Sonographic Evaluation of Abdominal Pain : Focus on Diverticulitis and

Mesenteric Ischemia

John S. Pellerito MD, FACR, FAIUM, FSRUVice Chairman, Clinical Affairs

Director of Peripheral Vascular Laboratory

North Shore - LIJ Health System

Associate Professor of Radiology

Hofstra North Shore – LIJ School Of Medicine

Objectives

•Discuss technique and application of bowel sonography

• Illustrate findings of acute diverticulitis

•Describe Doppler examination of the mesenteric arteries

•Review acute and chronic mesenteric ischemia

• Summarize key concepts to improve diagnosis

Applications

Trauma

• Bowel perforation

• Bowel wall hematoma

Obstruction

• Bowel obstruction

• Intussusception

• Midgut volvulus

• Pyloric stenosis

Inflammation

• Crohn disease

• Ulcerative colitis

• Mesenteric adenitis

• Necrotizing enterocolitis

Infection

• Enteritis

• Colitis

• Diverticulitis

• Appendicitis

• Ascariasis

• Infected mucocele

Neoplasm

• Adenocarcinoma

• Lymphoma

• GIST

• Serosal metastases

• Peritoneal carcinomatosis

Normal Bowel Anatomy/Physiology

L

Normal Bowel:

•At least 5 layers

•Wall thickness 2-4mm

•Compressible

•Demonstrates peristalsis

Serosa

Muscularis Propria

Submucosa

Muscularis Mucosa

Mucosa

Equipment/Technique

• Start with 2 - 5 MHz curvilinear transducer to assess entire abdomen

•Follow exam with high frequency linear transducer for more focal examination of the bowel wall.

Equipment/Technique

•Assess site of pain

•Always evaluate for abnormal echogenicity

of the perienteric/colonic fat.

• Evaluate for any masses/lymph

nodes/cystic lesions associated with the

antimesenteric bowel wall.

Diverticulitis

•Inflammation of colonic diverticula, usually sigmoid colon

•Patients over 60 years of age

•Complications include abscess, fistula, perforation and stricture

•Differential Diagnosis: colon carcinoma, colitis, ovarian dermoid

Imaging of Diverticulitis

•CT is standard examination

•Ultrasound can demonstrate similar findings

•Sensitivity 85%

•Specificity 84%

Pradel JA et al. Radiology1997

Ultrasound Findings in Diverticulitis

•Bowel wall thickening > 4mm

•Echogenic outpouchings

•Pericolonic fat infiltration

•Fluid, collection, mass

•Lack of peristalsis

•Ring down artifacts (air)

•Pain on compression

Diverticulitis

62 yo LLQ Pain

Findings:

1. Thickened wall

2. Saccular outpouching

3. Echogenic fat

4. Gas in the tissues

5. Pain on exam

57 yo presented to ED with acute pelvic pain

Findings:

•Wall thickening

•Outpouching

•Echogenic fat

•Pain on exam

Infiltration of

the fat

surrounding

inflamed

sigmoid

diverticulum

Diverticulitis55 yo with left lower quadrant abdominal pain

Mesenteric Ischemia

•Acute

•Severe abdominal pain

•Nausea, vomiting, diarrhea

•Chronic

•Postprandial abdominal pain

•“Fear of food” syndrome

•Weight loss, small meals

Intestinal Ischemia and Infarction

•Arterial stenosis or occlusion

•Venous thrombosis

•Nonocclusive disease

Intestinal Ischemia and Infarction

•Arterial stenosis or occlusion

•Embolic disease (most common) 40 – 50 %

•Heart disease

•Arrythmias

•Atherosclerosis 25 – 30 %

•Trauma

Intestinal Ischemia and Infarction

•Venous thrombosis 10%

• Hypercoagulable state or surgery

• Portal hypertension

•Inflammatory (pancreatitis)

