SBO Due to Incarcerated Inguinal Hernia

76-year-old female presenting with abdominal pain for 11 days • Xray of the Week

Figure 1. Describe the abdominal findings.

Figure 2. A. Axial CT scan of the abdomen and pelvis demonstrating small bowel obstruction secondary to hernia with collapsed small bowel distal to obstruction (yellow arrow), collapsed colon distal to obstruction (orange arrows), and dilated small bowel proximal to the obstruction (green arrow). B. Axial CT scan of the abdomen and pelvis demonstrating small bowel obstruction secondary to hernia with collapsed small bowel distal to obstruction (yellow arrow), collapsed colon distal to obstruction (orange arrows), and dilated small bowel proximal to the obstruction (green arrow). C. Coronal CT abdomen and pelvis demonstrating dilated small bowel proximal to the obstruction (green arrow) and collapsed small bowel distal to obstruction (yellow arrow). Note the loop of small bowel herniated through the right inguinal canal.

Discussion:

An abdominal wall hernia occurs when a portion of the bowel or peritoneum extends beyond the abdominal wall, resulting in a sac containing tissue or abdominal organs. Hernias can further be classified as inguinal, femoral, incisional, umbilical, or epigastric (1). The most common complications of abdominal wall hernias include small bowel obstruction (SBO) (2). A SBO is defined as a complete or partial blockage of the small intestine due to a functional or mechanical pathology (Figs. 1,2). This clinically presents as abdominal pain, distension, nausea, vomiting, constipation, and high-pitched or absent bowel sounds. The obstructions are commonly secondary to hernia incarceration or hernia strangulation (2). Incarceration of the hernia occurs when the hernial sac can no longer be reduced (3). This poses a risk for strangulation, which results in constriction of the vascular supply to the hernia sac (4). Strangulated hernias can be life-threatening for the patient and requires prompt surgical intervention (1,4).

CT imaging is helpful in identifying subtle signs of complications such as obstruction, incarceration, strangulation, and contents within the hernial sac (3). On CT imaging, key findings of SBO include small bowel dilation, a transition point from dilated to nondilated small bowel, colon compression, and air-fluid levels (5). The dilated bowel can be visualized as proximal to the obstruction, with reduced or collapsed bowel distal to the obstruction (Figs. 1,2) (2). Findings of ischemia secondary to strangulation include bowel wall thickening, mesenteric vessel engorgement, and ascites (2).

If asymptomatic, abdominal wall hernias are typically not operated on. However, if the abdominal wall hernia presents with incarceration or strangulation surgical management is indicated.

References:

1. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. Hernias: Overview. 2016 Sep 21 [Updated 2020 Jan 30]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK395554/

2. Aguirre DA, Santosa AC, Casola G, Sirlin CB. Abdominal wall hernias: imaging features, complications, and diagnostic pitfalls at multi-detector row CT. Radiographics. 2005;25(6):1501-1520. doi:10.1148/rg.256055018

3. Baiu I, Hawn MT. Small Bowel Obstruction. JAMA. 2018;319(20):2146. doi:10.1001/jama.2018.5834

4. Lassandro F, Iasiello F, Pizza NL, et al. Abdominal hernias: Radiological features. World J Gastrointest Endosc. 2011;3(6):110-117. doi:10.4253/wjge.v3.i6.110

5. Paulson EK, Thompson WM. Review of small-bowel obstruction: the diagnosis and when to worry. Radiology. 2015;275(2):332-342. doi:10.1148/radiol.15131519

Rabab Zaidi is an aspiring radiologist and fourth year medical student at the Loyola University Chicago Stritch School of Medicine (SSOM). She currently serves as the Community Support Co-Lead for the Loyola University COVID-19 Response Team and Co-President of the Radiology Interest Group at SSOM. At the Stritch School of Medicine, she has also worked with the Department of Radiation Oncology to study prostate cancer imaging and adaptive radiotherapy techniques, where she learned about the intersection of patient care and radiology. Rabab graduated magna cum laude with a degree in Economics from Loyola University Chicago in 2016. She is further passionate about mentorship, advocacy, and photography.

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Kevin M. Rice, MD is the president of Global Radiology CME

Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.

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