Presentation1.pptx, radiological imaging of large bowel diseases
Dr/ ABD ALLAH NAZEER. MD.
Radiological imaging of large bowel diseases.
Congenital Anomalies of the large bowel loops.
Congenital abnormalities involving the large bowel lops are
detected in neonates only when they are the direct cause of
obstruction. Such abnormalities must be rectified surgically if the
patient is to survive. Clinical signs and symptoms including
abdominal distention, vomiting, and obstipation prompt the
clinician to consult the radiologist, who must determine the
presence, location, and cause of an obstruction.
The diagnosis of obstruction is based on some interruption in this
dispersion of air. Delayed passage of gas through the neonatal gut
may occur as a result of traumatic delivery, septicemia,
hypoglycemia, or brain damage. Absence of gas in the bowel may be
noted in neonates with severe respiratory distress who are
undergoing mechanical ventilation and in cases of continuous
Radiographyis the most valuable means of determining whether
obstruction is present. This modality is often diagnostic; even if it is not,
however, it may help determine the next most useful diagnostic procedure.
Congenital anomalies causing incomplete obstruction (eg, stenoses, webs,
duplications, malrotations, peritoneal bands, aganglionosis) may not
manifest until later in life, and other types of examinations (eg, barium
enema studies, ultrasonography [US], computed tomography [CT],
magnetic resonance [MR] imaging) are generally needed for diagnosis.
In this article, we discuss the importance of pediatric radiation protection
and various means of ensuring adequate protection. We also discuss and
illustrate a variety of congenital anomalies affecting the small bowel,
colon, and rectum; evaluate the efficacy of various imaging modalities in
the diagnosis and management of these conditions; and discuss the
embryologic and pathologic basis of radiologic findings in appropriate
cases as well as differential diagnoses and diagnostic pitfalls.
Neonatal intestinal obstructions may be classified as high or low. Obstructions
occurring proximal to the mid ileum are called high or upper intestinal
obstructions, whereas those involving the distal ileum or colon are called low
intestinal obstructions. The distinction is critical because children with high
obstructions usually need little or no further radiologic evaluation after
radiography, and the specific diagnosis is made at surgery. Neonates with low
obstructions require a contrast enema examination, which frequently provides a
specific diagnosis and may be therapeutic.
Low intestinal obstruction is defined as an obstruction that occurs in the distal
ileum or colon. Signs include large bowel obstruction with vomiting, abdominal
distention, and failure to pass meconium. In neonates, the differential diagnosis
includes ileal and colonic atresia, meconium ileus or peritonitis, Hirschsprung
disease, and functional immaturity of the colon. Anorectal malformations are
also an important cause of low intestinal obstruction but are almost always
evident at physical examination. The diagnosis of low obstruction is usually
apparent at abdominal radiography because of the presence of many dilated
intestinal loops, but the differentiation between ileal and colonic obstruction is
difficult if not impossible. This distinction can readily be made with a barium
enema study, which helps determine the presence of microcolon, indicates the
position of the cecum with regard to possible malrotation, and shows the level of
the obstruction in colonic atresia.
Colonic atresia. (a) Radiograph shows distended loops of bowel similar to
those seen in low small bowel obstruction. (b) Image from a barium enema
study demonstrates microcolon with complete obstruction to the retrograde
flow of barium in the transverse portion of the colon.
Meconium ileus. (a) Abdominal scout radiograph shows marked distention of the
small bowel and a “soap bubble” appearance in the right side of the abdomen
(arrows), a finding suggestive of mottled air and feces. (b) US image shows
dilated, fluid-filled intestinal loops containing echogenic material (calcified
meconium) (arrows). Associated ileal atresia was seen at surgery.
Hirschsprung disease in a 6-month-old infant with a history of chronic constipation. (a, b)
Frontal (a) and lateral (b) images from a barium enema study show the proximal sigmoid
colon and descending colon as greatly dilated compared with the distal colon and rectum.
