Afferent loop syndrome (ALS) is a rare complication (0,2 - 1%) after gastric surgery. However it can be lethal if not treated properly. Its diagnosis is not easy and that usually delayed. Most of the times it complicates a Billroth II reconstruction following a subtotal gastrectomy or a even pancreaticoduodenectomy. ALS can occur since the first post-operative day till several years after surgery (it has been described 30-40 years after).
Complete or partial obstruction of the afferent loop.
It's the jejunal portion of the afferent loop that is implicated in this severe complication. ALS occurs because of a complete or partial obstruction of the afferent loop, which can occur in the gastrojejunal anastomosis or at the jejunal portion of the afferent loop. Obstruction can be due to internal hernia, volvulus, cancer recurrence, adhesions...
There are two forms of presentation: acute and chronic.
Acute ALS: complete obstruction of afferent loop (can occur years after surgery) causing nausea, vomiting, abdominal pain (epigastric, right or left upper quadrant); it is a surgical emergency because it can lead to ischemia of the afferent loop with perforation and peritonitis.
Chronic ALS: partial obstruction of the afferent loop, causing abdominal pain 10 min to 1 hour post-prandially, eventually with projectile bilious vomiting leading to sudden relief of symptoms.
Passage of food through the gastrojejunostomy into the efferent loop, causes the secretion of pancreatic juice and bile up to 1-2 L a day into the afferent loop. If the afferent loop is obstructed an increase in the intraluminal pressure will occur causing afferent loop distension and the above mentioned signs and symptoms. Additionally, ASL is one major cause of duodenal blowout, and also a cause of cholangitis, pancreatitis and obstructive jaundice. ALS has a mortality rate of 57%.
The acute form of ALS is a surgical emergency.
As it is mentioned above, the majority of ALS cases complicate a Billroth II reconstruction. According to some authors there are some factors in the surgery that increase the risk of this severe complication:
gastrojejunostomy placed antecolic
mesocolic defect not well closed if gastrojejunostomy is placed retrocolic
a jejunal portion of the afferent loop with more than 30-40 cm (Medscape)
ALS is a purely mechanical complication, and will not be solved without surgery or other interventional procedure. In fact, medical treatment has no role in acute ALS. In chronic ALS medical measures are useful to correct malnutrition and anemia (malabsortion of iron and vit. B12) before a surgical correction.
ALS will not be solved without surgery or other interventional procedure.
As all surgeons know, the most frequently used corrective surgery is deconstruct Billroth II and restore gastrointestinal continuity with another method, Billroth I or Roux-en-Y (the preferred method I think). Although surgery is the best treatment option, percutaneous drainage or stent placement (as in the case of malignant obstruction) can be used in patients not candidate for surgery.
The treatment option of constructing a Roux-en-Y anastomosis leads to the following case report that answers one simple question: is ALS possible after Roux-en-Y reconstruction? Since ALS treatment is to transform a Billroth II in a Roux-en-Y anastomosis, it would be normal to think that ALS does not complicate a Roux-en-Y anastomosis. Is this true? Probably yes and no!
ALS can complicate a improperly constructed Roux-en-Y.
Katagiri et al from Japan published in 2016 an interesting case report of a ALS after total gastrectomy with Roux-en-Y reconstruction. Abdominal pain and distention were noted, and an abdominal CT scan revealed a both duodenum and jejunum dilation, and also a dilation of main pancreatic duct and bile ducts. On laparotomy a volvulus of the jejunum from the Treitz to the jejunojunal anastomosis (biliopancreatic loop) was found (Figure). The jejunal portion of the biliopancreatic loop of the Roux-en-Y (afferent loop in this setting) had more than 50 cm length. This fact was pointed out by the authors as the cause of the the complete obstruction of the biliopancreatic loop and the consequent acute ALS. Manual reduction of the volvulus was the only treatment.
So... Is ALS possible after Roux-en-Y reconstruction?
Yes - if jejunum from the Treitz to the jejunojejunal anastomosis has more than 10-20 cm (ideal length)
No - it can be prevented if a well constructed Roux-en-Y is fashioned
Since ALS is rare and hard to diagnose, all surgeons must be aware of its possibility. Only with a low threshold of suspicion, a prompt corrective surgery can be offered to patients. ALS can complicate a Billroth II reconstruction, and an improperly constructed Roux-en-Y. Paying attention to details when performing a Roux-en-Y reconstruction can prevent this serious complication.
Do not forget that small details are what makes you a (very) good surgeon.
Suggested reading (Medscape):
Link to PubMed:
Dr. Carlos Eduardo Costa Almeida
General Surgeon