Acute abdomen Prof. M K Alam M S ; F R C S. Learning objectives Definition Anatomy and physiology of abdominal pain. Pathophysiology of common causes.

Acute abdomen

Prof. M K Alam M S ; F R C S

Learning objectives

Definition

Anatomy and physiology of abdominal pain.

Pathophysiology of common causes of acute abdomen.

Symptoms and signs of acute abdomen in relation to

the underlying pathology

Laboratory and imaging investigations

Initial and definitive management

Definition

A clinical presentation of

abdominal pain and tenderness,

that often requires emergency

surgical therapy.

• Spectrum of surgical & gynaecological conditions.

• Trivial to life-threatening conditions.

• 50% of general surgical emergencies.

• Some non-surgical or non intra-abdominal diseases.

• 30 days mortality: 4% among patients with abdominal pain

• Every attempt to make a correct diagnosis.

• Appropriate therapy

• The primary symptom: Abdominal pain

• Types of abdominal pain:

Visceral

Parietal

Visceral pain

• Visceral peritoneum invests abdominal viscera

• Shares its nerve supply (autonomic) with the viscera

• Visceral pain mediated through sympathetic ANS

• Visceral peritoneum insensitive to mechanical, thermal or chemical stimuli

• Sensitive to distension, traction on mesentery ,visceral muscle spasm & ischemia

• Visceral pain- dull & deep seated

• Vague, poorly localized

• Localized to the area of development

• Foregut organs- pain localized to epigastrium

• Midgut organs-, pain localized to periumbilical

• Hindgut organs- pain localized to hypogastrium

Parietal pain

• Originate from the irritation of parietal peritoneum

• Parietal peritoneum- somatic nerve

• Sensitive to mechanical, thermal & chemical stimulation

• When parietal peritoneum irritated- reflex contraction of

corresponding muscle segment (guarding)

• Pain sharp or knife like

• Well localized to the affected area

Referred pain

Definition: Pain perceived at a site distant from the source of stimulus.

Common examples of referred pain:

Right shoulder- Gall bladder

Left shoulder- Heart, tail of pancreas, spleen (Kehr's sign)

Scrotum and testis- ureter

Pain locations (Great degree of overlap)

• Right hypochondrium.- gallbladder

• Left hypochondrium.- pancreas

• Epigastrium.- Stomach and duodenum

• Lumber- kidney

• Umbilical- small bowel, caecum, retroperitoneal

• Right iliac fossa- Appendix, caecum

• Left iliac fossa- Sigmoid colon

• Hypogastrium- Colon, urinary bladder, adenexae

Pathogenesis

Surgical Causes of Acute Abdominal

• Inflammation: Appendicitis, cholecystitis, pancreatitis

• Perforation- Perforated duodenal ulcer, perforated

diverticulum, perforated appendix, perforated bowel

• Obstruction- Small bowel adhesions, obstructed hernia,

sigmoid volvulus, neoplasms

• Ischemia- Mesenteric ischemia (thrombosis/ embolism)

strangulated hernia

• Hemorrhage- Ruptured ectopic pregnancy, ruptured

aneurysms, solid organ trauma

Nonsurgical Causes of Acute Abdomen

• Diabetic crisis

• Uremia

• Hereditary Mediterranean fever

• Sickle cell crisis

• Acute leukemia

Common causes of acute abdominal pain

Adults• Non specific -35%• Acute appendicitis- 30%• Ac. Chole./ biliary colic -10%• PUD- 5%• Small bowel obstruction - 5%• Gynaecological disorders -5%• Ac. Pancreatitis -2%• Renal/ ureteric colic- 2%• Malignant disease - 2%• Acute diverticulitis -2%• Misc. - 2%

Children• Acute appendicitis• UTI• Mesenteric adenitis• Gastroenteritis

Inflammation

• Types: Infective or Non-infective

• Reactive hyperaemia- arteriolar/ capillary dilatation

• Exudation of fluid- increased vessel permeability

• Migration of leucocytes from vessels

• Clinical effect: depends on severity, duration, organ involved

• Abdominal pain, pyrexia, tachycardia, tenderness, guarding

Pathogenesis of Acute appendicitis

• Most common general surgical emergency

• Derived from the midgut

• Obstruction of the lumen (fecalith, lymphoid hyperplasia,

vegetable matter or seeds, parasites)

• Obstruction contributes to bacterial overgrowth,

Pathogenesis of Acute appendicitis

• Intraluminal distention.

