Routine Stool Parameters Six Months After Sleeve Gastrectomy vs. Gastric Bypass: Correlation With Weight Loss and Metabolic Outcomes
概览
- 阶段
- 不适用
- 状态
- 尚未招募
- 入组人数
- 50
- 试验地点
- 1
- 主要终点
- Change in Stool pH
概览
简要总结
The goal of this observational study is to learn whether routine stool tests can detect changes in gut function 6 months after two common types of weight loss surgery: sleeve gastrectomy and gastric bypass (including mini gastric bypass and Roux-en-Y gastric bypass). The main questions it aims to answer are:
Do stool tests show more signs of undigested food or carbohydrate malabsorption after gastric bypass compared to sleeve gastrectomy?
Do signs of gut inflammation in stool (like fecal calprotectin) decrease after surgery, and does this relate to improvements in blood sugar and weight loss?
Can simple stool test results at 6 months predict how much weight a person loses or how well their diabetes improves?
Researchers will compare stool test results between the two surgery groups (sleeve gastrectomy vs. gastric bypass) to see if the type of surgery leads to different changes in gut health.
Participants will:
Provide a stool sample before surgery and again 6 months after surgery
Provide a blood sample at the same time points to measure weight, blood sugar, and cholesterol
Undergo their planned weight loss surgery as part of their regular medical care
详细描述
Background:
Obesity is a global pandemic with rising incidence, contributing significantly to morbidity, mortality, and healthcare costs worldwide. Bariatric surgery, particularly sleeve gastrectomy (SG) and gastric bypass procedures (including Mini Gastric Bypass [MGB] and Roux-en-Y Gastric Bypass [RYGB]), remains the most effective and durable treatment for morbid obesity, achieving sustained weight loss and remission of metabolic comorbidities such as type 2 diabetes.
The gastrointestinal tract, particularly the gut microbiome, has emerged as a key metabolic regulator. Obesity is associated with dysbiosis-reduced microbial diversity and altered predominance of bacterial phyla-which contributes to systemic inflammation, insulin resistance, and metabolic syndrome. Bariatric surgery induces profound and durable changes in the gut environment, including alterations in gastric emptying, intestinal transit time, bile acid signaling, and the composition of the gut microbiota.
However, advanced microbiome sequencing is expensive, time-consuming, and not readily available in many clinical settings. Routine stool analysis, by contrast, is a simple, inexpensive, and universally available test that can provide valuable preliminary data on gut health. Parameters such as stool pH, the presence of leukocytes, undigested food particles, and quantitative markers like fecal calprotectin and reducing substances can offer indirect evidence of maldigestion, mucosal inflammation, and microbial activity.
Objective
The primary objective is to compare changes in routine stool parameters (physical examination, microscopic examination, undigested food particles, fecal calprotectin, and reducing substances) from baseline to 6 months postoperatively between patients undergoing SG and those undergoing Gastric Bypass (MGB or RYGB).
Secondary objectives include: correlating postoperative changes in stool parameters with clinical outcomes (%TWL, diabetes remission, changes in HbA1c and lipid profile); comparing the prevalence of specific stool findings between groups; evaluating whether baseline stool parameters can predict postoperative outcomes; and assessing the utility of routine stool analysis as a simple, low-cost tool for monitoring gut health after bariatric surgery.
Methods:
This is a prospective, two-arm, observational cohort study conducted at the Department of General Surgery, Kasr Al-Ainy University Hospitals, Cairo, Egypt. The study period is from March 2026 to December 2026.
Study Timeline and Data Collection:
Patients will be assessed at two predefined time points:
T0 (Baseline): 1-2 weeks preoperatively - informed consent, demographic data, medical history, anthropometric measurements, blood samples, stool sample
T1 (6 months): 6 months ± 2 weeks postoperatively - anthropometric measurements, blood samples, stool sample, assessment of comorbidities, final outcomes
Clinical and Anthropometric Measurements:
Body weight (kg) and height (m) for BMI calculation (kg/m²)
Percentage total weight loss (%TWL) at 6 months = [(initial weight - 6-month weight) / initial weight] × 100
Presence and status of comorbidities (diabetes, hypertension, dyslipidemia)
Diabetes remission defined as HbA1c < 6.5% off all antidiabetic medications at 6 months
A total of 46 patients with morbid obesity (BMI ≥40 or ≥35 kg/m² with comorbidities) scheduled for primary laparoscopic bariatric surgery will be enrolled and allocated into two groups: Group A (SG, n=23) and Group B (Gastric Bypass [MGB or RYGB], n=23). The type of gastric bypass (MGB vs. RYGB) will be determined by the surgical team based on patient anatomy, comorbidities, and surgeon preference, reflecting real-world clinical practice.
Blood Sampling and Biochemical Analysis:
After an overnight fast (8-12 hours), venous blood will be collected at both time points for:
- Fasting plasma glucose (mg/dL)
- Glycated hemoglobin (HbA1c %)
- Lipid profile: total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides (mg/dL)
- High-sensitivity C-reactive protein (hs-CRP) (mg/L) as a marker of systemic inflammation
Stool Sample Collection and Analysis:
Patients will be provided with a sterile, leak-proof stool collection container and written instructions. They will collect a fresh morning stool sample at home. Samples should be transported to the hospital laboratory within 2 hours of collection. If immediate transport is not possible, samples should be refrigerated (4°C) and transported within 12 hours.
