Sonographic applications GI tract

Gut signature Layers of bowel create a characteristic appearance on sonography Up to 5 layers may be visualized Uniform and compliant Sonographic appearance of bowel varies Depends on its contents May or may not contain air,gas,feces or fluid within the lumen Average thickness 3-5mm depending on distension From the lumen edge to outer wall

Measuring thickened wall

Doppler evaluation Normal gut : Neoplasia and inflammation : minimal doppler signal seen Neoplasia and inflammation : Increased vascularity Ischemia and edematous gut: hypovascular

Hyperemia Valuable supportive evidence Of inflammatory process

Peristalsis Normally seen in small bowel and stomach Activity may be increased with mechanical obstruction and inflammatory enteritides Decreased activity is seen with paralytic ileus and in end stages of mechanical obstruction Hypersecretion,mechanical obstruction and ileus are implicated when gut fluid is excessive

Small bowel Mesentery is a fold of peritoneum Connects small bowel to the spine Greater omentum lies anteriorly They become more echogenic and thicker adjacent to a diseased loop of bowel

Creeping fat Mesenteric edema and fibrosis Uniform echogenic halo around gut Most striking and detectable abnormality on sonography Detection should lead to a detailed evaluation of regional gut Thyroid within the abdomen sign-echogenic fat around inflammed bowel

Inflammed omental fat

Small bowel Valves of Kerckring(valvulae conniventes) Large folds of mucous membrane Project into the bowel lumen Provide greater absorption areas Slows passage of food

Intestinal sizes Small intestine: Large intestine: 6 meters long Duodenum-25 cm long Jejunem-2.3 meters long Ileum-3.5 meters long Large intestine: 2 meters long

Stomach

Small intestine

Large intestine

Lymphadenopathy Enlarged mesenteric and perienteric nodes Focal hypoechoic masses Frequently round with loss of linear streak of fat in hilum Hyperemic-inflammation Over 3 cm in diameter are suspect

Bowel Functions Small bowel Large intestine Much of the digestion and absorption of food takes place here Absorption of nutrients and minerals Large intestine Absorbs water from remaining indigestible food matter Passes useless waste material from the body

Large bowel haustra Teniae coli Produce haustra Longitudinal ribbons of smooth muscle on the outside of the colon Contract lengthwise Produce haustra Bulges in the colon Caused by contractions of the teniae coli

Thickening of the bowel wall Occurs with: Infiltration Inflammation Edema Neoplastic invasion

Wall thickening con’t Causes include: Pyloric stenosis Hematoma Intussusception Tumor Appendicitis Edema

Neoplasms May demonstrate decreased to intermediate echogenicity Differential diagnosis of gastric lesions Adenocarcinoma Lymphoma Leukemia Crohn’s disease Intussesception Metastases

Neoplasms con’t Most common cancer of colon: Less common: Adenocarcinoma Less common: Leiomyosarcoma Metastases lymphomas

Intussusception A proximal bowel segment invaginates into a distal segment Strangulation of vascular supply occurs May be caused by malignant lesions in adults Benign lipomas or polyps may cause this More commonly seen in children

Intassusception

Ulceration of bowel Caused by inflammation May also occur with: Lymphoma Edema Neoplasm Intussusception Thickened walls create a pseudokidney sign or doughnut sign

Meckels diverticulum Normal variant in 2-3% of population Remnant of prenatal yolk stalk-vitelline duct Projects from side of the ileum May cause intussesception in children 5-25cm in length Attached by a peritoneal fold

Appendicitis Inflammatory process of the appendix that may indent or displace the cecum Will not exhibit peristalsis Will not compress Appendicoliths and periappendiceal abcess may be visualized Normal appendix is rarely seen except in thin patients or in ascites filled abdomen

Appendicitis con’t Graded compression technique: Used to assess for non-compressible bowel Use a linear,broad footprint,high frquency transducer-7 mhz Displace the bowel loops while applying moderate compression Rebound pain will occur as probe is lifted off the patient fairly quickly Non-compression and rebound pain are good indicators of inflammation of appendix

Appendix -thickened

Ileocecal valve

Ileocecal valve-inflammed

Dilated bowel Occurs when it is obstructed or an ileus is present Causes paralysis of bowel loops Peristalsis is absent Gas accumulates in these loops Localized ileus may occur near an inflammatory process

Obstructed bowel Prevents gas from passing through the GI tract Builds up proximal to obstructed loop Portion distal to the obstruction becomes decompressed

Plain abdominal x-ray Bowel obstruction Air fluid levels

Malrotation of the bowel Can be assessed with doppler Frequently associated with malposition of SMA and SMV Varices may be detected Doppler evaluates blood flow to the bowel wall: Ischemia necrosis

Esophageal and gastric lesions Assessed with endoscopy Varices Intraluminal tumors Peptic ulcers Thickening of all layers occurs Transrectal endosonography used to evaluate rectum To identify and stage previously detected cancer

Other diagnostic tests Abdominal x-ray -plain film Fluid filled loops of bowel Abnormal gas patterns Barium swallow(upper GI series) Fluoroscopic radiologic exam Contrast material outlines mucosal detail

GI series stomach Small bowel follow through Small bowel

Other diagnostic tests con’t Barium enema Study of the colon Contrast material is used Visualizes the anatomy and mucosa of the large bowel A tube is inserted in the rectum to administer barium and air

Barium filled large bowel

Other diagnostic tests con’t Upper GI endoscopy Scope must be swallowed by the patient Used for diagnostic and therapeutic indications Provides direct visualization Cytology and biopsy can be performed Direct visualization of tract

Endoscopy

Other diagnostic tests con’t Colonoscopy,Sigmoidoscopy and Anoscopy: Further evaluates abnormalities seen on a barium enema Biopsy or lesion removal is possible Scope is inserted into the anus and moved up the colon to the required level