Gastric Foreign Bodies

Gastric foreign bodies (GFBs) refer to ingested objects that become lodged within the stomach, failing to pass through the pylorus into the duodenum. These objects can be either non-absorbable or absorbable, and may be composed of organic or inorganic materials. The presence of a GFB can lead to partial or complete gastric outlet obstruction, mucosal irritation, ulceration, perforation, peritonitis, and systemic metabolic derangements. In veterinary surgery, GFBs are a common indication for gastrotomy, a surgical procedure involving an incision into the stomach for retrieval. The clinical significance of GFBs lies in their potential to cause life-threatening complications if not promptly diagnosed and managed. Surgical intervention is often required, and the approach must be tailored to the size, shape, and location of the foreign body, as well as the patient's overall health status.

The etiology of gastric foreign bodies is primarily related to dietary indiscretion and behavioral factors. Dogs, especially those with a tendency to scavenge or chew on non-food items, are most commonly affected. Cats may also ingest foreign bodies, particularly linear objects such as string, ribbon, or tinsel, which can lead to a unique set of complications. Common foreign bodies include toys, bones, stones, fabric, plastic, rubber, coins, batteries, and fishing hooks. In some cases, trichobezoars (hairballs) can form in the stomach, especially in long-haired cats. Iatrogenic causes are rare but may include retained surgical sponges or instruments. The anatomical vulnerability of the stomach lies in its distensibility and the pyloric sphincter, which can become a site of obstruction for objects that are too large to pass. The cellular mechanisms involved include mechanical irritation, pressure necrosis, and ischemia of the gastric wall, leading to inflammation, ulceration, and potential perforation.

Gastric foreign bodies are most commonly diagnosed in young to middle-aged dogs, with a median age of 2 to 4 years. There is no strong sex predilection, but some studies suggest a slight male predominance. Certain breeds are overrepresented, including Labrador Retrievers, Golden Retrievers, German Shepherds, and other large-breed dogs, likely due to their chewing and scavenging behaviors. Working dogs, such as hunting and police dogs, may be at higher risk due to increased exposure to foreign objects. Cats of any breed can be affected, but those with access to string or linear objects are particularly vulnerable. The incidence of GFBs is relatively high in veterinary emergency practice, accounting for a significant proportion of gastrointestinal surgical cases. There is no known genetic predisposition, but behavioral factors, such as anxiety, boredom, or pica, can increase the risk.

The pathophysiology of gastric foreign bodies involves a cascade of events that can lead to severe complications. Initially, the foreign body causes mechanical irritation to the gastric mucosa, leading to inflammation (gastritis) and increased mucus production. If the object is large or irregular, it may become lodged in the pyloric antrum, causing partial or complete gastric outlet obstruction. This obstruction leads to gastric distension, increased intraluminal pressure, and impaired gastric emptying. The retained gastric contents, including food and gastric acid, can cause further mucosal damage and lead to vomiting, dehydration, and electrolyte imbalances (hypochloremia, hypokalemia, metabolic alkalosis). Prolonged pressure on the gastric wall can cause ischemia, necrosis, and ultimately perforation, resulting in septic peritonitis. Linear foreign bodies, such as string, can cause a plication (accordion-like) effect on the intestines, leading to linear foreign body syndrome, which may involve the stomach and intestines. Additionally, sharp objects can directly penetrate the gastric wall, causing localized peritonitis or abscess formation. The systemic inflammatory response syndrome (SIRS) can develop secondary to peritonitis, leading to sepsis and multi-organ dysfunction.

Predisposing factors for gastric foreign bodies include intrinsic and extrinsic elements. Intrinsic factors include age (young animals are more curious and prone to ingest non-food items), breed (retrievers and other chewers), and behavioral traits such as pica, anxiety, or boredom. Metabolic conditions like diabetes mellitus or hyperthyroidism may increase appetite and ingestion of unusual items. Extrinsic factors include environmental access to foreign objects (e.g., toys, bones, garbage), inadequate supervision, and lack of appropriate chew toys. Prior gastrointestinal surgery may predispose to stricture or altered motility, increasing the risk of foreign body impaction. Additionally, certain medical conditions like gastroparesis or pyloric stenosis can delay gastric emptying, making it easier for foreign bodies to become lodged.