• Distention produces the visceral pain- periumbilical pain.

• Promote a localized inflammatory process.

• May progress to gangrene and perforation.

• Inflammation of the adjacent peritoneum- localized pain RIF.

• Perforation usually after 48 hours from the onset.

Peritonitis

• Introduction of bacteria or irritating chemicals into the peritoneal cavity

by extension of inflammation or perforation of viscus

• Peritoneal inflammation

• Localized inflammation (appendicitis)- sharply localized pain, normal

bowel sounds

• Generalized peritonitis (perforated viscus) -generalized abdominal

pain, quiet abdomen

Types of peritonitis

• Primary peritonitis: Uncommon.

Children: Pneumococcus or hemolytic Streptococcus.

Adults: Peritoneal dialysis(gram +ve cocci).,

Ascites and cirrhosis(Escherichia coli and Klebsiella)

• Secondary peritonitis: Common, secondary to inflammatory insult from within abdomen, most gram-negative infections (enteric organisms or anaerobes). Example- perf. appendicitis

• Noninfectious : Pancreatitis (chemical peritonitis)

Obstruction

• Impedance to normal flow through hollow viscus

• Causes: 1. Lesion within lumen- stone, FB, worms, stool

2. Lesion of the wall- neoplasms,

stricture 3. Extrinsic

compression-adhesions, hernia

• Viscus contracts to overcome obstruction (colicky pain)

• Proximally- increased intraluminal pressure, dilatation, back

pressure effect- hydronephrosis, bowel ischemia (infarction,

perforation)

Aetiology of obstruction

Small bowel obstruction

• Post-operative adhesion- most common

• Hernia, tumour, Crohn’s disease- other causes

• Early- the intestinal contraction increases to propel contents past the obstructing point (colicky pain)

• Later- the intestine becomes fatigued and dilates, contractions becoming less intense.

• Bowel dilates, water and electrolytes accumulate in lumen and in the bowel wall.

• Massive third-space fluid loss: dehydration and hypovolemia.

• Intraluminal pressure increases in the bowel, a decrease in mucosal blood flow occurs.

Ischemia

• Occlusion of arterial supply or venous drainage

• Ischaemic coagulative necrosis (infarct)

• Inflammatory response along the margin

• Abdominal pain due to intestinal ischemia- common

• Other causes of ischemic abdominal pain- spleen,

kidney, liver, pancreas and ovaries

Mesenteric Ischemia

• Arterial: embolism, thrombosis

• Venous: thrombosis

• Superior mesenteric vessel distribution- most common

• Intestinal mucosal sloughing- within 3 hours of onset

• Full-thickness intestinal infarction by 6 hours

Symptoms & Signs in

Acute abdomen

Clinical assessment

• Good history

• Appropriate examination

• Full history and thorough examination (not always possible)

• Rapid evaluation

• Resuscitation

Main symptom- Abdominal pain

• Site: finger vs hand, most valuable indicator to underlying diagnosis (4 quadrants, 9 regions)

• Onset: Sudden- perforation, ischemia, biliary colic. Gradual- inflammation

• Severity: Visual analogue scale. Colicky pain- severe.

Inflammatory- initially mild, progress with time

• Progress: worsens over several hours- inflammation or infection

• Nature: Spasmodic: Biliary / ureteric colic. Constant- worse by movement- inflammatory

• Radiation and shift: cholecystitis, appendicitis

• Exacerbating factors: food worsen pain of bowel obstruction

• Relieving factors: food relieves pain- non-perforated PUD, gastritis.

Associated symptoms • Vomiting: pain presents first in acute surgical abdomen. Vomiting

precede significant abdominal pain in medical conditions.

