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Acute Abdominal Pain

Alex Mamunes

General Approach

  • Rule out life threatening causes: Obstruction, Perforation, Dissection, AAA rupture, Inferior MI, Ectopic Pregnancy

  • History: pain quality/timing/location/severity, aggravating and alleviating factors (eating, bowel movements, position), nausea/emesis, bowel changes, flatus & prior episodes

  • Initial labs: CBC, BMP, LFTs, INR, lactate, lipase, U/A, urine hCG

System Causes Common features Workup
Esophagus Esophagitis – GERD, EOE, candida, HSV, CMV, pill, functional Epigastric pain, nocturnal reflux, odynophagia, dysphagia, thrush, immunocompromised Trial PPI, nystatin swish and swallow, consider EGD
Stomach Dyspepsia Epigastric pain, indigestion, bloating H. pylori testing, Trial PPI, ± EGD
Peptic ulcer disease NSAID use, better or worse w/ food, ± melena CBC, H. pylori testing, EGD
Gastritis NSAID use, ETOH abuse, burning epigastric pain
Liver Hepatitis: Ischemic, Viral, ETOH, trauma, toxins, autoimmune, congestive

RUQ pain ± jaundice

EtOH, Tylenol or IVDU

LFTs, INR, ETOH, Tylenol lvl, viral panel, RUQ U/S + dopplers; CT
Spleen Splenomegaly: increased size, infarct, abscess LUQ pain Physical exam, CT
Biliary Biliary colic

Overweight, ♀, 40’s, lasts hrs, worse with food,

RUQ pain scapula

Cholecystitis RUQ pain (Murphy’s sign), nausea, emesis with fever
Choledocholithiasis RUQ pain, N/V with jaundice CBC, LFTs, RUQ U/S, blood cx
Ascending cholangitis RUQ pain, N/V, jaundice, fever; hypotension, AMS
Pancreas Acute or chronic Pancreatitis; Complications (fluid, collection, necrosis, pseudocyst)

ETOH use, gallstones, epigastric pain back, N/V

Chronic pancreatitis: calcifications on CT

Lipase, CT A/P (rarely necessary within 24-48 hrs), RUQ U/S for gallstones
Intestines Gastroenteritis N/V, sick contact, undercooked food, travel Supportive care
Diverticulitis Older, h/o diverticulosis, LLQ pain with fever

CBC (leukocytosis)

CT A/P w contrast

Constipation h/o IBS, narcotic use, unable to pass stool, straining KUB
Bowel Obstruction/Ileus Prior hernia, abd surgery or malignancy, pain, nausea, emesis, distention inability to pass stool or flatus

KUB (air fluid levels)

CT is more sensitive

If concerned, page EGS and consider NGT to suction

Acute Small Bowel Mesenteric Ischemia Vascular disease, A-Fib, dissection, thrombosis, rapid onset, severe, periumbilical with N/V, recent hypotensive episode, post-prandial

CBC (leukocytosis)

BMP (metabolic acidosis), Lactate

CT A/P w contrast (CTA if suspicion)

Colonic non-occlusive Mesenteric Ischemia: ischemic colitis Cramping pain, laterally (most often left), urge to defecate + hematochezia

CBC, BMP, Lactate

CT A/P w contrast

+/- colonoscopy

Appendicitis Periumbilical to RLQ with N/V, later fever CBC, Lactate, CT A/P w/contrast
IBD Flare H/o Crohn’s or UC, Abd pain, fever, diarrhea, hematochezia CBC, Lactate, CTE, ESR, CRP, C-diff, GIPP
C. diff colitis Antibiotic exposure, diarrhea, abdominal cramping

C-diff PCR, CBC (leukocytosis)

KUB (megacolon)

Ogilvie’s syndrome Pseudo-obstruction in elderly pt, signs of obstruction w/o mechanical cause CBC, lactate, CT A/P w contrast
Volvulus Progressive abdominal pain, nausea, distention, constipation, vomiting

CBC, lactate

CT A/P w contrast

Typhlitis Neutropenia, abdominal pain (often RLQ), fever

CBC with diff, CT A/P w/ contrast, blood cx, C-diff;

empiric abx

OBGYN Ectopic pregnancy Sexually active, 6-7 wks after LMP, RLQ or LLQ pain + vaginal bleeding Urine hCG, pelvic US, CBC, T&S

Pelvic inflammatory disease, endometritis,

Tubo-ovarian abscess

Sexually active, h/o STI, purulent discharge, cervical motion tenderness, ± fever Pelvic exam w/ culture, GC probe, pelvic US
Ovarian torsion Young, sudden onset & severe, often with N/V Pelvic US w/ doppler
Kidney Nephrolithiasis h/o kidney stones, Crohn’s disease, sharp flank pain, paroxysms, ± hematuria U/A, CT A/P without contrast
UTI Suprapubic pain, dysuria, cloudy urine, new odor U/A with culture
Pyelonephritis Flank pain, fever/chills, CVA tenderness, usually UTI symptoms

U/A with culture, BMP

CT A/P w/contrast

Urinary Retention Older pt, male with BPH, anticholinergics Post-void residual
Renal infarct h/o vascular disease or A-fib, acute flank pain with N/V, +/- fever, HTN

CBC, BMP, UA, ECG (r/o a-fib)

CT A/P w contrast

Vascular Myocardial infarction CAD risk factors, DoE, epigastric, diaphoresis ECG, troponin
Aortic Dissection Vascular Risk factors, sudden onset, tearing pain back CT dissection rule out
AAA rupture Vascular risk factors, sudden onset back, hypotensive, pulsatile abdominal mass CT A/P w contrast, consult vascular surgery
MSK/skin Herpes zoster Immunocompromised, dermatomal rash, burning pain

Physical exam

Vesicle PCR for zoster

Muscle strain h/o trauma, overuse, heavy exercise, worse with twisting or bending Physical exam; rest, NSAIDs
Hernia Bulge, worse w/valsalva CT A/P non con
Pulmonary Pneumonia Productive cough, fever CXR, CBC, sputum cx
Pulmonary embolus Tachycardia, tachypnea, hypoxemia

ECG, trop, BNP

CTA chest

Functional IBS, depression, dyspepsia, anxiety abdominal migraine, functional

Imaging negative

Otherwise negative workup

Above workup
Other Adrenal crisis Hypotension, fatigue, lethargy, N/V, weight loss, hyperpigmentation BMP (↓Na, ↑K, ↓ Glu) Cort. stim
Intra-abdominal abscess Prior intra-abdominal disease or surgery, fever

CBC, blood cx

CT A/P w/ contrast

DKA Nausea, emesis, general abdominal pain


β–hydroxy butyrate


N/V, constipation,

↑ thirst, ↑ urination, bone pain, muscle weakness, confusion, fatigue

BMP, ionized calcium, PTH, Vit D, PTHrp
Acute intermittent porphyria Severe, poorly localized with motor/sensory neuropathy, red urine, tachycardia Urinary PBG