229 lines
21 KiB
Markdown
229 lines
21 KiB
Markdown
---
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title: "Defect in Abdominal Wall (Hernia)"
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docid: "5af046fa-59ef-45b5-952b-acbcdee36196"
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authors:
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- key: "c1df94ab-4a9f-44c4-add7-1f174fb9ac45"
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value: "Siva P. Raman, MD"
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breadcrumbs:
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-
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name: "Gastrointestinal"
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slug: "gastrointestinal"
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treeNodeId: "b52263f7-5978-4a22-a17d-7260e0033943"
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-
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name: "Differential Diagnosis"
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slug: "differential-diagnosis"
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treeNodeId: "a0fd80ff-6231-49d3-94b8-ea083449979d"
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-
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name: "Abdominal Wall"
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slug: "abdominal-wall"
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treeNodeId: "08db01f7-2961-47f7-954d-2a5fca7e707d"
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-
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name: "Anatomically Based Differentials"
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slug: "anatomically-based-differentials"
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treeNodeId: "1525b44f-9d47-4ff4-8330-693211bd5eb5"
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-
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name: "Defect in Abdominal Wall (Hernia)"
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slug: "defect-in-abdominal-wall-hernia"
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treeNodeId: null
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category: "Gastrointestinal"
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documentVersionId: "284df942-e3e0-4957-8c3b-8b7855e23af9"
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imageCount: 16
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lastUpdated: "07/01/22"
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pageDescription: "Defect in Abdominal Wall (Hernia)"
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pageKeywords: "Gastrointestinal, Differential Diagnosis, Abdominal Wall, Anatomically Based Differentials, Defect in Abdominal Wall (Hernia)"
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pageTitle: "Defect in Abdominal Wall (Hernia) | STATdx"
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enhancedTitle: "Defect in Abdominal Wall (Hernia)"
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type: "DDX"
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references: true
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breadcrumbs:
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- "Gastrointestinal"
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- "Differential Diagnosis"
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- "Abdominal Wall"
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- "Anatomically Based Differentials"
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- "Defect in Abdominal Wall (Hernia)"
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---
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# ESSENTIAL INFORMATION
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- ## Key Differential Diagnosis Issues
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- CT is most accurate imaging modality for diagnosis of hernias and associated complications
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- US can be helpful for determining reducibility of hernias, as well as diagnosis of hernias, which are transiently reducible
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- Offers advantage of scanning patient in upright position or with Valsalva maneuver to elicit hernia
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- Efficacy of US for hernias is debatable in literature, and CT should certainly be 1st-line modality in patients with acute presentation or concerns for hernia-related complications
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- US should be reserved for nonurgent presentation in outpatient setting
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- Evaluate any hernia for presence of complications, including bowel involvement, obstruction, and ischemia
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- Different types of hernias are associated with very different risks of complications
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- Descriptive terms used to describe abdominal wall hernias
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- **Interparietal** (i.e., interstitial) hernia: Hernia sac is located in fascial planes between abdominal wall muscles without entering subcutaneous soft tissues
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- **Richter** hernia: Entirety of bowel circumference does not herniate (just antimesenteric border of bowel)
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- ## Helpful Clues for Common Diagnoses
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- **Inguinal Hernia**
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- Most common type of external hernia (~ 80%) with indirect hernias typically congenital (due to weakness of processus vaginalis), and direct hernias usually acquired due to abdominal wall weakness
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- Hernia seen in groin region anterior to horizontal plane of pubic tubercle
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- Do not result in compression of femoral vessels (unlike femoral hernia)
