Kingdom of Bahrain Arabian Gulf University College of
Kingdom of Bahrain Arabian Gulf University College of Medicine and Medical Sciences GI System – Review Problem (4) – Stomach Ali Jassim Alhashli, BSc www. alhashli. com
Anatomy, Histology & Physiology of Stomach • • • Stomach is composed of 5 parts: – Cardia. – Fundus – Body. – Antrum. – Pylorus. Blood supply of the stomach: – Lesser curvature: • Right gastric artery: from hepatic artery. • Left gastric artery: from celiac trunk. – Greater curvature: • Right gastroepiploic artery: from gastroduodenal artery. • Left gastroepiploic artery: from splenic artery. – Pylorus: gastroduodenal artery. – Fundus: short gastric arteries. Innervation of the stomach: – Sympathetic: T 5 -T 10. – Parasympathetic: • Anterior gastric wall: left vagus nerve (gives hepatic branch). • Posterior gastric wall: right vagus nerve (gives celiac branch).
Anatomy, Histology & Physiology of Stomach
Anatomy, Histology & Physiology of Stomach
Anatomy, Histology & Physiology of Stomach • Histology: – Cardia: glands secreting mucous. – Fundus: • Parietal cells: secreting HCl and intrinsic factor (which combines with vitamin B 12 and facilitates its absorption in terminal ileum). Acid secretion is regulated by: – Gastrin. – Histamine (via H 2 -receptors). – Vagal stimulation (via M 3 -receptors). • Chief cells: secreting pepsinogen which is converted to pepsin by the acidic environment and digests protein. – Antrum: • G-cells: secreting gastrin which functions in: – Stimulation of gastric acid secretion. – Growth of gastric mucosa. – Stimulation of pepsinogen secretion. Gastrin secretion is stimulated by Gastrin. Releasing Peptide (GRP) + presence of amino acids in the stomach. It is inhibited by somatostatin.
Anatomy of Duodenum • Anatomy: – General: • Length of small bowel: 5 -10 m • Consists of: duodenum, jejunum and ileum. • Duodenum is a retroperitoneal structure (except for the first 2 cm), while jejunum and ileum are intraperitoneal structures. – Duodenum: • Composed of 4 parts: – First part: 5 cm, common site for ulcers. – Second part: 10 cm, curves around head of pancreas. – Third part: 10 cm, anterior to aorta and IVC, posterior to superior mesenteric vessels. – Fourth part: 5 cm, forming duodenojejunal junction which is suspended by ligament of Treitz. • Blood supply: – Arterial: » Proximal (up to ampulla of Vater): gastroduodenal artery through anterior and posterior superior pancreaticoduodenal arteries. » Distal (below ampulla of Vater) superior mesenteric artery through anterior and posterior inferior pancreaticoduodenal arteries. – Venous drainage: through superior mesenteric vein which joins splenic vein behind the neck of the pancreas forming the portal vein.
Anatomy of Duodenum
Anatomy and Embryology
GI Hormones Hormone Gastrin Cholecystokinin (CCK) Site of release G-cells in antrum of stomach Duodenum Secretin Duodenum Somatostatin Pancreas Action Acid secretion and growth of gastric mucosa Contraction of the gallbladder, relaxation of sphincter of Oddi and inhibition of gastric emptying Stimulates pancreatic secretion of HCO 3 and inhibits gastric acid secretion General inhibitory function of GI tract Stimulated by Inhibited by Gastric distention, presence of amino acids in stomach and vagal stimulation Acidity and somatostatin Presence of fat in the duodenum Chymotrypsin and trypsin High acidity in the duodenum High duodenal p. H (alkaline environment) Catecholamines Acetycholine release • Immunological function of small bowel: • Secretion of Ig. A. • MALT (Mucosal Associated Lymphoid Tissue) is composed of: mucosal lymphocytes, lymphoid nodules, isolated lymphoid folicles in appendix and mesenteric lymph nodes.
