01Approach to the Critical Patient/attcp30

Acute ischemic emergencies

›Acute mesenteric ischemia presentation

›Sudden severe abdominal pain disproportionate to exam

›Celiac trunk thrombosis as rare MALS complication

›Especially in antiphospholipid syndrome patients

›Hemodynamic instability requiring immediate stabilization

›IV access and resuscitation

›Lactate measurement for ischemia severity

›If peritoneal signs or hemodynamic collapse, emergent surgical and vascular surgery consult

›CT angiography mesenteric vessels if stable

›Do not delay intervention for imaging if unstable

Monitoring and targets

›Hemodynamic monitoring

›Vital signs with MAP target > 65 mmHg

›Tachycardia suggests pain crisis or acute complication

›Hypotension mandates emergent evaluation

›Oxygen saturation continuous monitoring

›Malnutrition may affect baseline respiratory reserve

›SpO2 target >= 92%

›Fluid status assessment

›IV access for resuscitation if needed

›Electrolyte correction in malnourished patients

Early consult triggers

›Specialist activation

›Vascular surgery consult for definitive management planning

›Open versus laparoscopic versus robotic approach planning

›Celiac artery revascularization evaluation

›Gastroenterology for exclusion of competing diagnoses

02History/hx70

Cardinal symptoms

›Postprandial pain pattern

›Chronic epigastric pain present in 94% of MALS patients

›Postprandial onset in approximately 80%

›Typically within 15 to 30 minutes of eating

›Nausea and vomiting in 56%

›Sitophobia (fear of eating) due to anticipatory pain

›Severity correlates with meal size and fat content

›Unintentional weight loss in 50%

›Severe loss greater than 11 kg reported in 35.6% of one cohort

›Nutritional deficiencies from restricted intake

Symptom characterization

›Pain quality and modifying factors

›Epigastric location predominant

›Radiation to back possible

›Worsening with meals and exercise

›Partial relief with leaning forward or drawing knees to chest

›Position-dependent ligament tension

›Classic positional clue

›Exercise-induced pain in 8%

›Increased mesenteric blood demand

›Distinguishes from purely postprandial pattern

›Associated GI symptoms

›Bloating in 39%

›Impaired gut motility from ischemia

›Overlap with functional dyspepsia

›Diarrhea in 30%

›Mesenteric ischemia-related motility disturbance

03Physical Exam/exam31

Vitals and general appearance

›Vital signs assessment

›Usually normal in uncomplicated MALS

›Tachycardia or hypotension suggests acute complication

›Weight and BMI trend for nutritional monitoring

›General appearance

›Thin habitus and low BMI as supporting clue

›Signs of malnutrition: temporal wasting, muscle atrophy

›Skin and connective tissue assessment

›Skin hyperextensibility if hEDS suspected

›Joint hypermobility scoring (Beighton score) if indicated

Abdominal examination

›Focused abdominal exam

›Epigastric tenderness on palpation

›Typical finding in active pain episode

›Peritoneal signs absent in uncomplicated MALS

›Epigastric bruit on auscultation

›Present in approximately 30% of symptomatic patients

›Accentuated with deep expiration (expiratory phase amplification)

›Found in 16% of asymptomatic individuals (not specific alone)

