eMedicine Specialties > Radiology > Pediatrics
Meconium Plug Syndrome
Updated: May 12, 2009
Introduction
Background
Meconium plug syndrome, also termed functional immaturity of the colon, is a transient disorder of the newborn colon characterized by delayed passage (>24-48 h) of meconium and intestinal dilatation (see Image 1).
Supine frontal view of the abdomen in a newborn with meconium plug syndrome demonstrates multiple dilated loops of bowel but no rectal gas.
A frontal view from contrast enema in a patient initially given a diagnosis of small left colon syndrome. A long filling defect is seen in the rectosigmoid with gradual transition to a more dilated proximal bowel. The infant failed to improve, and rectal biopsy confirmed Hirschsprung disease.
A lateral view from contrast enema in a newborn demonstrates a normal-to-decreased caliber "empty" distal colon and dilated proximal bowel containing multiple plugs. The child responded clinically and radiographically to a single enema.
Contrast enema demonstrates the retained meconium as a filling defect or plug (see Image 2) that produces a double-contrast effect. Small left colon syndrome is a subset of meconium plug syndrome in which an enema demonstrates an apparent transition zone between the dilated and the normal-to-decreased caliber distal colon at the splenic flexure (see Image 3).
Pathophysiology
Early descriptions of meconium plug syndrome emphasized the contrast-enema appearance and ascribed a possible etiologic role to the retained meconium, which is often dislodged after the enema study. Meconium plug syndrome is understood as a transient functional disorder of the colon resulting from immaturity of the myenteric plexus nerve cells or their hormonal receptors. This distinguishes it from Hirschsprung disease, which may have identical clinical and radiographic findings in which nerve cells are absent in the distal diseased portion of the colon.1,2,3
Frequency
United States
Since meconium plug syndrome is a clinical and radiographic disorder without pathologic or laboratory confirmation, incidence figures are not available.
Mortality/Morbidity
Typically, the clinical course is benign; however, serious complications may occur, primarily including intestinal perforation and electrolyte imbalance secondary to obstruction or hypertonic contrast enema.
Race
No racial predilection is apparent.
Sex
No sex predilection is known.
Age
By definition, the disorder is found only in newborns.
Anatomy
Anatomic changes in meconium plug syndrome vary. Usually, the colon is normal or may be mildly enlarged and filled with meconium. A change in the colon's diameter at the splenic flexure may be seen and is indistinguishable from that observed in Hirschsprung disease, although in the latter disorder the transition zone usually is in the rectosigmoid. In preterm infants weighing less than 1000 g, the entire colon may be small, producing an enema appearance similar to ileal atresia or meconium ileus.
Presentation
Clinically, the hallmarks of the disorder are abdominal distention and failure to pass significant meconium in the first 24 hours of life. Bilious vomiting may occur.4 Symptoms often are present before the first feeding, which helps distinguish the disorder clinically from necrotizing enterocolitis.
The incidence is increased in premature infants of diabetic mothers (especially the small left colon variant) and in infants whose mothers received magnesium sulfate for treatment of toxemia. Newborns with cystic fibrosis also may present with meconium plug syndrome, although meconium ileus is more frequent and characteristic in these patients. Despite these associations, many patients have no apparent risk factor.
Preferred Examination
The initial imaging modality is plain film radiography, which includes supine and horizontal beam views (left lateral decubitus or cross-table lateral) of the abdomen. Follow plain films with contrast enema. Barium can be used but has been replaced by water-soluble contrast agents in most practices. Historically, Gastrografin was employed, which is a hypertonic solution containing both wetting and detergent agents. However, complications secondary to hyperosmolarity occurred that produced dehydration. Evidence exists that detergent and wetting additives may be toxic, and their possible therapeutic effect remains unproven.
Limitations of Techniques
Meconium plug syndrome is a diagnosis of exclusion. Contrast enema usually eliminates congenital small bowel obstruction and rare colon abnormalities such as atresia or duplication. The primary differential consideration is Hirschsprung disease, which is diagnosed eventually in approximately 10-30% of patients with apparent meconium plug syndrome (see Image 2).
