A 52-year-old woman with a history of peptic ulcer disease presents to the emergency department with sudden-onset severe epigastric pain radiating to the back. She is in severe distress, with a rigid, board-like abdomen and rebound tenderness. Her blood pressure is 110/70 mmHg and heart rate is 110 bpm. Plain abdominal radiograph (supine and erect views) shows a large collection of free air under both hemidiaphragms, with the stomach appearing as a large, gas-filled structure. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Acute Gastric Perforation ### Key Radiographic Sign: Pneumoperitoneum **Key Point:** Free air under the diaphragm (pneumoperitoneum) on an erect or left lateral decubitus radiograph is the hallmark of a perforated viscus. The location and clinical context help identify the source. ### Radiographic Features of Perforation | Feature | Appearance | Significance | |---------|-----------|---------------| | **Free air under diaphragm** | Lucent crescent or collection under the dome of the diaphragm | Pathognomonic for perforation | | **Rigler's sign** | Gas on both sides of the bowel wall (intraluminal and extraluminal) | Indicates pneumoperitoneum | | **Football sign** | Oval lucency in the pelvis (supine view) | Free air in the pelvis | | **Falciform ligament sign** | Gas outlining the falciform ligament | Indicates free air in the peritoneal cavity | | **Large gastric bubble** | Distended stomach with air | Suggests gastric perforation or outlet obstruction | ### Why Gastric Perforation in This Case 1. **History of peptic ulcer disease** — gastric ulcers can perforate, especially in the anterior wall 2. **Sudden-onset severe epigastric pain** — classic presentation of acute perforation 3. **Board-like, rigid abdomen with rebound tenderness** — peritonitis from gastric contents spilling into the peritoneal cavity 4. **Large amount of free air under both hemidiaphragms** — gastric perforation typically produces copious free air because the stomach is a large, air-filled organ 5. **Large gas-filled stomach on the radiograph** — suggests the source is gastric **Clinical Pearl:** Gastric perforation is a surgical emergency. The mortality rate increases significantly with delayed diagnosis and treatment. Unlike duodenal ulcer perforation (which may occasionally be managed conservatively with nasogastric suction and antibiotics in highly selected cases), gastric perforation almost always requires urgent surgical repair. **High-Yield:** The amount of free air on plain radiography does not correlate with the size of the perforation, but gastric perforations tend to produce more free air than small bowel perforations because of the large volume of gas in the stomach. ### Differential: Duodenal vs. Gastric Perforation | Feature | Duodenal Perforation | Gastric Perforation | |---------|---------------------|--------------------| | **Location of pain** | Epigastric, may localize to right upper quadrant | Epigastric, may radiate to back | | **Amount of free air** | Often less (duodenum is retroperitoneal) | Often more (stomach is intraperitoneal) | | **Gastric bubble size** | Normal or small | Often large and distended | | **Management** | May be managed conservatively in selected cases | Almost always requires surgery | **Mnemonic: PERFORATION** — Pneumoperitoneum, Epigastric pain, Rigid abdomen, Free air, Onset sudden, Rigler's sign, Acute peritonitis, Treat surgically, Imaging confirms, Omit conservative management (for gastric), Nasogastric tube as adjunct