A deep understanding of anatomy is mandatory for proper care of patients whether it is for diagnosing pathology, determining treatment options, or having meaningful discussions with other providers. In this chapter, we review the anatomy and embryology of the anal canal, pelvic floor, colon, and rectum. Special emphasis is placed on clinically meaningful concepts for the practicing surgeon.

This paper aims to answer the fundamental but still unan-swered question: how can brains represent 3D objects? Ratherthan building a model of visual processing, we focus on mod-eling the haptic sensorimotor processes through which objectsare explored by touch. This idea is inspired from two mainfacts: 1) in developmental terms, tactile exploration is the pri-mary means by which infants learn to represent object shapes;2) blind people can also represent and distinguish objects justby haptic exploration. Therefore, in this paper, we firstly es-tablish the relationship between the geometric properties of anobject and constrained navigation action sequences for tactileexploration. Then, a neural network model is proposed to rep-resent 3D objects from these experiences, using a mechanismthat is computationally similar to that used by hippocampalplace cells. Simulation results based on a 2 × 2 × 2 cube anda 3 × 2 × 1 cuboid show that the proposed model is effectivefor representing 3D objects via tactile exploration and compar-ative results suggest that the model is more efficient and accu-rate when learning a representation of the 3×2×1 cuboid withan asymmetrical geometrical structure than the 2 × 2 × 2 cubewith a symmetrical geometrical structure.

There is limited data regarding the risk factors of postoperative upper GI bleeding (UGIB) in patients undergoing colorectal resection. We sought to identify risk factors of UGIB after colorectal resection. The NIS database was used to evaluate all patients who had colorectal resection complicated by UGIB between 2002 and 2010. Multivariate analysis using logistic regression was performed to quantify the association of preoperative variables with postoperative UGIB. We sampled a total of 2,514,228 patients undergoing colorectal resection, of which, 12,925 (0.5%) suffered a postoperative UGIB. The mortality of patients who had UGIB was significantly greater than patients without UGIB (14.9 vs. 4.7%; OR, 3.57; CI, 3.40-3.75; P < 0.01). Patients suffering from UGIB had an associated 14.9% inhospital mortality. History of chronic peptic ulcer disease (6.75; CI, 5.75-7.91; P < 0.01) and emergency admission (OR, 4.27; CI, 4.09-4.45; P < 0.01) are associated with UGIB. Duodenal ulcer as the source of bleeding is a mortality predictors of patients (OR, 1.71; CI, 1.49-1.97; P < 0.01). Postoperative UGIB occurs in less than 1 % of colorectal resections. However, patients suffering from postoperative UGIB are over three times more likely to die. Chronic peptic ulcer disease and emergency admission are respectively the strongest predictors of postoperative UGIB.

Early postoperative enteric fistula (PEF) is a complication associated with a high rate of morbidity and mortality in colon and rectal surgery. We evaluated the effect of patient characteristics, comorbidities, pathology, resection type, surgical technique, lysis of adhesions, and admission type on the rate of PEF in colorectal surgery. Using the National Inpatient Sample database, we examined the clinical data of patients who underwent colon and rectal resection from 2009 to 2010. A total of 646,414 patients underwent colorectal resection during this period. Overall, the rate of PEF was 0.37 per cent (2407 patients). Using multivariate regression analysis, Crohn's disease (adjusted odds ratio [AOR], 4.68), lysis of abdominal adhesions (AOR, 4.25), open procedure (AOR, 3.18), and transverse colectomy (AOR, 2.13) significantly impacted the risk of PEF. Although teaching hospitals (AOR, 1.69), obesity (AOR, 1.40), male gender (AOR, 1.30), emergent surgery (AOR, 1.27), age older than 65 years (AOR, 1.24), and diabetes mellitus (AOR, 1.21) also had statistically significant impact on rates of PEF, these were less clinically significant than the other factors. The presence of Crohn's disease and lysis of abdominal adhesions are strongly associated with the development of PEF after colorectal surgery. Laparoscopic surgery was associated with a lower rate of PEF; further studies would be needed to evaluate the importance of this finding.

Background

There are limited data regarding the effects of ascites on outcome of patients undergoing colorectal resection. We sought to identify complications related to ascites.

Methods

The National Surgical Quality Improvement Program database was used to evaluate congestive heart failure (CHF) patients who had ascites before colorectal resection between 2005 and 2012. Multivariate regression analysis was performed to identify affected outcomes.

