Gynecologic Patients With And Without Mechanical Bowel Preparation Biology Essay

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Administration of various drugs to achieve mechanical cleansing of the bowel and to reduce the bacterial load contained within is known as bowel preparation. This has been a standard practice before several gynecologic surgeries. The rationale for its use would be to decrease the peritoneal contamination in case of iatrogenic injury and to empty the bowel of its contents to improve both surgical field visualization and handling of the bowel1.

Three randomized studies have shown no benefit of bowel preparation in elective colorectal surgery2,3,4 while other studies even suggest that it may be harmful, with higher rates of septic complications, anastomotic dehiscence and surgical wound infection5. However, the need for mechanical bowel preparation in abdominal gynecologic surgeries has been poorly investigated. The results of the studies on colorectal surgery can be extrapolated to the gynecological oncology setting, where bowel opening can be expected in some cases of advanced or recurrent cancer. There is no data to support its advantage for benign pathology where, except for cases of severe adhesions or advanced endometriosis, bowel opening is a rare event.6

If proven non beneficial, the procedure may be forgone for elective abdominal gynecologic surgery. In a ward where the nurse to patient ratio is 1:25, relief from the duty of administering mechanical bowel preparation is a huge diminution from the staff's workload. More importantly, the patient's expenses will be lessened and her anxiety over the surgery will not be heightened by the discomfort of the procedure.

References:

1. Muzii, L, Cutillo, G, Romanini ME. Bowel preparation before laparoscopy. Journal of American Association of gynecologic laparoscopists. 2001;8 S45-6.

2. Santos, J, Bautista J., Sirimarco, M, Guimaraes A, Levy C. Postoperative Randomized trial of mechanical bowel preparation in patients undergoing elective colorectal surgery. British Journal of Surgery 1990; 77:872-876.

3. Oliveira, L, Wexner SD, Daniel N, et al. Mechanical bowel preparation for elective colorectal surgery: a prospective, randomized, surgeon blinded trial comparing sodium phosphate and polyethylene glycol-based oral lavage solutions. Diseases of Colon and Rectum 1997;40:585-591. www.springerlink.com/index/K03517RJ3242P336.pdf.

4. Miettinen, RPG, Laitinen, ST, Makela, JT, Paakkonen, ME. Bowel preparation with oral polyethylene glycol electrolyte solution vs no preparation in elective open colorectal surgery: prospective, randomized study. Diseases of Colon and Rectum 2000;43:669-677.

5. Platell C, Hall, J, What is the role of mechanical bowel preparation in patients undergoing colorectal surgery? Diseases of

Colon & Rectum 1998;41:875-83

6. Johnston K, Rosen D, Cario G, Ghou D, Carlton M. Major complications arising from 1265 operative laparoscopic cases: a prospective review from a single center. Journal on Minimally Invasive Gynecology 2007; 14:339-344.

II. Relationships of research objectives, data substrates, operationally-defined variables and data analyses.

Objectives

Data substrates

Operationally-defined variables

Analyses

To describe the clinical profile of the patients

To compare the effect of mechanical bowel preparation (sodium phosphate) and no mechanical bowel preparation before abdominal gynecologic surgeries

Data collection form

data collection form

Age

- the number of years from birth up to present

Body mass index

- the measurement of body fat that is calculated from height and weight

Pre-operative diagnosis

- the diagnosis made on the patient's condition based on the clinical presentation

Surgical Procedure

- the type of surgery that is performed on the patient

Post-operative diagnosis

- the diagnosis made on the patient's condition based on the intraoperative findings.

Visibility of the operative field

The ability of the surgeon to see the operative field

Bowel handling

- the capacity to restrain the intestine away from the operative field

Intra-operative bowel movement

- the patient's passing out of fecaloid material from her anus intra-operatively

Operative time

- the length of time that the surgical procedure was performed

Post operative ileus

the length of time from the end of surgery until the time that the patient passed out flatus

Means for quantitative variables and proportions for qualitative variables

Categorical analysis using odds ratio and chi-square

INTRODUCTION

Topic Background

Administration of various drugs to achieve mechanical cleansing of the large bowel and to reduce the bacterial load contained within is known as bowel preparation. Clearing the bowel is an established practice before abdominal surgery. Most general surgeons would use both antibiotic prophylaxis and mechanical bowel preparation before bowel surgery. However, several studies have proven that mechanical bowel preparation has no benefit in open colorectal surgery. Ironically, current literature cannot provide us with sufficient data to support that bowel preparation is useful in gynecological surgery.

