Microcolon

Plain film shows numerous dilated loops of bowel occupying the entire abdominal cavity, including the pelvic portion, and multiple air-fluid levels in upright film (Fig. 1.19). With this degree of distension the mucosal pattern of the small bowel is effaced and it is impossible to differentiate the small bowel from the colon (Winters et al. 1992). Examination of the colon is then warranted to disclose the presence or absence of a colonic lesion. In ileal atresia, the colon is normally placed but has an abnormally small caliber, the so-called functional microcolon typical of distal small bowel obstruction (Dalla Vecchia et al. 1998) (Fig. 1.19d,e). The presence of pneumoperitoneum indicates that perforation has occurred and a colon examination is contraindicated. Intraperitoneal calcifications, indicative of meconium peritonitis, are not uncommon in ileal atresia. 

Fig. 1.22a,b. Meconium ileus, a Water-soluble contrast enema showing a microcolon with scattered filling defects that correspond to inspissated meconium, b The enema was continued with reflux of the contrast medium into the terminal ileum, showing Ailing defects that represent meconium pellets. The patient was discharged within 48 h of successful treatment... 

Contrast-enema usually reveals a microcolon distal to the atresia, with obstruction to the retrograde flow of barium at the site of the atresia (Fig. 1.29). A wind-sock appearance may be observed with membranous atresias (Winters et al. 1992). Calcification of meconium peritonitis due to in utero bowel perforation is present in about 12% of atresia cases, and can be diagnosed antenatally by sonography. 

Fig. 1.29a-d. Colon atresia, a Supine radiograph shows gaseous distension of howel. b,c Contrast enema, anteroposterior and lateral views show abnormally small colon (microcolon) with complete obstruction to retrograde flow of contrast material proximal to the middle transverse portion of colon, d Photograph at operation shows a distended colon up to the site of the atresia (arrow) and a microcolon distal to it... 

Amodio J, Berdon WE, Abramson SJ (1986) Microcolon of prematurity a form of functional obstruction. AJR Am J Roentgenol 146 239-244... 

Berdon WE, Baker DH, Santulli TV et al (1968) Microcolon in newborn infants with intestinal obstruction. Radiology 90 878-885... 

Kosloske AM, Love CL, Rohrer JE et al (2004) The diagnosis of appendicitis in children outcomes of a strategy based on pediatric surgical evaluation. Pediatrics 113 29-34 Krasna IH, Rosenfeld D, Salerno P (1996) Is it necrotizing enterocolitis, microcolon of prematurity, or delayed meconium plug A dilemma in the tiny premature infant. J Pediatr Surg 31 855-858... 

Duodenal Obstruction 170 Jejunal and Ileal Obstruction 172 Meconium Peritonitis 173 Meconium Ileus 173 Megacystis-Microcolon-Malrotation-Intestinal-Hypoperistalsis Syndrome (MMMIHS) 174... 

The radiological diagnosis of obstruction is usually visible on the conventional (plain) radiograph. In uncomplicated cases these radiographs of the abdomen are sufficient. The pre-atretic intestinal loops are dilated because of accumulation of large amounts of fluid and fluid levels are usually present on horizontal beam films. In case of jejunal atresia only a few loops of distended jejunum are present in the left upper abdomen, while in ileal atresia many dilated loops are identified. In complicated cases, especially with an abnormally distended and painful abdomen, a colon enema or US can be useful- particularly from the differential diagnostic point of view to exclude meconium ileus or meconium peritonitis. In case of atresia, a microcolon without the presence of meconium is usually found (Devos and Meradji 2003). 

A contrast examination of the upper G1 tract may show dilated small bowel without peristaltic activity while on a colon enema a microcolon will he noticed (Fig. 5.10). US demonstrates a large urinary bladder with dilated ureters and pyelocaliceal systems. 

Megacystis-Microcolon-Malrotation-Intestinal-Hypoperistalsis Syndrome (MMA/llHS)... 

Fig. 5.10a-c. MMMIHS highly distended stomach on contrast study with slow passage of contrast. Very little peristaltic activity. a,b Note the unusual microcolon and distended bladder (catheter). Secondary hydronephrosis because of dilated bladder, c Dilated system can be seen on EU, with the atonic, large bladder with dilatation of the pyelocaliceal system... 

Contrast enema will demonstrate a microcolon with visualization of the meconium pellets in the terminal ileum. The microcolon results from the failure of the meconium to pass into the colon, which would thereby allow the colon to assume its normal caliber (Fig. 5.26). In about 50% of cases the enema will be curative. 

Fig. 5.25. a Meconium ileus in a 3-day-old neonate. The small bowel is dilated and has a bubbly irregularity in the right lower quadrant, b On the lateral film of the abdomen no colonic loops are visible. There are no gas-fluid levels, c Contrast enema shows microcolon as a result of meconium ileus. Meconium pellets demonstrated in the terminal ileum (arrows)... 

Chronic intestinal pseudo-obstruction is a rare clinical condition also known as chronic adynamic ileus, pseudo-Hirschsprung s disease, and adynamic bowel syndrome. Megacystis-microcolon-intestinal hypoperistalsis syndrome is the most severe form of chronic intestinal pseudo-obstruction. 

In ultra-short segment Hirschsprung s disease the barium enema may show a large mega-rectum but no other specific findings. In NID, chronic intestinal pseudo-obstruction and total colonic agangiionosis the barium enema is often non-contributory. However, total colonic agangiionosis may sometimes have the appearance of a microcolon and therefore needs to be differentiated form ileal atresia and meconium ileus. 

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS)... 

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