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- **Direct** hernias: Hernia sac arises anteromedial to inferior epigastric vessels
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- **Indirect** hernia: Hernia sac arises superomedial to inferior epigastric vessels
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- 5x more common than direct hernias
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- Complications more common with indirect hernias
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- **Femoral Hernia**
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- Most commonly seen in older female patients (especially > 80 years) but much less common than inguinal hernias
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- Hernia extends into femoral canal medial to femoral vein and inferior to inferior epigastric vessels with frequent compression of femoral vein
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- Hernia sac located posterior and lateral to pubic tubercle
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- Very high risk of complications (incarceration, strangulation) and mortality compared to inguinal hernias
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- **Ventral Hernia**
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- General term encompassing hernias extending through anterior and lateral abdominal wall
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- Can be acquired or congenital
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- **Epigastric** hernias occur at midline through linea alba above umbilicus, while **hypogastric** hernias occur at midline below umbilicus
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- **Incisional** hernias occur through any prior surgical incision site
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- Most often occur within a few months (usually first 4 months) of surgery but can occur at later time points as well
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- **Parastomal hernias**(considered type of incisional hernia) are quite common adjacent to ileostomy or colostomy
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- Parastomal hernias tend to slowly develop and enlarge over time and are very common with end-colostomies (48%) and end-ileostomies (28%) but much less common with loop ileostomies (6%)
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- Even if asymptomatic, most ventral hernias get larger over time with increasing risk of complications, making surgical treatment advisable
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- **Spigelian Hernia**
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- Hernia extending through defect in aponeurosis of internal oblique and transverse abdominal muscles
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- Arise along lateral margin of rectus abdominis muscles, at level of arcuate line, inferior and lateral to umbilicus
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- Usually congenital in children and acquired in adults (prior surgery, obesity, pregnancies, etc. are risk factors)
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- High risk of strangulation and incarceration
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- **Lumbar Hernia**
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- Hernia extends through defect in lumbar muscle or thoracolumbar fascia (usually below 12th rib and above iliac crest)
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- Can herniate through superior (Grynfeltt-Lesshaft) or inferior (petit) lumbar triangles
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- Most (80%) are acquired, usually due to surgical incisions (especially renal surgery)
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- Complications uncommon due to typically large neck, which makes incarceration/strangulation uncommon
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- **Umbilical Hernia**
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- Hernia at midline extends through umbilical ring (usually upper 1/2 of umbilicus)
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- Can be congenital (diagnosed in infancy) or acquired (usually in middle age)
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- Congenital type 8x more common in Black patients but most resolve spontaneously by 4-6 years of age
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- Acquired hernias associated with obesity, multiparity, and ascites
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- Very common and usually small/asymptomatic, but larger or symptomatic hernias may require repair
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- **Subcutaneous Abdominal Wall Mass (Mimic)**
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- Any subcutaneous or intramuscular mass may be superficially mistaken for hernia on clinical examination, although distinction should be obvious on imaging
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- Consider inguinal lymphadenopathy, abdominal wall tumors, cryptorchidism (especially in children), abscess, hydrocele, varicocele, or hematoma as entities that may be mistaken for hernia on physical examination
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- **Enterocutaneous Fistula (Mimic)**
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- Gas- or contrast-filled tract from intraabdominal bowel loop into anterior abdominal wall may be confused for hernia
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- Bowel loops often tethered to anterior abdominal wall at site of fistula
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- Careful examination illustrates lack of true abdominal wall defect
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- ## Helpful Clues for Less Common Diagnoses
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- **Obturator Hernia**
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- Rare type of hernia extending through obturator foramen into superolateral obturator canal
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- Usually involves loop of ileum but can involve any pelvic viscera