Total colonic aganglionosis. (a, b) Frontal (a) and lateral (b) images from a
barium enema study show irregularity in the caliber of the colon with fewer
redundant flexures than normal.
Meconium plug syndrome. (a) Image from a barium enema study shows a normal-sized
rectum and colon with inspissated meconium filling defects (arrows). (b) Gross specimen
shows the colon (C) and the typical appearance of an evacuated plug (arrows).
Malrotation. On an image from a barium enema study, the intestine occupies an
intermediate position between that of nonrotation and the normal postnatal
position. The cecum and the terminal ileum are displaced upward and medially.
Cystic communicating duplication of the colon in a 54-year-old
woman with abdominal pain. Abdominal radiograph shows a round
collection of air near the ascending colon (arrows).
Imperforate anus. Lateral radiograph shows an imperforate anus below the “M” line
drawn through the junction of the upper two-thirds and lower one-third of the ischium
(perineal surgical approach). (19) Ectopic anus. Voiding cystogram demonstrates a recto-
urethral fistula (arrow). (20) Imperforate anus. Lateral voiding cystogram demonstrates
an air-filled distal rectal pouch (arrows) ending blindly below the “M” line, a finding
indicative of a low lesion. There is no fistula opening in the terminal bowel.
Benign tumours of the colon.
Benign colorectal polyps
About half of adults over the age of 40 develop lumps of tissue called polyps that
grow from the inner lining (mucosa) of the colon or rectum. In most people, it is
unclear how or why polyps develop. Polyps may look like a mushroom with a
head and a stalk (pedunculated polyps). They may also be flat and grow along
the inner surface of the wall of the colon or rectum (sessile polyps). Most polyps
are non-cancerous (benign), but some do have the potential to become
cancerous (malignant). Benign colorectal polyps are more common in men than
The most common type of benign polyp is hyperplastic polyp. Hyperplastic polyps
are usually less than 0.5 cm in diameter and most commonly occur in the rectum
and sigmoid colon.
There are several other types of benign polyps. The following benign polyps are
much less common than hyperplastic polyps:
inflammatory polyps (pseudopolyp)
usually associated with chronic inflammatory bowel diseases such as
Crohn's disease or ulcerative colitis.
Hamartomas contain normal cells that have an abnormal arrangement.
Juvenile polyps also called retention polyps that contain many mucous glands
usually occur as a single large polyp mostly found in children under 10 years of
lipomas develop within the fat cells in the colon.
Lymphoid polyps contain lymphoid cells, a type of white blood cell.
Signs and symptoms
Benign colorectal polyps usually do not have any symptoms. They are
usually found during colorectal screening tests or investigation of other
unrelated conditions. If symptoms are present, they may include:
Bleeding from the rectum.
Fatigue (caused by anemia).
If the signs and symptoms of colorectal polyps are
present, or if the doctor suspects colorectal polyps, tests
will be done to make a diagnosis. Tests may include:
digital rectal examination (DRE)
double-contrast barium enema
fecal occult blood test (FOBT)
Colon cancer is cancer of the large intestine (colon), the lower part of your
digestive system. Rectal cancer is cancer of the last several inches of the colon.
Together, they're often referred to as colorectal cancers.
Most cases of colon cancer begin as small, noncancerous (benign) clumps of cells
called adenomatous polyps. Over time some of these polyps become colon
Polyps may be small and produce few, if any, symptoms. For this reason, doctors
recommend regular screening tests to help prevent colon cancer by identifying
polyps before they become colon cancer.
Many cases of colon cancer have no symptoms. The following symptoms may
indicate colon cancer:
Abdominal pain and tenderness in the lower abdomen
Blood in the stool
Diarrhea, constipation, or other change in bowel habits
Weight loss with no known reason.
Large carcinoma of the sigmoid colonDistal transverse colon carcinoma.