[ Pobierz całość w formacie PDF ]

risk of rebleeding after an episode of bleeding is 25%.
Right-sided colonic diverticula occur less frequently
than left-sided or sigmoid diverticula but are responsible
for a disproportionate incidence of diverticular bleeding.
C.Operative management of diverticular bleeding is
indicated when bleeding continues and is not amenable
to angiographic or endoscopic therapy. It also should
be considered in patients with recurrent bleeding in the
same colonic segment. The operation usually consists
of a segmental bowel resection (usually a right
colectomy or sigmoid colectomy) followed by a primary
anastomosis.
VII.Arteriovenous malformations
A.AVMs or angiodysplasias are vascular lesions that
occur primarily in the distal ileum, cecum, and ascend­
ing colon of elderly patients. The arteriographic criteria
for identification of an AVM include a cluster of small
arteries, visualization of a vascular tuft, and early and
prolonged filling of the draining vein.
B.The typical pattern of bleeding of an AVM is recurrent
and episodic, with most individual bleeding episodes
being self-limited. Anemia is frequent, and continued
massive bleeding is distinctly uncommon. After
nondiagnostic colonoscopy, enteroscopy should be
considered.
C.Endoscopic therapy for AVMs may include heater
probe, laser, bipolar electrocoagulation, or argon beam
coagulation. Operative management is usually reserved
for patients with continued bleeding, anemia, repetitive
transfusion requirements, and failure of endoscopic
management. Surgical management consists of seg­
mental bowel resection with primary anastomosis.
VIII.Inflammatory bowel disease
A.Ulcerative colitis and, less frequently, Crohn's colitis
or enteritis may present with major or massive lower
gastrointestinal bleeding. Infectious colitis can also
manifest with bleeding, although it is rarely massive.
B.When the bleeding is minor to moderate, therapy
directed at the inflammatory condition is appropriate.
When the bleeding is major and causes hemodynamic
instability, surgical intervention is usually required.
When operative intervention is indicated, the patient is
explored through a midline laparotomy, and a total
abdominal colectomy with end ileostomy and
oversewing of the distal rectal stump is the preferred
procedure.
IX.Tumors of the colon and rectum
A.Colon and rectal tumors account for 5% to 10% of all
hospitalizations for lower gastrointestinal bleeding.
Visible bleeding from a benign colonic or rectal polyp is
distinctly unusual. Major or massive hemorrhage rarely
is caused by a colorectal neoplasm; however, chronic
bleeding is common. When the neoplasm is in the right
colon, bleeding is often occult and manifests as weak­
ness or anemia.
B.More distal neoplasms are often initially confused
with hemorrhoidal bleeding. For this reason, the treat­
ment of hemorrhoids should always be preceded by
flexible sigmoidoscopy in patients older than age 40 or
50 years. In younger patients, treatment of hemorrhoids
without further investigation may be appropriate if there
are no risk factors for neoplasm, there is a consistent
clinical history, and there is anoscopic evidence of
recent bleeding from enlarged internal hemorrhoids.
X.Anorectal disease
A.When bleeding occurs only with bowel movements
and is visible on the toilet tissue or the surface of the
stool, it is designated outlet bleeding. Outlet bleeding is
most often associated with internal hemorrhoids or anal
fissures.
B.Anal fissures are most commonly seen in young
patients and are associated with severe pain during and
after defecation. Other benign anorectal bleeding
sources are proctitis secondary to inflammatory bowel
disease, infection, or radiation injury. Additionally,
stercoral ulcers can develop in patients with chronic
constipation.
C.Surgery for anorectal problems is typically under­
taken only after failure of conservative medical therapy
with high-fiber diets, stool softeners, and/or
hemorrhoidectomy.
XI.Ischemic colitis
A.Ischemic colitis is seen in elderly patients with known
vascular disease. The abdomen pain may be postpran­
dial and associated with bloody diarrhea or rectal
bleeding. Severe blood loss is unusual but can occur.