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- Typically seen in older female patients (especially older or multiparous females) secondary to either pelvic floor defect or pelvic floor laxity
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- High risk of complications (incarceration, strangulation) and mortality
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- **Traumatic Abdominal Wall Hernia**
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- Hernia in anterior abdominal wall developing at site of focal trauma
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- Majority occur in lower abdomen with iliac crest region very common due to seat belt injuries
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- Most commonly seen in young children < 10 years due to bicycle injury (e.g., handlebar hernia) but can also be seen in adults after high-energy trauma (e.g., motor vehicle collisions)
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- **Sciatic Hernia**
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- Very uncommon hernia involving herniation of bowel loop through greater sciatic foramen laterally into subgluteal region
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- Occurs most often in female patients, likely as result of piriformis muscle atrophy
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- Can result in symptoms of sciatica as result of compression of sciatic nerve
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- **Perineal Hernia**
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- Uncommon hernia with hernia sac extending anteriorly through urogenital diaphragm (most common) or posteriorly between levator ani and coccygeus muscles
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- Usually diagnosed in older women (> 50 years of age) with history of prior surgery in deep pelvis/perineum, prior pregnancies, obesity, or ascites
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- **Spermatic Cord Lipoma or Liposarcoma (Mimic)**
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- Uncommon fat-containing mass arising in spermatic cord, which can extend into scrotum inferiorly or inguinal canal/retroperitoneum superiorly
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- When extending into inguinal canal, can mimic inguinal hernia, but lesion typically appears expansile and mass-like
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- Liposarcomas will often demonstrate internal complexity (or even soft tissue component) depending on degree of dedifferentiation
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- Well-differentiated liposarcomas may appear largely fat attenuation and are more apt to be confused for inguinal hernia containing omental fat
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- Usually appear hyperechoic on US (particularly when well differentiated) with similar echogenicity to subcutaneous fat
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## References
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# Selected References
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1. [Aly M et al: Should surgeons repair symptomatic, clinically occult, radiologically evident, inguinal hernias? A case-control study of patient-reported outcomes. Hernia. 25(5):1209-13, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=33428011%5Bpmid%5D)
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1. [Fezoulidi G et al: Amyand's hernia: presumptive diagnosis by CT and literature review. Radiol Case Rep. 16(4):911-5, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=33613803%5Bpmid%5D)
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1. [Ng M et al: Paratesticular liposarcoma: a rare cause of scrotal lump. BMJ Case Rep. 14(2):e240008, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=33568414%5Bpmid%5D)
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1. [Steenburg SD et al: Traumatic abdominal wall injuries-a primer for radiologists. Emerg Radiol. 28(2):361-71, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=32827286%5Bpmid%5D)
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1. [Kim AG et al: Inguinal and other hernias. Adv Pediatr. 67:131-43, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32591057%5Bpmid%5D)
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1. [Park J: Obturator hernia: clinical analysis of 11 patients and review of the literature. Medicine (Baltimore). 99(34):e21701, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32846788%5Bpmid%5D)
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1. [Keenan RA et al: Paratesticular sarcomas: a case series and literature review. Ther Adv Urol. 11:1756287218818029, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30671140%5Bpmid%5D)
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1. [Mnari W et al: Strangulated obturator hernia: a case report with literature review. Pan Afr Med J. 32:144, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31303916%5Bpmid%5D)
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1. [Tonolini M: A closer look at the stoma: multimodal imaging of patients with ileostomies and colostomies. Insights Imaging. 10(1):41, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30927144%5Bpmid%5D)
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1. [Park HR et al: Sonographic evaluation of inguinal lesions. Clin Imaging. 40(5):949-55, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27209238%5Bpmid%5D)
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1. [Stensby JD et al: Athletic injuries of the lateral abdominal wall: review of anatomy and MR imaging appearance. Skeletal Radiol. 45(2):155-62, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=26450606%5Bpmid%5D)
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1. [Valeshabad AK et al: An important mimic of inguinal hernia. Urology. 97:e11, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27502033%5Bpmid%5D)
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1. [Burkhardt JH et al: Diagnosis of inguinal region hernias with axial CT: the lateral crescent sign and other key findings. Radiographics. 31(2):E1-12, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21415178%5Bpmid%5D)
