patients with HNPCC to be familiar with their management related to CRC. Based on retrospective studies, screening colonoscopy is recommended every 1 to 2 years beginning at age 20 to 25, or 10 years younger than the earliest CRC in the family (whichever is earlier). HNPCC patients with colon cancer should be considered for total abdominal colectomy rather than a more limited segmental colon resection due to the increased risk of metachronous neoplasia associated with the condition. Rectal cancer in HNPCC has not been well studied, but discussions with the patient regarding surgical management should weigh the risks of metachronous CRC with the morbidity and quality of life issues associated with proctocolectomy. Regardless of the procedure, a patient with HNPCC requires close postoperative endoscopic surveillance of any remaining at-risk mucosa. In terms of chemoprevention, aspirin has been shown to be effective in preventing colorectal neoplasia in prospective trials and should be considered in patients who do not have a contraindication to the drug. Trials for other chemopreventative agents in HNPCC are ongoing. As more is learned about particular genotype-phenotype correlations with Lynch syndrome, this will likely affect surgical decision making. Despite all of these efforts in the management of patients with HNPCC or Lynch syndrome, incident CRCs still occur, thus reinforcing the need for further studies to better understand the optimal management of these patients.

Multi-Atlas Segmentation for Abdominal Organs with Gaussian Mixture Models.

Abdominal organ segmentation with clinically acquired computed tomography (CT) is drawing increasing interest in the medical imaging community. Gaussian mixture models (GMM) have been extensively used through medical segmentation, most notably in the brain for cerebrospinal fluid / gray matter / white matter differentiation. Because abdominal CT exhibit strong localized intensity characteristics, GMM have recently been incorporated in multi-stage abdominal segmentation algorithms. In the context of variable abdominal anatomy and rich algorithms, it is difficult to assess the marginal contribution of GMM. Herein, we characterize the efficacy of an a posteriori framework that integrates GMM of organ-wise intensity likelihood with spatial priors from multiple target-specific registered labels. In our study, we first manually labeled 100 CT images. Then, we assigned 40 images to use as training data for constructing target-specific spatial priors and intensity likelihoods. The remaining 60 images were evaluated as test targets for segmenting 12 abdominal organs. The overlap between the true and the automatic segmentations was measured by Dice similarity coefficient (DSC). A median improvement of 145% was achieved by integrating the GMM intensity likelihood against the specific spatial prior. The proposed framework opens the opportunities for abdominal organ segmentation by efficiently using both the spatial and appearance information from the atlases, and creates a benchmark for large-scale automatic abdominal segmentation.

Case report: patient portal versus telephone recruitment for a surgical research study.

BACKGROUND Patient portal adoption has rapidly increased over the last decade. Most patient portal research has been done in primary care or medical specialties, and few studies have examined their use in surgical patients or for recruiting research subjects. No known studies have compared portal messaging with other approaches of recruitment. OBJECTIVES This case report describes our experience with patient portal versus telephone recruitment for a study involving long-term follow up of surgical patients. METHODS Participants were recruited for a study of recurrence after ventral hernia repair through telephone calls and patient portal messaging based on registration status with the portal. Potential subjects who did not have a portal account or whose portal messages were returned after 5 days were called. The proportion of participants enrolled with each method was determined and demographics of eligible patients, portal users, and participants were compared. RESULTS 1359 patients were eligible for the hernia study, and enrollment was 35% (n=465). Most participants were recruited by telephone (84%, n=391); 16% (n=74) were recruited through portal messaging. Forty-four percent of eligible participants had a registered portal account, and 14% of users responded to the recruitment message. Portal users were younger than non-users (55 vs. 58 years, p<0.001); participants recruited through the portal versus telephone were also younger (54 vs. 59 years, p=0.001). Differences in the sex and racial distributions between users and non-users and between portal and telephone recruits were not significant. CONCLUSIONS Portal versus telephone recruitment for a surgical research study demonstrated modest portal recruitment rates and similar demographics between recruitment methods. Published studies of portal-only recruitment in primary care or medical-specialty patient populations have demonstrated higher enrollment rates, but this case study demonstrates that portal recruitment for research studies in the surgical population is feasible, and it offers convenience to patients and researchers.