eMedicine Specialties > Pediatrics: Surgery > General Surgery

Small Left Colon Syndrome

Erik Skarsgard, MD, Associate Professor of Surgery, Division of Pediatric Surgery, University of British Columbia, Children's and Women's Health Center of British Columbia
Geoffrey Blair, MD, Clinical Professor of Pediatric General Surgery, Department of Pediatric Surgery, University of British Columbia; Head, British Columbia's Children's Hospital

Updated: Sep 30, 2008

Introduction

Intestinal obstruction is one of the most frequent reasons for obtaining surgical consultation in newborns. Distal intestinal obstruction of the newborn may be anatomic (eg, imperforate anus, colonic atresia, colonic stenosis) or functional. Most cases of functional colonic obstruction are caused by Hirschsprung disease; however, a subset of term or near-term babies experience colonic obstruction with a characteristic caliber reduction in the sigmoid and descending colon unrelated to meconium inspissation or aganglionosis. This condition, which has a frequent association with maternal gestational diabetes mellitus and seldom requires surgical intervention, is termed the neonatal small left colon syndrome (NSLCS).

History of the Procedure

In 1974, Davis coined the term small left colon syndrome in his initial description of 20 infants with colonic obstruction not caused by a meconium plug or Hirschsprung disease.¹ In all patients, a contrast enema revealed a narrowed descending and sigmoid colon, with a caliber transition at the splenic flexure; of these, 17 patients experienced immediate and complete resolution of obstruction without operation. Although Davis observed that 8 of the 20 infants were born to mothers with diabetes mellitus, he hypothesized that the apparent dysmotility syndrome was neurogenically determined.

In 1975, Philippart et al reported 8 patients with a similar clinical and radiographic presentation, all born to mothers treated for gestational diabetes mellitus with either insulin or oral hypoglycemic agents.² In 4 of 8 cases, resolution of obstruction after contrast enema was uncomplicated. One patient presented with a cecal perforation requiring emergency operation, one patient underwent operation for suspected Hirschsprung disease (which was subsequently disproved by biopsy), and 2 patients required a delayed operation (one for persistent obstruction and the other for sudden distension and cecal perforation occurring after institution of oral feedings).

Philippart et al speculated on the effects that neonatal hypoglycemia have on intestinal motility via activation of the autonomic nervous system and through stimulated glucagon release.² They also identified a small group of patients who developed late complications and advocated close surveillance for the minority who did not respond promptly to decompressive enemas.

Problem

Neonatal small left colon syndrome is an uncommon cause of neonatal intestinal obstruction characterized by an abrupt intestinal caliber transition at or near the splenic flexure and associated, in approximately half of cases, with a maternal history of gestational diabetes mellitus.

Frequency

The frequency with which neonatal small left colon syndrome occurs is difficult to estimate because the entire subject literature contains only case reports and a few case series.

In one institution's review of consecutive suction rectal biopsies performed in 456 pediatric patients (median age of 13 d) for symptoms of constipation, abdominal distension, and bloody stools, 61 cases of Hirschsprung disease (13%) were identified. The remaining cases included 7 neonates who had a clinical and radiologic picture consistent with neonatal small left colon syndrome. In this study cohort, the incidence of symptoms of distal intestinal obstruction and/or enterocolitis is 1.5%.³

Etiology

Although the precise cause of this form of neonatal intestinal obstruction, which has a typical radiologic picture but is distinctly unusual, is unknown, numerous theories have been proposed, including neural, humoral, and drug-induced etiologic mechanisms.

In 1974, Davis et al reported the association of neonatal small left colon syndrome with abnormalities of intestinal neurohistology.¹ Their initial report described increased numbers of immature small ganglion cells in the myenteric plexus (in both the narrowed and dilated portions of the colon) in 4 of 20 patients with neonatal small left colon syndrome. They compared the histology from patients with small left colon syndrome with that of control subjects, including infants of diabetic mothers without colon changes, premature infants, and term infants. They concluded that the hypercellularity observed in the specimens from patients with neonatal small left colon syndrome most closely resembled the histology observed in the colons of premature infants. Despite this conclusion, they did not provide gestational age data on the patients; therefore, at least some of them assumably were premature.

