Chapter 4: The Abdominal Wall and Diaphragm PDF

Chapter 4 The Abdominal Wall and Diaphragm Glossary Term Definition Abscess a cavity containing dead tissue and pus that forms owing to an infectious process Ascites an accumulation of serous fluid in the peritoneal cavity Erythema redness of the skin o...

Chapter 4 The Abdominal Wall and Diaphragm Glossary Term Definition Abscess a cavity containing dead tissue and pus that forms owing to an infectious process Ascites an accumulation of serous fluid in the peritoneal cavity Erythema redness of the skin owing to inflammation 2 Copyright © 2023 Wolters Kluwer · All Rights Reserved Glossary Term Definition Linea alba fibrous structure that runs down the midline of the abdomen from the xyphoid process to the symphysis pubis separating the right and left rectus abdominis muscles Peristalsis rhythmic wavelike contraction of the gastrointestinal tract that forces food through it Pneumothorax collapsed lung that occurs when air leaks into the space between the chest wall and lung 3 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Body Cavity Video Introduction Body is divided into two major cavities: 1. Dorsal cavity Encased in bone Subdivisions: Cranial cavity- houses the brain Spinal cavity-houses the spinal cord 2. Ventral cavity Divided by the diaphragm Thoracic cavity- superior, lungs/heart Abdominopelvic cavity- inferior, all other trunk organs Enclosed by the abdominal wall 4 Copyright © 2023 Wolters Kluwer · All Rights Reserved Regions and Quadrants 5 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Anatomy No physical divisions of the abdominal wall – Continuous structure with overlapping divisions General Divisions: – Anterior – Right lateral – Left lateral – Posterior – Anterolateral Copyright © 2023 Wolters Kluwer · All Rights Reserved Anterolateral Wall Anatomy Extends from the thoracic cage to the pelvis – Superior border- 7th-10th ribs and xiphoid process – Inferior border- iliac crests and pubic symphysis of the pelvic bones 7 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Anterolateral Wall Anatomy Anatomical structures – Fascia- fibrous tissue network located between the skin and the underlying structures Contains many blood vessels and nerves Two Fascial layers: 1. Superficial fascia (subcutaneous tissue) Attached to skin Connective tissue and fat 2. Deep fascia Posterior to superficial layer Loosely joined fibrous strands that cover the muscles and separates them into groups Densely packed layer (stronger than superficial fascia) – Aponeuroses Layers of flat tendinous, fibrous sheets fused with strong connective tissue that serve as tendons to attach muscles to fixed points Minimal blood vessels and nerves Primarily located in the ventral abdominal regions Primary function to join muscles to the body parts Strong 8 Copyright © 2023 Wolters Kluwer · All Rights Reserved Anterolateral Wall Anatomy – Multilayered Abdominal Wall consists of Skin Subcutaneous tissue (superficial fascia) Muscles and their (Deep) aponeuroses Deep fascia Extraperitoneal fat Parietal peritoneum 9 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Anterolateral Wall Anatomy Subcutaneous tissue – Posterior to skin/anterior to muscle layers – Makes up the superficial fascia – Reinforced with elastic and collagen fibers – Divided into two layers: 1. Superficial fatty layer (Camper fascia) Contains small vessels and nerves 2. Deep membranous layer (Scarpa fascia) Consists of a combination of fat and fibrous tissue that blends with the deep fascia 10 Copyright © 2023 Wolters Kluwer · All Rights Reserved Anterolateral Wall Muscle Anatomy 11 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Muscle Anatomy Figure 4-6 Abdominolateral wall muscles. A: The bilaterally paired, vertically oriented rectus abdominis muscles and the small triangular pyramidalis muscle are located on the anterior wall. B – D: The three flat, bilaterally paired muscles comprising the anterolateral group include the external oblique, the internal oblique, and the transverse abdominal. The strength of the muscles can be contributed to the collaborative relationship of the orientation of the fiber of each muscle. (Reprinted with permission from Moore KL, Agur AM. Essential Clinical Anatomy. 3rd ed. Lippincott Williams & Wilkins; 2007:122.) 