Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Amit Merchea is active.

Publication


Featured researches published by Amit Merchea.


Surgery | 2010

Esophagogastroduodenoscopy-associated gastrointestinal perforations: A single-center experience

Amit Merchea; Daniel C. Cullinane; Mark D. Sawyer; Corey W. Iqbal; Todd H. Baron; Dennis A. Wigle; Michael G. Sarr; Martin D. Zielinski

BACKGROUND Esophagogastroduodenoscopy (EGD) is commonly used in the diagnosis and treatment of gastrointestinal (GI) disorders. Our aim was to define the risk of perforation associated with EGD and identify patients who required operative intervention. METHODS We retrospectively reviewed 72 patients from our institution plus 5 transferred patients who sustained EGD-associated perforations from January 1996 through July 2008. Percutaneous endoscopic gastrostomy, endoscopic ultrasonography, endoscopic retrograde cholangiopancreatography, transthoracic echocardiography, and concurrent colonoscopy procedures were excluded. RESULTS Perforations in 72 of 217,507 EGD procedures were identified (incidence, 0.033%); 124,844 EGDs included an interventional procedure and 92,663 were examination only. The incidence of perforation was similar whether an interventional procedure was performed or not (0.040% vs 0.029%; P = .181). The esophagus was injured most commonly (51%), followed by the duodenum (32%), jejunum (6%), stomach (3%), and common bile duct (3%). Overall mortality after perforation was 17% with a morbidity rate of 40%. Thirty-eight patients (49%) were initially treated nonoperatively, 7 of whom (18%) failed nonoperative management. The only factors we could determine that were associated with failure were free fluid or contrast extravasation on computed tomography (75% vs 23% [P < .005] and 33% vs 0% [P = .047], respectively). The morbidity of failures was equivalent to those who underwent initial operative management (63% vs 61%; P = .917), with mortality seeming to be greater (43% vs 21%; P = .09). CONCLUSION EGD is safe in the majority of patients; however, iatrogenic perforation is associated with considerable morbidity and mortality. Nonoperative management of GI perforation can be successful if there is no evidence of contrast extravasation or free fluid on radiographic studies. If nonoperative management fails, the outcomes may be worse than those treated initially with operative repair.


Journal of Gastrointestinal Surgery | 2011

Emergency Management of Perforated Colon Cancers: How Aggressive Should We Be?

Martin D. Zielinski; Amit Merchea; Stephanie F. Heller; Y. Nancy You

BackgroundEmergency treatment of perforated colon cancer has traditionally been linked with dismal outcomes due to the double jeopardy of a septic insult combined with a malignant disease, leaving unclear how aggressive emergency surgical procedures should be. We aimed to define short- and long-term outcomes in the current era of critical care support and oncologic advances, to provide updated data for decision making.Study DesignPatients with perforations associated with a primary colon cancer were identified. Peri-operative and long-term survival were compared among free (FP; n = 41) and contained perforations (CP; n = 45) and to age-, stage-, and resection status case-matched, non-perforated (NP; n = 85), controls.ResultsTumors were completely resected in 67% of FP but fewer lymph nodes were harvested (median, 11 vs. 11 and 16 in CP and NP; p = 0.21 and p < 0.001). Peri-operative mortality was highest in FP: 19% vs. 0% and 5% in CP and NP (p = 0.038), respectively. After adjusting for peri-operative mortality, 5-year overall survival was comparable: 55%, 59%, and 54% for FP, CP, and NP, respectively. Advanced age, higher ASA class, presence of residual disease, and advanced stage, but not perforation, were independent predictors of poorer long-term overall survival.ConclusionsPatients with malignant colonic perforation face high risk of peri-operative death, making septic source control the priority in the acute setting. Pursuit of an oncologically oriented resection and long-term cancer-directed treatments, however, may lead to improved long-term outcomes.


Diseases of The Colon & Rectum | 2012

Colectomy for endoscopically unresectable polyps: how often is it cancer?

Noelle L. Bertelson; Kristen Kalkbrenner; Amit Merchea; Eric J. Dozois; Ron G. Landmann; Giovanni De Petris; Tonia M. Young-Fadok; David A. Etzioni