›Auscultate epigastrium during deep expiration specifically

›Bruit accentuation with expiration is the diagnostic maneuver

›Bruit diminishes on deep inspiration

PITFALLS

›Diagnostic pitfalls

›Unremarkable physical exam despite significant disease

›MALS diagnosis cannot rely on exam alone

›Extensive imaging and vascular assessment required

04Differential Diagnosis/ddx48

Life-threatening diagnoses

›Vascular emergencies

›Acute mesenteric ischemia

›ICD-10 K55.0

›Sudden severe pain, lactic acidosis, hemodynamic instability

›Celiac trunk thrombosis

›Rare MALS complication especially with antiphospholipid syndrome

›CT angiography required for diagnosis

›Pancreatic malignancy

›ICD-10 C25

›Rapid weight loss, jaundice, epigastric pain

Functional and structural mimics

›Upper GI pathology

›Peptic ulcer disease and gastritis

›ICD-10 K27, K29

›Most common mimic; rule out with EGD

›Gastroparesis

›ICD-10 K31.84

›Gastric emptying study to differentiate

›Functional dyspepsia

›ICD-10 K30

›Disorders of gut-brain interaction with significant overlap

›Biliary and pancreatic pathology

›Cholelithiasis and biliary dyskinesia

›ICD-10 K80, K82.8

›RUQ ultrasound and HIDA scan

›Chronic pancreatitis

›ICD-10 K86.1

05Laboratory Tests/lt40

Exclusion and baseline labs

›Core metabolic panel

›Complete blood count

›Typically normal in MALS

›Anemia from malnutrition or concurrent pathology

›Comprehensive metabolic panel

›Renal function for imaging contrast safety

›Hepatic function panel to exclude biliary pathology

›Lipase and amylase

›Pancreatitis exclusion

›Normal expected in MALS

Ischemia and nutrition markers

›Ischemia assessment

›Lactate

›Elevated when acute mesenteric ischemia suspected

›>= 2 mmol/l suggests significant tissue hypoperfusion

›Normal lactate does not exclude chronic ischemia

›D-dimer when celiac thrombosis suspected

›Sensitive but not specific

›Elevated warrants CTA

›Nutritional status

›Albumin and prealbumin

›Assess degree of malnutrition

›Guide preoperative optimization

›Vitamin levels in significantly malnourished patients

›B12, folate, vitamin D

›Iron studies for deficiency anemia

06Diagnostic Tests/dt73

Scoring Systems

›No validated MALS-specific scoring system exists

›Diagnosis relies on clinical criteria plus imaging

›Symptom triad: postprandial pain, nausea, weight loss

›Vascular compression on imaging with respiratory variation

›Severity stratification elements

›Degree of celiac stenosis (grade I to IV on imaging)

›Weight loss severity and nutritional status

›Response to celiac plexus block

›Prognostic factors for surgical success

›Lower BMI associated with better outcome

›Absence of psychiatric comorbidity predicts better outcome

›Positive celiac plexus block response predicts surgical benefit

MRI

›MR angiography role in MALS

›Indications

›Contrast allergy precluding CTA

›Radiation minimization in young patients

›Problem solving when CTA inconclusive

›Findings on MRA

›Focal proximal celiac artery narrowing on expiratory images

›Poststenotic dilatation

›Hook sign may be visible

›Limitations

›Reduced availability compared to CTA

›Longer acquisition time

›Motion artifact from respiratory maneuvers

›Dynamic respiratory MRA protocols

›Inspiratory and expiratory image acquisition required

›Less standardized than duplex ultrasound protocols

CT

›CT angiography as primary confirmatory modality

›Indications

›Confirmation of duplex ultrasound findings

›Surgical planning including vessel anatomy

›Exclusion of competing diagnoses

›CTA findings in MALS

›Hook sign or J-hook deformity of celiac artery origin

›Fold angle less than 135 degrees significantly associated with symptomatic MALS

›Focal proximal stenosis with poststenotic dilatation

›Crural bands indenting celiac origin

›Protocol requirements

›Multidetector CTA with 3D reconstruction

›Expiratory phase images essential; inspiration phase for comparison

›Collateral vessels (enlarged pancreaticoduodenal arcade) suggest chronic ischemia

›CTA limitations

›Asymptomatic celiac compression in 7 to 21% of population

›Anatomic finding alone insufficient without clinical syndrome

›Renal function assessment before contrast administration

›Lateral mesenteric angiography

›Criterion standard for dynamic celiac compression

›Breathing maneuvers demonstrate dynamic narrowing

›Used in 12 to 36% of surgical candidates for preoperative planning

Ultrasound

›Duplex ultrasound as first-line modality

›Technique requirements

›Mesenteric duplex with respiratory maneuvers (inspiration and expiration)

›Celiac artery PSV measured during expiration and inspiration

›Dynamic respiratory variation is pathognomonic finding

›Diagnostic thresholds

›Celiac artery peak systolic velocity greater than 200 cm/s during expiration

›End-diastolic velocity >= 350 cm/s with deflection angle >= 50 degrees achieves 83% sensitivity and 100% specificity

›Velocities normalize with deep inspiration (key distinguishing feature)