• Malignancy

Intestinal Ischemia and Infarction

•Nonocclusive Ischemia 20%

• Shock

• CHF

• Hypotension

• Sepsis

Acute Mesenteric Ischemia

• Interruption of blood supply

• Ischemia disrupts mucosal barrier

•Releases toxins and vasoactive substances

•Multisystem organ failure

Acute Mesenteric IschemiaCT Findings

•Pneumatosis intestinalis

•Portal vein gas

•Bowel wall thickening

•Ascites

•Free air

Angiography

MRA CTA

Ultrasound Examination of the Mesenteric Arteries

•Not recommended for acute presentation

•Evaluate for stenosis or occlusion of celiac, SMA or IMA near origin from aorta

•Chronic mesenteric ischemia associated with compromise of 2 or more vessels

Chronic Mesenteric Ischemia

•Mesenteric angina

•Progressive atherosclerosis

•Older patients

•Females > males

Ultrasound of Bowel Ischemia

•Nonspecific

•Bowel wall thickening

•Bowel distension

•Ascites

•Doppler evaluation for vascular disease

Arterial Blood Supply Of The Abdomen

CELIAC

SMA

IMA

Mesenteric Circulation

Collateral Circulation

ARC OF RIOLAN

MESENTERIC ARCHADES

GASTRODUODENAL

MARGINAL ARTERY

Patient Preparation

• 12 hour fast preferred

•Reduces scatter and attenuation from bowel gas

•No medication

Equipment

•Modern US instrument

• 2.5 - 7.0 MHz transducer

•Color and power Doppler

• Sensitive pulsed Doppler

•Harmonic imaging

Technical Shortcuts

•Optimize color Doppler image

•Adjust color gain, PRF, wall filter

•Normalize to laminar flow

•“Screen” vessel quickly

•Aliasing or color bruit

Normal Arterial Flow

•Low resistance pattern

•Proximal aorta

•Celiac artery

•Renal artery

•High resistance pattern

•Distal aorta

•Mesenteric arteries (fasting)

From: Introduction to Vascular Ultrasonography 6th ED

Aorta, Celiac Artery

and SMA

Celiac Artery

SMA

AO

Aorta

Diagnostic CriteriaPractical Approach

•Atherosclerotic plaque usually at origin and proximal segments of vessels

•Evaluate for flow disturbance with color Doppler

•Perform pulsed Doppler in regions of abnormal flow

•Analyze velocity measurements and flow patterns

Diagnostic CriteriaGray Scale

•Presence or absence of thrombus or plaque

•Dilatation or narrowing

• Irregular plaque or ulceration

•Dissection

•Free fluid

Diagnostic CriteriaColor And Power Doppler

•Luminal narrowing

•Aliasing - stenosis

•Color bruit

•Absent color flow -occlusion

•Collateral vessels

Diagnostic CriteriaPulsed Doppler

•Primary

•Peak systolic velocity

• Secondary

•Velocity ratios

•Post - stenotic turbulence

•Tardus parvus waveforms

•Evaluate for 2 or more pulsed Doppler criteria for significant stenosis

Post-stenoticTurbulence

Celiac Stenosis

•Mesenteric arteries

•Abdominal aorta

•Samples of celiac, superior mesenteric and inferior mesenteric arteries

Arterial Protocols

From: Introduction to Vascular Ultrasonography 6th ED

Duplex Criteria For Mesenteric Stenosis

• Significant stenosis > 70% diameter reduction

•Celiac PSV > 200 cm / sec

Sens 75% sens 89%

• SMA PSV > 275 cm / sec

Sens 89% sens 92%

Moneta, et al. J Vasc Surg 1991

Inferior Mesenteric Artery

• Visualized in 86% of casesDenys, et al. J Ultrasound Med 1995;14:435-439

• Stenosis at PSV > 200 cm/sPellerito et al. J Ultrasound Med 2009; 28:641–650

Diagnostic Criteria

•Peak systolic velocity

• PSV > 200 cm/sec in celiac and IMA

• PSV > 275 cm/sec in SMA

•Mesenteric / aortic ratio > 3:1

•Post stenotic turbulence

Celiac Stenosis

From: Introduction to Vascular Ultrasonography 6th ED

SMA Stenosis

IMA Stenosis

Chronic Abdominal Pain

IMA

AORTA

Mesenteric Ischemia

Median Arcuate Ligament

Syndrome (MALS)

•Patients may present with abdominal pain

•Diaphragm leaflet crosses celiac artery

•Formed by muscular fibers that connect right and left crura

•Uncertain if pain related to vascular or nerve compression

• Surgical release of ligament may improve symptoms

Courtesy of Dr Matt Skalski, Radiopaedia.org

MALS

•Elevated velocities at rest

•Relieved with inspiration

•May cause a fixed stenosis

•Common finding in thin women

Celiac Inspiration

PSV = 176

Celiac Expiration

PSV = 452MALS

Visceral Artery Dissection

• Spontaneous dissection unusual without underlying aortic dissection

• SMA > Celiac

•Risk factors: AS, hypertension, FMD, trauma, pregnancy, cystic medial necrosis and CTD

• Spontaneous resolution, occlusion, aneurym or rupture can occur

Visceral Artery Dissection

• Imaging Findings

•CT is primary technique

•Intimal flap

•Mural thrombus

•Hepatic or splenic infarcts

•Aneurysm

48 yo Male with Abdominal Pain

Spontaneous SMA Dissection

Venous Disease

•Venous thrombosis

•Portal vein gas

Conclusions

•Ultrasound can identify specific signs of diverticulitis and distinguish from other causes of pelvic pain

•Doppler can identify signs of vascular compromise and determine the hemodynamic significance of arterial disease