Constipation or obstipation can be a result of either mechanical

obstruction or decreased peristalsis (ileus).

• Diarrhea is associated with several medical causes of acute

abdomen, including infectious enteritis, inflammatory bowel

disease (IBD), and parasitic contamination

• Bloody diarrhea- IBD, Colonic ischemia

EXAMINATIONInspection of the patient

• Ischemic bowel and ureteral and biliary colic, typically cause

patients to continually shift and fidget in bed while trying to

find a position that lessens their discomfort.

• Patients with peritonitis lie very still in the bed during the

evaluation and often maintain flexion of their knees and

hips to reduce tension on the anterior abdominal wall.

General Examination

• Vital signs- pulse, BP, temperature, RR

• Anemia

• Jaundice

• Sweating

• Dehydration

Inspection of the abdomen

• Distension: Obstruction

• Restricted mobility- ?peritonitis

• Scars of previous surgery- ?adhesion

• Hernias- cough impulse, reducible/irreducible

• Mass effect, distended veins

• Visible peristalsis

• Ecchymosis ? Acute pancreatitis (Cullen’s, Grey Turner’s sign)

Palpation of the abdomen

• Gently / deep , away from the area of pain.

• Severity/ location of tenderness- localized/ generalized

• Involuntary guarding

• Organomegaly, any mass

• Murphy’s sign, Rovsing’s sign,

• Rebound tenderness (Blumberg’s sign)

Percussion of the abdomen

• Hyperresonance :distended bowel loops

• Dullness due to organomegaly or mass

• Liver dullness lost- free intra-abdominal air is suspected.

• Shifting dullness- fluid

• Tenderness (tap tenderness)

Auscultation of the abdomen

• Quiet abdomen- ileus

• Hyperactive bowel sounds- bowel obstruction,

gastroenteritis

• Mechanical bowel obstruction- high-pitched “tinkling”

sounds that come in rushes and are associated with pain

• Bruits- high-grade arterial stenosis

Digital rectal examination

• Routine ? selective

• Check for mass, tenderness, or intraluminal blood

• Pelvic examination in female

Part 2

Investigations

Routine laboratory investigations

• Hematology: WBC / differential count, hemoglobin, platelets, RBC, sickle test

• Electrolytes, urea, creatinine, C-reactive protein, ca

• Amylase, lipase

• LFTs: Bilirubin (T & D), alkaline phosphatase, aminotransferase,

• Serum lactate & arterial blood gas

• Urine analysis

• Urine human chorionic gonadotropin

• Stool for parasites

• Lactate levels and arterial blood gas: intestinal

ischemia or infarction.

• Urinalysis: bacterial cystitis, pyelonephritis, diabetes.

• Urinary human chorionic gonadotropin: suggest

pregnancy as a factor in the patient's presentation or aid in

decision making regarding therapy.

• Stool: occult blood, parasite, Cl. Difficile (toxin & culture).

Plain radiographs

• Upright chest radiographs – free gas under the dome of diaphragm Perforated duodenal ulcer-75%

• Lateral decubitus abdominal radiographs- pneumoperitoneum in patients who cannot stand

Plain x-ray abdomen

• Limited usefulness

• Calcifications: renal stones 90%, chronic

pancreatic, aortic aneurysms, fecalith

• Supine and upright films: distension, fluid levels,

gas distribution (small vs large bowel), volvulus

of sigmoid colon/ cecum

Contrast X-ray

• Water soluble contrast

• Oral/ nasogastric- small bowel follow through

• Less specific

• Obstruction/ perforation (rarely used)

• Contrast not reached caecum in 4 hours-

complete obstruction, needs surgery

Abdominal ultrasonography

• Gallbladder: stone, wall thickness, fluid around

gallbladder, diameter of bile ducts

• Liver: abscess, other masses

• Pelvis: Ovarian, adnexal & uterine pathologies

• Free fluid in peritoneum

• Limited evaluation of pancreas

• Limitations: bowel gas, person dependent, difficult to

interpret for most surgeons

Liver abscess (US)

