CASE 4344 Published on 09.04.2006

Fecal impaction

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Ahmed Haroun Mohamed

Patient

66 years, female

Clinical History
66 Y.O. female with abdominal pain and vomiting for 15 days. Known case CRF. Palpable mass on PR.
Imaging Findings
66 Y.O. female presented with abdominal pain and vomiting for 15 days. There is palpable mass on PR. Plain x-ray abdomen showed dilated colon filled with soft tissue density containing multiple small, irregular lucent areas reflecting pockets of gases within fecal masses. Sigmoidoscopy showed extrinsic indentation on rectum with no rectal masses. CT scan revealed dilated colon filled with fecal matter. Sigmoid colon was marked dilated, tortuous and compresses rectum (the clinically palpable mass on PR). Small bowel were slightly compressed by the colon. There were no free intraperitoneal air, fluid or rectal masses. High impaction interfered with manual removal. Disimpaction using fiberoptic endoscopy failed. Laparotomy was done to relieve obstruction. Multiple perforations were found for which resection and colostomy was performed.
Discussion
Incomplete evacuation of feces, leads to formation of a large, firm, immovable mass of stool in the rectum (70%), sigmoid flexure (20%) or proximal colon (10%). The rectosigmoid colon dilates to accommodate the mass, which, in turn, is not pliable enough to pass through the disproportionately small anal canal by the patient's weak defecation effort. Impacted stool may exist as a single mass (stercolith) or as a composite of small, rounded fecal particles (scybalum). The most common SYMPTOMS are: intense urge to have a bowel movement, inability to have a bowel movement, rectal pain, abdominal crampingand nausea. CAUSES of fecal impaction include: 1-inadequate consumption of fiber & fluids. 2- Medications (pain relieving, antidepressant, antacids containing aluminum, excessive laxative use). 3- Bed rest. 4- Painful rectal conditions inhibiting voluntary defecation, (anal fissure, hemorrhoids).5- Neoplastic or inflammatory obstructing lesions (rectal bezoars). 6- Kidney and cardiovascular disease. 7- Hypothyroidism, Hypokalemia, Hypercalcemia. LABORATORY FINDINGS include: 1• Leukocytosis to 15,000 WBC/cu.mm 2• Hyponatremia 3• Hypokalemia 4• Stool may be positive for occult blood 5• Anemia, due to blood loss. COMPLICATION: necrosis (tissue death) or rectal tissue injury, Ulceration of the rectal tissue IMAGING: • Plain abdominal radiography identifies masses of stool or signs of obstruction if digital exam unrevealing. • Barium enema can differentiate feces (mobile, on dependent surface, inconstant location, irregular configuration, impregnated with barium) from tumor. Adherent stool can be difficult to differentiate (repeat fluoroscopy-guided enema and proper cleansing of bowel can reduce confusion). • CT show level of obstruction, exclude other organic causes (e.g. neoplasm) or complication (e.g. perforation).
Differential Diagnosis List
Intestinal obstruction due to fecal impaction in sigmoid colon.
Final Diagnosis
Intestinal obstruction due to fecal impaction in sigmoid colon.
Case information
URL: https://www.eurorad.org/case/4344
DOI: 10.1594/EURORAD/CASE.4344
ISSN: 1563-4086