Biomedical subjects

Hamish Hwang

Publications and source records attributed to Hamish Hwang.

3 recordsLinked to original sources

PubMed2006

Ex vivo sentinel lymph node mapping in colon cancer: improving the accuracy of pathologic staging?

BACKGROUND: A subset of patients with colon cancer staged by conventional methods have occult micrometastases and do not receive adjuvant chemotherapy. Sentinel lymph node (SLN) mapping and staining by immunohistochemistry is a technique that may identify such occult micrometastases, thereby upstaging patients with positive findings. The purpose of this study was to determine whether ex vivo SLN mapping in colon cancer could be applied successfully to patients at our institution. METHODS: Seventeen patients with intraperitoneal colon tumors undergoing resection were studied prospectively. SLNs were identified as the first blue stained node(s) after ex vivo peritumoral injection of isosulfan blue dye. Additional lymph nodes were harvested and processed in accordance with standard pathologic evaluation for colon cancer. All nodes were examined after routine hematoxylin and eosin (H&E) staining. SLNs that were negative on H&E were analyzed further by multilevel sectioning and immunohistochemistry staining using anticytokeratin monoclonal antibody. RESULTS: Of the 17 study patients, SLNs were identified in 16 (94%) cases. The SLN was the only positive node in 3 patients. An identified SLN was positive (by H&E) in all patients with associated positive non-SLN nodes. The average number of nodes retrieved per patient was 16 (range, 4-54). Overall, SLNs accurately reflected the status of the entire lymph node basin in 16 (94%) patients. Two (12%) patients with negative nodes by H&E potentially were upstaged after further SLN analysis. The negative predictive value for SLN mapping was 89%. CONCLUSIONS: The ex vivo technique of SLN mapping for colon cancer is feasible. In the current study, SLN results were concordant with non-SLNs in the majority of patients. Furthermore, this technique may have upstaged 2 (12%) patients. Whether this ultimately will affect overall survival has yet to be determined.

Adenoma, Villous↗

PubMed2005

Examining the learning curve of laparoscopic fundoplications at an urban community hospital.

BACKGROUND: Laparoscopic fundoplication for gastroesophageal reflux disease is a procedure associated with specific complications, especially in a surgeon's early experience. The learning curve of this procedure was examined at a tertiary community institution. METHODS: A retrospective review of the first 100 cases performed at Royal Columbian Hospital was conducted. Two surgeons performed the majority of cases and routinely assisted each other. Patients were grouped chronologically with the first 50 cases defined as early institutional experience and a surgeon's first 20 cases defined as early personal experience. RESULTS: Operative time was longer in both the early institutional (117.8 versus 91.3 minutes, P < .001) and personal experience (126.8 versus 89.7 minutes, P < .001). The rate of dysphagia requiring intervention was higher during the early institutional (22% versus 4%, P = .017) but not personal experience (19% versus 8%, P = not significant). The conversion rate was 0%, reoperation rate was 1%, mean length of stay was 2.5 +/- 1.4 days, and the readmission rate was 5%; these outcomes were unaffected by the learning curve. CONCLUSIONS: There is a definable learning curve in laparoscopic fundoplication in terms of operative time. However, an acceleration of the personal learning curve in terms of dysphagia was observed with a two-surgeon collaborative approach. With careful patient selection conversion, reoperation, readmission, and complication rates equivalent to experienced centers can be achieved in the community setting early in the personal and institutional experience.

Adult↗

PubMed2003

Are localized intestinal perforations distinct from necrotizing enterocolitis?

BACKGROUND/PURPOSE: Localized intestinal perforation (LP) is thought to be a distinct entity when compared with perforation associated with necrotizing enterocolitis (NEC). Studies have indicated that LP is more amenable to percutaneous drainage and associated with a better outcome. We sought to determine whether LP and NEC could be distinguished based on clinical parameters alone. METHODS: A retrospective review of 40 neonates with gastrointestinal perforations between January 1990 and May 1998 was performed. All had undergone laparotomy and had histologic specimens available for evaluation. RESULTS: Twenty-one neonates had necrotizing enterocolitis (NEC), and 19 had localized perforation (LP) based on histologic criteria. More neonates with LP were exposed to prenatal indomethacin (37% v 5%; P <.05), received intravenous dexamethasone (42% v 10%; P <.05), had umbilical artery catheters (63% v 14%; P <.05), and had a higher white blood cell (WBC) count (27.1 +/- 23.1 v 14.3 +/- 11.5; P <.05). More neonates with NEC had pneumatosis intestinalis (47% v 11%; P <.05). No significant differences existed in enteral feeding (16% LP v 38% NEC) or overall mortality rate (37% LP v 38% NEC). No statistical differences in the timing of perforation or clinical presentation were found. CONCLUSIONS: NEC and LP are difficult to distinguish based on clinical parameters alone. The authors did find associations between LP and prenatal indomethacin, intravenous dexamethasone, umbilical artery catheters, and a higher WBC count. Mortality rate and clinical outcome were nearly identical in both groups. Pneumatosis intestinalis, thought to be pathognomonic for NEC, was seen on abdominal radiograph in 2 babies with histologically proven LP.

Adult↗