Results

We sampled a total of 2,178 patients who suffered CHF and underwent colorectal resection, of which 195 (9%) had preoperative ascites. The mortality rate of patients who had preoperative ascites was 46.2% compared to 25.7% for patients without ascites (adjusted odd ratio [AOR], 3.38; P < .01). Complications affected by ascites include (P < .05) ventilator dependency (AOR, 2.40), acute renal failure (AOR, 2.18), and wound disruption (AOR, 2.44; P < .05). There was no increase in superficial surgical site infection rate in patients with ascites (AOR, 1.01; P = .9).

Conclusions

The presence of ascites in CHF patients is associated with increased mortality in patients undergoing colorectal surgery. There is no correlation between ascites and surgical site infection but wound disruption increases in the presence of ascites.

Background

Clostridium difficile colitis (CDC) is a major health concern in the United States (US), with earlier reports demonstrating a rising incidence. Studies analyzing predictors for total colectomy and mortality after colectomy are limited by small numbers.

Study design

The Nationwide Inpatient Sample (NIS) 2001 to 2010 was retrospectively reviewed for CDC trends, the associated colectomy and mortality rates. Patient and hospital variables were used in the LASSO algorithm for logistic regression with 10-fold cross validation to build a predictive model for colectomy requirement and mortality after colectomy. The association of colectomy day with mortality was also examined on multivariable logistic regression analysis.

Results

An estimated 2,773,521 discharges with a diagnosis of CDC were identified in the US over a decade. Colectomy was required in 19,374 cases (0.7%), with an associated mortality of 30.7%. Compared with the 2001 to 2005 period, the 2006 to 2010 period witnessed a 47% increase in the rate of CDC and a 32% increase in the rate of colectomies. The LASSO algorithm identified the following predictors for colectomy: coagulopathy (odds ratio [OR] 2.71), weight loss (OR 2.25), teaching hospitals (OR 1.37), fluid or electrolyte disorders (OR 1.31), and large hospitals (OR 1.18). The predictors of mortality after colectomy were: coagulopathy (OR 2.38), age greater than 60 years (OR 1.97), acute renal failure (OR 1.67), respiratory failure (OR 1.61), sepsis (OR 1.40), peripheral vascular disease (OR 1.39), and congestive heart failure (OR 1.25). Surgery more than 3 days after admission was associated with higher mortality rates (OR 1.09; 95% CI 1.05 to 1.14; p < 0.05).

Conclusions

Clostridium difficile colitis is increasing in the US, with an associated increase in total colectomies. Mortality rates after colectomy remain elevated. Progression to colectomy and mortality thereafter are associated with several patient and hospital factors. Knowledge of these risk factors may help in risk-stratification and counseling.

Background

Recent published articles reported a wide geographic variation in the utilization of laparoscopic colectomy in the United States.

Objectives

This study aimed to report the current rates of laparoscopic colon resection in different types of hospitals in the United States.

Design

The Nationwide Inpatients Sample database was used to examine the clinical data of patients undergoing elective colon resection for the diagnosis of colon cancer or diverticular disease from 2009 to 2012.

Setting

Multivariate regression analysis was performed to compare different hospital types and regions regarding the utilization of laparoscopy.

Patients

Patients undergoing elective colon resection for the diagnosis of colon cancer or diverticular disease from 2009 to 2012 were selected.

Main outcome measures

The primary outcome measured was the rates of laparoscopic colon resection in different types of hospitals.

Results

We sampled a total of 309,816 patients who underwent elective colon resection. Of these, 171,666 (55.4%) had a laparoscopic operation. The utilization of a laparoscopic approach increased from 51.3% in 2009 to 59.3% in 2012. The increased utilization of a laparoscopic approach was seen in both urban (53.6% vs 61.6%) and rural hospitals (33.4% vs 42.3%), for colon cancer (45% vs 53.5%), and diverticular disease (61.9% vs 68.2%). The conversion rate to open surgery for diverticular disease was significantly higher than for colon cancer (adjusted odds ratio (AOR), 1.23; p < 0.01). After adjustment, urban hospitals (AOR, 2.13; p < 0.01), teaching hospitals (AOR, 1.13; p < 0.01), and large hospitals (AOR, 1.33; p < 0.01) had a greater utilization of laparoscopic surgery.

Limitations

This study was limited by its retrospective nature.

Conclusions

Although we have finally reached the point where a majority of patients undergoing an elective colectomy for diverticular disease and colon cancer receive a laparoscopic operation, there is wide variation in the implementation of laparoscopic surgery in colon resection in the United States. The utilization of a laparoscopic approach has associations with hospital factors such as size, teaching status of the hospital, and geographic location (urban vs rural).

Background

The utilization of minimally invasive surgery is increasing in colorectal surgery. We sought to compare the outcomes of patients who underwent elective open, laparoscopic, and robotic total abdominal colectomy.