In 1991, Schofield and Yunis reported an association in 7 patients with clinical and radiographic neonatal small left colon syndrome and suction rectal biopsy histology demonstrating intestinal neuronal dysplasia (IND).³ In all 7 cases, the biopsies, which were stained with hematoxylin and eosin (H&E) and acetylcholinesterase (AChE), demonstrated an increase in the number of AChE-stained fibers in the mucosa and increased submucosal ganglia or large ganglia. These changes are also observed with prematurity, and because most of the infants with neonatal small left colon syndrome in this report were indeed premature, gestational age seems to have had a confounding effect on the biopsy results.

In a 1975 report, Philippart et al focused on humoral and autonomic nervous system changes, which occur in response to neonatal hypoglycemia in developing a mechanistic explanation.²

Glucagon release and sympathoadrenal stimulation are typical in vivo responses to hypoglycemia, and both result in blood glucose stabilization through hepatic gluconeogenesis and glycogenolysis. Along with several effects on the GI tract, glucagon release is known to decrease motility in the jejunum and left colon. Hypoglycemia also stimulates sympathetic and parasympathetic arms of the autonomic nervous system. Maximal vagal (parasympathetic) stimulation results in increased motility in its area of distribution, which ends at the splenic flexure, whereas sympathetic stimulation results in diminished motility. Therefore, a composite effect of glucagon release with sympathetic and parasympathetic nervous system stimulation would hypothetically be an overall diminution in intestinal motility, with a functional block in the colon beyond the splenic flexure.

Philippart et al point out that precipitants other than hypoglycemia (eg, stress) may mediate the same changes through similar mechanisms, thereby explaining the phenomenon when it occurs in the absence of maternal diabetes mellitus.²

Other possible contributors to intestinal hypomotility include maternal drugs used during the third trimester that cross the placenta and affect the fetus. This concept is supported by the report of 2 cases of neonatal small left colon syndrome in infants born to mothers using psychotropic drugs with known anticholinergic effects and the recognized association between hypermagnesemia (in infants born to eclamptic mothers treated with magnesium sulfate) and hypomotility conditions.

Although earlier reports of neonatal colonic obstruction undoubtedly included cases of neonatal small left colon syndrome in the spectrum of obstructive conditions referred to as meconium plug syndrome, obstruction in neonatal small left colon syndrome is not typically associated with the presence of a mucus or meconium plug in the distal constricted segment. No analytical abnormality has been reported in the meconium of infants with neonatal small left colon syndrome, with the exception of a single case report of an infant with cystic fibrosis who presented with a meconium ileus–like obstruction at the splenic flexure with distal microcolon. In contrast, the meconium in meconium plug syndrome is reported to have an elevated protein content with altered enzymatic activity, suggesting that the obstruction is caused by an immobile luminal obturator rather than mural constriction and diminished peristalsis. 

A more contemporary report illustrates the continued challenges of an accurate and etiologic diagnosis of the cause of neonatal meconium plug obstruction. This review of 21 neonates with meconium obstruction revealed 8 patients (38%) with Hirschsprung disease, 4 patients (19%) with small left colon syndrome, and 9 (43%) with meconium plug syndrome.⁴

Presentation

The clinical features of infants described in all English language case series of neonatal small left colon syndrome are summarized in the table below. Most are born at or near term and are of normal birth weight. Approximately 50% have a history of maternal diabetes mellitus, and other maternal comorbidities (usually eclampsia), which contribute to neonatal stress, may also be present. All patients do not pass meconium within the first 24 hours of life, and they all develop abdominal distension with bilious vomiting or nasogastric aspirates. A small number of infants develop progressive distension leading to perforation, typically in the cecum, within the first 24-36 hours of life.

