Non-Radio Notes: Gastroenterology

Oesophagus

Upper esophageal sphincter:

-          high pressure 50-100mmHg

-          consists of striated muscles of cricopharyngeal muscle

-          normally in relaxed state, stimulated by vagus nerve

Lower esophageal sphincter:

-          resting pressure 10-30mmHg

-          circular smooth muscle, reinforced by surrounding striated muscle of the crural diaphragm

Swallowing

Peristaltic wave brings down food particles at 3-5cm/sec

Reaches the lower esophageal sphincter after about 6sec

Wihin 2sec after the initiation of swallowing, LES relaxes until the food bolus reaches into the stomach

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Hepatomegaly Causes

Carcinoma (primary / secondary)
Cirrhosis (EtOH, PBC)
Congestive heart failure
Budd-Chiari syndrome
Hepatitis A/B/C, EBV, CMV, Toxoplasma, Leptospira
Infiltration (Fat - EtOH, Amyloidosis, Hemochromatosis, Sarcoidosis, Lymphoproliferative disease)
"Apparent hepatomegaly"

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Cirrhosis causes:
EtOH
Hep.B/C
Primary biliary cirrhosis (PBC)
Haemochromatosis
Wilson's disease
Alpha1 antitrypsin deficiency
Drugs: Methyldopa, Amiodarone
Autoimmune hepatitis
Budd-Chiari syndrome
Cystic fibrosis
NASH

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Complication of Cirrhosis:
- Portal HT
- Variceal haemorrhage
- Ascites, Spontaneous Bacterial Peritonitis (SBP)
- Hepatorenal syndrome
- HCC
- Coagulopathy
- Encephalopathy

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Causes of Jaundice
Obstructive:
- Gallstones
- Pancreatic head CA
- Nodes in porta hepatis
- CholangioCA
- Benign bile duct strictures
- Sclerosing cholangitis
- Post-procedure

Haemolysis:
- Resolving haematoma
- Incompatible blood transfusion
- Drugs

Drugs:
- Paracetamol
- Anti-TB meds
- Na Valproate
- Herbal meds

Hepatitis:
- HepA,B,C
- CMV
- EBV
- Toxoplasma
- Leptospira
- Schistosoma
- Alcoholic hepatitis
- Autoimmune hepatitis

Cirrhosis
Hepatic metastasis
Hepatic abscess
Primary sclerosing cholangitis (PSC)
Primary biliary cirrhosis (PBC)

Gilbert's syndrome
Wilson's disease
Haemochromatosis
Alpha1 antritrypsin deficiency
Budd-Chiari syndrome
Septicaemia

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Courvoisier's law:

Findings: Non-tender palpable gallbladder AND jaundice
Unlikely to be due to chronic gall disease, usually due to CA distal to CBD eg Pancreatic head CA, Periampullary tumor

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Laparoscopic Cholecystectomy:

Advantage:
- Less post-op pain
- Shorter hospital stay
- Better cosmetic effect
- Early mobility
- Earlier return to work

Disadvantage:
- Longer operation
- Risk of unrecognised visceral injuries
- Risk of conversion to open surgery
- Increased risk of bile duct injury

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Contraindiction to laparoscopic cholecystectomy:

- Medically high risk for open cholecystectomy
- Peritonitis
- Advanced cholecystitis
- Cirrhosis
- Cholangitis
- Pancreatitis
- Coagulopathy
- Previous upper abdominal surgery
- Pregnancy
- Patient's choice

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Complication of cholecystectomy

- Bleeding
- Infection
- Bile leak => leading to Generalised peritonitis, Sepsis
- CBD injury (leading to fibrotic stricture) / ligation
- Bowel injury
- Blood vessel injury
- Pneumoperitoneum (usually well tolerated)
- Insufflation of CO2:
   => CVS: Tachycardia, Increased CVP, HT, decreased cardiac output
   => Respi: Increased PCO2, Decreased pH
- Retained stone
   => Pain, Jaundice
   => Further procedure
- Ascending cholangitis due to anastomosis between bile duct and bowel
- Subphrenic abscess

Specific for Laparoscopic cholecystectomy:

- Gallbladder perforation
- Bleeding & bile leakage from liver bed
- Post-op shoulder tip pain (referred pain)
- Conversion to open surgery

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Complications of gallstones:

- Biliary colic
- Cholecystitis (acute or chronic)
- Empyema
- Mucocele
- Cancer
- Obstructive jaundice
- Pancreatitis
- Cholangitis
- Gallstones ileus
- Malabsorption

