Abdominal Wall Hernias A Case of Three Hernias and Anatomy of Inguinal, Femoral, and Obturator Regions

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Abdominal Wall

Hernias

A Case of Three Hernias and

Anatomy of Inguinal, Femoral, and

Obturator Regions

David Furfaro, HMS 3rd_{Year Medical Student}

Gillian Lieberman, MD Radiology Core Clerkship August 2012

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Presentation Outline

1. Case Presentation

2. Differential Diagnosis

3. Small Bowel Obstruction

A. Imaging Approach to Diagnosis

B. Differential Diagnosis for Cause

4. Hernias

1. Anatomy and Types of Hernias

2. Imaging

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F.L. ED Presentation

CC:

Vomiting, abdominal pain, and leg pain

HPI:

86 year old female began having pain along anterior

right thigh about one week prior to presentation. Soon

after, she began experiencing diffuse, colicky abdominal

pain. She has been vomiting and unable to eat x 6 days.

Denies flatus or bowel movements for past few days.

ROS:

Oliguria for few days. Denies fevers, chills, chest pain

or tightness, cough, SOB, jaundice, urinary symptoms,

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F.L. History

•

PMH:

Hypertension, spinal arthritis, remote

history of breast cancer s/p mastectomy

•

PSH:

Hysterectomy 14 years ago, Mastectomy 30

years ago, left wrist surgery 30 years ago

•

Meds:

Atenolol

•

Allergies:

NKDA

•

SH:

Remote history smoking. No ETOH or illicit

drug use

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F.L. Physical

• Vitals: 98.2 112 143/65 32 95% on RA • General: Awake, alert, no acute distress, cooperative • HEENT: Anicteric sclera, EOMI, PERRL

• Neck: Supple, JVP not elevated, no lumps or masses • CV: RRR, normal S1 and S2, no m/r/g

• Lungs: Crackles in bases of left lung

• Abdomen: Bowel sounds present all quadrants. Soft, non-distended. Tender to palpation on right side. Slight guarding, no rebound tenderness

• Ext: Reducible right inguinal hernia. 2+ pulses bilaterally

• Neuro: A&Ox3, cranial nerves intact. 5/5 strength and intact light sensation in all extremities

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F.L. Differential Diagnosis

Anatomic:

• Bowel obstruction • Mechanical

• Functional

• Strangulated hernia (hiatal, inguinal, other) • Gallstone ileus • Cholelithiasis • Nephrolithiasis Metabolic / Electrolyte • Hypercalcemia • Hypokalemia • Hypernatremia • Hyponatremia • Uremia

• Diabetic Ketoacidosis (first presentation diabetes) Infectious / Inflammatory: • Gastroenteritis • Biliary pathology • Cholecystitis, cholangigits etc. • Appendicitis • Pancreatitis

• Right sided diverticulitis

• Pyelonephritis • Peritonitis • Hepatitis • Abscess • Pneumonia with diaphragmatic irritation Vascular • Mesenteric ischemia • Ischemic colitis • SMA syndrome Gynecologic • Adnexal pathology • Cysts or neoplasms of ovaries, fallopian tubes

• Endometriosis

Trauma

• Viscus rupture

• Solid organ laceration or rupture

• Hematoma

Malignancy

• Metastatic tumor

• Carcinomatosis

• Primary tumors – colon, pancreas, liver etc.

• Lymphoma

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F.L. Labs

141 101 67 3.9 29 1.7

11.2 34.5

N: 87.1 L: 6.4 M: 6.1 E: 0.2 Bas 0.1 Bands 28% (earlier CBC) PT: 11. 7 PTT: 24.6 INR: 1.1

• Elevated BUN and Cr. BUN:Cr > 20

• White count WNL, but bands and left shift 127

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Suspected Complete Bowel

Obstruction

• Diffuse abdominal pain • Nausea

• Vomiting

• Absences of flatus and bowel movements • Dehydration – oliguria, pre-renal azotemia

• Previous abdominal surgery and presence of hernia • Classic findings absent in L.B.