Clinical Features of Infants Described in All English Language Case Series of NSLCS

*Death was due to an unrelated cause.

^† Seven out of 14 (50%) underwent colostomy for incorrect diagnosis of Hirschsprung disease.

Indications

As discussed in the sections below, the indications for operation in neonatal small left colon syndrome (NSLCS) include intestinal perforation and failure of resolution of obstruction following contrast enema administration.

Relevant Anatomy

The neonatal colon is the anatomy relevant to this discussion.

Contraindications

No absolute contraindications to surgery for neonatal small left colon syndrome (NSLCS) are recognized. Remember that the diagnosis is not definitive until Hirschsprung disease has been excluded by rectal biopsy findings; therefore, any surgical procedure must take into account this diagnostic similarity.

Workup

Laboratory Studies

Perform basic laboratory investigations, including complete CBC count and differential, C-reactive protein, coagulation profiles, and blood cultures. Measure serum levels of glucose, calcium, and magnesium in infants of mothers with diabetes mellitus or eclampsia or in infants who otherwise appear stressed. Cross-matched blood should be available.

Imaging Studies

Two-view abdominal radiography should be promptly performed. Typically, distal intestinal obstruction with air-fluid levels is revealed (see Media file 1). Occasionally, infants (especially those in whom the recognition of intestinal obstruction has been delayed) have pneumoperitoneum on plain film radiography, which may be the result of a cecal perforation.

Other Tests

Because Hirschsprung disease with a splenic flexure transition zone is clinically and radiologically indistinguishable from neonatal small left colon syndrome (NSLCS), all infants must have a suction rectal biopsy performed to exclude aganglionosis. Cystic fibrosis that produces a colonic variant of meconium ileus should be considered, and the appropriate DNA testing should be performed, as well as a sweat chloride test when the infant is older, if appropriate.¹⁰

Diagnostic Procedures

If plain film radiography does not reveal perforation, the infant should undergo a contrast enema examination, usually with a water-soluble medium. Because the choice of contrast medium and experience with neonatal conditions are critical to the interpretive accuracy and safety of the examination, the contrast enema examination should be performed by a radiologist who has pediatric expertise.

The diagnosis of neonatal small left colon syndrome on contrast enema examination is based on the following fluoroscopic findings: (1) proximal dilation of colon (and, to a lesser extent, small bowel) with abundant intraluminal meconium; (2) an abrupt cone-shaped caliber transition at or just distal to the splenic flexure; and (3) a constricted but smooth contoured, and often foreshortened, descending and sigmoid colon devoid of meconium with a slightly larger caliber rectum (see Media file 2).

Treatment

Medical Therapy

As for any newborn with intestinal obstruction, the first priority of treatment should include resuscitation, such as intravenous fluids, nasogastric decompression, and intravenous antibiotics (if clinically indicated). Once plain film abdominal radiography has revealed a distal obstruction without pneumoperitoneum, the infant should undergo contrast enema.

Fortunately, for most patients with neonatal small left colon syndrome (NSLCS), the contrast enema is not only diagnostic of the condition but also therapeutic. The vast majority of infants experience spontaneous passage of meconium after the examination, their abdominal distension resolves, and, soon after, enteral feedings can be cautiously introduced and carefully advanced.

As noted above, excluding other diagnoses, even if the infant has the expected clinical response to a contrast enema, is important; thus, a suction rectal biopsy and workup for cystic fibrosis are always indicated.

