Small Left Colon Syndrome Flashcards
Discuss SLCS (Small Left Colon Syndrome).
SLCS was originally described by Davis, et al., in 1974.
It is a rare clinical entity in which newborns present with symptoms of distal intestinal obstruction.
Infants of insulin dependent diabetic mothers are at increased risk for developing SLCS.
Contrast enema demonstrates a small caliber colon up to the level of the splenic flexure with dilated proximal bowel.
This is a functional obstruction, which typically resolves after a diagnostic and therapeutic contrast enema.
If normal, spontaneous bowel movements follow the contrast enema, no further intervention is warranted.
Surgical intervention is indicated in cases of complicated SLCS.
Additional diagnostic evaluation is appropriate in patients who do not resume a normal, spontaneous stooling pattern.
There are no sequelae of SLCS at long-term follow-up.
What is the typical clinical presentation of SLCS?
Term or near-term infants typically present within the first 24–48 h of life with abdominal distention, failure to pass meconium, and bilious emesis.
These infants may also manifest sequelae of a diabetic gestation including hypoglycemic cardiomyopathy, cyanosis and persistent fetal circulation.
Plain radiographs demonstrate dilated loops of bowel.
Occasionally, pneumoperitoneum may be present on initial plain radiographs.
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What patients are at risk for developing SLCS?
Patients born to diabetic mothers are at increased risk for developing SLCS.
In the original series described by Davis, 40% of patients of patients with SLCS were born to insulin-dependent diabetic mothers [1].
Subsequent series have demonstrated this rate to be as high as 50% [3, 4].
In a study of asymptomatic patients born to diabetic mothers, six of twelve infants were found to have features of small left colon on contrast enema [5].
As most efforts to identify an etiology for SLCS have focused on diabetes, no other specific risk factors have been identified.
What is the cause of SLCS?
The cause of SLCS has not been clearly defined.
In the original series by Davis, et al., histology samples in four patients demonstrated an increased ratio of small cells to multipolar ganglion cells in the myenteric plexus.
This was felt to reflect immaturity of the myenteric plexus, though these changes were found in both the normal caliber and contracted bowel thus making it difficult to ascribe the presence of SLCS to these changes.
A subsequent series by Philippart et al. demonstrated normal ganglion cells in all cases where biopsy was performed.
They concluded SLCS, in the setting of maternal diabetes, is due to a hypoglycemia-induced alteration in intestinal motility that is a composite neurohumoral response.
Increased glucagon levels decrease motility in the descending colon while increased vagal output stimulates the mid-gut leading to the typical abrupt splenic flexure transition.
They further postulated a similar mechanism may account for SLCS seen in infants of non-diabetic mothers who may have elevated glucagon levels due to neonatal stress response.
No recent studies have further evaluated the etiology of SLCS.
How is SLCS diagnosed?
SLCS is diagnosed with contrast enema.
From the anus to the splenic flexure, the colon has a decreased caliber.
At the splenic flexure, there is an acute transition to dilated proximal bowel.
The descending colon may be foreshortened and lack nor- mal tortuosity.
Contrast is promptly evacuated [1].
Meconium plugs may be found on contrast enema in the setting of SLCS and are thought to be secondary to impaired colonic motility rather than to the intrinsic composition of the meconium.
Are there other conditions that mimic SLCS?
Patients with Hirschsprung’s disease and SLCS present with similar patterns.
However, there are features on contrast enema that can be used to distinguish the two entities.
In SLCS, the descending colon has a significantly decreased caliber consistent with microcolon, the transition between proximal dilation and distal microcolon is located at the splenic flexure, and the transition is relatively abrupt.
Patients with Hirschsprung’s disease differ in that the aganglionic segment is normal in caliber (not a microcolon), most patients with Hirschsprung’s disease will have a rectosigmoid transition zone, and the transition zone is typically gradual and cone-shaped.
If an abnormal stooling pattern persists in a patient diagnosed with SLCS, further evaluation for the presence of ganglion cells should be undertaken.
Furthermore SLCS may be difficult to distinguish from meconium plug syndrome (originally described by Clatworthy in 1956) and colonic inertia (originally described by Berdon in 1968), and there is likely overlap in the clinical spectrum, diagnostic criteria and nomenclature of these entities [6].
Reports have associated meconium plug syndrome with both Hirschsprung’s disease and cystic fibrosis.
Given the overlap between meconium plug syndrome and SLCS, it is important to note that a recent review of meconium plug syndrome found no association with cystic fibrosis and a 13% incidence of Hirschsprung’s disease in meconium plug syndrome [4].
How is SLCS treated?
The contrast enema in SLCS is often diagnostic and therapeutic.
There is typically prompt evacuation of contrast and meconium with subsequent normal stooling.
Repeat enemas may be necessary if abdominal distention persists.
Is operative intervention required in patients with SLCS?
In cases of complicated SLCS where pneumoperitoneum is identified, surgical exploration is necessary and temporary intestinal diversion is usually performed.
Perforation may occur at the time of initial presentation or may be delayed.
Persistent abdominal distention following contrast enema has been reported in patients presenting with delayed perforation.
The cecum is the most common site of perforation.
Is rectal biopsy necessary in SLCS?
The diagnosis of SLCS does not mandate rectal biopsy.
Rectal biopsy is indicated
only if abnormal stooling follows attempted therapeutic enemas.
What are the long-term consequences of SLCS?
No long-term sequelae of SLCS have been reported.
Most series report follow-up duration of 1–2 years and all report normal stooling patterns.
In the original series by Davis et al. repeat enemas were performed on three separate patients at different intervals of follow-up in each patient.
These intervals were 1, 2, and 11 months of age.
In each patient, the left colon remained small despite a normal stooling pattern.
One patient had a repeat enema at 6 years of age and the colon appeared normal [1].