Mechanical bowel preparation is routinely used by many surgeons before several gynecologic surgeries. The rationale for its use would be to decrease the peritoneal contamination in case of iatrogenic injury and to empty the bowel of its contents to improve both surgical field visualization and handling of the bowel.

In our local setting, mechanical bowel preparation for gynecologic surgery involves using either the oral and enema form of sodium phosphate. The procedure has been shown to be of great discomfort to the patient and it takes too much of the nurses' time considering the number of patients that they are handling and the multitude of tasks at hand. It was assumed that with the improvement in surgical technique together with the use of more effective prophylactic antibiotics, it was possible that the procedure would no longer be required. This study will determine if mechanical bowel preparation is really necessary in gynecologic surgery.

Review of Related Literature

There are a wide range of surgical procedures that have been developed to treat the various conditions that affect the female reproductive organs. The most common gynecologic laparotomy procedures are the hysterectomy/hysterectomy with salpingo-oophorectomy with a mean operating time of 2-3 hours, myomectomy with a mean operating time of 2 hours and 30 minutes, and adnexal procedures, like salpingo-oophorectomy, salpingectomy, oophorectomy and ovarian cystectomy, with a mean operating time of 1 hr and 25 minutes1-3. In all these procedures, the current practice of many gynecologists has been to provide mechanical bowel preparation preoperatively.

Several reports have questioned the need for mechanical bowel preparation. Successes of primary repairs of gunshot and stab wounds to the colon without bowel preparation have been reported4. Other studies indicate potential benefits, namely reducing infectious complications and anastomotic leakage following repair of inadvertent bowel injury. In reality, the vast majority of general surgeons continue to use some form of bowel preparation and it is the standard of care for elective intestinal surgery. For these reasons, bowel preparation is strongly promoted for the gynecologic surgeon operating on a pelvic mass, endometriosis, or malignancy, or when difficult dissection is anticipated with the potential for inadvertent enterotomy and spillage of intestinal contents. 5

Bowel preparation consists of two phases: antibiotic administration and mechanical cleansing. As claimed, the postoperative infection rate can be reduced to well below 10% when these are properly performed6. Antibiotics decrease the bacterial concentration within the bowel lumen and are thought to reduce contamination and the likelihood of intra-abdominal abscess and wound infections. The recommended antibiotic regimens are intravenous second generation cephalosporin and metronidazole. Mechanical cleansing reduces the bulk of stool content within the lumen of the bowel, which also decreases the absolute amount of bacteria. Perforation and spillage of colon contents contaminates the peritoneal cavity with more than 400 species of bacteria the predominant forms of which are the anaerobres.7

Mechanical bowel preparation with hyperosmotic laxatives is routinely used by many surgeons before gynecologic procedures, both for benign and malignant conditions. The rationale for the use of mechanical bowel preparation is to empty the bowel of its contents to improve the surgical field and to decrease peritoneal contamination in case of bowel injury.8 In gynecology, improved field visualization and bowel handling is probably the most important issue. The small pelvic size and its relatively non expandable boundaries have been perceived as a major problem in gynecologic surgery. The decrease in visibility might oblige the surgeon to increase the number of maneuvers, thereby possibly increasing surgical time and incidence of surgical complications. The second justification, however, is only true for cases of iatrogenic bowel injury or complicated cases like advanced or recurrent cancer, radiotherapy complications and some benign gynecological conditions such as severe endometriosis, severe adhesions, and pelvic abscess in which bowel opening can be anticipated. The other gynecological procedures have a low incidence of bowel injury.9

There is no published randomized study on mechanical bowel preparation before gynecological oncology surgery10. The current practice includes both antibiotic prophylaxis and mechanical bowel preparation before oncology surgery. The results of the studies on mechanical bowel preparation before elective colorectal surgery can be extrapolated to the gynecological oncology setting, where bowel opening can be expected in some cases of advanced or recurrent cancer. However, there is no data to support the advantage of mechanical bowel preparation for benign pathology where, except for cases of severe adhesions or advanced endometriosis, bowel opening is a rare event.11

The issue of mechanical bowel preparation before elective colorectal surgery has been focused on in five randomized clinical trials. In two trials, oral polyethylene glycole has been compared with no treatment, in one trial sodium picosulfate has been compared with no treatment, in one study enemas and mannitol have been compared with controls, whereas in one study polyethylene glycol was compared with sodium phosphate. A metanalysis published in 1998 that considered the above mentioned studies, reported a significantly higher incidence of wound infection in patients receiving MBP versus no bowel preparation before colorectal surgery. A randomized study published by Miettinen et al. in 2000 showed no difference in anastomotic leaks or in surgical site infections, median time to restoration of normal bowel function and median postoperative stay in colorectal surgeries performed with or without bowel preparation.12 All these would lead us to a conclusion that mechanical bowel preparation seems to offer no benefit in elective colorectal surgery.