Clinical signs of gastric foreign bodies vary depending on the size, location, and duration of the foreign body. Common signs include acute or chronic vomiting, which may be intermittent or persistent. Vomiting may occur immediately after eating or at any time, and can be projectile if there is complete obstruction. Anorexia, lethargy, and weight loss are common. Abdominal pain may be evident on palpation, and in some cases, the foreign body may be palpable if it is large. If the foreign body has caused perforation, signs of peritonitis, such as fever, abdominal distension, and severe pain, may be present. In cases of linear foreign bodies, the owner may notice the object protruding from the anus, and the patient may show signs of tenesmus. Dehydration and electrolyte imbalances can lead to weakness, depression, and in severe cases, shock. Physical examination may reveal a tense, painful abdomen, and in cases of gastric dilation, a tympanic sound on percussion.

Differential diagnoses for gastric foreign bodies include: 1) Gastritis (acute or chronic) - may present with similar vomiting but typically no palpable foreign body; 2) Gastric ulcers - can cause vomiting and abdominal pain, but imaging may show ulceration rather than a foreign body; 3) Gastric neoplasia (e.g., adenocarcinoma, lymphoma) - may cause chronic vomiting and weight loss, but imaging and biopsy are needed; 4) Pyloric stenosis - congenital or acquired, leading to outflow obstruction; 5) Gastric dilation-volvulus (GDV) - acute, severe distension with non-productive vomiting; 6) Intestinal foreign body - if the object has passed into the intestines, clinical signs may be similar, but imaging can localize the obstruction; 7) Pancreatitis - can cause vomiting and abdominal pain, but laboratory findings and imaging help differentiate; 8) Gastroenteritis - infectious or dietary, usually self-limiting; 9) Parasitic infections (e.g., Physaloptera) - can cause chronic vomiting; 10) Inflammatory bowel disease (IBD) - chronic vomiting and diarrhea, diagnosed by biopsy. Definitive diagnosis is made through imaging and/or endoscopy.

The diagnostic algorithm for gastric foreign bodies begins with a thorough history and physical examination. If a foreign body is suspected, abdominal radiographs (plain and contrast) are the first-line imaging modality. Plain radiographs may reveal a radiopaque foreign body or signs of gastric distension. If the foreign body is radiolucent, a positive contrast study (barium or iohexol) may be performed to outline the gastric lumen and identify filling defects. However, if perforation is suspected, contrast studies should be avoided or use a non-ionic iodinated contrast agent. Ultrasonography is also useful for detecting foreign bodies, especially those that are not radiopaque, and can assess gastric wall thickness and peristalsis. In stable patients, endoscopy can be both diagnostic and therapeutic, allowing visualization and retrieval of the foreign body. If endoscopy is not available or the foreign body is too large or sharp, exploratory laparotomy and gastrotomy are indicated. Preoperative laboratory workup, including complete blood count, serum biochemistry, and electrolyte panel, is essential to assess metabolic derangements and surgical risk.

Laboratory findings in gastric foreign bodies are often non-specific but can reflect the severity and duration of the obstruction. Hematology may show a stress leukogram or, in cases of peritonitis, a left shift and toxic neutrophils. Biochemistry may reveal dehydration (elevated total protein, BUN, creatinine), electrolyte imbalances (hypochloremia, hypokalemia, metabolic alkalosis), and in cases of prolonged vomiting, a metabolic acidosis may develop. Liver enzymes may be mildly elevated due to decreased hepatic perfusion. In cases of perforation, inflammatory markers such as C-reactive protein (CRP) may be elevated. Coagulation panel (PT/aPTT) is recommended if sepsis or disseminated intravascular coagulation (DIC) is suspected. Blood gas analysis can help assess acid-base status. Urinalysis may show concentrated urine due to dehydration. Synovial fluid analysis is not relevant in this condition.

Imaging plays a crucial role in the diagnosis of gastric foreign bodies. Plain radiography (lateral and ventrodorsal views) is the initial step. Radiopaque foreign bodies (e.g., metal, bone, some plastics) are readily visible. However, many foreign bodies are radiolucent and may not be seen. Signs of gastric obstruction include gastric distension with gas or fluid, and delayed gastric emptying. If a radiolucent foreign body is suspected, a positive contrast study using barium sulfate (if no perforation suspected) or iohexol (if perforation is possible) can be performed. The contrast agent will outline the gastric mucosa and reveal filling defects or retention of contrast in the stomach. Ultrasonography is highly sensitive for detecting foreign bodies, especially those with a hyperechoic surface and acoustic shadowing. It can also assess gastric wall thickness, peristalsis, and the presence of free abdominal fluid (suggestive of perforation). Computed tomography (CT) is increasingly used in veterinary medicine and provides excellent detail, especially for complex cases or when neoplasia is suspected. CT can identify the exact location, size, and shape of the foreign body, as well as any complications such as abscesses or peritonitis. Endoscopy is both diagnostic and therapeutic, allowing direct visualization and retrieval of the foreign body. Fluoroscopy may be used during endoscopic retrieval to guide the procedure.

