Inguinal Hernia Imaging and Reduction

Written by: Jesus Trevino MD, MBA (NUEM PGY-3) Edited by: Samia Farooqi, MD (NUEM 2016 Graduate) Expert Commentary by: Adriana Segura Olson, MD


Mr. FJ is a 84 year old male with history of bilateral inguinal hernias status post repair with mesh 26 years ago who presents with constipation.  Five days ago, he suffered from a profuse diarrheal illness that also affected his household members.  Two days ago, he developed constipation with gradually progressive abdominal bloating, belching, and today bilious emesis.  On exam, he is afebrile, hemodynamically stable with moderate abdominal distention and right inguinal swelling that is tender, non-mobile and without overlying skin changes.

A CT abdomen and pelvis revealed a small bowel obstruction secondary to a right-sided incarcerated inguinal hernia!

Types of abdominal hernias

Abdominal hernias can be classified based on etiology (i.e., congenital vs acquired) and location (Adams): 

A retrospective review of 2510 hernia repairs from a single institution in Scotland (1985-2008) found the following distribution of abdominal hernias by location (Dabbas):

  • Inguinal (70.7%)

  • Umbilical (13.9%)

  • Epigastric (6.6%)

  • Incisional (4.7%)

  • Femoral (3.7%)

  • Spigelian/other (0.4)

Of inguinal hernias, the indirect form account for 65% of cases (Adams).

Clinical presentation and physical exam findings

Patient characteristics associated with an increased risk of abdominal hernia include (Fitzgibbons):

  • Male sex

  • Lower BMI

  • Family history of abdominal hernia

  • COPD

  • Smoking

  • Collagen vascular disease

  • Thoracic or abdominal aortic aneurysm

  • Open abdominal surgery

  • Peritoneal dialysis

On presentation, patients typically complain of abdominal or scrotal pain with or without superficial abdominal wall swelling that may worsen with maneuvers that increase intra-abdominal pressures (Adams).  There may be a preceding event involving heavy lifting, coughing or other form of straining.  (Adams).  Symptoms such as nausea, emesis, constipation, and abdominal distention raise concern for small bowel obstruction.

On exam, inspection may reveal swelling in a ventral, umbilical, inguinal or femoral location.  Often, the swelling can be reduced with gentle pressure - a reducible hernia; those that cannot be reduced at bedside are classified as incarcerated hernias.  Tenderness to palpation and overlying skin changes, such as red, purple or blue coloration, increases suspicion for strangulated hernia.


CT abdomen and pelvis is a good imaging modality to assess for abdominal hernia, especially when there is concern for acute incarceration or strangulation.  CT findings include a “zone of transition” depicting a change in diameter of small bowel from dilated to a normal or decreased diameter such as the “pinch point” seen in the case image.  Signs concerning for strangulation include engorged vessels within incarcerated hernia, fat stranding and thickened bowel wall (Strange).

A prospective study in Australia of patients with abdominal pain presenting to an ambulatory practice showed CT without contrast was 90% sensitive and 97% specific for the diagnosis of abdominal hernia, yielding a LR+ 26 and LR- 0.10 (Garvey). Assuming greater acuity of symptoms in the Emergency Department is associated with greater anatomical abnormalities more easily detected on CT, these test statistics can be generalized to the emergency setting.


Bedside reduction is indicated when a hernia is incarcerated without evidence of strangulation.  Signs suggestive of necrosis of hernia contents include peritonitis and erythema or necrosis of the overlying skin (Adams).

To prepare for reduction, place the patient supine in Trendelenburg (-20 degrees) with an ice pack overlying the area of swelling (Roberts).  In addition to procedural sedation, immediate pain control soon after ED arrival facilitates abdominal wall muscle relaxation and increases likelihood of reduction success, sometimes even spontaneously when the patient is properly positioned.

Next, palpate the outline of the abdominal wall defect with the nondominant hand and place gentle inward pressure with the dominant hand at the base (i.e., the most proximal portion) of the hernia contents to slide the contents intra-abdominally.  As the hernia contents slide through the abdominal wall defect, take care to avoid completely collapsing the lumen of the trapped small bowel at the “pinch point” as this will lead the remaining trapped bowel to distend (i.e., the ballooning effect), exceed the dimension of the wall defect and reduce the chances of a successful reduction at the bedside.


Reducible abdominal wall hernias without signs of bowel ischemia can be discharged with appropriate outpatient general surgery follow-up for elective repair.

Hernias that remain incarcerated or have evidence of strangulation require general surgery consult for eventual OR reduction.  Factors associated with difficult bedside reduction include duration of incarceration and small abdominal wall defect.

Case resolution

Bedside reduction failed; in retrospect, there was a low likelihood success based on the small “pinch point” (1.3 cm) relative to the bulk of the hernia contents.  Mr. FJ was admitted and underwent open inguinal hernia repair with small bowel resection, primary anastomosis and discharged on post-operative day 14.

Expert Commentary

This is an excellent summary by Dr. Trevino of the Emergency Department management of hernias with respect to imaging and reduction.

As mentioned in this post, it is important to determine whether an incarcerated hernia is associated with strangulation, which indicates bowel necrosis. Hernias that are clearly strangulated should not be reduced at the bedside and surgical consultation is warranted; however, these are not always easily distinguishable on physical exam. While patients with incarcerated hernias without strangulation can present with systemic symptoms including nausea and vomiting, signs of strangulation include toxic appearance of the patient, significant systemic symptoms, or pain that persists after reduction of the hernia. A lactate is often sent in cases of an incarcerated hernia, but its sensitivity and specificity is limited and therefore, when there is a high index of suspicion, a normal lactate level should not be used to rule out strangulation (Derikx). 

We often feel reassured with a normal lactate, but be wary of relying on this test and don’t let your surgical consultants rely too heavily on the lactate either!

It’s worth mentioning cases of internal hernias, which involve bowel protrusion through the peritoneum or mesentery into another compartment in the abdominal cavity. While rare, they are important to keep on the differential of undifferentiated abdominal pain as they can lead to small bowel obstruction or bowel necrosis. Internal hernias can be difficult to diagnose clinically because their presentation is often vague and intermittent, and they are not palpable on physical exam. CT scan of the abdomen and pelvis is the diagnostic modality of choice and this imaging may be normal in cases of reducible internal hernias. When diagnosed, prompt surgical consultation is indicated.


Adriana Segura Olson, MD

Assistant Professor, UT San Antonio Department of Emergency Medicine

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How to cite this post

[Peer-Reviewed, Web Publication] Trevino J,  Farooqi S (2017, Aug 15). Inguinal Hernia Imaging and Reduction.  [NUEM Blog. Expert Commentary By Olson AS]. Retrieved from


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Solomon, Caren G., Robert J. Fitzgibbons, and R. Armour Forse. "Groin Hernias in Adults." New England Journal of Medicine N Engl J Med 372.8 (2015): 756-63. Print.

Strange, Chad D., Krista L. Birkemeier, Spencer T. Sincleair, and J. Robert Shepherd. "Atypical Abdominal Hernias in the Emergency Department: Acute and Non-acute." Emerg Radiol Emergency Radiology 16.2 (2008): 121-28. Print.

Derikx, Joep P.m., Dirk H.s.m. Schellekens, and Stefan Acosta. "Serological markers for human intestinal ischemia: A systematic review." Best Practice & Research Clinical Gastroenterology 31, no. 1 (2017): 69-74.

Adriana Segura Olson, MD. Assistant Professor, Assistant Program Director, Department of Emergency Medicine, University of Texas Health San Antonio