12 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Anterolateral Wall Anatomy- Other Structures Rectus Sheath – Strong, fibrous compartment for the rectus abdominis muscle, pyramidalis muscle, arteries, veins, lymphatic vessels, and nerves – Anterior and posterior layers formed by intercrossing and Stronger area interweaving of the aponeuroses of the flat abdominal muscles Weaker area – Inferior, posterior portion of the sheath (below the arcuate line) is covered by the transversalis fascia only Lies below the rectus muscles and is all that separates the rectus muscles from the peritoneum Abdominal Wall Anatomy Video 13 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Anatomy Linea Alba – Oriented vertically and courses the length of the anterior abdominal wall – Separates/connects the bilateral rectus sheaths – It is wider superiorly, and it narrows inferior to the umbilicus to the width of the pubic symphysis. – Transmits small vessels and nerves to the skin 14 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonographic Appearances and Techniques Figure 4-12 (Above the arcuate line) A panoramic image of the anterior abdominal wall superior to the umbilicus demonstrates the muscles and fascia of the anterolateral abdominal wall. EO, external oblique muscle; IO, internal oblique muscle; TA, transversus abdominus muscle; RA, rectus abdominus muscle; LA, linea alba. 15 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Anatomy Umbilicus – A break within the linea alba where all layers of the anterolateral abdominal wall fuse Umbilical ring- the area through which the fetal umbilical vessels pass to and from the umbilical cord and placenta – After birth, fat accumulation in the subcutaneous tissue raises the umbilical ring and depresses the umbilicus 16 Copyright © 2023 Wolters Kluwer · All Rights Reserved Anatomy Inguinal Ligament Formed as the inferior border of the external oblique extends between the anterior superior iliac spine and the pubic tubercle Inguinal Canal Located in the inguinal region ~4cm long Important canal where structures exit and enter the abdominal cavity Males- canal houses spermatic cord Females- canal houses round and uterine ligaments Exit and entry pathways are potential sites of herniation Two openings 1. Deep inguinal ring- internal opening 2. Superficial inguinal ring- external opening 17 Copyright © 2023 Wolters Kluwer · All Rights Reserved  18 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Posterior Abd Wall Anatomy Composition – Lumbar vertebra – Posterior abdominal wall muscles – Diaphragm – Fascia – Fat – Nerves – Blood vessels – Lymphatic vessels 19 Copyright © 2023 Wolters Kluwer · All Rights Reserved Post Abd Wall Muscle Anatomy 20 Copyright © 2023 Wolters Kluwer · All Rights Reserved Post Abd Wall Anatomy Iliopsoas muscle group Psoas major Psoas minor Iliacus Deep Latissimus dorsi Superficial 21 Copyright © 2023 Wolters Kluwer · All Rights Reserved Diaphragm Anatomy Major muscle responsible for inspiration Double-domed, musculotendinous partition separating the thoracic cavity from the abdominal cavity – Convex superior surface faces and forms the floor of the thoracic cavity. – Concave inferior surface faces and forms the roof of the abdominal cavity. Concave surfaces form the right and left domes – Right dome slightly higher because of the presence of the liver – Central part slightly depressed by the heart Central tendon- the peripheral muscular portions of the diaphragm converge centrally to form an aponeurotic area – No bony attachments – Cloverleaf shaped 22 Copyright © 2023 Wolters Kluwer · All Rights Reserved Diaphragm Anatomy Diaphragmatic Apertures (openings) – Permit several structures (esophagus, blood vessels, nerves, and lymphatic vessels) to pass between the thorax and the abdomen – Three largest apertures: 1. Caval (IVC) 2. Esophageal 3. Aortic 23 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Diaphragm Anatomy Diaphragmatic Crura – Musculotendinous bands projecting from the right and left domes Right crus: Larger and longer than the left crus Seen posterolateral to the IVC Left crus: Seen as a triangular mass anterior to aorta Right Crus Left Crus 24 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Abdominal wall tissues and membranes lining its spaces can be affected by – Inflammatory processes – Trauma – Masses 25 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Inflammatory Response: – Inflammation can be acute or chronic Acute inflammation Cuts, scrapes, crushing injuries, or surgical trauma Deep abdominal organs can be the source of infection spreading to the abdominal wall Bacterial infection of the skin can also affect underlying tissues of the abdominal wall – Four main clinical symptoms of inflammatory response are: 1. Heat 2. Redness (Erythemia) 3. Pain 4. Swelling 26 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Chronic inflammation – Inflammation of the tissues goes unresolved, and necrosis begins to occur Chronic suppurative inflammation aka pyogenic inflammation Suppurative= formation of pus Persistent infection resulting in abscess formation Abscess A collection of infectious pus and dead tissue cells within a cavity, tissue or organ Typically round or ovoid with irregular borders and some fluid content Can compress or displace surrounding structures Abdominal wall abscesses commonly form due to surgical incision infections or as an extension of a superficial intraperitoneal abscess If abscesses go untreated, calcifications may form, and the fluid component resorbs/thickens (inspissation) 27 