A randomized study by Oliveira et al. showed that patients who received polyethylene glycol had significantly more side effects when compared with patients who received sodium phosphate. However, assessment of bowel cleansing by blinded surgeons revealed no significant differences between the two regimens.13 The authors concluded that the efficacy of polyethylene glycol and sodium phosphate solutions was similar. The sodium phosphate solution was, however, better tolerated.

Phosphosoda is an over the counter saline laxative consisting mostly of monobasic sodium phosphate monohydrate and dibasic sodium phosphate heptahydrate. This laxative works by drawing liquid from the body into the colon; therefore it can cause severe dehydration if not used properly, and sometimes can even then. It promotes hyperosmotic effect in small intestines and increase water retention which indirectly stimulates peristalsis. Its laxative action is gentle, virtually free from the likelihood of gastrointestinal discomfort or irritation. Generally, it produces a bowel movement in 30 minutes to 6 hours.14 The side effects include no bowel movement after use, seizure (black-out or convulsions), fast, slow, or irregular heart rate, drowsiness, confusion, mood changes, increased thirst, loss of appetite, nausea and vomiting. Less serious side effects may include: bloating, stomach pain, nausea, vomiting, tightness in your throat and dizziness or headache.

Mechanical bowel preparation may cause discomfort to the patient, prolonged hospitalization, and water and electrolyte imbalance. Mechanical bowel preparation is not harmless. It almost invariably causes significant discomfort to the patient, including nausea, abdominal bloating, and diarrhea. Mechanical bowel preparation is also associated with electrolyte imbalance and dehydration, which may complicate the induction of anesthesia and perioperative care.15 With the improvement in surgical technique and the use of more effective prophylactic antibiotics, it is possible that mechanical bowel preparation would no longer be necessary in gynecologic surgery.

Research Question

Are the effects among gynecologic patients with mechanical bowel preparation and no mechanical bowel preparation the same?

Significance of the Study

Mechanical bowel preparation is routinely used by many surgeons before several gynecologic surgeries, either for benign or malignant conditions. The rationale for its use would be to decrease the peritoneal contamination in case of iatrogenic injury and empty the bowel of its contents to improve both surgical field visualization and handling of the bowel.

As healthcare providers it is our utmost responsibility to provide comfort and convenience to our patients. As long as the surgeon's ease at operation is not compromised, forgoing the procedure will prove beneficial as it minimizes the patient's discomfort and expense. Add to that, in a ward where the nurse to patient ratio is 1:25, relief from the duty of administering mechanical bowel preparation will be a big help.

Objectives of the Study

1. To describe the clinical profile of study participants who will undergo major elective abdominal gynecologic procedures.

2. To compare the effect of mechanical bowel preparation in the form of sodium phosphate and no mechanical bowel preparation before abdominal gynecologic surgeries as to the:

Visibility of the operative field

Bowel handling

Intraoperative bowel movement

Operative time

Duration of post operative ileus

METHODOLOGY

Research Design

The study will utilize a randomized controlled trial.

Setting

This study will be held in Davao Medical Center, a local tertiary government hospital from January 11, 2009 to April 9, 2009.

Participants

The study will include women who will undergo an elective major abdominal gynecologic procedure. Inclusion criteria will be a BMI of 18-30 kg/m2 and no previous history of abdominal surgery. All patients with pre-operative suspicion of malignancy, who are pregnant, high risk for intra-operative adhesions and with documented history of allergy to sodium phosphate will be excluded in the study.

Interventions & Comparisons

The intervention will be those given bowel preparation while the comparison group are those not given bowel preparation.

Randomization

The patients meeting all of the inclusion and none of the exclusion criteria will be randomly assigned to the two treatment groups using electronic random number generator by the investigator.

Data Gathering

The independent variable is the treatment group while the dependent variables are the visibility of operative site, bowel handling, intra-operative bowel movement, operative time and duration of post-operative ileus.

