ВУЗ: Не указан
Категория: Не указан
Дисциплина: Не указана
Добавлен: 09.04.2024
Просмотров: 202
Скачиваний: 0
2.C. difficile, an organism that is normally suppressed by colonic bacteria, emerges as a pathogen and causes mild diarrhea to severe life-threatening colitis.
CDiagnosis
1.A history of diarrhea after treatment with an antibiotic is suspicious.
2.Proctoscopy or colonoscopy may reveal pseudomembranes, which are virtually diagnostic if present.
3.A stool sample should be sent for C. difficile toxin titer.
DTreatment
1.The causative antibiotic should be stopped.
2.Metronidazole is the treatment of choice and may be given orally or intravenously. Oral vancomycin is also effective but is reserved for refractory or persistent cases. The daily cost for metronidazole treatment is less than $1 but is $200 for vancomycin.
3.Constipating agents (e.g., loperamide) should be avoided.
4.Cholestyramine may be administered to bind the toxin, but it may also inhibit the therapeutic antibiotic and therefore is seldom indicated.
5.Recurrence is common (25%) and requires retreatment. Metronidazole is again the agent of choice if the patient initially responded to it.
6.Abdominal colectomy with ileostomy has been required for rare cases of fulminant pseudomembranous colitis.
IX Ischemic Colitis
AEtiology
1.Points of communication between collateral arteries are theoretically at increased risk for ischemia. These points include the splenic flexure and the midsigmoid colon. However, any segment of the colon may be involved (rectal involvement is very rare).
2.Predisposing factors include:
a.Surgery, especially ligation of the inferior mesenteric artery during aortic surgery
b.Atherosclerosis, vasculitis, collagen vascular diseases
P.240
c.Polycythemia vera
d.Congestive heart failure
e.Digitalis, oral contraceptives, antihypertensive medications, and vasopressors
f.Low-flow states (myocardial infarction, sepsis)
3.Three phases of ischemic colitis may be recognized.
a.Transient ischemia (mucosal involvement)
1.Symptoms are usually mild abdominal pain and passage of maroon-colored stool.
2.Barium enema may reveal “thumbprinting” (mucosal hemorrhage).
3.Colonoscopy reveals dusky, hemorrhagic mucosa.
b.Partial-thickness ischemia with late stricture. Symptoms are more severe and include abdominal tenderness,
fever, and leukocytosis.
c.Gangrenous ischemia. Symptoms of an acute abdomen are present with abdominal pain, peritonitis, and signs of sepsis.
BTreatment
1.Transient ischemia is treated symptomatically.
a.Hospitalization and observation are indicated until the severity of disease is determined.
b.Any causative factors should be corrected, if possible.
2.Partial-thickness ischemia
a.Close observation, intravenous fluids, and broad-spectrum antibiotics are usually required.
b.If a stricture develops and is asymptomatic, no treatment is required. Symptomatic strictures require resection.
3.Gangrenous ischemia
a.Emergency resection of nonviable bowel is required.
b.Anastomosis is not usually safe in such circumstances, thus a colostomy is required.
X Volvulus
AOverview
1.Volvulus is a twist or torsion of an organ on a pedicle.
2.Symptoms are produced by occluding the bowel lumen (obstruction) or occluding the blood supply (ischemia).
3.The incidence is low in the United States.
a.Diverticulitis and cancer are more common causes of colon obstruction.
b.Volvulus is the most common cause of colon obstruction in Africa.
B
Sigmoid volvulus accounts for more than 80% of cases of colonic volvulus. Patients with this condition are often from nursing homes or mental institutions. Sigmoid volvulus is most common in men, and it occurs more often in blacks. The average age of a patient with this condition is 60 years.
1.Etiology. Several predisposing conditions are required:
a.A long, freely movable sigmoid colon
b.An ample, freely mobile sigmoid mesentery
c.A point of fixation about which the colon can twist (a loop of bowel with the limbs lying close together)
2.Pathogenesis. The sigmoid colon usually twists counterclockwise around the axis of the mesentery. This torsion about the mesentery is accompanied by an axial torsion of the bowel wall. The combined torsions of the mesentery and bowel cause obstruction of the colon lumen.
3.Diagnosis
a.History usually indicates increasing abdominal distention, discomfort, and obstipation.
b.Physical examination reveals abdominal distention and tympany.
c.Abdominal radiographs usually show a massively distended loop of bowel, with both ends in the pelvis and the
1.Etiology
a.Mechanical defects of the anal sphincter
1.Episiotomy injuries
2.Previous anal fistulotomies
3.Anorectal trauma (impalement injuries)
b.Neurogenic causes
1.Pudendal nerve injury due to prolonged labor
2.Pudendal nerve injury due to perineal descent
3.Systemic neurologic disease (multiple sclerosis)
c.Systemic disease
1.Scleroderma
2.Diabetes
P.242
d.Causes unrelated to the anal sphincter
1.Severe diarrhea
2.Severe proctitis with decreased rectal capacity
3.Fecal impaction with overflow incontinence
4.Large rectal tumors
2.Evaluation. History and anorectal examination often suffice to establish the diagnosis.
a.Anterior sphincter defect and patulous anus after midline episiotomy may be confirmed by a thorough examination and, if necessary, endorectal ultrasound of the anal musculature.
b.Physiologic evaluation may be helpful if the cause of incontinence is not obvious.
1.Anal manometry can document the resting pressure, squeeze pressure, sphincter length, and minimal sensory volume of the rectum.
2.Pudendal nerve terminal motor latency can be tested to determine if the cause of incontinence is neurogenic in nature.
3.Surgical treatment
a.Sphincter defects, such as those caused by obstetric injuries, may be corrected by anal sphincter repair with excellent results.
b.More extensive loss of the anal sphincter may be treated by gracilis muscle transposition, which mobilizes the gracilis muscle to encircle the anus or by implantation of an artificial anal sphincter device.
c.Colostomy may be required for severe sphincter injuries or for neurogenic or systemic causes of incontinence.
B Obstructed defecation (pelvic floor–outlet obstruction)
1.Anal stenosis may be caused by circumferential hemorrhoidectomy (Whitehead deformity), trauma, or radiation. It may result in the inability to evacuate formed stool, with resultant abdominal bloating, intestinal dilatation, and discomfort. Treatment generally entails repeated dilation or advancing full-thickness pedicles of skin to the anal canal.
2.Nonrelaxation of the puborectalis is a functional disorder characterized by the inability to relax the puborectalis muscle at the time of defecation.
a.Symptoms include the need for digital maneuvers to eliminate stool, pelvic pain, a sense of incomplete