›Advantages

›No radiation

›Dynamic assessment in real time

›Cost-effective initial evaluation

›ACEP Level B recommendation for initial vascular assessment

›Limitations

›Operator dependent

›Body habitus may limit windows

›Bowel gas interference

›Intraoperative duplex ultrasound

›Used during surgical decompression

›Confirms adequate celiac artery decompression intraoperatively

›Identifies residual stenosis requiring additional intervention

›Guides decision for concurrent revascularization

07Disposition/dispo40

Outpatient management pathway

›Discharge criteria for non-surgical presentations

›Hemodynamically stable with no acute ischemia signs

›Normal lactate

›No peritoneal signs

›Tolerating oral intake

›Pain manageable with oral analgesics

›No severe vomiting or dehydration

›Appropriate outpatient follow-up arranged

›Vascular surgery referral within 2 to 4 weeks

›Gastroenterology for competing diagnosis exclusion

Admission indications

›Criteria for hospital admission

›Acute complication presentations

›Suspected acute mesenteric ischemia

›Celiac trunk thrombosis

›Hemodynamic instability

›Nutritional emergency

›Severe malnutrition requiring parenteral nutrition

›Inability to maintain adequate oral intake as outpatient

›Postoperative monitoring

›Laparoscopic approach median stay 1.7 days

›Open approach median stay 4.6 days

›Robotic approach comparable to laparoscopic

›Transfer criteria

›Transfer to vascular surgery center for definitive surgical management

›Centers with experience in laparoscopic MALS release preferred

›Revascularization capability if needed

08Treatment/t72

Conservative and initial management

›Dietary modification

›Small frequent low-fat meals to reduce postprandial mesenteric blood demand

›Avoid large meals and high-fat foods that maximally stimulate splanchnic flow

›Adequate hydration

›Nutritional support in malnourished patients

›Enteral nutrition preferred route if gut accessible

›Parenteral nutrition for severe preoperative malnutrition

›Albumin optimization before surgery

›Pharmacologic symptomatic management

›Analgesics for pain control

›NSAIDs and acetaminophen first-line

›Opioid use with caution due to dependence risk

›Antiemetics for nausea

›Ondansetron 4 to 8 mg PO/IV as needed

›Metoclopramide 10 mg PO/IV three times daily (short-term)

›Proton pump inhibitor trial

›If concurrent GERD or gastritis suspected

›Omeprazole 20 to 40 mg daily

Celiac plexus block

›Percutaneous celiac plexus block

›Dual diagnostic and therapeutic role

›Pain relief response helps predict surgical success

›Performed in 75 to 78% of surgical candidates preoperatively

›Technique

›CT-guided or endoscopic ultrasound-guided approach

›Local anesthetic with or without corticosteroid

›Neurolytic block for longer-term relief in poor surgical candidates

09Special Populations/sp51

Pregnancy

›MALS in pregnancy

›Physiologic considerations

›Increased intraabdominal pressure from gravid uterus may worsen compression

›Pregnancy-related nausea and weight changes confound symptom assessment

›Delayed gastric emptying in pregnancy overlaps with MALS symptoms

›Imaging approach

›Duplex ultrasound preferred: no radiation, dynamic assessment

›MRA if further characterization needed with contrast discussion

›CTA with fetal shielding only when acute ischemia suspected and benefits outweigh risks

›Management approach

›Conservative management (dietary modification, symptom control) preferred during pregnancy

›Surgical decompression deferred to postpartum when feasible

›Nutritional support to prevent fetal growth restriction

›Medication safety

›Ondansetron for nausea (category B with caution in first trimester)

›Avoid NSAIDs in third trimester

›Acetaminophen preferred analgesic

Geriatric

›Older adult considerations

›Presentation differences

›MALS predominantly affects younger adults (median age 38 to 40)

›Older patients presenting with celiac compression more likely have atherosclerotic disease

›Distinguish extrinsic MALS from atherosclerotic mesenteric ischemia by CTA

›Surgical risk assessment

›Higher baseline comorbidity increases operative risk

›Frailty assessment before surgical referral

›Multidisciplinary perioperative optimization required

10Background/b63

Epidemiology

›Prevalence and demographics

›Rare condition; exact prevalence not established

›Asymptomatic celiac compression found in 7 to 21% of general population

›Symptomatic MALS is a small fraction of incidental compression

›Female predominance 4:1 ratio

›Typical age 30 to 50 years

›Median surgical series age approximately 38 to 40 years

›Diagnostic delay

›Median time from symptom onset to surgical referral 10.5 to 24 months

›Diagnosis of exclusion requiring extensive prior workup

›Associated conditions

›Hypermobile Ehlers-Danlos syndrome association described

›Abdominal compression syndromes cluster in hEDS population

›Nutcracker and May-Thurner may coexist

›Mast cell activation syndrome overlap

›Associated with persistent symptoms after surgery

›Prevalence in MALS cohorts under study

›Dysautonomia and POTS

›Preliminary data suggest association with worse surgical outcomes

›Emerging recognition in MALS literature

Pathophysiology

›Anatomical basis

›Median arcuate ligament anatomy

›Fibrous arch connecting diaphragmatic crura over aortic hiatus

›Normally passes superior to celiac artery origin

›Low insertion compresses celiac artery origin in MALS

›Compression mechanism

›Extrinsic compression of celiac artery and celiac ganglion

›Compression worsens on expiration (diaphragm rises, ligament tightens)

›Compression lessens on inspiration (diaphragm descends)

›Disease mechanisms

›Vascular ischemia component

›Reduced celiac artery flow causes foregut ischemia

›Postprandial demand outstrips compromised supply

›Collateral circulation via pancreaticoduodenal arcade may partially compensate

›Neuropathic component

›Celiac ganglion compression causes visceral neuropathic pain

›Explains non-postprandial constant pain in some patients

›Celiac ganglionectomy addresses this component surgically

›Combined pathophysiology explains surgical approach

›Ligament release addresses vascular ischemia

›Ganglionectomy addresses neuropathic pain

›Both components may require treatment for optimal outcomes

Therapeutic Considerations

›Evidence base for surgical treatment

›No randomized controlled trials; evidence from case series and cohort studies

›Surgical success rate 70 to 85% across series

›Laparoscopic approach has become preferred due to shorter hospital stay and comparable efficacy