Gastroschisis and Omphalocele • • Gastroschisis: – Congenital, full-thickness defect of the abdominal wall which is found right to the umbilicus and resulting in exposed bowel (with no covering). – Diagnosis: • Often detected by pre-natal ultrasound. • Associated with ↑ alpha-fetoprotein (AFP). • Not associated with other anomalies. – Treatment: • Temperature regulation. • Sterile covering with a plastic wrap. • NG decompression with Total Parenteral Nutrition (TPN). • Broad-spectrum antibiotics. • Surgical correction and closure of the abdomen. – Prognosis: 20% of cases are complicated with necrotizing enterocolitis. Omphalocele: – Herniation of abdominal contents into the base of umbilical cord (with a covering made of peritoneum and amnion). – Associated anomalies: • Beckwith-Wiedmann syndrome (gigantism, macroglossia, hypoglycemia, umbilical defect and organomegaly). • Trisomy 13 and 18. • Extrophy of urinary bladder. – There are two types: • Small: containing only intestine. • Large: liver, spleen and GI tract. – Treatment: • Intact sac: not urgent. • Ruptured sac: similar to gastroschisis. Emergency surgical repair is required.
Pyloric Stenosis • Pyloric stenosis: – Definition: it is the narrowing of pyloric canal due to hypertrophy of smooth muscle. This is more common among males, those with family history and firstborn males. – Signs and symptoms: • They will appears between 2 weeks – 2 months of age. • Olive-like mass in the midepigastric area. • Projectile, non-bilious vomiting obstruction is proximal to ampulla of vater). • Visible peristalsis. • Hypokalemic, hypochloremic metabolic alkalosis with paradoxical aciduria. – Diagnosis: ultrasound which will show: • Elongation of pyloric canal (> 14 mm). • Thickened pyloric wall (> 4 mm). If ultrasound is not diagnostic, barium swallow shows string sign. – Treatment: • Fluid replacement, correction of electrolytes and acid-base disturbance. • Surgery: Ramstedt pyloromyotomy. Remember that vein of Mayo crosses the pylorus.
Gastritis • • • Definition: Definition It is acute or chronic inflammation of gastric lining. Causes: Causes “GNASHING” – G: Gastric reflux. – N: Nicotine. – A: Alcohol. – S: Stress. – H: H. pylori. – I: Ischemia. – N: NSAID’s. – G: Glucocorticoids. There are 2 types: – Type-A (fundal): autoimmune destruction of parietal cells of the stomach resulting in pernicious anemia and achlorhydria. – Type-B (antral): H. pylori infection. Diagnosis: Diagnosis endoscopy. Treatment: Treatment same as medical treatment for PUD. Complications: – Gastric atrophy. – Gastric metaplasia: with increased risk of MALT lymphoma and gastric adenocarcinoma.
Peptic Ulcer Disease (PUD) – Introduction • • • Definition of PUD = duodenal ulcer + gastric ulcer. Risk factors for development of PUD: – Helicobacter pylori infection. – NSAIDs (due to inhibition of PG which acts as a protective barrier of gastric mucosa) and corticosteroids. – Smoking. – Burns (curling ulcer): due to sluggish blood flow to gastric mucosa. – Head trauma (cushing ulcer): due to increased vagal stimulation which in turn increases gastric acid production. – Smoking. – Family history of PUD. – Zollinger-Ellison syndrome. Complications of PUD: – Bleeding (20%): • Occurs with posterior ulcers. • Gastric ulcer: left gastric artery. • Duodenal ulcer: gastroduodenal artery. • Signs and symptoms: dizziness, syncope, hematemesis/melena. – Perforation (7%): • Occurs with anterior ulcers. • Characterized by sudden, severe epigastric pain radiating to the right shoulder + air under diaphragm (with x-ray). • Valentino’s sign: RLQ pain/peritonitis as a result of succus collecting from a perforated peptic ulcer. • What is a Graham patch? Piece of omentum incorporated into the suture closure of perforation.