• Distended abdomen

• Red flags:

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Diagnostic Imaging Approach for

Bowel Obstruction

Silva AC, Pimenta M, Guimaraes LS. Small bowel obstruction: what to look for. Radiographics. 2009 Mar-Apr;29(2):423-39

LBO

Barium enema

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Appropriate Imaging for SBO

American College of Radiology. ACR Appropriateness Criteria®: Suspected complete or high-grade partial SBO. Available at:

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American College of Radiology. ACR Appropriateness Criteria®: Suspected complete or high-grade partial SBO. Available at:

http://www.acr.org/~/media/ACR/Documents/AppCriteria/Diagnostic/SuspectedSmallBowelObstruction.pdf. Accessed August 2012

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Abdominal Plain Film in Bowel

Obstruction

• Controversy in the literature about utility

• Some studies show 80-90% sensitivity, while others show diagnosis rates as low as 30-70% (ACR, 2010)

• Rarely helpful in determining site or cause of obstruction (Maglinte et al. 1996)

• Recent studies have shown that more experienced radiologists have higher rates of detection (ACR, 2010)

• Still considered by many to be first line imaging for suspected bowel obstruction

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• Dilated small bowel

• Can infer transition point because paucity of gas in the colon

• Incidental finding – left thoracolumbar scoliosis and

degenerative changes

Upright KUB, Image from PACS, BIDMC

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Air fluid levels

Lateral decubitus KUB. Image from PACS, BIDMC

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Approach to Abdominal Plain Film

Concerning for Obstruction

1. Look for dilated loops of bowel

2. Determine if large bowel or small bowel

3. Mechanical or functional

• Mechanical see marked dilation and a transition point

• Functional see mild distension of entire bowel with no transition point

• Exception is focal ileus = sentinel loop

4. Rule of 3s

• Bowel lumen dilated > 3 cm

• Thickened folds > 3mm

• More than 3 air fluid levels

Present Small bowel Markedly dilated and transition point  mechanical Dilated > 3cm More than 3 air-fluid levels Case of F.L.

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Differential Diagnosis for

Mechanical Bowel Obstruction

In the lumen • Foreign body • Bezoar • Gallstone • Worm ball • Intussusception • Fecal impaction In the wall Benign • Adenoma • Leiomyoma • Lipoma Malignant • Primary adenocarcinoma • Metastases – melanoma • Lymphoma Extrinsic causes • Adhesions -2/3 • Hernia • Adjacent mass • Volvulus

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Why we care / complications

of SBO

• Strangulation: bowel wall edema and increasing intraluminal

pressure  compromised perfusion

• Ischemia and necrosis ensues

• Fever and leukocytosis

• Progress to perforation

• Most common with closed loop obstructions and hernias

Furukawa A, Kanasaki S, Kono N, Wakamiya M, Tanaka T, Takahashi M, Murata K. Ct Diagnosis of Acute Mesenteric Ischemia from Various Causes. AJR. 2009, 192 (2): 408-416.

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HERNIAS

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Imaging Recommendations and

Algorithm

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Silva AC, Pimenta M, Guimaraes LS. Small bowel obstruction: what to look for. Radiographics. 2009 Mar-Apr;29(2):423-39

Imaging Recommendations and

Algorithm

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Axial, C- Abdominal CT Image from PACS, BIDMC

Our Patient: SBO on CT

Coronal, C- Abdominal CT Image from PACS, BIDMC

• Air fluid level

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Our Patient: Serial CT Images - 1

Axial, C- CT Abdomen. Image from PACS, BIDMC

• Umbilical hernia

• Decompressed colon

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Our Patient: Serial CT Images - 2

• Hernia

• Inguinal ligament

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• Inguinal hernia Decompressed bowel entering hernia sac • Decompressed bowel leaving the hernia • It would be easy to confuse this inguinal hernia as the site of obstruction, but there is no transition point; it is all decompressed bowel

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Our Patient: Serial CT Images - 4

Sagittal, C- CT Abdomen. Image from PACS, BIDMC

• Decompressed bowel entering inguinal hernia • Decompressed bowel leaving the hernia • On sagittal view it is clearer that all the bowel in the inguinal hernia is

decompressed and there is no transition point

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• Where is the transition point then?

• Follow this loop of bowel

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Our Patient: Serial CT Images - 6

• Where is the transition point then? • Bowel entering obturator foramen

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• Follow the loop of bowel

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Our Patient: Serial CT Images - 8

• Obturator hernia

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Coronal, C- CT Abdomen. Image from PACS, BIDMC

• Follow this loop of bowel.

