afferent loop syndrome

Roux-en-Y
gastric bypass surgery • Gastric remnant obstruction due to adenocarcinoma after remote roux-en-y gastric bypass - Ganzer Fall bei Radiopaedia
Hartung M, Gastric remnant obstruction due to adenocarcinoma after remote roux-en-y gastric bypass. Case study, Radiopaedia.org (Accessed on 18 Mar 2023) https://doi.org/10.53347/rID-60338 • CC by-nc-sa 3.0 (modified)
Roux-en-Y
gastric bypass surgery • Afferent loop syndrome - secondary to incarcerated trocar site hernia - Ganzer Fall bei Radiopaedia
Riahi P, Afferent loop syndrome - secondary to incarcerated trocar site hernia. Case study, Radiopaedia.org (Accessed on 18 Mar 2023) https://doi.org/10.53347/rID-82959 • CC by-nc-sa 3.0 (modified)
Afferent loop
syndrome • Afferent loop syndrome due to internal hernia and closed-loop obstruction - Ganzer Fall bei Radiopaedia
Hartung M, Afferent loop syndrome due to internal hernia and closed-loop obstruction. Case study, Radiopaedia.org (Accessed on 19 Jul 2024) https://doi.org/10.53347/rID-97027 • CC by-nc-sa 3.0 (modified)
Radiopaedia • CC-by-nc-sa 3.0 • de

Afferent loop syndrome is an intermittent partial or complete mechanical obstruction of the afferent limb of a gastrojejunostomy.

The syndrome classically refers to obstruction of the upstream limb of a side-to-side gastrojejunostomy but has also been used to refer to the biliopancreatic limb of a Roux-en-Y gastrojejunostomy. It can be seen after:

Epidemiology

Afferent loop syndrome is not an uncommon postoperative complication, and one study has estimated that it occurs in 13% of post-pancreaticoduodenectomy patients . Afferent limb syndromes have decreased in incidence with newer surgical techniques to decrease the size of the limb.

Clinical presentation

Patients usually present with epigastric pain, abdominal distention, nausea, and potentially bilious vomiting. It has been classified as acute (<7 days postoperative) or chronic (>7 days postoperative). Bilious vomiting is presumed to occur from regurgitation of bilious contents in the afferent limb into the stomach after release from intermittent obstruction.

Pathology

Possible causes of afferent loop syndrome include kinking at the anastomosis, radiation stricture, internal hernia, or recurrent tumor at the anastomosis.

Radiographic features

Abdominal radiograph
  • dilated bowel in the right upper quadrant
  • no dilated bowel may be present, and a high clinical suspicion should be maintained in the appropriate setting
Fluoroscopy
  • non-opacification of the afferent loop on an upper GI study
  • possible delayed filling of an enlarged afferent loop
CT
  • "U-shaped" loop of bowel, adjacent to the pancreas, usually containing water attenuation fluid
  • common bile duct should enter into the loop
  • possible gallbladder and biliary dilatation

Treatment and prognosis

Both transhepatic and transgastric approaches to relieve the obstruction have been used. An open procedure is also possible but second line.

Practical points

  • there is some differing use of the term "afferent limb" in the literature and depending on the type of surgery
    • in some sources, "afferent limb" is used to refer to stump of small bowel upstream from the Roux limb; some sources use it to refer to the biliopancreatic limb; always check the context to understand the function of the "afferent limb"
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