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Appendicitis Essays

Abstract

Appendicitis is a common disorder which requires careful diagnosis to avoid complications. Ultrasound is being increasingly used for diagnosis because of its ease and simplicity. In this series, a range of abnormal findings are presented, as well as useful teaching points on technique and pitfalls.

Normal appendix

Fig. 1: A normal appendix is seen in this patient with right iliac fossa pain; a pelvic ultrasound later demonstrated an ovarian cause for the patient's symptoms.

The appendix can usually be located at the base of the ascending colon and requires gentle graded transducer pressure to displace bowel from the region of interest. In this example, the appendix is found anterior to the external iliac vessels. Note the blind‐ending nature of the appendix and its normal thickness.

Fig. 2: A normal appendix is easily compressible, non tender and with a mucosal thickness of < 6 mm as in this case.

Bowel

Fig. 3: An image of the small bowel, which could be mistaken for the appendix. Careful surveillance of this structure over several minutes should reveal normal peristalsis and confirm that it is not truly blind‐ending.

Acute appendicitis – position

Fig. 4: This image demonstrates one of the typical positions that the appendix can be found, namely draping over the right iliac vessels; it extends medially from the ileocecal region towards the umbilicus or pelvis. It is best identified by finding the ascending colon and then moving the transducer inferiorly toward the right iliac fossa. In my experience it is possible to distinguish between small and large bowel by virtue of their different gas patterns (small bowel is associated with more crisp posterior acoustic shadowing and large bowel tends to have more “dirty” shadowing). In the above example the appendix is abnormally thickened.

Acute appendicitis – positions

Fig. 5: This image shows that the position of the appendix can vary; the appendix has a retro‐cecal position and is directed anteriorly. Rather than draping over the external iliac vessels, the appendix is deeper and more medial in this case. Note the abnormal thickness (8 mm). Retrocecal appendices occur in about 15–20% of cases; in my experience, these require more constant transducer pressure to detect.

Fig. 5

Acute appendicitis positions.

Acute appendicitis – positions

Fig. 6: This is another example of a retrocecal appendix; note its origin deep to the cecum (C) and its location posterior to the iliac vessels. Again, the appendix is abnormally thickened.

Fig. 6

Acute appendicitis positions.

Acute appendicitis – positions

Fig. 7: This image shows a retrocecal appendix, but in this case its orientation is more cranially directed; the aperistaltic and blind ending nature of the structure confirms that it is the appendix. There is an abnormal thickness and no compressibility with gentle transducer pressure.

Fig. 7

Acute appendicitis positions.

Graded compression

Fig. 8: This image demonstrates an inflamed appendix that is non compressible. Non compressibility is an important ultrasonographic finding. It is important to include either a split‐screen or series of images which confirms the response of the appendix to compression.

Acute appendicitis – fat oedema

Fig. 9: This image shows peri‐appendiceal fat oedema. Often, it is possible to detect inflamed fat adjacent to the inflamed appendix and this is a useful ancillary finding.

Fig. 9

Acute appendicitis fat oedema.

Acute appendicitis – free fluid (right iliac fossa)

Fig. 10: Free fluid is another important ancillary finding and should be specifically sought in the right iliac fossa or pelvis. In this example, there is a moderate amount of free fluid in the right iliac fossa.

Fig. 10

Acute appendicitis – free fluid (right illiac fossa).

Free fluid‐pelvis

Fig. 11: Echogenic fluid is seen in the pelvis on a transvaginal scan, in a patient who had a ruptured appendix.

Fig. 11

Acute appendicitis – free fluid pelvis.

Acute appendicitis – fecolith

Fig. 12: This image demonstrates a fecolith within the lumen of the appendix; in my experience this is seen in at least 50% of cases of appendicitis. However, it requires careful inspection of the entire appendix and is usually located proximally to the inflamed portion of the appendix. Accordingly, it may be difficult to demonstrate in a retrocecal appendix.

Fig. 12

Acute appendicitis – fecolith.

Acute appendicitis – colour Doppler

Fig. 13: Increased vascularity is seen in association with appendicitis. Colour Doppler can be useful, it may disclose increased vascularity in the mucosa, as in this case. I use low filter settings and/or amplitude imaging. However, it is rare to see abnormal vascularity in proven cases of appendicitis; this could reflect the fact that the depth of the appendix can reduce the sensitivity of colour Doppler or that many cases of appendicitis are mild in nature.

Fig. 13

Acute appendicitis – colour Doppler.

Lymph nodes

Fig. 14: In some cases of confirmed appendicitis, it is possible to identify mesenteric lymph nodes in the right iliac fossa. Although mesenteric adenopathy can be an alternative cause of acute right iliac fossa pain, the identification of an abnormal appendix in this case suggests that the lymph nodes are reactive in nature.

Take home messages

Appendicitis is an important cause of acute abdominal pain. Ultrasound is increasingly being employed as a first line imaging modality.

The appendix can be identified in about two‐thirds of cases using a patient graded compression approach and high frequency linear transducer (usually ~8–9MHz). It usually takes 5–10 minutes to conduct an appropriate assessment.

The appendix is apersistaltic and blind‐ending and usually located anterior to the external iliac vessels. However, retrocecal appendices have a deeper lie and variable orientation and these require slightly more transducer pressure to identify.