Dilated bowel starting to

enter obturator hernia

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Our Patient: Serial CT Images - 10

• Where is the transition point then? • Loop of bowel going through the obturator foramen

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• Obturator hernia

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Our Patient: Serial CT Images - 12

• Where is the transition point then? • Bowel loop in obturator hernia

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• Where is the transition point then? • Bowel loop in obturator hernia

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Our Patient: Serial CT Images - 14

• Follow this loop of bowel out of the obutrator hernia

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Our Patient: Serial CT Images - 16

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• Decompressed bowel leaving the obturator hernia • Dilated bowel entered the hernia and decompressed bowel exited, so this is the transition point and site of obstruction

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Our Patient: Obutrator Hernia on KUB?

Upright KUB. Image from PACS, BIDMC

• Loop of bowel going into obturator hernia? • This is a zoomed in portion of the KUB viewed earlier. It is possible that seeing the obturator hernia on this imaging modality

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Review of Hernias

and Anatomy

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Hernias in General

• Protrusion of an organ, fascia, or tissue through the wall of the cavity that normally contains it

• Bulge on outside, depending on type, location and size • See on imaging – CT is normally diagnostic

• Reducible – hernia sac can be pushed back into cavity easily • Incarcerated – hernia cannot be reduced

• Strangulated – incarcerated hernia with a compromised blood supply

• Lead to necrotic bowel and perforation • Surgical emergency

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Types of Hernias

• Brain herniation • Diaphragmatic hernia • Hiatal hernia • Type 1: sliding • Type 2: paraesophageal • Type 3: mixed

• Type 4: abdominal organ herniated above diaphragm

• Congenital diaphragmatic hernia

• Bochdalek – postero-lateral hernia • Morgagni – anterior hernia

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Abdominal Wall Hernias

• Inguinal • Femoral • Umbilical • Obturator • Richter’s hernia • Incisional • Parastomal • Epigastric • Spigelian hernia • Littre hernia • Lumbar hernia • Many, many more

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Menu of Radiologic Tests for

Hernias

• Computed Tomography – currently test of choice • Sonography (US)

• Dynamic exam  can detect transient hernias

• High sensitivity and specificity for inguinal and femoral hernias • May miss in obese patients

• Plain film – rarely useful

• Magnetic Resonance Imaging

• Increasing in use due to lack of ionizing radiation

• Herniogram

• 40 – 50 ml of contrast injected into peritoneum under fluoroscopic guidance

• Images taken at rest and straining / coughing • Invasive

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Imaging for Hernias

American College of Radiology. ACR Appropriateness Criteria®: Palpable abdominal mass. Available at:

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Brooks, D. Overview of Abdominal Wall. UpToDate 2012.

http://tinyurl.com/kga7aa7

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Inguinal Hernias - Anatomy

• Inguinal canal

• Inferior wall / floor = inguinal ligament

• From ASIS to pubic tubercle

• Thickening of aponeurosis external oblique fascia

• Anterior wall = external abdominal

• Superficial ring is opening in this layer

• Poster wall = transversalis fascia

• Deep inguinal ring is opening in this layer

• Superior wall = transversus abdominus and internal oblique

• Canal contents

• Spermatic cord in men

• Round ligament of uterus in women • Ilioinguinal nerve

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Image from CFAA Science Anatomy and Physiology:

Abdomen/ Pelvis: Inguinal Canal. Available online at :

http://cfaascience.wordpress.co m/2010/10/22/anatomy-and- physiology-abdomenpelvis-inguinal-canal/

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Hesselbach’s Triangle

Image available online at:

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Inguinal Hernias

• Most common type of hernia

• In groin 96% are inguinal, 4% are femoral

• More common in men (9:1)

• Femoral are more common in women, although inguinal still most common type found in women

• Indirect inguinal hernia

• Most common type – can be congenital from patent processus vaginalis – extension of peritoneum in development

• Hernia sac through internal ring, lateral to inferior epigastrics

• Direct inguinal hernia

• Through Hesselbach’s triangle

• Hernia sac through weakness in posterior wall of inguinal canal

• Cannot always distinguish type on imaging

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Axial, C+ CT abdomen. Sinha R, Rajiah P, Tiwary P. Abdominal Hernias: Imaging Review and Historical Perspectives. Current Problems in Diagnostic Radiology. 2007 Jan-Feb; 36(1): 30-42

Companion Patient #1: Indirect Hernia

• Inferior epigastric vessels • Hernia sac with loop of bowel in it • Hernia is lateral to inferior epigastric vessels, so is an indirect hernia

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Femoral Hernias

• Rare, < 10% of all hernias, but 40% present with incarceration or strangulation

• Defect in attachment of trasversalis fascia to pubic tubercle • Occur in femoral triangle