CT abdomen• Widely available • Easier to interpret by surgeons• Imaging modality of choice in acute abdomen,

following plain abdominal radiographs.• Accuracy and utility of CT abdomen and pelvis in

acute abdominal pain is well established.• Most common causes of acute abdomen are

readily identified by CT• Highly accurate in acute appendicitis,

mechanical bowel obstruction, intestinal ischemia

Liver abscess Paracolic abscess

SMA Thrombosis

DIAGNOSTIC LAPAROSCOPY

• Ability to diagnose and treat a number of the conditions causing an acute abdomen

•High sensitivity and specificity

• Decreased morbidity and mortality, decreased length of stay, and decreased overall hospital costs

• Advances in equipment and greater availability

DIFFERENTIAL DIAGNOSIS

• Differential diagnosis of acute abdominal pain is extensive.

• Comprehensive knowledge of the medical and surgical conditions that create acute abdominal pain

• Mild, self-limited illness to the rapidly progressive and fatal

• Evaluated immediately upon presentation and reassessed at frequent intervals.

• Many acute abdomen require surgical intervention but some abdominal pain are medical in aetiology.

Management

Preoperative preparation

• Fluid and electrolyte abnormalities corrected

• Antibiotic infusions for the bacteria common in acute abdominal emergencies (gram-negative enteric organisms and anaerobes)

• Nasogastric tube to decrease the likelihood of vomiting and aspiration

• Foley catheter- to assess urine output -0.5 mL/kg/hour

• Blood typed and cross matched for operation

Preoperative preparation

• Frequent evaluation of the patient

• Stabilization of co-morbid conditions

• Surgical vs non- surgical management

• Consent for surgery

Surgical intervention

• Excision: Appendectomy, cholecystectomy, tumors.• Resection and anastomosis: Bowel tumors, gangrenous

bowel,• Relieve obstruction: Hernia, division of adhesion.

• Repair of perforation: Perforated DU, stomach, ileum

• Drainage: Appendicular abscess.

• Bowel diversion: Colostomy.

Non-surgical intervention

• Conservative management: NPO, IV fluid, antibiotics Example: Appendicular mass

• Radiological intervention: PCD (liver abscess, appendicular abscess), placing stents in obstructed bowel ( carcinoma colon).

• Endoscopic intervention: Bile duct decompression. Example : ERCP in cholangitis

Common Causes of

Acute Abdomen

Acute appendicitis

• Most common general surgical emergency

• Derived from the midgut

• Obstruction of the lumen (fecalith, lymphoid hyperplasia,

vegetable matter or seeds, parasites) is the major cause of

acute appendicitis.

• Obstruction contributes to bacterial overgrowth,

Acute appendicitis

• Continued secretion of mucus leads to intraluminal distention.

• Distention produces the visceral pain sensation as

periumbilical pain.

• Promote a localized inflammatory process

• May progress to gangrene and perforation.

• Inflammation of the adjacent peritoneum- localized pain in

the right lower quadrant.

• Perforation usually occurs after 48 hours from the onset of

symptoms

Acute appendicitis- symptoms

• Typical periumbilical pain (activation of visceral afferent neurons)

followed by anorexia and nausea.

• Pain localizes to the right lower quadrant (inflammatory process

progresses to involve the adjacent parietal peritoneum)

• Migratory pain is the most reliable symptom.

Acute appendicitis- signs

• Ill looking patient, low grade fever

• Coughing (Dunphy's sign), may cause increased pain

• Tenderness at McBurney’s point, involuntary guarding

• Site of tenderness may vary depending on the position of the

appendix.