Cytology and histopathology are not typically required for the diagnosis of gastric foreign bodies, but they may be performed if there is suspicion of an underlying pathology, such as neoplasia or inflammatory bowel disease. During gastrotomy, if the gastric wall appears abnormal, biopsies may be taken for histopathology. Histological findings may include chronic gastritis, ulceration, fibrosis, or neoplasia. If a mass is present, fine-needle aspiration cytology may be performed preoperatively, but this is rare. In cases of perforation, peritoneal fluid analysis may be performed, which can show septic suppurative inflammation with intracellular bacteria. Histopathology of the gastric wall at the site of foreign body impaction may reveal pressure necrosis, ischemia, and inflammatory infiltrate.

Treatment of gastric foreign bodies depends on the size, type, and location of the object, as well as the patient's clinical status. In some cases, small, smooth foreign bodies may pass spontaneously, but if they remain in the stomach for more than 24-48 hours or cause clinical signs, intervention is warranted. Endoscopic retrieval is the preferred method for many foreign bodies, especially those that are small, smooth, or located in the gastric lumen. Endoscopic retrieval can be performed using a flexible endoscope with grasping forceps, baskets, or snares. If the foreign body is too large, sharp, or firmly lodged, surgical removal via gastrotomy is necessary. Preoperative stabilization is crucial: intravenous fluids to correct dehydration and electrolyte imbalances, antiemetics (e.g., maropitant 1 mg/kg IV q24h), and gastric acid suppressants (e.g., omeprazole 1 mg/kg IV q12h or pantoprazole 1 mg/kg IV q12h). Broad-spectrum antibiotics (e.g., ampicillin 22 mg/kg IV q8h and enrofloxacin 10 mg/kg IV q24h) are indicated if perforation or peritonitis is suspected. Surgical technique for gastrotomy: The patient is positioned in dorsal recumbency. A ventral midline celiotomy is performed from the xiphoid to the umbilicus. The stomach is exteriorized and packed off with laparotomy sponges. Stay sutures are placed in the gastric wall to stabilize it. A stab incision is made in an avascular area of the gastric body, avoiding the greater curvature and pylorus. The incision is extended with Metzenbaum scissors or a scalpel. The foreign body is carefully removed, and the gastric lumen is inspected for additional foreign bodies or mucosal damage. The gastrotomy is closed in two layers: a continuous appositional pattern (e.g., 3-0 polydioxanone or polyglactin 910) for the mucosa and submucosa, followed by a continuous or interrupted seromuscular layer (e.g., 3-0 polydioxanone). The abdomen is lavaged with warm sterile saline if there is contamination. Postoperative care includes continued fluid therapy, analgesics (e.g., opioids such as buprenorphine 0.01-0.02 mg/kg IV q8-12h or methadone 0.2-0.5 mg/kg IV q4-6h), and antiemetics. Feeding is typically resumed 12-24 hours postoperatively with a bland diet. If the foreign body has caused gastric necrosis or perforation, partial gastrectomy may be required. In cases of linear foreign bodies, multiple enterotomies may be necessary to remove the object, and the stomach may be involved.

The prognosis for gastric foreign bodies is generally good if treated promptly and appropriately. The overall success rate for surgical removal is high, with most patients recovering without complications. Short-term prognosis is excellent for uncomplicated cases, with a return to normal function within a few days. Medium-term prognosis is also good, but complications such as wound infection, dehiscence, or peritonitis can occur, especially if there was perforation or severe contamination. Long-term prognosis is excellent, with no lasting effects on gastric function. Negative prognostic indicators include delayed presentation, presence of peritonitis, gastric necrosis, and concurrent systemic disease. The mortality rate for uncomplicated gastrotomy is low (<5%), but it increases to 20-30% if peritonitis is present.

Postoperative follow-up for gastric foreign body surgery is essential to monitor recovery and detect complications. Suture removal is typically not required for skin sutures if absorbable sutures are used, but if non-absorbable skin sutures are placed, they are removed in 10-14 days. Patients should be re-evaluated at 2 weeks postoperatively to assess wound healing and overall condition. Serial radiographs are not routinely needed unless there are concerns about gastric emptying or complications. Activity restriction is recommended for 2 weeks to allow for healing of the gastrotomy site. A bland diet is fed for 3-5 days, then gradually transitioned to the patient's regular diet. Owners should monitor for signs of vomiting, anorexia, or abdominal pain, which may indicate complications such as dehiscence or peritonitis. Long-term follow-up is generally not required, but if the patient has a history of pica or dietary indiscretion, behavioral modification and environmental management are recommended to prevent recurrence.