A frontal view from contrast enema in a patient initially given a diagnosis of small left colon syndrome. A long filling defect is seen in the rectosigmoid with gradual transition to a more dilated proximal bowel. The infant failed to improve, and rectal biopsy confirmed Hirschsprung disease.
Rare disorders that may partially simulate meconium plug syndrome include neuronal intestinal dysplasia, visceral neuropathies, and megacystis-microcolon-intestinal hypoperistalsis syndrome, also termed Berdon syndrome. However, radiographic and clinical features in these diseases usually are distinguished readily from meconium plug syndrome. A more common problem is an infant with sepsis or a metabolic disorder who presents with nonobstructive ileus.
Differential Diagnoses
| Hirschsprung Disease | Meconium Ileus |
| Ileal Atresia | Midgut Volvulus |
| Intussusception, Child | Necrotizing Enterocolitis |
| Meckel Diverticulum | Small-Bowel Obstruction |
Other Problems to Be Considered
Adynamic ileus
Imperforate anus
Inguinal hernia
Malrotation of the intestine with volvulus or Ladd bands
Megacystis-microcolon-intestinal hypoperistalsis (Berdon syndrome)
Neuronal intestinal dysplasia
Radiography
Supine frontal view of the abdomen in a newborn with meconium plug syndrome demonstrates multiple dilated loops of bowel but no rectal gas.
A frontal view from contrast enema in a patient initially given a diagnosis of small left colon syndrome. A long filling defect is seen in the rectosigmoid with gradual transition to a more dilated proximal bowel. The infant failed to improve, and rectal biopsy confirmed Hirschsprung disease.
A lateral view from contrast enema in a newborn demonstrates a normal-to-decreased caliber "empty" distal colon and dilated proximal bowel containing multiple plugs. The child responded clinically and radiographically to a single enema.
Findings
Plain films usually demonstrate multiple dilated loops of bowel with absence of rectal gas. The presence or absence of air-fluid levels in the bowel is not helpful. Findings are similar to those of structural colonic or distal small bowel obstruction and help to exclude malrotation with volvulus or obstructing Ladd bands, in which the blockage usually occurs at the duodenum.
Contrast enema usually shows a moderately dilated colon filled with radiolucent material (the meconium plug). In the small left colon variant (see Image 3), a transition is seen from a relatively small to normal or increased caliber bowel in the region of the splenic flexure.
Degree of Confidence
Meconium plug syndrome is a diagnosis of exclusion. Contrast enema usually excludes congenital small bowel obstruction and rare colon abnormalities such as atresia or duplication. The main differential consideration is Hirschsprung disease, which is diagnosed eventually in approximately 10-30% of patients with apparent meconium plug syndrome (see Image 2).
Rare disorders that may partially simulate meconium plug syndrome include neuronal intestinal dysplasia, visceral neuropathies, and megacystis-microcolon-intestinal hypoperistalsis syndrome, also termed Berdon syndrome. However, radiographic and clinical features in these disorders usually are distinguished readily from meconium plug syndrome. A small (micro or mini) colon characterizes many of these diseases.
A more common problem is an infant with sepsis or metabolic disorder who presents with a nonobstructive ileus. In these patients, the intestinal dilatation resolves once the primary problem is treated.
The main problem in differential diagnosis, after the contrast enema has been performed, is Hirschsprung disease. The enema findings in neonatal Hirschsprung disease are not distinguishable from meconium plug syndrome. The most important point is the infant's response to supportive care and enemas.
Evaluate any infant with apparent meconium plug syndrome for Hirschsprung disease (rectal-suction biopsy) and other possible underlying disorders when findings persist after 1-2 enemas.
