Gastroenterology

Alcoholic Liver Disease
Alcoholic liver disease diagnosis is suggested by an established history of habitual alcohol intake of sufficient length and intensity.
Toxic daily threshold of alcohol consumption is 40-80 g for males and 20-40 g for females for 10-12 years.
Signs of alcohol abuse and hepatic injury include malnutrition and muscle wasting, cutaneous telangiectasia, palmar erythema, finger clubbing, Dupuytren's contracture, peripheral neuropathy, parotid gland enlargement and signs of gynecomastia and hypogonadism may also be present.
Anal Fissure
An anal fissure is a disruption of the skin at the distal anal canal.
Most fissures are seen by separating the buttocks with opposing traction of the thumbs.
Majority of fissures are located in the posterior midline of the anus.
Acute fissures are simple splits or cracks in the anoderm while chronic fissures may show secondary changes eg sentinel tag, hypertrophied anal papilla, rolled edges, fibrosis of the edges or deep ulceration with exposure of the underlying internal sphincter muscle.
Barrett's Esophagus
Barret's esophagus is defined as a change in the esophageal epithelium of any length that can be recognized at endoscopy, confirmed to have intestinal metaplasia (columnar epithelium replaces the stratified squamous epithelium) by biopsy of the esophagus and excludes cardia-type epithelium in the esophagus.
It is considered a premalignant metaplastic condition that usually involves the distal esophagus.
It is postulated that exposure of the esophageal epithelium to acid damages the lining resulting in chronic esophagitis and its healing involves metaplastic process.
Clostridium difficile Infection
Clostridium difficile infection is commonly associated with antibiotic treatment and is one of the most common nosocomial infections.
Symptoms usually start on days 4-9 of antibiotic treatment, but may also occur up to 8-10 weeks after discontinuation of antibiotics.
Discontinuation of antibiotics may be the only measure needed for patients with only mild diarrhea, no fever, no abdominal pain nor a high WBC count.
Cessation of antibiotics allows for reconstitution of the normal colonic microflora and markedly reduces risk of relapse.
Colorectal Cancer
Colorectal cancer is a carcinoma arising from the luminal surface of the colon.
It is the 2nd most common cancer in women and third most common cancer in male worldwide. It commonly arises from adenomatous polyps.
It is strongly linked to age with 83% occurring in people ≥60 years old.
Rectal cancer is defined as cancerous lesions located within 12 cm of the anal verge.
Constipation in Adults - Chronic Functional
Constipation is an unsatisfactory defecation distinguished by difficult stool passage, infrequent stools or both.
Difficult stool passage may include straining, feeling of difficulty in passing stool, incomplete evacuation, lumpy/hard stools, prolonged time to defecate, need for manual maneuver to pass stool, abdominal discomfort and feeling of anorectal blockade.
Chronic constipation is considered when symptoms of constipation have existed ≥3 months.
Symptoms of chronic constipation may be due to dysfunction of intestinal motility, visceral sensitivity, anorectal musculature or the enteric nervous system.
Diarrhea in Adults - Chronic
Chronic diarrhea is defined as the abnormal passage of ≥3 loose or liquid stools per day for ≥4 week with or without a daily stool weight >200 g/day.
The definition of chronic diarrhea based on symptoms alone will lead to an overlap with functional bowel disorders eg irritable bowel syndrome.
Diarrhea that is continuous or nocturnal and lasting <3 months is more likely due to an organic disease.
The absence of abdominal pain during defecation and presence of weight loss are points against the diagnosis of functional bowel syndrome eg irritable bowel syndrome.
Diarrhea in Adults - Infectious
Diarrhea is a change in normal bowel movements characterized by increased frequency, water content or volume of stools.
Infectious diarrhea is diarrhea of infectious origin (bacteria, virus, protozoal) and is usually associated with symptoms of nausea and vomiting and abdominal cramps.
Dysentery (invasive diarrhea) has the presence of visible blood in diarrheic stool.
Diverticulitis
Diverticulitis is the acute inflammation of the diverticulum or saclike protrusion from the wall of the intestines caused by injury and bacterial proliferation. 
Abdominal pain is usually localized to the left lower quadrant, is abrupt, steady, severe and worsens over time.
Other signs and symptoms are fever, anorexia, nausea, vomiting, and altered bowel movements especially constipation but may also present with diarrhea or tenesmus.
Dyspepsia

Dyspepsia is having any one of the following: disturbing postprandial fullness, early satiation, epigastric pain and/or burning felt predominantly in the upper abdomen.

It is considered a symptom complex rather than a specific diagnosis.

Acid suppression is the recommended initial therapy.