Clinical pearls: 1) Always perform a thorough abdominal palpation, but be aware that many foreign bodies are not palpable. 2) Use a non-ionic iodinated contrast agent (e.g., iohexol) if perforation is suspected, as barium can cause severe peritonitis. 3) During gastrotomy, place stay sutures to minimize gastric content spillage. 4) Always inspect the entire gastrointestinal tract for additional foreign bodies, especially in cases of linear foreign bodies. 5) Consider endoscopic retrieval for small, smooth foreign bodies to avoid surgery. 6) In cases of gastric dilation, decompress the stomach before surgery to improve visualization and reduce the risk of aspiration. Pitfalls: 1) Failure to correct electrolyte imbalances preoperatively can lead to cardiac arrhythmias. 2) Incomplete closure of the gastrotomy can lead to leakage and peritonitis. 3) Missing a second foreign body can lead to persistent clinical signs. 4) Using barium in a patient with suspected perforation can cause severe peritonitis. 5) Overlooking gastric necrosis can lead to delayed perforation. 6) Inadequate postoperative analgesia can lead to prolonged recovery and complications.

Perioperative drug protocols for gastric foreign body surgery are based on Plumb's Veterinary Drug Handbook. Preoperative: 1) Antimicrobial prophylaxis: Cefazolin 22 mg/kg IV at induction, repeated every 90 minutes during surgery if needed. If perforation is suspected, continue with ampicillin 22 mg/kg IV q8h and enrofloxacin 10 mg/kg IV q24h or clindamycin 11 mg/kg IV q12h for 24-48 hours postoperatively. 2) Analgesia: Preoperative opioids such as methadone 0.2-0.5 mg/kg IV or buprenorphine 0.01-0.02 mg/kg IV. Intraoperative: 1) Local anesthesia: Lidocaine 2 mg/kg IV slow bolus, then CRI at 50-100 mcg/kg/min for analgesia and to reduce anesthetic requirements. 2) Antiemetics: Maropitant 1 mg/kg IV q24h. Postoperative: 1) Analgesia: Continue opioids (e.g., methadone 0.2-0.5 mg/kg IV q4-6h or buprenorphine 0.01-0.02 mg/kg IV q8-12h) for 24-48 hours, then transition to oral NSAIDs (e.g., carprofen 2.2 mg/kg PO q12h or meloxicam 0.1 mg/kg PO q24h) if no contraindications. 2) Gastroprotectants: Omeprazole 1 mg/kg IV or PO q12h or famotidine 0.5-1 mg/kg IV or PO q12h. 3) Antiemetics: Maropitant 1 mg/kg PO q24h for 2-3 days. 4) Fluid therapy: Balanced crystalloids (e.g., lactated Ringer's solution) at maintenance rates (60-100 ml/kg/day) with additional potassium chloride as needed to maintain serum potassium >3.5 mEq/L. 5) Nutritional support: If the patient is anorexic for >3 days, consider enteral feeding via esophagostomy or gastrostomy tube. 6) Antibiotics: If peritonitis was present, continue broad-spectrum antibiotics for 7-10 days based on culture and sensitivity.

Evidence-based literature on gastric foreign bodies is limited but provides valuable insights. A retrospective study by Hayes (2009) in the Journal of Small Animal Practice reported that the most common foreign bodies in dogs were toys and bones, and that surgical removal was required in 80% of cases. The study found that the presence of peritonitis was a negative prognostic indicator. Another study by Papazoglou et al. (2003) in Veterinary Record evaluated the use of endoscopy for foreign body removal and reported a success rate of 90% for gastric foreign bodies, with complications in 5% of cases. A more recent study by Gianella et al. (2017) in the Journal of Veterinary Emergency and Critical Care compared surgical and endoscopic removal and found that endoscopic removal was associated with shorter hospital stays and lower costs. However, surgical removal was more effective for large or sharp objects. Consensus guidelines from the American College of Veterinary Surgeons (ACVS) recommend that surgical intervention be considered if a foreign body remains in the stomach for more than 24 hours or if clinical signs are severe. The use of prophylactic antibiotics is recommended only if there is contamination or perforation. Overall, the evidence supports early intervention and the use of minimally invasive techniques when feasible.