False Positives/Negatives
The normal infant's intestinal gas pattern often appears "gassy" by adult criteria. Typically, the width of a bowel loop does not exceed the width of one of the patient's lumbar vertebral bodies. Rectal gas often may be absent in the normal infant because the rectum is dependent and filled with meconium when the patient is supine. With the exception of the rectum, the colon and small bowel usually cannot be differentiated on plain film.
Intervention
In addition to contributing to diagnosis, contrast enema may be therapeutic.5 In most patients, the enema probably speeds what otherwise may be a slower spontaneous recovery.
Historically, Gastrografin, a hypertonic solution containing both wetting and detergent agents, was employed for contrast. However, complications secondary to hyperosmolarity occurred that produced dehydration. Evidence exists that the detergent and wetting additives may be toxic, and their possible therapeutic effect remains unproven.
Current practice uses low-osmolar contrast, which is adequately radiopaque at iso-osmolar levels if a low-kV technique is used. No evidence exists that the newer low-osmolar agents are less therapeutic than hyperosmolar media.
Contrast enema technique
- Perform the enema with attention to the delicate temperature stability of the newborn infant. Use blankets and lamps and warm the contrast to body temperature.
- Advance a small-caliber soft, rubber catheter (10-14F) into the rectum using minimal lubricant. Hold the catheter in place primarily by taping the patient's buttocks tightly together.
- Some radiologists deploy a small Foley balloon (5 mL) to aid contrast retention. However, do not inflate the balloon until a preliminary injection of a small amount of contrast under fluoroscopy demonstrates adequate caliber of the rectum. Initial injection without an inflated balloon also assesses for a possible low-transition zone in patients with Hirschsprung disease.
- Because the internal volume of the colon may be low, at the author's institution, contrast is injected by hand using a syringe under careful and almost continuous fluoroscopic monitoring. Others use a low-capacity reservoir, such as an intravenous bag, and infuse via gravity drip.
- Opacify the entire colon both to maximize the therapeutic effect of the enema and to identify the position of the cecum.
- Carefully attempt to reflux contrast into the distal ileum in patients who may have meconium ileus.
- After the colon has been filled and the appropriate films obtained, remove the catheter without attempting to drain the colon. Allowing the patient to expel the contrast may help dislodge the meconium plug.
Response to the enema often is dramatic, with immediate passage of meconium and resolution of intestinal dilatation. In some patients, clinical findings persist and a second enema is performed for therapy. Since the plug is a symptom in this disorder, rather than its cause, little justification is found for multiple repeat procedures.
Special Concerns
- The primary complication of this disorder is intestinal perforation, which may be spontaneous or secondary to overdistention during an enema.
- Iatrogenic complications include fluid/electrolyte disorders resulting from hyperosmolar enema contrast and hypothermia from inadequate temperature control during the procedure.
Multimedia
Media file 1: Supine frontal view of the abdomen in a newborn with meconium plug syndrome demonstrates multiple dilated loops of bowel but no rectal gas.
Media file 2: A frontal view from contrast enema in a patient initially given a diagnosis of small left colon syndrome. A long filling defect is seen in the rectosigmoid with gradual transition to a more dilated proximal bowel. The infant failed to improve, and rectal biopsy confirmed Hirschsprung disease.
Media file 3: A lateral view from contrast enema in a newborn demonstrates a normal-to-decreased caliber "empty" distal colon and dilated proximal bowel containing multiple plugs. The child responded clinically and radiographically to a single enema.
References
Keckler SJ, St Peter SD, Spilde TL, Tsao K, Ostlie DJ, Holcomb GW 3rd, et al. Current significance of meconium plug syndrome. J Pediatr Surg. May 2008;43(5):896-8. [Medline].
American Pediatric Surgical Association. Meconium Plug/Small Left Colon Syndrome. American Pediatric Surgical Association. Available at http://www.eapsa.org/parents/resources/plug.cfm. Accessed May 11, 2009.
Burge D, Drewett M. Meconium plug obstruction. Pediatr SurgInternational. 2004;20(2):108-10. [Medline].
