Sunday, December 28, 2008
Afferent Loop Syndrome
I performed a Whipple not too long ago for a pancreatic head mass. On the fifth post-op day, she started spiking fevers. The ensuing fever work-up included a CT scan of the abdomen (images shown above). What we see is a dilated loop of small bowel trekking transversely across the abdomen. The rest of the bowels appear normal. Closer inspection also reveals some oral contrast refluxing back into the intrahepatic biliary branches.
What we're dealing with is a classic case of Afferent Loop Syndrome. When you do a Whipple or a Billroth II gastrectomy, there is a loop of bowel (jejunum and/or duodenum) that extends upstream from the gastrojejunostomy toward the pancreas and common bile duct. The efferent limb extends downstream through the distal jejunum and on down towards the cecum. Afferent loop syndrome is a mechanical bowel obstruction (internal hernia, volvulus, stricturing, etc) that results in an effective biliary outlet obstruction.
In a post-op Whipple patient, an acute afferent limb obstruction is especially concerning because there's a fresh bilary anastomosis potentially at risk. If the intestinal limb of the choledochojejunostomy is all dilated and inflamed, you worry about suture line breakdown and development of a bile leak. Moreover, if the bile can't flow downstream, it's going to tend to reflux back into the liver, along with the bacterial flora of the small intestine. This can lead to a severe form of ascending cholangitis, with liver abscess formation.
Now you can't screw around if you suspect afferent loop syndrome. The treatment is surgical. It's a mechanical problem. Sitting around and assuming there's just an ileus or a motility problem will only delay the inevitable. The longer you wait, the worse your patient will do.
When I took her back, the obstructed, summer sausage-swollen afferent limb was confirmed. The choledochojejunostomy looked ok, but seemed to be ready to burst at the seams. The etiology wasn't entirely clear to me. It wasn't a volvulus. There wasn't an internal hernia. It just didn't seem to want to "lay right" without kinking (perhaps secondary to some redundancy in the afferent limb). So I rerouted the afferent limb downstream via a Roux-en-Y reconstruction. Subsequently, the cholangitis cleared up and she ultimately went home a week or so later...