Stool analysis parameters include:
Physical Examination: Color, consistency, odor, mucus, pH
Microscopic Examination: White Blood Cells (WBCs), Red Blood Cells (RBCs), trophozoites, cysts, ova, larva, flagellates, ciliate
Undigested Food Particles: Meat fibers, vegetable particles, starch granules, fat globules
Quantitative Tests: Fecal calprotectin (ELISA), Reducing substances (Clinitest tablets)
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 60 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Male and female patients aged 18 to 60 years
- •Body Mass Index (BMI) ≥ 40 kg/m², OR BMI ≥ 35 kg/m² with at least one obesity-related comorbidity (type 2 diabetes, hypertension, dyslipidemia, osteoarthritis, obstructive sleep apnea)
- •Patients scheduled for primary laparoscopic bariatric surgery (either SG or Gastric Bypass \[MGB or RYGB\]) at Kasr Al-Ainy University Hospitals
- •Provision of written informed consent
排除标准
- •Age \< 18 years or \> 60 years
- •Previous bariatric surgery or major gastrointestinal surgery (gastric, intestinal, or colorectal resection)
- •Chronic kidney disease (eGFR \< 60 mL/min/1.73m²) or previous renal transplant
- •Chronic liver disease (cirrhosis, chronic hepatitis) or liver failure
- •Chronic inflammatory bowel disease (Crohn's disease, ulcerative colitis), celiac disease, or chronic pancreatitis
- •Active malignancy or history of chemotherapy/radiotherapy in the past 5 years
- •Pregnancy or breastfeeding
- •Chronic alcohol abuse or substance abuse
- •Use of antibiotics, probiotics, or prebiotics within 4 weeks prior to stool sample collection (to avoid confounding effects on gut flora)
- •Acute gastrointestinal infection at the time of sample collection
研究组 & 干预措施
Sleeve Gastrectomy (SG)
Patients undergoing primary laparoscopic sleeve gastrectomy as treatment for morbid obesity. This group serves as the restrictive procedure comparator.
干预措施: Laparoscopic Sleeve Gastrectomy (Procedure)
Gastric Bypass (MGB/RYGB)
Patients undergoing primary laparoscopic gastric bypass, including both Mini Gastric Bypass (MGB) and Roux-en-Y Gastric Bypass (RYGB), as treatment for morbid obesity. This group serves as the diversionary procedure comparator.
干预措施: Mini Gastric Bypass (Procedure)
Gastric Bypass (MGB/RYGB)
Patients undergoing primary laparoscopic gastric bypass, including both Mini Gastric Bypass (MGB) and Roux-en-Y Gastric Bypass (RYGB), as treatment for morbid obesity. This group serves as the diversionary procedure comparator.
干预措施: Roux-en-Y Gastric Bypass (Procedure)
结局指标
主要结局
Change in Stool pH
时间窗: At Baseline and at 6 months postoperatively
Change in stool pH measured by pH indicator strip from preoperative baseline to 6 months after surgery. Comparison will be made between Sleeve Gastrectomy (SG) and Gastric Bypass (MGB/RYGB) groups.
Change in Fecal Calprotectin Level
时间窗: At Baseline and at 6 months postoperatively
Change in fecal calprotectin concentration (μg/g) measured by ELISA from preoperative baseline to 6 months after surgery. Comparison will be made between Sleeve Gastrectomy (SG) and Gastric Bypass (MGB/RYGB) groups.
Presence of Undigested Food Particles
时间窗: At Baseline and at 6 months postoperatively
Presence or absence of undigested meat fibers and vegetable particles on microscopic examination at 6 months after surgery. Comparison of prevalence between Sleeve Gastrectomy (SG) and Gastric Bypass (MGB/RYGB) groups.
Presence of Reducing Substances
时间窗: At Baseline and at 6 months postoperatively
Presence or absence of reducing substances (indicating carbohydrate malabsorption) measured by Clinitest tablets at 6 months after surgery. Comparison of prevalence between Sleeve Gastrectomy (SG) and Gastric Bypass (MGB/RYGB) groups.
Change in Stool White Blood Cell Count
时间窗: At Baseline and at 6 months postoperatively
Change in white blood cell count (cells per high-power field) on microscopic examination from preoperative baseline to 6 months after surgery. Comparison will be made between Sleeve Gastrectomy (SG) and Gastric Bypass (MGB/RYGB) groups.
Change in Stool Red Blood Cell Count
时间窗: At Baseline and at 6 months postoperatively
Change in red blood cell count (cells per high-power field) on microscopic examination from preoperative baseline to 6 months after surgery. Presence of RBCs may indicate mucosal irritation at staple lines or altered barrier function. Comparison will be made between Sleeve Gastrectomy (SG) and Gastric Bypass (MGB/RYGB) groups.
次要结局
- Change in Lipid Profile(At Baseline and at 6 months postoperatively)
- Percentage Total Weight Loss (%TWL)(6 months postoperatively)
- Diabetes Remission Rate(6 months postoperatively)
- Change in Fasting Plasma Glucose(At Baseline and at 6 months postoperatively)
- Change in HbA1c(At Baseline and at 6 months postoperatively)
- Change in High-Sensitivity C-Reactive Protein (hs-CRP)(At Baseline and at 6 months postoperatively)
- Correlation Between Stool Parameters and Clinical Outcomes(6 months postoperatively)
- Prevalence of Elevated Fecal Calprotectin(At Baseline and at 6 months postoperatively)
- Prevalence of Positive Reducing Substances(At Baseline and at 6 months postoperatively)
- Prevalence of Mucus in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Elevated White Blood Cells in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Elevated Red Blood Cells in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Trophozoites in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Cysts in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Ova in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Larva in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Flagellates in Stool(At Baseline and at 6 months postoperatively)
- Prevalence of Ciliates in Stool(At Baseline and at 6 months postoperatively)
研究者
Ahmed Eid Ali Ahmed Aziz
Lecturer
Cairo University