Gastric Cancer
Gastric cancer is the cancer originating in the esophagus, esophagogastric junction and stomach.
Most of gastric cancers are adenocarcinomas, subdivided according to histological appearances into diffuse (undifferentiated) and intestinal (well differentiated) types.
It is the 4th most common cancer and the 2nd most common cause of cancer-related deaths worldwide.
Most common sites of gastric cancer are the proximal lesser curvature, cardia and esophagogastric junction.
Gastroesophageal Reflux Disease
Gastroesophageal reflux disease is a disorder in which gastric contents recurrently reflux into the esophagus, causing troublesome symptoms and/or complications.
It is produced by various mechanisms such as frequent occurrence of transient relaxation of the lower esophageal sphincter or pressure abnormalities in the lower esophageal sphincter (which can be caused by hormonal and neural mediators, food, drugs and patient lifestyle).
Typical symptoms are acid regurgitation and heartburn.
Regurgitation is the perception of flow of refluxed gastric contents into the mouth or hypopharynx.
Heartburn is defined as burning sensation in the retrosternal region.
Gastrointestinal Stromal Tumor
Gastrointestinal stromal tumors are morphologically spindle cell, epithelioid, or occasionally pleomorphic mesenchymal tumors of the gastrointestinal tract.
Signs and symptoms of gastrointestinal tumor include presence of abdominal mass (which may be an incidental finding in endoscopy), gastrointestinal bleeding, hemoperitoneum, anemia and gastrointestinal perforation.
Helicobacter pylori Infection
Helicobacter pylori is a spiral-shaped gram-negative bacterium involved in the development of gastritis, duodenal and gastric ulcers, and gastric cancer.
Infection is strongly associated with the development of gastric epithelial and lymphoid malignancies.
Acute infection is mostly asymptomatic and is acquired through human-to-human contact via gastro-oral and fecal-oral routes.
Adaptability in gastric conditions and production of urease allow it to colonize the stomach.
Hemorrhoids
Hemorrhoids are swollen and inflamed vascular structures or veins around the anus or in the lower rectum.
External hemorrhoids are located closer to the anal verge and are covered with squamous epithelium. It produces symptoms only when thrombosed or when they give rise to large skin tags which make hygiene difficult. Common symptoms are anal pain of acute onset and a palpable lump in the perianal area.
Internal hemorrhoids originate above the dentate line and are covered with rectal or transitional mucosa. It does not cause cutaneous pain. Prolapse of internal hemorrhoids may cause bleeding, mucus discharge, fecal soiling and anal pruritus.
Hepatitis - Viral
The majority of acute viral hepatitis infections are asymptomatic or they can cause an anicteric illness that may not be diagnosed as hepatitis.
Hepatitis A generally causes minor illness in childhood with >80% of infections being asymptomatic but more likely to produce clinical symptoms in adults. 
Hepatitis B, C, & D may also be asymptomatic.
Hepatitis A is predominantly transmitted through oral-fecal route.
Hepatitis B is transmitted through perinatal, percutaneous, or sexual routes or close person-to-person contact via open cuts and sores.
Hepatitis C infections are transmitted through perinatal, percutaneous, or sexual routes, blood transfusions, or organ transplants.
Hepatitis D's route of transmission is sexual or percutaneous, especially IV drug use.
Hepatitis E is transmitted primarily through contaminated drinking water and oral-fecal transmission.
Inflammatory Bowel Disease
Inflammatory bowel disease consists of ulcerative colitis and Crohn's disease.
Ulcerative colitis is a diffuse mucosal inflammation limited to the colon while Crohn's disease is a patchy, transmural inflammation that occurs in any part of the gastrointestinal tract.
The ileum and colon are the most frequently affected sites.
Intra-Abdominal Infections
Intra-abdominal infections (IAI) occur due to disruption of the normal anatomic barrier.
In the hollow viscera is where common disruptions occur, which allows intraluminal bacteria to invade and proliferate in the usually sterile area (ie peritoneal cavity or retroperitoneum).
Community-acquired intra-abdominal infection is usually secondary to gastroduodenal perforation, ascending cholangitis, cholecystitis, appendicitis, colon diverticulitis with or without perforation, or pancreatitis.
Uncomplicated IAI infectious process involves only a single organ and does not extend to the peritoneum.
Complicated IAI is when infection extends beyond the hollow viscus of origin into the peritoneal space and may be associated with peritonitis or abscess formation.
Irritable Bowel Syndrome
Irritable bowel syndrome is a common chronic gastrointestinal condition characterized by abdominal pain and bloating with altered bowel habits.
There are no identifiable physical, radiologic or lab abnormalities indicative of organic disease.
Symptoms may be exacerbated by stress, alcohol or food.
Liver Abscess
Liver abscess may result from peritonitis and bowel leakage via portal circulation, direct spread from biliary disease or from hematogenous seeding.
Classical presentation includes fever, jaundice, and right upper quadrant symptoms (pain, guarding, rocking and rebound tenderness).
Biliary tract disease is the most common cause of bacterial liver abscess.
Most pyogenic liver abscesses are polymicrobial (eg enteric facultative and anaerobic species).
Nausea & Vomiting
Nausea is the sensation felt immediately before vomiting.
Vomiting is a partially voluntary act of forceful expelling of stomach contents up to and out of the mouth that may or may not be preceded by nausea.
Retching or repetitive active contraction of the abdominal muscles occurs between nausea and vomiting.
Management includes correction of clinically relevant metabolic complications, pharmacological therapy and treatment of underlying cause.
Neuroendocrine Tumors
Neuroendocrine tumors are rare, small, slow-growing epithelial neoplasms with predominant neuroendocrine differentiation found in most organs of the body.
They arise from cells throughout the diffuse endocrine system.
Carcinoid tumors and pancreatic neuroendocrine tumors are the most common.
Carcinoid tumors arise from the lungs & bronchi, stomach, small intestine, appendix, rectum or thymus.
Majority of the neuroendocrine tumors are sporadic but some tumors are caused by inherited genetic syndromes such as multiple endocrine neoplasia, Von-Hippel Lindau disease, tuberous sclerosis complex and neurofibromatosis.
They have the ability to store and secrete various peptides and neuroamines.
Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease is having excessive fat (in the form of triglycerides) accumulation not due to excessive alcohol consumption or other secondary causes.