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Treatment for Common Bile Duct (CBD) stones:
(1) Laparoscopic cholecystectomy & Post-op Endoscopic Retrograde Cholecystopancreaticogram (ERCP)
(2) Laparoscopic cholecystectomy & Laparoscopic choledochoscopy via cystic duct / Laporoscopic choledochotomy
(3) Open CBD exploration

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Bacteria commonly cultured from bile:

- E.coli
- Klebsiella
- Enterococci
- Pseudomonas
- Bacteroides fragilis

Treatment: 2nd generation Cephalosporin, Expanded spectrum penicillins

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Risk factors for cholelithiasis

- Female
- Forty
- Fertile (Multiparity)
- Fat
- Rapid Wt loss
- Pregnancy
- Total parenteral nutrition (TPN) dependent patient

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Types of Gallstones:

(1) Cholesterol stones
     - Cause: Increased cholesterol concentration or Decreased bile salt concentration
(2) Black pigment stones
     - Seen in Cirrhosis / Hemolytic anaemia
(3) Brown pigment stones
     - Cause: Primary bile duct stones associated with infections

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Hepatobiliary anatomy: (surgical)

Triangle of Calot
- Area between the liver, cystic duct & common hepatic duct
- Cystic artery is usually present here

Duct of Luschka
- Drain directly from liver into the gallbladder
- Sometimes responsible for post-cholecystectomy bile leaks

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Complications of acute pancreatitis:

- Mortality
- Pancreatic necrosis
- Pancreatic infection
- Pancreatic pseudocyst
- Pancreatic abscess
- Hypocalcaemia
- Chronic pancreatitis- DM (late)
- Malabsorption (late)
- Multi-organ dysfunction syndrome (MODS)
- Adult respiratory distress syndrome (ARDS)
- Pleural effusion
- Acute tubular necrosis (ATN)

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Causes of mass in iliac fossa:

(Either side)
- Crohn's disease
- Iliac lymph nodes
- Iliac artery aneurysm
- Psoas abscess
- Chondroma of ilium
- Tumor in an undescended testis
- Actinomycosis
- Ruptured epigastric artery

(Right)
- Appendicitis
- Carcinoma of caecum
- Tuberculosis (intestinal)

(Left)
- Diverticulitis
- Carcinoma of sigmoid colon

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Differential diagnosis for RLQ pain

- Meckel's diverticulitis
- Diverticulitis
- Appendicitis
- Crohn's disease
- Cholecystitis
- Carcinoid tumor
- Pelvic inflammatory disease (PID)
- Ectopic pregnancy
- Tubo-ovarian abscess

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Complication of diverticular disease

- Spreading pericolic inflammation
- Pericolic abscess
- Intraperitoneal perforation => peritonitis
- Acute rectal hemorrhage
- Fistula formation
- Bowel adhesions
- Fibrous strictions => obstruction

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Causes of Lower GI haemorrhage:

- Diverticular disease
- Ischaemic colitis
- Angiodysplasia
- Inflammatory bowel disease (IBD)
- Carcinoma
- Infectious colitis
- Post-polypectomy
- Haemorrhoids
- Anal fissure
- Meckel's diverticulum

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Causes of Upper GI haemorrhage:

- Gastritis
- Peptic ulcer disease (PUD)
- Gastric erosion (due to Alcohol, Drug, Stress)
- Oesophagitis
- Oesophageal varices
- Mallory-Weiss tear

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Diarrhoea causes:

- Infection: rotavirus, astrovirus, campylobacter, salmonella, shigella, E.coli, clostridium, giardia
- Infective colitis: Campylobacter, Haemorrhagic E.coli, Entamoeba, Salmonella, Shigella
- IBD
- Malabsorption
- Medication: laxative, antibiotic
- Overflow diarrhoea
- Endocrine: Thyrotoxicosis, DM
- Ischaemic colitis
- Diverticulitis
- Malignancy

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Causes of fat malabsorption:
- Chronic pancreatitis
- Cystic fibrosis
- Pancreatic CA
- Post-gastrectomy syndrome
- Biliary tract obstruction
- Terminal ileal resection / disease
- Cholestatic liver disease
- Gastroenteritis
- Lymphatic disease - lymphoma
- Small bowel bacterial overgrowth
- Zollinger-Ellison syndrome