• Posterior / inferior to inguinal ligament • Medial to femoral vessels: NAVEL

• Occur more in older women because weaker pelvic floor muscles

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Image available online at http://tinyurl.com/m5 hw3r6

Anatomy

of

Femoral

Region

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Distinguishing Femoral and

Inguinal Hernias on CT

• Look for position relative to inguinal ligament

• Two other tricks from review of 215 groin hernia CTs and 46 femoral hernia CTs

• Look if sac extends medial past pubic tubercle – likely inguinal • Look if sac compresses femoral veins – likely femoral

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Axial, C+ CT abdomen. Suzuki S, Furui S, Okinaga K, Sakamoto T, Murata J, Furukawa A, Ohnaka Y. Differentiation of Femoral Versus Inguinal Hernia: CT Findings. AJR. August 2007; 189(2): W78-W83.

Companion Patient #2: Femoral Hernia

• Black arrow head = pubic tubercle • White arrow = compression of the femoral vein by the hernia sac

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Our Patient: Inguinal Hernia

Axial, C- Abdominal CT, Image PACS, BIDMC

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Umbilical Hernia

• Opening in the linea alba

• Linea alba = aponeurosis of rectus sheath formed by fascia of abdominal muscles

• Separates left and right rectus muscle

• Congenital or acquired

• Acquired is more common in females than males 3:1

• Due to increased abdominal pressure from obesity, distension, ascites or pregnancy

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Axial, C+ CT abdomen. Sinha R, Rajiah P, Tiwary P. Abdominal Hernias: Imaging Review and Historical Perspectives. Current Problems in Diagnostic Radiology. 2007 Jan-Feb; 36(1): 30-42

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Obturator Hernia

• Hernia through obturator foramen

• Obturator foramen is formed by ischium and pubis bones and • Obturator membrane within creates the obturator canal

• Obturator canal contains the obturator artery, vein, and nerve which supplies the medial compartment of the thigh

• Referred to as “little old lady” hernia due to demographic • Accounts for 0.2 – 0.4 % obstructions and has 25% mortality

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A. Upright KUB.

B. Axial, C- CT abdomen Sinha R, Rajiah P, Tiwary P. Abdominal Hernias: Imaging Review and Historical Perspectives. Current Problems in Diagnostic Radiology. 2007 Jan-Feb; 36(1): 30-42

Companion patient #4: Obturator Hernia

White arrows identify obturator hernia sacs.

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Abdominal Wall Hernias

• Inguinal

• Femoral

• Umbilical

• Obturator

• Richter’s hernia –counts one sidewall of bowel, usually anti-mesenteric

• Can cause ischemia without obstruction • Incisional – at site of previous incision

• Parastomal – adjacent to stoma, similar to incisional

• Epigastric – through linea alba above umbilicus

• Spigelian hernia – through linea semilunaris

• Littre hernia – Involves a Meckel’s diverticulum

• Lumbar hernia

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References

• Kendrick ML. Partial small bowel obstruction: clinical issues and recent technical advances. Abdom Imaging. 2009; 34(3):329.

• Maglinte DD, Reyes BL, Harmon BH et al. Reliability and role of plain film radiography and CT in diagnosis of small-bowel obstruction. AJR 1996; 167(6):1451-1455.

• Shrake PD, Rex DK, Lappas JC, Maglinte DD. Radiographic evaluation of suspected small bowel obstruction. Am J Gastroenterol 1991;86(2): 175-178.

• Silva AC, Pimenta M, Guimaraes LS. Small bowel obstruction: what to look for.

Radiographics. 2009 Mar-Apr;29(2):423-39

• Sinha R, Rajiah P, Tiwary P. Abdominal Hernias: Imaging Review and Historical

Perspectives. Current Problems in Diagnostic Radiology. 2007 Jan-Feb; 36(1): 30-42

• Small WC, Rose TA, Rosen MP, Blake MA, Baker ME, Cash BD, Fidler JL, Greene FL, Jones B, Katz DS, Lalani T, Miller FH, Sudakoff GS, Tulchinsky M, Yee J. Suspected Small-Bowel Obstruction. ACR Appropriateness Criteria. 1996, last reviewed 2010.

• Suzuki S, Furui S, Okinaga K, Sakamoto T, Murata J, Furukawa A, Ohnaka Y.

Differentiation of Femoral Versus Inguinal Hernia: CT Findings. AJR. August 2007; 189(2): W78-W83.