It is considered as a hepatic manifestation of metabolic syndrome.

Progression of nonalcoholic fatty liver disease is variable.

Pancreatic Cancer
Pancreatic cancer is malignancy arising from the pancreas.
It is the 13th most common cancer in the world, 10th most common in the United States, and 4th leading cause of cancer-related deaths in the United Stated and Europe.
Exocrine tumors account for 95% of malignant pancreatic disease.
It is more common in women.
The median age of occurrence is at 71 years old.
Pancreatitis - Acute
Acute pancreatitis is inflammation of the pancreas that occurs suddenly.
Abdominal pain is the most prominent symptom of acute pancreatitis.
It is diagnosed by at least two of the following: characteristic abdominal pain, serum amylase or lipase levels ≥3 times the upper limit of normal and characteristic abdominal imaging findings.
Mild acute pancreatitis does not have any organ failure or local or systemic complication.
Moderately severe acute pancreatitis has the presence of local or systemic complication and/or transient organ failure in <48 hours.
Severe acute pancreatitis has organ failure persistent in >48 hours.
Pancreatitis - Chronic
Chronic pancreatitis develops from irreversible scarring sustained by the pancreas from prolonged inflammation.
Signs and symptoms include abdominal pain that is epigastric in location that radiates to the back and frequently occurs at night or after meals, symptoms of fat, protein & carbohydrates maldigestion that become apparent with advanced chronic pancreatitis and presence of diarrhea.
Chronic pancreatitis results in destruction of alpha and beta cells which gives rise to deficiencies of both insulin and glucagon.
Parasitic Infections
Gastrointestinal parasitic infection symptoms include abdominal pain, diarrhea, dysentery, flatulence, malabsorption and symptoms of biliary obstruction.
It can be caused by protozoan parasites and helminths.
Host susceptibility factors in gastrointestinal parasitic infections are nutritional status, intercurrent disease, pregnancy, immunosuppressive drugs and presence of a malignancy.
Knowledge of the geographic distribution of parasites is helpful in the diagnosis of patients.
Peptic Ulcer Disease
Peptic ulcer disease is the presence of ulceration in the stomach and proximal duodenum commonly and in the lower esophagus, distal duodenum or jejunum infrequently. It is characterized by mucosal damage secondary to pepsin and gastric acid secretion.
It is the principal cause of upper gastrointestinal hemorrhage.
Appropriate therapy depends on the cause of peptic ulcer disease.
Primary Biliary Cirrhosis

Primary biliary cirrhosis is chronic, progressive, autoimmune, cholestatic liver disease more common in middle-aged women. It is characterized by destruction of small to medium bile ducts, leading to cholestasis and frequently, end-stage liver disease.
Diagnostic features are chronic biochemical cholestasis, presence of antimitochondrial antibodies and the characteristic liver biopsy findings.
At present, the diagnosis is most often made in an asymptomatic patient who presents with abnormal lab results on a routine checkup or as part of workup for an associated illness.


 

Zollinger-Ellison Syndrome
Zollinger-Ellison syndrome (ZES) is a disease entity which refers to the triad of severe peptic ulcer disease (PUD), gastric acid hypersecretion and non-beta cell gastrin-secreting tumor primarily of the pancreas and duodenum (gastrinoma).
Approximately two-thirds of patients have sporadic ZES while the rest is part of multiple endocrine neoplasia type 1.
ZES should be considered in the differential diagnoses of patients who present with abdominal pain, malabsorption and chronic watery diarrhea.
A high index of clinical awareness is necessary to correctly diagnose ZES.