Surgical Therapy

Surgery is reserved for infants with intestinal perforation or for those in whom obstruction is refractory or recurrent, despite appropriate conservative measures. Surgery in infants with intestinal perforation includes the following:

• Following appropriate fluid, antibiotic, and, if necessary, blood product resuscitation, the infant is taken to the operating room and explored, usually through a transverse upper abdominal incision.
• Once the point of perforation has been identified, consideration should be given to determining the diagnosis because, in most cases, Hirschsprung disease still has not been excluded at this time.
• Assuming that the infant's condition is stable and a pathologist with the appropriate expertise is available, seromuscular biopsy samples from the distal colon, in what obviously would appear to be aganglionic bowel, should be obtained for frozen section examination. If a distal biopsy is aganglionic, biopsy samples should be obtained near the transition zone and proximally to localize the transition zone, and a stoma should be created in ganglionic bowel. If the transition zone is at the splenic flexure, leaving the distal aganglionic bowel in place as a long Hartman pouch is reasonable; however, if the transition zone is in the small bowel, a decompressive mucous fistula should be created. In cases of long segment disease, the aganglionic colon should be left undisturbed so as to retain all subsequent reconstructive options.
• In the rare case of intestinal perforation occurring after the diagnosis of Hirschsprung disease has been satisfactorily excluded, the safest operative strategy would involve a formal stoma or exteriorization of the perforation.

Complications

Refractory or recurrent obstruction

After the diagnosis of neonatal small left colon syndrome (NSLCS) has been adequately established, the need for surgical intervention seems unlikely. Historically, most operations have been performed because of a mistaken diagnosis of Hirschsprung disease, although Philippart et al reported 2 patients who required delayed operations and did not have aganglionosis; one patient developed recurrent obstruction after initial successful enema decompression and required transition zone colostomy, and the other developed an obstruction with cecal perforation 6 days after institution of oral feedings.²

Outcome and Prognosis

Most infants completely respond to contrast enema decompression and are able to progress quite rapidly to full enteral feedings. Numerous patients who have undergone follow-up examinations of their colon have demonstrated normalization of caliber within a few weeks. In a 1975 report, Philippart et al warned of the small number of patients who experience delayed complication, either recurrent or persistent obstruction or delayed perforation, mandating close surveillance during the first week or 2 of life.²

Future and Controversies

Apart from more definitive understanding of the pathophysiology of this condition, no real areas of controversy surround the treatment of neonatal small left colon syndrome (NSLCS).

Multimedia

Media file 1: Supine shoot-through lateral abdominal radiograph of an infant with abdominal distension, bilious nasogastric aspirates, and failure to pass meconium at 24 hours of life. Distended loops of bowel with air-fluid levels are evident.

Media file 2: Contrast enema of same infant as in Media file 1 demonstrates a normal caliber rectum, a small caliber sigmoid, and descending colon with an abrupt caliber transition at the splenic flexure. These findings are characteristic of neonatal small left colon syndrome (NSLCS).

References

1. Davis WS, Allen RP, Favara BE, Slovis TL. Neonatal small left colon syndrome. Am J Roentgenol Radium Ther Nucl Med. Feb 1974;120(2):322-9. [Medline].

2. Philippart AI, Reed JO, Georgeson KE, Slovis TL. Neonatal small left colon syndrome: intramural not intraluminal obstruction. J Pediatr Surg. Oct 1975;10(5):733-40. [Medline].

3. Schofield DE, Yunis EJ. Intestinal neuronal dysplasia. J Pediatr Gastroenterol Nutr. Feb 1991;12(2):182-9. [Medline].

4. Burge D, Drewett M. Meconium plug obstruction. Pediatr Surg Int. Feb 2004;20(2):108-10. [Medline].

5. Berdon WE, Slovis TL, Campbell JB, et al. Neonatal small left colon syndrome: its relationship to aganglionosis and meconium plug syndrome. Radiology. Nov 1977;125(2):457-62. [Medline].

6. Rangecroft L. Neonatal small left colon syndrome. Arch Dis Child. Aug 1979;54(8):635-7. [Medline].

7. Stewart DR, Nixon GW, Johnson DG, Condon VR. Neonatal small left colon syndrome. Ann Surg. Dec 1977;186(6):741-5. [Medline].