Appendicitis is associated with an abnormal thickness, tenderness and non‐compressibility with gentle pressure. In some cases, one can also see a fecolith, increased mucosal vascularity, inflamed peri‐appendiceal fat, free fluid and regional lymphadenopathy.

Articles from Australasian Journal of Ultrasound in Medicine are provided here courtesy of Australasian Society for Ultrasound in Medicine

Author

Adam C Alder, MD Assistant Professor, Department of Surgery, Division of Pediatric Surgery, Children's Medical Center, University of Texas Southwestern Medical Center at Dallas, Southwestern Medical School

Adam C Alder, MD is a member of the following medical societies: American College of Surgeons, Society of American Gastrointestinal and Endoscopic Surgeons, Texas Medical Association, International Pediatric Endosurgery Group

Disclosure: Nothing to disclose.

Coauthor(s)

Robert K Minkes, MD, PhD Medical Director of Pediatric Surgical Services, Golisano Children's Hospital of Southwest Florida; Lee Physicians Group

Robert K Minkes, MD, PhD is a member of the following medical societies: Alpha Omega Alpha, American College of Surgeons, American Medical Association, American Pediatric Surgical Association, Phi Beta Kappa

Disclosure: Nothing to disclose.

Chief Editor

Carmen Cuffari, MD Associate Professor, Department of Pediatrics, Division of Gastroenterology/Nutrition, Johns Hopkins University School of Medicine

Carmen Cuffari, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, Royal College of Physicians and Surgeons of Canada

Disclosure: Received honoraria from Prometheus Laboratories for speaking and teaching; Received honoraria from Abbott Nutritionals for speaking and teaching. for: Abbott Nutritional, Abbvie, speakers' bureau.

Acknowledgements

Kirsten A Bechtel, MD Associate Professor, Department of Pediatrics, Yale University School of Medicine; Attending Physician, Department of Pediatric Emergency Medicine, Yale-New Haven Children's Hospital

Kirsten A Bechtel, MD is a member of the following medical societies: American Academy of Pediatrics

Disclosure: Nothing to disclose.

Deborah F Billmire, MD Associate Professor, Department of Surgery, Indiana University Medical Center

Deborah F Billmire, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Surgeons, American Pediatric Surgical Association, Phi Beta Kappa, and Society of Critical Care Medicine

Disclosure: Nothing to disclose.

Jeffrey J DuBois, MD Chief of Children's Surgical Services, Division of Pediatric Surgery, Kaiser Permanente, Women and Children's Center, Roseville Medical Center

Jeffrey J DuBois, MD, is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Surgeons, American Pediatric Surgical Association, and California Medical Association

Disclosure: Nothing to disclose.

Michael Stephen Freitas, MS State University of New York at Buffalo School of Medicine and Biomedical Sciences

Michael Stephen Freitas, MS is a member of the following medical societies: American College of Surgeons, American Medical Association, American Physical Therapy Association, and Medical Society of the State of New York

Disclosure: Nothing to disclose.

Philip Glick, MD, MBA Professor, Departments of Surgery, Pediatrics, and Gynecology and Obstetrics, Vice-Chairperson for Finance and Development, Department of Surgery, State University of New York at Buffalo

Philip Glick, MD, MBA is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Surgeons, American Medical Association, American Pediatric Surgical Association, American Thoracic Society, Association for Academic Surgery, Association for Surgical Education, Central Surgical Association, Federation of American Societies for Experimental Biology, Medical Society of the State of New York, Phi Beta Kappa, Physicians for Social Responsibility, Royal College of Surgeons of England, Sigma Xi, Society for Pediatric Research, Society for Surgery of the Alimentary Tract, Society of Critical Care Medicine, and Society of University Surgeons

Disclosure: Nothing to disclose.

Kara E Hennelly, MD Fellow, Department of Pediatric Emergency Medicine, Children's Hospital Boston

Kara E Hennelly, MD is a member of the following medical societies: American Academy of Pediatrics

Disclosure: Nothing to disclose.

Michael S Katz, MD Research Fellow, Department of Pediatric Surgery, St Christopher's Hospital for Children

Michael S Katz, MD is a member of the following medical societies: American College of Surgeons, American Medical Association, and American Medical Student Association/Foundation

Disclosure: Nothing to disclose.

Robert Kelly, MD Chairman, Department of Surgery, Departments of Surgery and Pediatrics, Children's Hospital of the King's Daughters; Associate Professor, Eastern Virginia Medical School

Robert Kelly, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Surgeons, American Medical Association, American Pediatric Surgical Association, American Society of Abdominal Surgeons, Medical Society of Virginia, Norfolk Academy of Medicine, and Southern Medical Association

Disclosure: Nothing to disclose.

David A Piccoli, MD Chief of Pediatric Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia; Professor, University of Pennsylvania School of Medicine

David A Piccoli, MD is a member of the following medical societies: American Association for the Study of Liver Diseases, American Gastroenterological Association, and North American Society for Pediatric Gastroenterology and Nutrition

Disclosure: Nothing to disclose.

Jeffrey R Tucker, MD Assistant Professor, Department of Pediatrics, Division of Emergency Medicine, University of Connecticut School of Medicine, Connecticut Children's Medical Center

Disclosure: Merck Salary Employment

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Wayne Wolfram, MD, MPH Associate Professor, Department of Emergency Medicine, Mercy St Vincent Medical Center

Wayne Wolfram, MD, MPH is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Pediatrics, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

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