Methods

The NIS database was used to examine the clinical data of patients who underwent an elective total colectomy procedure during 2009-2012. Multivariate regression analysis was performed to compare the three surgical approaches.

Results

We sampled a total of 26,721 patients who underwent elective total colectomy. Of these, 16,780 (62.8 %) had an open operation, while 9934 (37.2 %) had a minimally invasive approach (9614 laparoscopic surgery, and 326 robotic surgery). The most common indication for an operation was ulcerative colitis (31 %). Patients who underwent open surgery had significantly higher mortality and morbidity compared to laparoscopic (AOR 2.48, 1.30, P < 0.01) and robotic approaches (AOR 1.04, 1.30, P < 0.01 and P = 0.04, respectively). There was no significant difference in mortality and morbidity between the laparoscopic and robotic approaches (AOR 0.96, 1.03, P = 0.10, P = 0.78). However, conversion rate of laparoscopic surgery to open was significantly higher than that of robotic approach (13.3 vs. 1.5 %, P < 0.01). Patients who underwent laparoscopic surgery had significantly lower total hospital charges compared to patients who underwent open surgery (mean difference = $21,489, P < 0.01). Also, total hospital charges for a robotic approach were significantly higher than for a laparoscopic approach (mean difference = $15,595, P < 0.01).

Conclusion

Minimally invasive approaches to total colectomy are safe, with the advantage of lower mortality and morbidity compared to an open approach. Although there was no significant difference in the morbidity between minimally invasive approaches, robotic surgery had a significantly lower conversion rate compared to laparoscopic approach. Total hospital charges are significantly higher in robotic surgery compared to laparoscopic approach.

Background

The NiTi CAR™ 27 is a newer device that uses compression to create an anastomosis. An analysis of this device in the creation of colorectal anastomoses in humans has yet to be reported in the USA.

Methods

A non-randomized, prospective pilot study of the NiTi CAR™ 27 device in patients undergoing a left-sided colectomy between March 2008 and August 2009 was performed.

Results

Twenty-three patients (9 men and 14 women) underwent a left-sided colectomy and compression anastomosis with the CAR™ 27 device. Minor morbidities, 3 of 23 (13%) patients, included one small postoperative abscess requiring antibiotics alone and two postoperative anastomotic strictures requiring balloon dilation. Major morbidities, 1 of 23 (4%) patients, included a partial anastomotic dehiscence/leak requiring surgical dismantling of the anastomosis and diversion.

Conclusion

The CAR™ 27 device shows promise as a safe and effective alternative for the creation of colorectal anastomoses. However, studies in a larger patient population are warranted to demonstrate equivalence of this device.

Introduction

The utilization of laparoscopy in colorectal surgery is increasing. However, conversion to open surgery remains relatively high.

Objective

We evaluated (1) conversion rates in laparoscopic colorectal surgery; (2) the outcomes of converted cases compared with successful laparoscopic and open colorectal operations; (3) predictive risk factors of conversion of laparoscopic colorectal surgery to open surgery.

Methods

Using the National Inpatient Sample database, we examined the clinical data of patients who underwent colon and rectal resection from 2009 to 2010. Multivariate regression analysis was performed to identify factors predictive for conversion of laparoscopic to open operation.

Results

A total of 207,311 patients underwent intended laparoscopic colorectal resection during this period. The conversion rate was 16.6 %. Considering resection type and pathology, the highest conversion rates were observed in proctectomy (31.4 %) and Crohn's disease (20.2 %). Using multivariate regression analysis, Crohn's disease (adjusted odds ratio [AOR], 2.80), prior abdominal surgery (AOR, 2.45), proctectomy (AOR, 2.42), malignant pathology (AOR, 1.90), emergent surgery (AOR, 1.82), obesity (AOR, 1.63), and ulcerative colitis (AOR, 1.60) significantly impacted the risk of conversion. Compared with patients who were successfully completed laparoscopically, converted patients had a significantly higher complication rate (laparoscopic: 23 %; vs. converted: 35.2 % vs. open: 35.3 %), a higher in-hospital mortality rate (laparoscopic: 0.5 %; vs. converted: 0.6 %; vs. open: 1.7 %) and a longer mean hospital stay (laparoscopic: 5.4 days; vs. converted: 8.1 days; vs. open: 8.4 days); however, converted patients had better outcomes compared with the open group.

Conclusions

The conversion rate in colorectal surgery was 16.6 %. Converted patients had significantly higher rates of morbidity and mortality compared to successfully completed laparoscopic cases, although lower than open cases. Crohn's disease, prior abdominal surgery, and proctectomy are the strongest predictors for conversion of laparoscopic to open in colorectal operations.