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## Images
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### Selected Images
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**Inguinal Hernia**
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*Axial CECT shows a large right inguinal hernia <img src='img/arrows/WS.png'/> containing multiple loops of small bowel without evidence of obstruction. Inguinal hernias account for the vast majority of external hernias.*
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**Inguinal Hernia**
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*Axial CECT shows a large right inguinal hernia <img src='img/arrows/WS.png'/> containing multiple loops of small bowel without evidence of obstruction. Inguinal hernias account for the vast majority of external hernias.*
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**Inguinal Hernia**
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*Coronal NECT shows a classic right inguinal hernia <img src='img/arrows/WS.png'/> containing loops of small bowel <img src='img/arrows/WC.png'/> without evidence of obstruction.*
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**Femoral Hernia**
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*Axial CECT shows a herniated bowel loop <img src='img/arrows/WS.png'/> in the left groin. Note the close relationship of the hernia to the femoral vessels at the level of the symphysis pubis, characteristic of a femoral hernia.*
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**Ventral Hernia**
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*Sagittal volume-rendered CECT shows a ventral hernia containing loops of small bowel <img src='img/arrows/WS.png'/>. The small bowel proximal to the hernia sac is dilated <img src='img/arrows/WC.png'/>, compatible with small bowel obstruction.*
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**Ventral Hernia**
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*Axial CECT in a patient with a history of prior thoracic surgery shows a fat-containing ventral hernia <img src='img/arrows/WS.png'/> arising in the upper abdomen. Ventral hernias occurring above the umbilicus, as in this case, are termed epigastric hernias.*
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**Spigelian Hernia**
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*Axial CECT shows a left abdominal spigelian hernia <img src='img/arrows/WS.png'/> with multiple dilated loops of small bowel <img src='img/arrows/WC.png'/>, compatible with small bowel obstruction.*
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**Lumbar Hernia**
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*Axial NECT shows a large lumbar hernia <img src='img/arrows/WS.png'/> in the right flank containing a portion of the right kidney <img src='img/arrows/WC.png'/>.*
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**Lumbar Hernia**
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*Coronal CECT shows a large lumbar hernia containing colon <img src='img/arrows/WS.png'/>, small bowel <img src='img/arrows/WO.png'/>, as well as a portion of the right hepatic lobe <img src='img/arrows/WC.png'/>. Lumbar hernias are often secondary to prior surgical incisions and are particularly common after renal surgeries.*
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**Umbilical Hernia**
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*Sagittal CECT shows an umbilical hernia containing ascites <img src='img/arrows/WC.png'/> in a patient with cirrhosis and portal hypertension.*
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**Enterocutaneous Fistula (Mimic)**
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*Axial CECT shows an enterocutaneous fistula with enteric contrast directly extending from the small bowel into the anterior abdominal wall <img src='img/arrows/WS.png'/>.*
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**Obturator Hernia**
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*Axial CECT shows a loop of small bowel <img src='img/arrows/WC.png'/> lying between the obturator externus and pectineus muscles, compatible with an obturator hernia.*
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**Traumatic Abdominal Wall Hernia**
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*Axial CECT in a trauma patient shows disruption of the musculofascial plane <img src='img/arrows/WO.png'/> near the insertion into the iliac crest and thoracolumbar fascia. Note the presence of adjacent subcutaneous hematoma. The spleen was also lacerated (not shown). These findings are compatible with a traumatic hernia.*
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**Spermatic Cord Lipoma or Liposarcoma (Mimic)**
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*Axial T1 MR shows a large mass with fat signal <img src='img/arrows/WS.png'/> extending through the inguinal canal into the left scrotum. This was found to be a spermatic cord liposarcoma at resection.*
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**Spermatic Cord Lipoma or Liposarcoma (Mimic)**
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*Sagittal US in the same patient shows that the mass <img src='img/arrows/WS.png'/> is very echogenic as a result of its fatty component, a fairly common appearance for these lesions, and extends down to just above the testicle <img src='img/arrows/WC.png'/>.*
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### Additional Images
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**Subcutaneous Abscess (Mimic)**
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*Axial CECT shows a loculated fluid collection <img src='img/arrows/WS.png'/> in the subcutaneous tissue adjacent to the site of incisional hernia repair <img src='img/arrows/WC.png'/> (abdominal wall abscess).*
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**Soft Tissue Neoplasm (Mimic)**
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*Axial CECT shows a partly calcified mass <img src='img/arrows/WS.png'/> in the abdominal wall adjacent to a descending colostomy (metastatic colonic carcinoma).*
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