The Acute Abdomen

1. The Acute Abdomen Jason E. Davis, MD

2. Abdominal Pain • A leading cause for hospital admissions • Most self-limited and of little consequence • Subset of serious acute pathology may require acute medical and/or surgical intervention • This latter group referred to as ‘acute abdomen’ • Not all acute abdomens = surgical abdomen • Renal colic, gastroenteritis, infectious colitis*, PID • Mesenteric ischemia, ruptured AAA, appendicitis, perforated bowel, perf’d peptic ulcer, inc’d hernia

3. Broad Differential Dx

4. Anatomic Considerations • Embryonic origin & Blood supply • Foregut: esophagus, stomach, proximal duodenum, pancreas, liver, biliary tract, spleen • Celiac artery • Midgut: distal duodenum, jejunem, ileum, cecum, appendix, proximal 2/3 transverse colon • Superior mesenteric artery • Hindgut: remaining colon and rectum • Inferior mesenteric artery

5. Anatomic Considerations • Innervation • Visceral pain: autonomic, dull, cramping, poorly localized, often assoc with nausea and diaphoresis • Often midline secondary to embryonic origin • Parietal pain: somatic, sharp, severe, persistent, loc • Referred visceral sensation • Foregut pain: Epigastric • Midgut pain: Peri-umbilical • Hindgut pain: Hypogastrium

6. Anatomic Considerations

7. Anatomic Considerations

8. Approach to Acute Abdomen • Age • Location and character of pain • Pain duration and progression • Associated symptoms • Nausea • Emesis • Anorexia • Constipation/Diarrhea

9. Approach to Acute Abdomen Most important symptom is PAIN. Accordingly, history should include all of the following: 1. Onset 2. Severity 3. Type of pain 4. Radiation of pain 5. Change in nature of pain 6. Associated bowel or urinary symptoms 7. Aggravating or relieving factors

10. Approach to Acute Abdomen • Diagnosis according to onset of pain: • Sudden • Rapid • Gradual • Chronic (exacerbation) Stereotypes of Pain Onset and Associated Pathology • Position of patient(motionless vs. writhing in pain vs. rolling restlessly  appendicitis/peritonitis vs. mesentary ischemia vs. ureteral/intestinal colic)

11. Approach to Acute Abdomen

12. Named Exam Findings

13. Imaging and Laboratory Studies • Laboratory examinations • CBC with differential, type & screen • Chem-10, amylase, LFT’s, urinanalysis • X-rays of the chest and abdomen (upright/supine) • Distended loops of bowel, kidney stones, perf free gas • Ultrasound: cholelithiasis, bile duct obstruction, AAA • Abdominal CT: AAA, abdominal abscess, severe diverticulitis • Endoscopy: perforated peptic ulcer, SBO, gastric cancer • Colonoscopy: carcinoma of the colon • Angiography: mesenteric ischemia • Radionuclide scans

14. Appendiceal Disease • Appendicitis • 7% lifetime risk of appendicitis • Most common cause of acute abdominal surgery in the U.S. • Though living in Lehigh Valley appears to be risk for gallbladder disease • Must be considered in every patient with acute abdomen • Especially common during pregnancy (also important to consider ectopic pregnancy in women of reproductive age) • Constipation: “the great imitator” • Less common among differential diagnoses • Mucocele, carcinoid, appendiceal carcinoma

15. Special Considerations • Elderly patients • May not mount febrile response • Atypical pain presentation (severity/location) • Immunosuppressed patients • Opportunistic infections, lymphomas • Corticosteroids may mask pain • Obese patients • May be more difficult to palpate • Patients taking pain medications • Opioids may cause constipation and mask/distort pain • Pregnant women • Distorted abdomen & pregnancy may mimic Sx’s

16. Beyond Appendicitis

17. Beyond Appendicitis • Appendiceal Neoplasms • Carcinoid • Marjority of appendiceal neoplasms • Derived from neural crest cells • <2cm (90%)  appendectomy • >2cm (10%)  right hemicolectomy • Slow mets, 5 yr survival >50% w/ mets • Primary Adenocarcinoma • Mucinous more favorable than Colonic • Assoc with colon and ovarian CA (15 – 30%) • Lymphoma (often AIDS-associated)

18. Acute Abdomen Algorhithm adopted from Vanderbilt Medical Center

19. RLQ Pain Adopted from Vanderbilt Medical Center

20. Case 1: Ms. Jones • 27 years old, pregnant female • ED presentation • Crampy peri-umbilical pain • Nausea, emesis and anorexia x 12 hours • Pain has ‘migrated’ to RLQ over past several hours, becoming constant and intense • Urinanalysis: mild hematuria and pyuria • CT scan – deferred for preg

21. Case 1: Ms. Jones revisited • Appendicitis • Classic chronologic presentation • Especially common during pregnancy • 1 out of every 1750 pregnancies! • May be in RUQ due to enlarged uterus • Mild hematuria and pyuria are common in appendicitis with pelvic inflammation • Radiopaque fecalith present only 5% x’s • Open or Laparoscopic appendectomy

22. Case 2: Mr. Smith • 42 year-old male • ED presentation • Fever, vomiting and diarrhea • Constant abdominal pain 4hrs, radiates to back • Last bowel movement yesterday, flatus unsure • FUA: non-specific bowel gas pattern

23. Case 2: Mr. Smith revisited • Gastroenteritis • Classic presentation • Pain often follows N/V • Non-surgical, medical management

24. Summary • Differential diagnosis for acute abdomen is lengthy • Many presentations will not require admission or surgery • Ischemic colitis, ruptured AAA, intestinal or ulcer perforation, and ectopic pregnancy are important causes not to be missed • Common differentials include appendicitis, cholecystitis, obstruction, and ischemia, but will vary per population

25. Thank you