Factors in fat absorption:
- Pancreatic lipase & colipase
- pH 6-8
- Bile salt to solubilise
- Healthy intestinal cells
- Healthy intestinal lymphatics

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Causes of Paralytic ileus:
- Abdominal surgery
- Peritonitis
- Generalised sepsis
- Retroperitoneal haemorrhage
- Electrolyte imbalance (Hypokalaemia)
- Spinal / Pelvic fractures
- Drugs: Phenothiazines, Narcotics

Rx:
- Nasogastric tube suction
- IV fluid replacement

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Causes of Small bowel obstruction:
1. Intraluminal:
- Gallstone, Bezoars, Foreign body
2. Intramural:
- Inflammatory Bowel Disease (IBD)
- Fibrous structure secondary to Trauma / Ischaemia / Radiation
- Intussusception
3. Extrinsic:
- Adhesions
- Malignancy
- Hernia
- Volvulus

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Causes of Large Bowel Obstruction:
- Carcinoma (52% of cases)
- Volvulus
- Diverticular disease
- Stricture
- Hernia
- Intussusception
- Benign tumor
- Faecal impaction

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Complication of large bowel surgery:

Early:
- Wound infection: Abscess, cellulitis
- Intraperitoneal abscess: at site of surgery, subphrenic, pelvic
- Anastomotic leak / breakdown
- Systemic sepsis & multi-organ dysfunction syndrome
- Inadvertent damage to other organs
- Stoma problems: sloughing, retraction

Late:
- Diarrhoea: short bowel
- SBO: Adhesion, tangled to ileostomy/colostomy, radiotherapy
- Division of pelvic parasympathetic nerves: Impotence

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Complication of Ileostomy & Colostomy:

Early:
- Mucosal sloughing or necrosis of the terminal bowel (due to ischaemia)
- Obstruction of stoma due to oedema or faecal impaction
- Skin erosion due to leakage between the skin and stoma bag

Late:
- Prolapse of bowel
- Parastomal hernia
- Parastomal fistula
- Retraction of 'spout' ileostomy
- Stenosis of stomal orifice
- Perforation o=after colonic irrigation
- Psychological and psychosexual dysfunction

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Cirrhosis

Regenerative nodules

–        formed by hyperplastic hepatocytes

–        surrounded by fibrous tissue

–        lack of central veins

Portal hypertension due to:

-          Hepatic venules compressed by the regenerative nodules

-          Loss of the normal portal vein and hepatic artery branches

-          Sinusoids fibrosis

-          Sinusoids compressed by the hyperplastic hepatocytes

Portal hypertension => portal venous congestion => splenomegaly => sequestration of platelets => thrombocytopaenia

Spontaneous bacterial peritonitis:

Enteric bacteria, eg E.coli

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Hepatorenal syndrome

In advanced cirrhosis, poor prognosis

Salt / Water retaining

Oliguria and renal failure

Urine contains no sodium

Renal angiography: complete shutdown of blood flow to the renal cortex, diversion of blood to juxtamedullary nephrons (more efficient in salt absorption in this area)

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Causes of Hepatosplenomegaly:
- Myeloproliferative disease
- Lymphoproliferative disease
- Portal Hypertension
- Megaloblastic anaemia
- Infection (Hep.B, C, EBV, CMV, Leptospirosis, Toxoplasmosis, TB)
- Amyloidosis

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Causes of Portal Hypertension:
- Pre: Portal / Splenic vein thrombosis
- Hep: Cirrhosis, Schistosomiasis
- Post: Budd-Chiari syndrome, Congestive heart failure, Constrictive pericarditis

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Ascites:

Transudative: Cirrhosis, CCF, Constrictive pericarditis, nephritic syndrome

Exudative: peritonitis (infection), neoplasm, pancreatitis, hypothyroidism

Chylous: lymphoma (blocking of the lymphatic drainage system)

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Reye’s syndrome

Manifests after acute viral infection

Abrupt and profound impairment of hepatic mitochondrial function => liver failure

a/w childhood use of Aspirin.

Clinical: abrupt onset of N&V, confusion, somnolence, fulminant hepatic failure, cerebral oedema

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Irritable Bowel Syndrome (IBS)
Rome II criteria:
- Absence of structural / metabolic abnormality to explain the symptoms
- A functional bowel disorder at least 3mth in the past 12mth of abdominal discomfort / pain
In addition, 2 or all of following:
- Relief with defecation
- Onset associated with change in stool frequency
- Onset associated with change in form / appearance of stool