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Abscess – Sonographic appearance: hypoechoic fluid masses irregular borders internal echo patterns that range in echogenicity Floating debris or microbubbles posterior enhancement Hyperemia Scanning technique – High frequency linear probe – If the area of concern has a wound or incision, bandages must be removed, and a sterile probe cover and sterile gel should be used while scanning – For very superficial structures, a standoff pad can be used 28 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Subcutaneous tissues Peritoneum Figure 4-14 D Extended field-of-view image (D) shows abscess extension to the peritoneum. (Images courtesy of Ted Whitten, Ultrasound Practitioner, Elliot Hospital, Manchester, NH.) 29 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Trauma/Tear – Abdominal muscles may be injured by 1. Penetrating wounds 2. Blows to the abdomen Subcutaneous edema or muscle contusions are commonly seen with blunt trauma Contused muscle will appear thicker and very hypoechoic if edema is present 30 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Hematomas – Hematomas are generally associated with muscular trauma that results in hemorrhage – Most common superficial abdominal wall hematoma= rectus sheath hematoma Seroma- a collection of serum in the tissue resulting from a surgical incision or from liquification of a hematoma Usually resolves on its own 31 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Abdominal Wall Hernias – A break or tear in the muscle layer which may allow fat or intestine to protrude through the abdominal wall and create a skin bulge – Can be intermittent or consistent – Level of discomfort can vary based upon size of herniation and the structures that protrude through the opening – Two main categories: 1. Ventral anterior or anterolateral abdominal wall One of the most common surgical treatments worldwide 2. Groin indirect inguinal, direct inguinal, and femoral – Three major factors lead to a weakened abdominal wall 1. Abnormal collagen metabolism 2. Pressure overload such as obesity, heavy lifting, coughing, straining, smoking 3. Naturally weak areas of the abdominal wall Where vessels penetrate the abdominal wall Abdominal wall hernias Fetal migration path of testis, spermatic consist of three parts: cord, or round ligament (inguinal canal) 1. the neck Areas of aponeuroses 2. the sac 3. the contents of the sac 32 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Herniated fat Break in the Linea Alba Figure 4-17 E and F E: This transverse image shows a midline ventral wall hernia in the epigastric region. These occur at the medial attachment of the rectus abdominus muscle to the linea alba. F: The ventral wall hernia seen in image (E) is outlined. (Images courtesy of Ted Whitten, Ultrasound Practitioner, Elliot Hospital, Manchester, NH.) 33 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Hernias Two complications that may occur with hernias that contain bowel Both scenarios can cause bowel obstruction 1. Strangulation Compromised blood supply to the intestine causing ischemia 2. Incarceration Hernia is nonreducible but still has blood supply irreducible sac where contents cannot be pushed back into the abdomen 34 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Figure 4-17 A and B Ventral hernias: A: A transverse image at the level of the umbilicus shows bowel and fluid protruding through the umbilical ring. The neck of the hernia is located between the calipers. B: Color Doppler demonstrates vascular flow within the hernia contents, reducing concerns for strangulation and ischemia. 35 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Inguinal Hernia Video Pathology Types of groin hernias 1. Inguinal hernias (occur commonly on the right side) Indirect inguinal hernia most common type of hernia Men>women LEFT GROIN hernia that passes through the deep inguinal ring and extends inferomedially down the inguinal canal and through the superficial inguinal ring Males- the hernia will project into the scrotal sac Females- the hernia will project into the labia majora Direct inguinal hernia Hernia does not pass through deep inguinal ring to enter the inguinal canal It protrudes into the canal through an area medial to the inferior epigastric arteries 2. Femoral hernias are outside the inguinal canal and form within the femoral canal Bulge typically seen in the leg crease 36 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology RIGHT GROIN Figure 4-18 A, B, and C Groin hernias. A: A direct inguinal hernia is seen medial to the inferior epigastric arteries. B: The small arrows indicate the inferior epigastric artery and vein. The larger arrows indicate the direct inguinal hernia just anterior and medial to the vessels. 