8. Woodhurst WB, Kliman MR. Neonatal small left colon syndrome: report of two cases. Am Surg. Jul 1976;42(7):479-81. [Medline].

9. Falterman CG, Richardson CJ. Small left colon syndrome associated with maternal ingestion of psychotropic drugs. J Pediatr. Aug 1980;97(2):308-10. [Medline].

10. Ellerbroek C, Smith WL. Neonatal small left colon in an infant with cystic fibrosis. Pediatr Radiol. 1986;16(2):162-3. [Medline].

11. Sokal MM, Koenigsberger MR, Rose JS, et al. Neonatal hypermagnesemia and the meconium-plug syndrome. N Engl J Med. Apr 13 1972;286(15):823-5. [Medline].

12. 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].

Keywords

small left colon syndrome, neonatal small left colon syndrome, NSLCS, imperforate anus, colonic atresia, colonic stenosis, Hirschsprung disease, colonic obstruction, gestational diabetes mellitus, meconium plug, dysmotility syndrome, hypoglycemia, constipation, enterocolitis, infants of diabetic mothers, cystic fibrosis, eclampsia, abdominal distension, intestinal perforation

Contributor Information and Disclosures

Author

Erik Skarsgard, MD, Associate Professor of Surgery, Division of Pediatric Surgery, University of British Columbia, Children's and Women's Health Center of British Columbia
Erik Skarsgard, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Surgeons, American Pediatric Surgical Association, and Royal College of Physicians and Surgeons of Canada
Disclosure: Nothing to disclose.

Coauthor(s)

Geoffrey Blair, MD, Clinical Professor of Pediatric General Surgery, Department of Pediatric Surgery, University of British Columbia; Head, British Columbia's Children's Hospital
Geoffrey Blair, MD is a member of the following medical societies: American Pediatric Surgical Association
Disclosure: Nothing to disclose.

Medical Editor

Robert Kelly, MD, Chairman, Department of Surgery, Departments of Surgery and Pediatrics, Children's Hospital of the King's Daughters; Associate Professor, Eastern Virginia Medical School
Robert Kelly, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Surgeons, American Medical Association, American Pediatric Surgical Association, American Society of Abdominal Surgeons, Medical Society of Virginia, Norfolk Academy of Medicine, and Southern Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

Managing Editor

Deborah F Billmire, MD, Associate Professor, Department of Surgery, Indiana University Medical Center
Deborah F Billmire, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Surgeons, American Pediatric Surgical Association, Phi Beta Kappa, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

CME Editor

H Biemann Othersen Jr, MD, Professor of Surgery and Pediatrics, Emeritus Head, Division of Pediatric Surgery, Medical University of South Carolina
H Biemann Othersen Jr, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Association for the Surgery of Trauma, American Burn Association, American Cancer Society, American College of Surgeons, American Medical Association, American Pediatric Surgical Association, American Society for Parenteral and Enteral Nutrition, American Surgical Association, American Thoracic Society, British Association of Paediatric Surgeons, Society for Surgery of the Alimentary Tract, Society of Critical Care Medicine, South Carolina Medical Association, Southeastern Surgical Congress, Southern Medical Association, Southern Society for Pediatric Research, and Southern Thoracic Surgical Association
Disclosure: Nothing to disclose.

Chief Editor

Harsh Grewal, MD, FACS, FAAP, Professor of Surgery and Pediatrics, Temple University School of Medicine; Chief, Section of Pediatric Surgery, Temple University Children's Medical Center
Harsh Grewal, MD, FACS, FAAP is a member of the following medical societies: American Academy of Pediatrics, American College of Surgeons, American Pediatric Surgical Association, Association for Surgical Education, Children's Oncology Group, Eastern Association for the Surgery of Trauma, International Pediatric Endosurgery Group, Society of American Gastrointestinal and Endoscopic Surgeons, Society of Laparoendoscopic Surgeons, and Southwestern Surgical Congress
Disclosure: Nothing to disclose.

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