American College of Radiology ACR Appropriateness Criteria. Vomiting in Infants up to 3 Months of Age. American College of Radiology. Available at http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonPediatricImaging/VomitinginInfantsupto3MonthsofAgeDoc11.aspx. Accessed May 12, 2009.
American College of Radiology. ACR Practic Guideline for the Performance of Pediatric Fluoroscopic Contrast Enema Examinations. American College of Radiology. Available at http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/pediatric/pediatric_contrast_enema.aspx. Accessed May 12, 2009.
Krasna IH, Rosenfeld D, Salerno P. Is it necrotizing enterocolitis, microcolon of prematurity, or delayed meconium plug? A dilemma in the tiny premature infant. J Pediatr Surg. Jun 1996;31(6):855-8. [Medline].
McAlister WH, Kronemer KA. Emergency gastrointestinal radiology of the newborn. Radiol Clin North Am. Jul 1996;34(4):819-44. [Medline].
Olsen MM, Luck SR, Lloyd-Still J. The spectrum of meconium disease in infancy. J Pediatr Surg. Oct 1982;17(5):479-81. [Medline].
Sokal MM, Koenigsberger MR, Rose JS. Neonatal hypermagnesemia and the meconium-plug syndrome. N Engl J Med. Apr 13 1972;286(15):823-5. [Medline].
Steves M, Ricketts RR. Pneumoperitoneum in the newborn infant. Am Surg. Apr 1987;53(4):226-30. [Medline].
Swischuk LE. Meconium plug syndrome: a cause of neonatal intestinal obstruction. Am J Roentgenol Radium Ther Nucl Med. Jun 1968;103(2):339-46. [Medline].
Wood BP, Katzberg RW. Tween 80/diatrizoate enemas in bowel obstruction. AJR Am J Roentgenol. Apr 1978;130(4):747-50. [Medline].
Keywords
meconium plug syndrome, functional immaturity of the colon, small left colon syndrome, Hirschsprung disease
Contributor Information and Disclosures
Author
Michael J Diament, MD, Associate Professor, Department of Radiology, University of California at Los Angeles School of Medicine
Michael J Diament, MD is a member of the following medical societies: American Roentgen Ray Society, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.
Medical Editor
Beverly P Wood, MD, PhD, Professor Emerita, Departments of Radiology and Pediatrics, Division of Medical Education, Keck School of Medicine, University of Southern California; Professor of Clinical Radiology, Loma Linda University School of Medicine
Beverly P Wood, MD, PhD is a member of the following medical societies: American Academy of Pediatrics, American Association for Women Radiologists, American College of Radiology, American Institute of Ultrasound in Medicine, American Medical Association, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.
Pharmacy Editor
Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.
Managing Editor
David A Stringer, BSc, MBBS, FRCR, FRCPC, Professor, National University of Singapore; Head, Diagnostic Imaging, KK Women's and Children's Hospital, Singapore
David A Stringer, BSc, MBBS, FRCR, FRCPC is a member of the following medical societies: British Columbia Medical Association, Canadian Association of Radiologists, European Society of Paediatric Radiology, Ontario Medical Association, Radiological Society of North America, Royal College of Physicians and Surgeons of Canada, Royal College of Radiologists, and Society for Pediatric Radiology
Disclosure: Sirius d'innovation None Board membership
CME Editor
Robert M Krasny, MD, Consulting Staff, Department of Radiology, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.
Chief Editor
John Karani, MBBS, FRCR, Clinical Director of Radiology and Consultant Radiologist, Department of Radiology, King's College Hospital, London
John Karani, MBBS, FRCR is a member of the following medical societies: British Institute of Radiology, British Society of Interventional Radiology, Cardiovascular and Interventional Radiological Society of Europe, European Society of Gastrointestinal and Abdominal Radiology, European Society of Radiology, Radiological Society of North America, and Royal College of Radiologists
Disclosure: Nothing to disclose.