After giving their informed consent, the patients will be allocated to one of the two groups two days before their scheduled surgery. The patients who are in group 1 will receive mechanical bowel preparation with sodium phosphate. One day before the surgery, at 10 in the morning, the patient will drink a bottle of sodium phosphate solution (sodium phosphate 45 ml incorporated into 120 ml of water or any clear liquid). At 7 in the evening, the nurse will administer one sodium phosphate enema per rectum. This will be followed at 2 in the morning with another dose of enema. Those in group 2 will not have preoperative mechanical bowel preparation. In preparation for the contemplated surgery, the diet of all study participants will be modified as follows:

2 days before surgery- soft diet

1 day before surgery- soft diet for breakfast & lunch

- clear liquids and crackers for dinner

Starting 12 midnight prior to the day of surgery, the patient will receive nothing per orem.

All patients will receive pre-operative broad-spectrum intravenous antibiotics (Cefradine), which will be continued for at least 24 h after surgery. Prophylactic intravenous antibiotics could be continued for longer periods at the discretion of the surgeon. All surgical procedures will be performed by senior Obstetrics & Gynecology residents. After each surgery, the surgeon will answer the data collection form (see Appendix A). The first part of the form contains items pertaining to the clinical profile of the included participants. The second part pertains to the outcome measures.

VARIABLES

OPERATIONAL DEFINITION

MEASUREMENT

Age

The number of years from birth up to present

As reported

Body mass index

The measurement of body fat that is calculated based on weight and height

As reported in kg/m2

Pre-operative diagnosis

The diagnosis made on the patient's condition based on the clinical presentation

As reported

Surgical Procedure

The type of surgery that is performed on the patient

As reported

Surgical Diagnosis

The diagnosis made on the patient's condition based on the intra-operative findings.

As reported

VARIABLES

OPERATIONAL DEFINITION

OUTCOME MEASURES

Visibility of operative field

The ability of the surgeon to visualize the operative field

YES/NO

Bowel handling

the capacity to restrain the intestine away from the operative field

YES/NO

Intraoperative bowel movement

the patient's passing out of fecaloid material from her anus intra-operatively

YES/NO

Operative time

the length of time that the surgical procedure was performed

SHORT/LONG

Post-operative ileus

the length of time from the end of surgery until the time that the patient passed out flatus

SHORT/LONG

Sample Size Computation

There will be a total of 43 patients per treatment group that will be included in the study.

z1- √ 2P(1-P) + z1- √ P1(1-P1) + P2(1-p2) 2

n= ---------------------------------------------------------

(P1-P2)2

Where

P1 = 90%

P2 = 65%

P = (.9+.65)/2 = .775

Data Handling & Analysis

The data will be analyzed using both the descriptive and analytical study design. The data will be encoded into the computer using Microsoft Excel and it will be converted into Epi Info file format for analysis. For the descriptive analysis, the means for quantitative data and proportions for the qualitative data will be used. In order to determine the significant outcome of the treatment groups, a categorical analysis will be employed using Odds ratio and chi-square. The level of significance will be set at 0.05, any statistical test with a p-value lower than 0.05 is considered significant.

Ethical Considerations

A. Approval from the Research Committee and Ethics Committee

A research proposal will be submitted and presented to the Research Committee and Ethics Committee for review. When approved, data gathering will ensue.

B. Permission to Conduct Study

Hospital Administration

A letter will be sent to the Chief of Hospital that a study will be conducted among patients for elective abdominal gynecologic surgery in the Department of Obstetrics and Gynecology.

Informed Consent

As soon as the conduct of research is granted, permission from the participating individuals will be sought. An informed consent will be used. The participating individuals will sign the informed consent as a gesture that they will agree to participate. (see Appendix B)

DUMMY RESULTS

Table 1: Distribution of Study Participants According to Clinical Profile

Clinical Profile

MBP

NO MBP

P VAL

FREQ

%

FREQ

%

Age (years)

< 20

20 -29

30-39

40-49

50-59

≥60

Body Mass Index (kg/m2)

18-21

21-25

25-30

Pre-Operative Diagnosis

Myoma Uteri

Adenomyosis

ONG prob benign

Others________

Surgical Procedure

TAH

TAHBSO/TAHUSO

myomectomy

SO

Oophorectomy

Ovarian cystectomy

Others________

Surgical Diagnosis

Myoma Uteri

Adenomyosis

ONG prob benign

Others________

Table 2: Distribution of Study Participants According to Surgeon's

Intra-Operative Evaluation

Surgeon's intra-op evaluation

MBP

NO MBP

OR

(95%CI)

p-value

FREQ

%

FREQ

%

Visibility of operative field

Yes

No

Bowel handling

Yes

No

Intraoperative bowel movement

Yes

No

Operative time

long

short

Post-operative ileus

long

short

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