›Open approach may offer modestly superior symptom relief

›Predictors of favorable outcome

›Lower BMI

›Positive celiac plexus block response

›Absence of psychiatric comorbidity, MCAS, and dysautonomia

›Postprandial rather than constant pain pattern

›Controversy and evolving understanding

›MALS as a diagnosis of exclusion remains controversial

›Asymptomatic celiac compression common in population

›Clinical correlation and symptom-imaging concordance mandatory

›Role of psychiatric and functional factors

›Comorbid disorders predict poorer outcomes but are not contraindications

›Multidisciplinary evaluation recommended before surgery

›Recurrence management

›Up to 45% symptom recurrence often without radiographic correlate

›Residual neuropathic pain may respond to repeat celiac plexus block

›Revascularization for confirmed residual or recurrent fixed stenosis

11Patient Discharge Instructions/pdi36

copy discharge instructions

›MALS home care instructions

›Eat small frequent low-fat meals to reduce postprandial pain

›Avoid large meals and high-fat foods

›Try 5 to 6 small meals per day rather than 3 large ones

›Stay well hydrated throughout the day

›Sip fluids between meals

›Nutritional supplements if recommended by your doctor

›Body position during and after meals

›Sit upright during meals

›Leaning forward or drawing knees to chest may reduce pain during episodes

›Medication instructions

›Take pain medications as prescribed

›Acetaminophen or NSAIDs for mild to moderate pain

›Anti-nausea medications as directed

›Avoid ergot medications and triptans

›These can worsen blood flow to the intestines

›Discuss all medications with your doctor

›Warning signs to return to the emergency room

›Sudden severe abdominal pain

›Much worse than your usual pain

›Especially with fever or inability to move

›Signs of vascular emergency

›Pain accompanied by bloody stools or vomiting blood

›Lightheadedness, dizziness, or fainting

›Rapid heart rate with severe abdominal pain

›Signs of severe malnutrition

›Inability to keep any food or fluids down

12References/r31

Guidelines and key sources

›Primary references

›Goodall R, Langridge B, Onida S, et al. Median Arcuate Ligament Syndrome. Journal of Vascular Surgery. 2020. PMID 31882314

›Comprehensive review of diagnosis and management

›Epidemiology, imaging criteria, surgical outcomes

›Kim EN, Lamb K, Relles D, et al. Median Arcuate Ligament Syndrome: Review of This Rare Disease. JAMA Surgery. 2016. doi:10.1001/jamasurg.2016.0002

›JAMA Surgery diagnostic algorithm

›Symptom prevalence data

›Skelly CL, Mak GZ. Median Arcuate Ligament Syndrome: Current State of Management. Seminars in Pediatric Surgery. 2021. PMID 34930594

›Pediatric MALS management review

Surgical outcomes literature

›Key surgical series

›Alsabbagh Y, Erben Y, Lanka SP, et al. Balancing Operative Risk and Symptom Relief: Outcomes of Open Versus Laparoscopic Release for MALS. Journal of Vascular Surgery. 2026. PMID 41380920

›Open versus laparoscopic comparative outcomes

›Pain and nausea improvement rates

›Boaz E, Aeschbacher P, Okida F, et al. Minimally Invasive Surgery for MALS: Clinical Outcomes and Recurrence Patterns. Surgery. 2026. PMID 41924797

›Recurrence patterns and thrombotic complications

›Diab J, Diab V, Berney CR. A Diagnostic Workup and Laparoscopic Approach for MALS. ANZ Journal of Surgery. 2022. PMID 35104014

›Diagnostic workup protocol and celiac plexus block role

›Woestemeier A, Semaan A, Block A, et al. Prognostic Factors for Long Term Outcome After Surgical Celiac Artery Decompression in MALS. Orphanet Journal of Rare Diseases. 2023. PMID 37872625

›Prognostic factors for surgical success

Imaging and special topics

›Imaging references

›Chan SM, Weininger G, Kozhimala M, et al. Utility of Hook Sign in the Diagnosis of MALS. Annals of Vascular Surgery. 2023. PMID 37023920

›Hook sign CT criteria and diagnostic utility

›Horton KM, Talamini MA, Fishman EK. Median Arcuate Ligament Syndrome: Evaluation With CT Angiography. Radiographics. 2005. PMID 16160104

›CTA protocol and imaging findings

›Expert Panel on Interventional Radiology, Lam A, Kim YJ, et al. ACR Appropriateness Criteria Radiologic Management of Mesenteric Ischemia: 2022 Update. JACR. 2022

Evidence & Review

Evidence & Review