An Approach to Acute Abdominal Pain

An Approach to Acute Abdominal Pain Naresh T. Gunaratnam MD Huron Gastroenterology Associates Clinical Instructor in Medicine University of Michigan www.hurongastro.com Anatomic Basis of Pain • Sensory neuroreceptors in abdomen located in: – mucosa and muscularis propria of hollow viscera – on serosal structures like the peritoneum – in the mesentery – sensory neuroreceptors involved in regulation of secretion, motility, and blood flow Neuroreceptors in nociception • Two types of afferent nerve fibers involved in the perception of noxious stimuli – myelinated A- and unmyelinated C fibers – myelinated A- found on skin and muscle • mediate sudden sharp well localized pain following acute injury – C fibers found in muscle, periosteum, mesentary, peritoneum and viscera • pain usually dull, burning poorly localized, gradual onset and long duration Stimulants of Pain • Abdominal visceral nociceptors respond to mechanical and chemical stimuli – principal mechanical signal is stretch – cutting, tearing or crushing of viscera does not result in pain – mechanoreceptor stimulated with: • rapid distention of hollow viscus (intestinal obstruction) • forceful muscular contraction (biliray/renal colic) • rapid stretching of organ or capusle (hepatic congestion) Types of Pain • Visceral pain: – visceral nociceptors triggered – dull, poorly localized pain in midline epigastrium, periumblical region or lower midabdomen – crampy, burning and gnawing • Somatoparietal Pain: – noxious stimuli to parietal peritoneum – intense, well localized (McBurney’s point) • Referred Pain: – pain felt in areas remote to the disease organ (subphrenic absess felt as shoulder pain) Obtaining a history • Chronology – Sudden onset, well localized= intra-abdominal catastrophe (perforated viscus, mesentaric infarction, ruptured aneurysm) – Progression (appendicitis increases, gastroenteritis decreases, colic crescendo/decrescendo) – Duration hours to days more severe than pain lasting weeks Obtaining a history • Location – may not be specific – pain of diaphragmatic irritation will present as shoulder pain – changes in location may be marker of progression (visceralparietal irritation) – appendicitis  McBurney’s point – perforated ulcer  vague pain to peritonitis Obtaining a history • Aggravating and Alleviating Factors – peritonitis  lie motionless – renal colic  writhe, unable to find comfortable position – Fatty foods  biliary colic – Pain improves with eating  DU – Worse with eating  GU, mesentaric ischemia • Intensity and character – perception of intensity is dependent of point of reference of patient – not very useful Obtaining a history • PMH – bowel obstruction, renal colic, PID tend to recur • ROS – fever, chills  infectious – nausea, vomiting with no flatus  bowel obstruction – dysuria, pregnancy, menstrual history Physical Examination • Still patient  peritonitis • Writhing patient  colic, bowel obstruction • Remember the old and the young may present very atypically – elderly, diabetics, immunocompromised may present with minimal symptoms Physical Examination • Severe tenderness with rigidity  peritonitis  surgical colleagues • Mild tenderness  gastroenteritis • Palpate from areas of least pain to areas with most pain • Peritonitis (shake bed, deep breath) • Pelvic, Genital and Rectal exam on every patient with severe abdominal pain Laboratory Evaluation • CBC, UA, Electrolytes • Urine and serum pregnancy test in all women of reproductive age with lower abdominal pain • LFT , amylase/lipase on all with upper abdominal pain Radiographic Evaluation • Plain radiograph – upright and supine abdomen and chest x-ray • Ultrasound on patients with biliary and pelvic symptoms • CT Abdomen and Pelvis – evaluates vasculature, inflammation and solid organs The differential • Acute Cholecystitis – cystic duct obstructed, RUQ pain  R scapula – Murphy’s sign, LFTS, amylase • Acute Appendicitis – – – – anorexia, N/V and vague periumbilical pain 6-8 hrs pain migrates to RLQ, fever Progresses to localized peritoneal irritation CT useful in diagnosis The differential • Pancreatits • Acute Diverticulitis – most commonly in sigmoid colon – symptoms related to inflammation or obstruction – CT useful early to r/o absess, BE/Endoscopy contraindicated  wait 4-6 wks – Rx bowel rest, IV abx, surgery for failures The differential • SBO – 70% of cases in adults are post-op – adhesions, incarcerated hernias – bilious emesis, feculent emesis distal obstruction – X-rays  dilated bowel with AF levels • Perforated DU – usually in the anterior duodenal bulb – usually sudden acute pain with peritonitis – Chest x-ray will show free air under diaphram The differential • Acute mesenteric ischemia – intestinal angina (ab pain with eating) – “vasculopath” (cad, pvod, ab bruits etc) – acute onset of periumbilical abdominal pain out of proportion to physical findings – CT abdomen, angiogram – acidosis may herald intestinal infarction – surgery if acute vascular occlusion noted The differential • AAA – acute onset of tearing abdominal pain – tender abdominal mass in 90% – triad of hypotension, pulsatile ab mass and abdominal pain noted in 75% – Rx surgically • Others: – endometriosis, salpingitis, tubo-ovarian absess, ovarian cysts or torsion, ectopic pregnancy Special Circumstances • Pregnancy – appendicitis, cholecystitis, pyelonephritis, – adnexal problems (ovarian torsion, ovarian cyst rupture) – appendicitis 7/1000 pregnancies – 3% fetal loss with surgery, but 20% with perforated appendix Special Circumstances • Very Young – appendicitis and abdominal trauma secondary to abuse – PID, Meckel’s diverticulum, cystitis, enteritis, IBD • Very Old – symptoms may be subtle – compulsive evaluation Special Circumstances • Immunocompromised – chemotherapy, organ transplants, immunosupression for autoimmune disease, AIDS – symptoms are subtle – unique to immunocompromised host (neutropenic enterocolitis, GVH, CMV infections, KS, lymphoma/leukemia obstruction) Chronic Abdominal Pain • 15% of American complain of recurrent chroinic abdominal pain – – – – – Abdominal pain lasting > 6 months IBS (Rome Criteria) Women 70% of all IBS patients obtain history of abuse (physical/sexual) exhaustive work-up usually negative Summary • Obtain detailed history • Careful exam • Consider patient circumstances (PVOD, diabetes, age, previous ab surgery) • Early thorough work-up (labs/x-rays) • Frequent evaluation of progression • Ask for help if confused!!