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Zorluk: OrtaInterpreting Imaging Results

A 76-year-old woman is brought to the emergency department from a skilled nursing facility due to a 3-day history of diffuse abdominal pain, progressive distension, and nonbilious emesis that has recently become feculent. She has a history of type 2 diabetes mellitus, hypertension, and recurrent symptomatic gallstones for which she previously declined surgery. Her temperature is 37.8°C (100.0°F), blood pressure is 105/65 mmHg, pulse is 112/min, and respiratory rate is 18/min. Physical examination reveals a distended and tympanitic abdomen with high-pitched, tinkling bowel sounds. There is diffuse mild tenderness but no rigidity or guarding. A contrast-enhanced CT scan of the abdomen and pelvis is performed. The radiologist's report describes the following key findings:

1. Markedly dilated loops of small bowel measuring up to 4.5 cm in diameter, with a distinct transition point in the right lower quadrant.
2. A 3.2-cm lamellated, calcified mass located intraluminally at the transition point in the terminal ileum.
3. Branching, linear radiolucencies over the central portion of the liver that do not extend to the liver capsule.

Which of the following is the most likely underlying mechanism for these imaging findings?

  1. Fistulous communication between the biliary system and the enteric tractCevap
  2. B
    Ischemic necrosis of the bowel wall with gas translocating into the portal venous system
  3. C
    Gas-forming bacterial infection of the gallbladder wall with paralytic ileus
  4. D
    Obstructing primary intestinal neoplasm with dystrophic calcification and microperforation
  5. E
    Impaction of a biliary calculus within the common bile duct causing upstream dilation

Cevap

Fistulous communication between the biliary system and the enteric tract
The correct answer is a fistulous communication between the biliary system and the enteric tract. The patient's clinical presentation and CT imaging findings represent Rigler's triad: (1) small bowel obstruction (dilated loops with a transition point), (2) pneumobilia (branching radiolucencies in the central liver), and (3) an ectopic gallstone (lamellated, calcified mass in the terminal ileum). This triad is pathognomonic for gallstone ileus. It occurs when a large gallstone causes chronic inflammation, eroding through the gallbladder wall directly into the adjacent bowel (most commonly the duodenum) to form a cholecystoenteric fistula. The stone then travels through the gastrointestinal tract until it impacts at the narrowest point, which is typically the ileocecal valve, resulting in a mechanical obstruction.

Adım Adım Çözüm

1
Analyze the CT findings of the small bowel.
Identify markedly dilated loops of small bowel with a transition point in the right lower quadrant and a 3.2-cm intraluminal calcified mass.
Establishes the presence of a mechanical small bowel obstruction caused by a large, ectopic calcified object (gallstone).
2
Analyze the hepatic CT findings.
Identify branching, linear radiolucencies in the central liver.
Differentiates pneumobilia (biliary gas, which is central due to bile flow direction) from portal venous gas (which is peripheral due to portal blood flow direction).
3
Synthesize the imaging findings with the patient's history.
Combine the history of gallstones with the imaging findings of small bowel obstruction, ectopic gallstone, and pneumobilia (Rigler's triad).
Confirms the diagnosis of gallstone ileus, which occurs when a gallstone erodes through the gallbladder wall into the GI tract, creating a cholecystoenteric fistula.

Anahtar Kavram

Rigler's triad on abdominal imaging (small bowel obstruction, pneumobilia, and an ectopic gallstone) is pathognomonic for gallstone ileus resulting from a cholecystoenteric fistula.
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Interpreting Imaging Results

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