B.Abdominal films may reveal "thumb-printing" caused
by submucosal edema. Colonoscopy reveals a well­
demarcated area of hyperemia, edema and mucosal
ulcerations. The splenic flexure and descending colon
are the most common sites. Most episodes resolve
spontaneously, however, vascular bypass or resection
may be required.
Acute Pancreatitis
The incidence of acute pancreatitis ranges from 54 to 238
episodes per 1 million per year. Patients with mild pancre­
atitis respond well to conservative therapy, but those with
severe pancreatitis may have a progressively downhill
course to respiratory failure, sepsis, and death (less than
10%).
I.Etiology
A.Alcohol-induced pancreatitis. Consumption of
large quantities of alcohol may cause acute pancreati­
tis.
B.Cholelithiasis. Common bile duct or pancreatic duct
obstruction by a stone may cause acute pancreatitis.
(90% of all cases of pancreatitis occur secondary to
alcohol consumption or cholelithiasis).
C.Idiopathic pancreatitis. The cause of pancreatitis
cannot be determined in 10 percent of patients.
D.Hypertriglyceridemia. Elevation of serum triglycer­
ides (>l,000mg/dL) has been linked with acute pancre­
atitis.
E.Pancreatic duct disruption. In younger patients, a
malformation of the pancreatic ducts (eg, pancreatic
divisum) with subsequent obstruction is often the cause
of pancreatitis. In older patients without an apparent
underlying etiology, cancerous lesions of the ampulla of
Vater, pancreas or duodenum must be ruled out as
possible causes of obstructive pancreatitis.
F.Iatrogenic pancreatitis. Radiocontrast studies of the
hepatobiliary system (eg, cholangiogram, ERCP) can
cause acute pancreatitis in 2-3% of patients undergoing
studies.
G.Trauma. Blunt or penetrating trauma of any kind to
the peri-pancreatic or peri-hepatic regions may induce
acute pancreatitis. Extensive surgical manipulation can
also induce pancreatitis during laparotomy.
Causes of Acute Pancreatitis
Alcoholism Infections
Cholelithiasis Microlithiasis
Drugs Pancreas divisum
Hypertriglyceridemia Trauma
Idiopathic causes
Medications Associated with Acute Pancreatitis
Definitive Association: Probable Association:
Azathioprine (Imuran) Acetaminophen
Sulfonamides Nitrofurantoin
Thiazide diuretics Methyldopa
Furosemide (Lasix) Erythromycin
Estrogens Salicylates
Tetracyclines Metronidazole
Valproic acid (Depakote) NSAIDS
Pentamidine ACE-inhibitors
Didanosine (Videx)
II.Pathophysiology. Acute pancreatitis results when an
initiating event causes the extrusion of zymogen granules,
from pancreatic acinar cells, into the interstitium of the
pancreas. Zymogen particles cause the activation of
trypsinogen into trypsin. Trypsin causes auto-digestion of
pancreatic tissues.
III.Clinical presentation
A.Signs and symptoms. Pancreatitis usually presents
with mid-epigastric pain that radiates to the back,
associated with nausea and vomiting. The pain is
sudden in onset, progressively increases in intensity,
and becomes constant. The severity of pain often
causes the patient to move continuously in search of a
more comfortable position.
B.Physical examination
1.Patients with acute pancreatitis often appear very
ill. Findings that suggest severe pancreatitis include
hypotension and tachypnea with decreased basilar
breath sounds. Flank ecchymoses (Grey Tuner's
Sign) or periumbilical ecchymoses (Cullen's sign)
may be indicative of hemorrhagic pancreatitis.
2.Abdominal distension and tenderness in the
epigastrium are common. Fever and tachycardia
are often present. Guarding, rebound tenderness,
and hypoactive or absent bowel sounds indicate
peritoneal irritation. Deep palpation of abdominal
organs should be avoided in the setting of sus­
pected pancreatitis.
IV.Laboratory testing
A.Leukocytosis. An elevated WBC with a left shift and
elevated hematocrit (indicating hemoconcentration) [ Pobierz całość w formacie PDF ]