BACKGROUND: Colonoscopy has an established role in reducing the burden of colorectal cancer through early detection and removal of polyps. For endoscopically unresectable polyps, colectomy is generally indicated to prevent malignant transformation or to remove cancer already present. OBJECTIVE: This study aimed to determine the incidence of malignancy and the factors predictive of malignancy in surgically resected benign polyps. DESIGN/PATIENTS/SETTING: This study was a retrospectivechart review of patients undergoing a colectomy for a colonic polyp (no preoperative diagnosis of cancer) in 4 hospitals within the Mayo Clinic Health System. MAIN OUTCOME MEASURES: Patient characteristics, endoscopic location and size, and preoperative and operative polyp pathology were tabulated. Correlations between these features and the finding of invasive carcinoma on surgical pathology were assessed. RESULTS: A total of 750 patients met our inclusion criteria. Patients were predominantly male (55.2%) with an average age of 69.4 ± 9.8 years. A majority of polyps were located in the right colon (70.9%). Invasive cancer was identified in 133 patients (17.7%). Multivariate analysis revealed polyps in the left colon (adjusted OR 2.13, 95% CI (1.22–3.72)), and those with high-grade dysplasia (adjusted OR 4.60, 95% CI (2.91–7.27)) were more likely to harbor carcinoma. Age, sex, polyp dimension, and villous features were not predictive of malignancy. Of the patients with cancer, 31 (23.3%) had nodal disease. LIMITATIONS: This study is limited by its retrospective nature, the change in terminology and technique over time, and the partially subjective nature of an endoscopically unresectable polyp. CONCLUSIONS: The finding that polyp size and villous features do not strongly predict malignancy differs from previous endoscopic studies. This study confirms that polyps located in the left colon or with high-grade dysplasia are more likely to harbor cancer. The results of this study suggest that endoscopically unresectable polyps are best treated by radical oncologic resection.


Diseases of The Colon & Rectum | 2013

Surgery for locally advanced recurrent colorectal cancer involving the aortoiliac axis: can we achieve R0 resection and long-term survival?

Zaid M. Abdelsattar; Kellie L. Mathis; Dorin T. Colibaseanu; Amit Merchea; Thomas C. Bower; David W. Larson; Eric J. Dozois

BACKGROUND: Locally advanced, recurrent colorectal cancer involving the aortoiliac axis may be considered a contraindication for curative surgery because of the technical challenges of achieving a negative margin resection and an assumed poor prognosis. OBJECTIVE: The aim of this study was to assess oncologic outcomes and the ability to achieve an R0 resection in these patients. DESIGN: A retrospective review of a prospectively maintained colorectal cancer database identified 406 consecutive patients who underwent surgery for locally recurrent colorectal cancer between 1997 and 2007. SETTING: This study was conducted at an academic multidisciplinary tertiary center. PATIENTS: The demographic and clinicopathological features of patients undergoing resection for locally advanced disease involving the aortoiliac axis at our institution were reviewed. RESULTS: Twelve patients (7 women, median age 51 years) were identified. Major vessel involvement included internal iliac artery (n = 7), common iliac artery (n = 5), external iliac artery (n = 3), aorta (n = 3), internal iliac vein (n = 2), and external iliac vein (n = 1). R0 resection was achieved in 7 patients, and R1 resection in 5. Eleven patients received intraoperative radiation therapy. Vascular reconstruction (3 aorta, 5 common iliac, 3 external iliac) included synthetic interposition grafts, femoral-femoral bypasses, or primary anastomosis. One patient underwent venous reconstruction of the external iliac vein. No graft complications were encountered, and graft patency at 4 years was 100%. Thirty-day morbidity was seen in 9 patients, 8 of whom had Clavien grade <3. Thirty-day mortality was nil. Overall and disease-free survival at 4 years was 55% and 45%. LIMITATIONS: This study was limited by its sample size, retrospective design, and the number of outcome events. CONCLUSION: R0 resection of locally advanced recurrent colorectal cancer involving the aortoiliac axis was achieved in over 50% of patients. Overall and disease-free survival was comparable to outcomes seen with locally advanced disease to nonvascular structures.


Diseases of The Colon & Rectum | 2013

The value of preoperative biopsy in the management of solid presacral tumors.

Amit Merchea; David W. Larson; Martin Hübner; Doris E. Wenger; Peter S. Rose; Eric J. Dozois