• Pain in the right lower quadrant during palpation of the left lower

quadrant (Rovsing's sign)

• Perforated appendicitis: more severe and diffuse abdominal pain,

tenderness and abdominal wall rigidity

Acute appendicitis- investigations• Elevated WBC and neutrophil • Normal WBC in 10%

• Very high WBC (>20,000/ml)- complicated appendicitis

• Urine analysis- exclude urinary system disease

• Abdominal x-ray- generally not indicated, ? ureteric calculi, small bowel obstruction, perforated ulcer

• Ultrasonography: Appendix of 7 mm or more in anteroposterior diameter, thick-walled, noncompressible luminal structure in cross section (target lesion), the presence of an appendicolith

• CT abdomen: appendix > 7mm in diameter, wall thickening, periappendiceal edema or fluid

Surgical treatment (Acute appendicitis)

• Uncomplicated:

Appendectomy - Laparoscopic vs open surgery

• Complicated:

Localized perforation (abscess): percutaneous

drainage under CT or ultrasound guidance

Free perforation (peritonitis): laparotomy vs

laparoscopic appendectomy

Perforated peptic ulcer

• 5% of peptic ulcers penetrate through the

duodenal wall into the peritoneal cavity

• Produce chemical peritonitis

Clinical features of perforated peptic ulcer

• Sudden onset epigastric pain

• Fever and tachycardia

• Abdominal tenderness, rigidity, rebound tenderness

• Absent bowel sound

• Free air underneath the diaphragm on an upright

chest radiograph.

Perforated peptic ulcer- treatment

• Fluid resuscitation

• Early surgery to close the perforation by laparoscopy or open surgery

Small bowel obstruction

• Post-operative adhesion- most common

• Hernia, tumour, Crohn’s disease- other causes

• Early- the intestinal contraction increases to propel contents past the obstructing point (colicky pain)

• Later- the intestine becomes fatigued and dilates, contractions becoming less intense.

• Bowel dilates, water and electrolytes accumulate in lumen and in the bowel wall.

• Massive third-space fluid loss: dehydration and hypovolemia.

• Intraluminal pressure increases in the bowel, a decrease in mucosal blood flow occurs.

Clinical features

• Colicky abdominal pain, nausea, vomiting, abdominal

distention, and a failure to pass flatus and feces-obstipation

• Examination:

Distended abdomen

Surgical scars/ hernia

Hyperactive bowel sounds

Mild abdominal tenderness

Investigations

• Tests for fluid & electrolytes abnormality

• Leukocytosis may be found in patients with strangulation

• Plain x-ray abdomen: dilated bowel loops (supine) & multiple air-fluid levels (upright)

• Patient in whom the diagnosis is not readily apparent- CT abdomen

Treatment

• Isotonic saline solution such as lactated Ringer's

• Antibiotics-prophylactically

• Nasogastric suction

• Partial intestinal obstruction may be treated

conservatively with resuscitation and tube decompression

• Operative Management:

• Adhesive obstruction- laparotomy & release of adhesions.

• Hernia- operative reduction and repair

Mesenteric Ischemia

• Arterial: embolism, thrombosis

• Venous: thrombosis

• Superior mesenteric vessel distribution

• Intestinal mucosal sloughing within 3 hours

• Full-thickness intestinal infarction by 6 hours

Symptoms & signs

• Abdominal pain- sudden onset

• Severity- out of proportion to the degree of tenderness

• The pain is colicky, most severe in the mid-abdomen.

• Associated symptoms- nausea, vomiting, and diarrhea

• Physical findings- absent early in the course.

• Later- abdominal distention, tenderness, guarding and

passage of bloody stools.

Investigations

• Leukocytosis, • Acidosis, and • Elevated amylase and creatine kinase- late

• CT scanning: Acute arterial mesenteric ischemia-64 to 82%. Acute mesenteric venous thrombosis- 90%

Mesenteric ischemia- treatment

• Fluid resuscitation

• Laparotomy

• Test for viability of bowel

• Resection of infarcted segment

• Anticoagulation for SMV thrombosis

Conclusion• A challenging part of a surgeon's practice.

• Careful history and physical examination remain the most

important part of the evaluation.

• Laboratory investigations and imaging techniques have

improved the diagnostic accuracy

• Surgeon often make the decision to perform surgery with a

good deal of uncertainty

• Morbidity and mortality associated with a delay in the

treatment demand an expeditious approach

Thank you!