Complicated Peptic Ulcer Findings on Abdominal CT Scan
Executive Summary
Peptic Ulcer Disease (PUD), while decreasing in overall prevalence due to the recognition of Helicobacter pylori and the use of proton-pump inhibitors (PPIs), remains a significant source of morbidity and mortality in emergency settings. Complicated PUD presents a disproportionate risk, with mortality rates exceeding ten times those of acute appendicitis or cholecystitis. While endoscopy remains the preferred diagnostic tool for non-perforated cases, Computed Tomography (CT) has emerged as the modality of choice for assessing acute abdominal pain and suspected perforation.
Crucial to effective CT diagnosis is the use of appropriate distention techniques—specifically low-attenuation oral agents like water—and the identification of discrete signs such as mucosal disruption, luminal outpouching, and perigastric fat stranding. Perforation and hemorrhage represent the most critical complications, with perforation alone accounting for up to 48% of nontraumatic pneumoperitoneum cases.
Clinical Overview of Peptic Ulcer Disease (PUD)
PUD is characterized by mucosal ulceration in the esophagus, stomach, or duodenum, primarily caused by gastric acid effects.
Symptomatology
Uncomplicated PUD: Primarily presents as epigastric pain described as a gnawing or burning sensation, typically occurring after meals. Clinical findings are often nonspecific.
Complicated PUD: Signs warranting prompt investigation include excruciating pain, acute anemia, bleeding, unexplained weight loss, recurrent vomiting, and progressive dysphagia.
Perforation: Usually marked by the sudden onset of severe, sharp abdominal pain.
Epidemiology and Complications
The distribution of PUD complications varies significantly by region, likely due to differences in NSAID use, H. pylori prevalence, and gastritis distribution:
Note: Perforation carries the highest mortality rate among all PUD complications.
CT Imaging Methodology and Protocols
Effective CT evaluation of the stomach and duodenum requires specific protocols to ensure adequate distention and visualization of the gastric wall.
Distention and Oral Contrast Agents
Adequate distention is essential; collapsed gastric walls can mask disease or create pseudotumors.
Water (Preferred): Water is inexpensive, well-tolerated, and does not interfere with 3D imaging or CT angiography. It allows for better visualization of the enhancing gastric wall compared to positive contrast agents.
Protocol: 750 mL administered 15 minutes before scanning, followed by an additional 250 mL immediately prior to the study.
Positive Contrast Agents: High-attenuation agents can mask subtle mucosal disease because the gastrointestinal wall itself enhances up to 120 HU after intravenous contrast administration.
Alternatives:
Whole Milk: Empties slowly and provides good distention but can cause diarrhea in lactose-intolerant patients.
Oil-based Agents: Provide good wall depiction but are unpalatable and cause steatorrhea.
Intravenous Contrast and Positioning
IV Contrast: Essential for evaluating inflammatory and neoplastic diseases. The recommended dose is 120 mL of nonionic contrast at a rate of 3 mL/s, with a 60-second delay (portal venous phase).
Positioning: While dorsal decubitus is standard, combining prone and supine imaging, or using decubitus imaging, can optimize the distention of the gastric antrum and pyloric region.
Diagnostic CT Findings in Peptic Ulcer Disease
Recognizing discrete signs is vital for identifying underlying PUD on a CT scan, as these findings can often be subtle.
Focal Luminal Outpouching: This represents the actual ulcer crater and is one of the earliest recognized CT signs of PUD.
Disruption of Mucosal Enhancement: Indicates erosion through the muscularis mucosa; this is a key marker for identifying the site of gastrointestinal perforation.
Low-Attenuation Wall Thickening: Represents submucosal edema, signaling underlying bowel inflammation.
Mucosal Hyperenhancement: Indicates mucosal hyperemia associated with gastritis or duodenitis.
Perigastric/Periduodenal Inflammation: Characterized by fat stranding in the tissues surrounding the stomach or duodenum.
Analysis of Major Complications
Hemorrhage
Hemorrhage is the most common complication in some regions (e.g., the US).
Vascular Involvement: Gastric ulcers along the lesser curvature typically affect the left gastric artery, while duodenal ulcers often affect the gastroduodenal artery.
CT Identification: Requires a multiphase scan (non-contrast, arterial, and delayed) without positive oral contrast.
Evidence of Bleeding:
Active extravasation of intravenous contrast into the bowel lumen.
Presence of amorphous high-attenuation content (clots or hematomas) measuring more than +40 HU.
Perforation and Penetration
Perforation results in free communication between the lumen and the peritoneal space.
Perforation Locations: Generally occurs in ulcers on the anterior wall of the stomach/duodenum or the gastric curvatures. Duodenal perforations may be intraperitoneal or retroperitoneal.
Ulcer Penetration: Occurs when an ulcer enters beyond the serosa into adjacent soft tissue (e.g., the pancreas). This typically involves posteriorly located ulcers.
Primary CT Findings of Perforation:
Pneumoperitoneum (often abundant).
Bowel wall thickening and discontinuity (visualization of the crater).
Extravasation of ingested oral contrast (observed in less than 50% of cases as many ulcers seal off rapidly).
Secondary CT Findings: Loculated gas collections or fluid in unusual peritoneal or retroperitoneal locations.
Obstruction
While less common in Western populations (3%), obstruction remains a leading complication in other regions, such as Nigeria (56%), often requiring surgical intervention.