BACKGROUND: Surgical decision making and the use of neoadjuvant therapy in the management of solid presacral tumors rely greatly on an accurate preoperative diagnosis. The utility of preoperative biopsy has been questioned because of potential complications and the increasing accuracy of modern imaging. OBJECTIVE: The aim of this study was to analyze biopsy-related morbidity and to compare the accuracy of imaging versus biopsy in making a preoperative diagnosis. DESIGN: This study is a retrospective review of all patients who underwent biopsy of presacral tumors at Mayo Clinic Rochester between 1990 and 2010. The demographics, pathology, complications of biopsy, and imaging were reviewed. Biopsy results and radiologic findings were matched with the final pathology and analyzed. SETTINGS: This study was conducted at a tertiary care center. PATIENTS: Adult patients with solid presacral tumors who underwent preoperative biopsy were evaluated. MAIN OUTCOME MEASURES: The primary outcomes measured were the biopsy-related complications and the accuracy of preoperative imaging and biopsy in comparison with final pathology. RESULTS: Seventy-six biopsies were performed in 73 patients. Fifty-six patients underwent percutaneous biopsies, 14 underwent open biopsies, and 3 underwent both. Biopsy-specific complications included 2 hematomas (1 open, 1 percutaneous). Preoperative biopsy correlated with the postoperative pathologic diagnosis in 63 patients (91%). Of the 6 solid presacral tumors diagnosed incorrectly on biopsy, 1 was falsely reported as benign. Sensitivity, specificity, and positive and negative predictive values of biopsy to detect malignant disease was 96%, 100%, 100%, and 98%. Ten of 35 patients (29%) with a definitive imaging diagnosis were given incorrect diagnoses. Sensitivity, specificity, and positive and negative predictive values of imaging to diagnose malignant disease was 83%, 81%, 83%, and 81%. LIMITATIONS: This investigation was designed as a retrospective study. CONCLUSION: Preoperative biopsy of presacral tumors is safe and highly concordant with postoperative pathology in comparison with imaging. Given the significant differences in therapeutic approach for benign versus malignant solid presacral tumors, as well as the current limitations of imaging, a percutaneous preoperative biopsy should be obtained to guide management decisions.


Diseases of The Colon & Rectum | 2012

Clinical features and oncologic outcomes in patients with rectal cancer and ulcerative colitis: a single-institution experience.

Amit Merchea; Bruce G. Wolff; Eric J. Dozois; Zaid M. Abdelsattar; W. Scott Harmsen; David W. Larson

BACKGROUND:Patients with chronic ulcerative colitis are at increased risk of developing colorectal cancer. Limited data exists in ulcerative colitis patients with rectal cancer regarding clinical and oncologic outcomes, and the ideal operative approach. OBJECTIVE:To describe our experience in the management of patients with rectal cancer in the setting of chronic ulcerative colitis and their outcomes. DESIGN:This study is a retrospective review of all patients with ulcerative colitis who underwent a colorectal operation between 1990 and 2009. SETTINGS:This study was conducted at a tertiary care center. PATIENTS:Adult patients with rectal adenocarcinoma undergoing a colorectal operation for chronic ulcerative colitis were included in this study. Patients with colonic malignancy, indeterminate colitis, and Crohn’s disease were excluded. MAIN OUTCOME MEASURES:Clinical features and long-term oncologic outcomes are described. RESULTS:Forty-one patients were identified; their mean age was 53.9 years. Mean duration of ulcerative colitis was 22.5 years. Thirty-four patients (83%) were known to have cancer preoperatively; in 7 patients it was discovered on postoperative pathology. Eight of the tumors were in the proximal rectum, 19 in the mid rectum, and 13 in the distal rectum. The most common operation performed was total proctocolectomy with end ileostomy (n = 21), followed by IPAA. The majority of patients (n = 28, 68%) had stage I or II disease. Estimates of overall survival at 1 and 5 years were 83% and 62%, and, for disease-free survival, the estimates were 93% and 62%. Local and distant recurrence was seen in 5 and 9 patients. Eighty-nine percent of the observed recurrences were in patients with stage III and IV disease. Pouch failure occurred in 2 patients. LIMITATIONS:This retrospective study was possibly underpowered, given the small sample sizes. CONCLUSION:In our cohort, rectal cancer in the setting of chronic ulcerative colitis was rare, often presented at an early stage, and was not always diagnosed preoperatively. The presence of early-stage rectal cancer should not be considered a contraindication for IPAA.


Clinical Anatomy | 2012

Anatomic mechanisms for splenic injury during colorectal surgery

Amit Merchea; Eric J. Dozois; Jeffrey K. Wang; David W. Larson

Intraoperative iatrogenic splenic injury during colorectal surgery is rare but may cause significant morbidity. We aimed to describe the anatomic mechanisms of iatrogenic injury to the spleen during colonic surgery. All adult surgical patients who sustained a splenic injury during colectomy at our institution from 1992 to 2007 were retrospectively identified. The operative and pathologic reports were reviewed, and anatomic details of the injuries were collected. Results are reported as a proportion or median, with range reported in brackets. Of 13,897 colectomies, 71 splenic injuries among 58 patients were identified. Splenic flexure colonic mobilization occurred in 53 (91%) of these patients. The median number of tears was 1 (1–3). The average length of tear was 4.59 cm. The distribution of injury location on the spleen was 24 (34%) inferior, 14 (20%) hilar, 3 (4%) posterior, 2 (3%) lateral, and 1 (1%) superior. Three (4%) patients suffered from splenic rupture. The location of 24 (34%) injuries was not described. Capsular tears were the cause of splenic injury in 55 (95%) patients. Intraoperative splenic injury ultimately resulted in splenectomy in 44 (76%) patients. Splenic injury was a delayed finding requiring reoperation in 4 (7%) patients. The primary mechanism of intraoperative splenic injury during colectomy is capsular tears and lacerations secondary to misplaced traction and tension on the spleen during colonic mobilization. Techniques to lessen these forces may decrease the number of injuries and subsequent splenectomy. Clin. Anat. 25:212–217, 2012.