Peptic Ulcer Disease (PUD) – Introduction
Peptic Ulcer Disease (PUD) – Duodenal Ulcer • • • It occurs mainly in males and discovered 2 decades earlier than gastric ulcer. In duodenal ulcer, there is increased acid production and the most common location is posterior wall in the first 2 cm of the duodenum. Causes: – Almost always caused by H. pylori infection which is a urease-producing organism that damages gastric mucosa. – It can also be caused by NSAIDs/steroids. – Suspect that patient has Zollinger-Ellison syndrome when there are recurrent duodenal ulcers not responding to H. pylori treatment. Signs and symptoms: – Burning epigastric pain which is relieved by food. – Nausea and vomiting. – Association with blood type (O). Diagnosis: – Mainly a clinical diagnosis. – Endoscopy is done when there alarming symptoms: bleeding/anemia, weight loss, dysphagia and recurrent vomiting. – Detection of H, pylori infection: can be done with serology (Ig. G) or ureas-breath test (ingestion of C 13/14 labeled urea). When treatment to eradicate H. pylori infection is given to the patient, follow-up is with detection of stool antigen. Treatment: – Medical: • Stop smoking, NSAIDs and steroids + lifestyle modifications. • Proton-Pump Inhibitors (PPIs: omeprazole): 90% cure after 4 weeks. • H 2 -blockers (ranitidine): 85% cure after 8 weeks. • Antacids: symptomatic relief. • Eradication of H. pylori infection: – Triple therapy (for 2 weeks): amoxicillin, clarithromycin and PPI. – Quadraple therapy (for 2 weeks): bismuth, tetracycline, metronidazole and PPI. – Surgical: • Indicated when there is: hemorrhage, perforation or obstruction. • Procedure: highly selective vagotomy.
Peptic Ulcer Disease (PUD) – Gastric Ulcer • • • There is decreased acid production and damage to mucosal protective mechanisms (↓ mucous and bicarbonate production). Causes: – H. pylori infection. – NSAIDs/ steroids. – Smoking. Signs and symptoms: – Burning epigastric pain which is increased by food. Therefore, patient will avoid eating and this will result in weight loss. – Nausea and vomiting. – Association with blood type (A). Diagnosis: – When clinically suspected, you have to do endoscopy and take a biopsy because here there is a risk of gastric adenocarcinoma and you want to rule it out. Treatment: Treatment depends on classification of gastric ulcers Type Location Treatment I Most common; lesser curvature Distal gastrectomy with ulcer excision II Associated with DU Antrectomy + ulcer excision + truncal vagotomy III Prepyloric IV Near gastroesophageal junction Distal gastrectomy + ulcer excision + esophagogastrojejunostomy
Gastric Adenocarcinoma • Adenocarcinoma (95%): – Incidence increases with advanced age (> 60 years). It is more common among males and blacks. In addition, it is considered to be the leading cause of cancer-related deaths in Japan. – Risk factors: • Familial adenomatous polyposis. • Chronic atrophic gastritis. • H. pylori infection. • Smoked food. • Smoking. – Pathological types: • Polypoid (25 -50%). • Ulcerative (25 -50%): with sharp margins. • Superficial spreading (3 -10%): involves mucosa and submucosa only; has the best prognosis. • Linitis plastica (7 -10%): involves all the layers; extremely poor prognosis. – Histologic types: • Intestinal: well-differentiated, distal, progressing to cancer slowly, secondary to environmental factors, usually 1 mass identified. • Diffuse: poorly-differential, proximal, aggressive, congenital, characterized by generalized gastric hypertrophy. – Signs and symptoms: • Constant epigastric pain which increases with food. • Hematemesis. • Melena. • Weight loss and anorexia. • Blumer’s shelf: metastasis to pelvic cul-de-sac; felt by digital rectal examination. • Krukenberg’s tumor: metastasis to ovaries. • Virchow’s node: metastasis to left supraclavicular lymph node. • Sister Mary Joseph’s nodule: periumbilical metastatic nodule. • Irish’s node: left axillary adenopathy from gastric cancer.
Gastric Adenocarcinoma
Gastric Adenocarcinoma
Gastric Adenocarcinoma • Adenocarcinoma (continued): – Diagnosis: • Best: upper GI endoscopy with biopsy. • Endoscopic ultrasound. • Abdomino-pelvic CT-scan: for staging. – Staging (TNM): • Tumor: – Tx: tumor cannot be assessed. – T 0: no evidence of tumor. – Tis: carcinoma in situ. – T 1: involving submucosa. – T 2: reaching muscularis propria. – T 3: subserosal, not reaching adjacent structures. – T 4: involving adjacent structures. • Nodes: – Nx: lymph nodes cannot be assessed. – N 0: no evidence of lymph node involvement. – N 1: 1 -2 regional lymph nodes. – N 2: 3 -6 regional lymph nodes. – N 3: ≥ 7 regional lymph nodes. • Metastasis: – Mo: no distant metastasis. – M 1: distant metastasis. – Treatment (gastrectomy with lymph node disection + chemotherapy/radiation): • Proximal and midbody tumors: total gastrectomy. • Antrum tumor: distal subtotal gastrectomy. – Prognosis: tumor markers (not specific) → CEA and CA 19 -9
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