37 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Sonographic Evaluation Can Determine: 1. Location, size of a hernia 2. Contents of the hernia Fluid Bowel Motion (peristalsis) Gas-shadowing Fluid/fecal material Mesenteric fat Highly reflective, lacks both peristalsis and shadowing Herniation of bowel-fecal Herniation of fluid Herniation of fat matter/peristalsis seen 38 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Sonographic Evaluation – Scanning protocol to document hernia: 1. Demonstrate and measure the defect in the abdominal wall or groin 2. Determine contents within the hernia (fat/loop of bowel/fluid) If bowel present, determine if strangulation or incarceration is present 3. Visualize any exaggerated protrusion of the hernia with Valsalva maneuver (straining of the abdominal musculature) 4. Determine the reducibility of the lesion by using probe pressure to compress the hernia bulge Valsalva Video Sonographer impression: the area of superficial palpable lump at the level of the umbilicus demonstrates a fat containing, reducible hernia with a 2.8cm abdominal wall defect. Change in size noted with valsalva maneuver. 39 Copyright © 2023 Wolters Kluwer · All Rights Reserved Abdominal Wall Pathology Figure 4-19 C C: Transverse image of femoral hernia, indicated by the arrows in the Valsalva image. These images show the relationship of the femoral hernia to the common femoral vessels. The femoral canal is located inferior to the inguinal canal. They also demonstrate the importance of utilizing the Valsalva maneuver to optimize visualization of hernias. (Image courtesy of Amanda Auckland.) 40 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Neoplasms – Abdominal wall tumors Lipomas- benign fatty tumor Most common tumor of the abdominal wall and subcutaneous tissues Can form anywhere fat is present May cause pain if get large enough Mostly surgically removed for cosmetic reasons Sono Characteristics: Superficial mass of abdominal wall Isoechoic-hyperechoic Well-defined, encapsulated mass Mostly homogenous, possible striations Little to no color flow No posterior shadowing 41 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Neoplasms – Desmoid Tumors A type of aggressive fibromatosis Benign fibrous tissue mass Arise from muscle, fascia, or aponeuroses Commonly found in the anterior abdominal wall 25-40 year olds, women>men, often related to pregnancy Sono Characteristics: homogeneous hypoechoic may have a similar appearance to muscle may be lobulated can show vascularity 42 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Abdominal Wall Pathology Neoplasms – Neuromas Benign mass of the nerve tissue that forms when a nerve gets damaged after injury, trauma or surgery Occur at the end of a severed nerve Common after hernia repair surgery Symptoms- pain in the region of surgery, may or may not feel a palpable lump Sonographically: Usually solitary, hypoechoic, and may or may not have enhancement No blood flow 43 Copyright © 2023 Wolters Kluwer · All Rights Reserved Sonographic Appearances and Techniques Figure 4-13 Diaphragm. A longitudinal section through the right liver lobe shows the normal sonographic appearance of the thin, curvilinear, hyperechoic diaphragm (arrows). 44 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Diaphragmatic Pathology Pleural Effusion – Accumulation of fluid within the pleural cavity (lung cavity) – Many different causes common causes are cancer, heart failure, pneumonia, and pulmonary embolism – Sometimes found incidentally during RUQ or Abdominal US – Variable sono appearances: anechoic areas on one or both sides of the chest superior to the diaphragm Complex septations within fluid Hyperechoic – Pleural effusion can lead to diaphragmatic inversion due to the increased pressure in the pleural cavity 45 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Diaphragmatic Pathology Paralysis – Caused by damage to the phrenic nerve – Can be unilateral or bilateral – Paralysis may be suspected after a chest radiograph demonstrates an elevated or obscured portion of the diaphragm Investigative US may be ordered M-mode used to evaluate movement of the diaphragm Will see absent or reduced movement on the paralyzed side compared with normal or exaggerated movement on the opposite side 46 Copyright © 2023 Wolters Kluwer · All Rights Reserved  Diaphragmatic Pathology Diaphragmatic Hernia – Abdominal contents enter into the thorax through a defect in the diaphragm – May be either congenital or acquired – Causes of acquired diaphragm hernias: 1. Surgery 2. Trauma 3. Increased thoracic or abdominal pressures – Most commonly occur at the left posterior lateral diaphragm 47 Copyright © 2023 Wolters Kluwer · All Rights Reserved Diaphragmatic Pathology Figure 4-26 Diaphragmatic hernia. A: The sonographic evaluation on a prenatal patient reveals a diaphragmatic hernia. The liver is seen on both sides of the diaphragm (arrows). B: The gallbladder (GB) is also seen superior to the diaphragm. (Images courtesy of Dr. Nakul Jerath, Falls Church, VA.) 48 Copyright © 2023 Wolters Kluwer · All Rights Reserved