Annals of Surgery | 2018

Infectious Surgical Complications are Not Dichotomous: Characterizing Discordance Between Administrative Data and Registry Data.

David A. Etzioni; Cynthia Lessow; Heather D. Lucas; Amit Merchea; James A. Madura; Raman C. Mahabir; Nitin Mishra; Nabil Wasif; Yu Hui H Chang; Robert R. Cima; Elizabeth B. Habermann

Objective: To characterize reasons for discordance between administrative data and registry data in the determination of postoperative infectious complications. Background: Data regarding the occurrence of postoperative surgical complications are identified through either administrative or registry data. Rates of complications vary significantly between these two types of data; the reasons for this are not well-understood. Methods: The occurrence of 30-day inpatient infectious complications (pneumonia, sepsis, surgical site infection, and urinary tract infection) was compared between the NSQIP and administrative mechanisms at 4 academic hospitals between 2012 and 2014. In each situation where the NSQIP and administrative data were discordant regarding the occurrence of a specific complication, a 2-clinician chart abstraction was performed to characterize the reasons for discordance as (i) administrative coding error, (ii) NSQIP coding error, (iii) “question of criteria”, where the discordance was the result of differences in criteria, or (iv) “dually incorrect”, where both data sources coded the complication incorrectly. Results: The cohort included 19,163 patients undergoing surgery in 4 different academic hospitals. Rates of infectious complications varied up to 5-fold between the two data sources. A total of 717 discordant complications were identified. Of these, the greatest portion (43%) was due to “question of criteria,” followed by administrative coding error (37%), NSQIP error (15%), and dually incorrect (5%). Conclusions: With a goal of improving existing mechanisms for measuring surgical quality, definitions for the occurrence of a postoperative complication need to be developed and applied consistently. Progress toward this goal will enable patients and payers to better take advantage of recent advances in healthcare data transparency.


Clinics in Colon and Rectal Surgery | 2016

Perioperative Considerations in Crohn Disease and Ulcerative Colitis

T. Paul Nickerson; Amit Merchea

The management of inflammatory bowel disease (IBD) is medically and surgically complex. Numerous patient- and disease-oriented factors must be considered in treating patients with IBD, including nutritional replenishment/support, effect of immunosuppressive medications, extent of resection, and use of proximal diversion. Perioperative planning and optimization of the patient is imperative to ensuring favorable outcomes and limiting morbidity. These perioperative considerations in Crohn disease and ulcerative colitis are reviewed here.


Diseases of The Colon & Rectum | 2013

Neurological outcome following resection of benign presacral neurogenic tumors using a nerve-sparing technique.

Marie Noëlle Hébert-Blouin; Patrick S. Sullivan; Amit Merchea; Daniel Léonard; Robert J. Spinner; Eric J. Dozois

BACKGROUND: Benign presacral nerve sheath tumors represent up to 10% of all presacral tumors. Limited data exist regarding the impact of the surgical technique on neurological outcomes following resection. OBJECTIVE: The aim of this study was to test our hypothesis that a nerve-sparing resection technique results in the improvement of preoperative neurological dysfunction and minimal postoperative neurological morbidity. DESIGN: This study is a case series of all patients with benign neurogenic presacral tumors operated on by the same 2 surgeons between 2004 and 2010 at our institution. SETTINGS: This study was performed at a tertiary care center. PATIENTS: Adult patients with benign presacral neurogenic tumors who underwent a nerve-sparing resection were included. MAIN OUTCOME MEASURES: Postoperative urogenital, anorectal, and lower-extremity neurological functions were analyzed. RESULTS: Seventeen patients were identified with a mean age of 40 years; 14 were women. Preoperatively, 13 patients had symptoms from neurological dysfunction or presumed mass effect of the tumor. The mean tumor size was 7.4 cm. The pathology was a schwannoma in 12 patients and neurofibroma in 5 patients. Mortality was nil, and 30-day morbidity was noted in 3 patients (hemorrhage, ileus, acute respiratory distress syndrome, deep vein thrombosis, and transient foot drop). Mean follow-up was 36 months. Of the 13 symptomatic patients, 7 achieved complete resolution of symptoms and 5 had improved, but persistent symptoms. None of the 4 asymptomatic patients developed postoperative neurological dysfunction. LIMITATIONS: Small sample size was a limitation of this study. CONCLUSIONS: With the use of a nerve-sparing technique, function-preserving resection can be safely completed with an overall improvement in symptoms.

Collaboration


Dive into the Amit Merchea's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge