The diagnosis is mainly established based on the characteristic symptoms. Stomach pain is usually the first signal of a peptic ulcer. In some cases, doctors may treat ulcers without diagnosing them with specific tests and observe whether the symptoms resolve, thus indicating that their primary diagnosis was accurate.

More specifically, peptic ulcers erode the muscularis mucosae, at minimum reaching to the level of the submucosa (contrast with erosions, which do not involve the muscularis mucosae).

Confirmation of the diagnosis is made with the help of tests such as endoscopies or barium contrast x-rays. The tests are typically ordered if the symptoms do not resolve after a few weeks of treatment, or when they first appear in a person who is over age 45 or who has other symptoms such as weight loss, because stomach cancer can cause similar symptoms. Also, when severe ulcers resist treatment, particularly if a person has several ulcers or the ulcers are in unusual places, a doctor may suspect an underlying condition that causes the stomach to overproduce acid.

An esophagogastroduodenoscopy (EGD), a form of endoscopy, also known as a gastroscopy, is carried out on people in whom a peptic ulcer is suspected. By direct visual identification, the location and severity of an ulcer can be described. Moreover, if no ulcer is present, EGD can often provide an alternative diagnosis.

One of the reasons that blood tests are not reliable for accurate peptic ulcer diagnosis on their own is their inability to differentiate between past exposure to the bacteria and current infection. Additionally, a false negative result is possible with a blood test if the person has recently been taking certain drugs, such as antibiotics or proton-pump inhibitors.

The diagnosis of "Helicobacter pylori" can be made by:

- Urea breath test (noninvasive and does not require EGD);

- Direct culture from an EGD biopsy specimen; this is difficult to do, and can be expensive. Most labs are not set up to perform "H. pylori" cultures;

- Direct detection of urease activity in a biopsy specimen by rapid urease test;

- Measurement of antibody levels in the blood (does not require EGD). It is still somewhat controversial whether a positive antibody without EGD is enough to warrant eradication therapy;

- Stool antigen test;

- Histological examination and staining of an EGD biopsy.

The breath test uses radioactive carbon to detect H. pylori. To perform this exam the person will be asked to drink a tasteless liquid which contains the carbon as part of the substance that the bacteria breaks down. After an hour, the person will be asked to blow into a bag that is sealed. If the person is infected with H. pylori, the breath sample will contain radioactive carbon dioxide. This test provides the advantage of being able to monitor the response to treatment used to kill the bacteria.

The possibility of other causes of ulcers, notably malignancy (gastric cancer) needs to be kept in mind. This is especially true in ulcers of the "greater (large) curvature" of the stomach; most are also a consequence of chronic "H. pylori" infection.

If a peptic ulcer perforates, air will leak from the inside of the gastrointestinal tract (which always contains some air) to the peritoneal cavity (which normally never contains air). This leads to "free gas" within the peritoneal cavity. If the person stands erect, as when having a chest X-ray, the gas will float to a position underneath the diaphragm. Therefore, gas in the peritoneal cavity, shown on an erect chest X-ray or supine lateral abdominal X-ray, is an omen of perforated peptic ulcer disease.

People under 55 years without alarm symptoms can be treated without investigation. People over 55 years with recent onset dyspepsia or those with alarm symptoms should be urgently investigated by upper gastrointestinal endoscopy. This will rule out peptic ulcer disease, medication-related ulceration, malignancy and other rarer causes.

People under the age of 55 years with no alarm features do not need endoscopy but are considered for investigation for peptic ulcer disease caused by "Helicobacter pylori" infection. Investigation for "H. pylori" infection is usually performed when there is a moderate to high prevalence of this infection in the local community or the person with dyspepsia has other risk factors for "H. pylori" infection, related for example to ethnicity or immigration from a high-prevalence area. If infection is confirmed, it can usually be eradicated by medication.

Medication-related dyspepsia is usually related to NSAIDs and can be complicated by bleeding or ulceration with perforation of stomach wall.

GAVE is usually diagnosed definitively by means of an endoscopic biopsy. The tell-tale watermelon stripes show up during the endoscopy.

Surgical exploration of the abdomen may be needed to diagnose some cases, especially if the liver or other organs are involved.

The diagnosis of GERD is usually made when typical symptoms are present. Reflux can be present in people without symptoms and the diagnosis requires both symptoms or complications and reflux of stomach content.

Other investigations may include esophagogastroduodenoscopy (EGD). Barium swallow X-rays should not be used for diagnosis. Esophageal manometry is not recommended for use in diagnosis, being recommended only prior to surgery. Ambulatory esophageal pH monitoring may be useful in those who do not improve after PPIs and is not needed in those in whom Barrett's esophagus is seen. Investigation for H. pylori is not usually needed.

The current gold standard for diagnosis of GERD is esophageal pH monitoring. It is the most objective test to diagnose the reflux disease and allows monitoring GERD patients in their response to medical or surgical treatment. One practice for diagnosis of GERD is a short-term treatment with proton-pump inhibitors, with improvement in symptoms suggesting a positive diagnosis. Short-term treatment with proton-pump inhibitors may help predict abnormal 24-hr pH monitoring results among patients with symptoms suggestive of GERD.

A gastric peptic ulcer is a mucosal perforation which penetrates the muscularis mucosae and lamina propria, usually produced by acid-pepsin aggression. Ulcer margins are perpendicular and present chronic gastritis. During the active phase, the base of the ulcer shows 4 zones: fibrinoid necrosis, inflammatory exudate, granulation tissue and fibrous tissue. The fibrous base of the ulcer may contain vessels with thickened wall or with thrombosis.

The tests that are considered to evaluate of the passage of blood in the stool are based on the characteristics of bleeding (color, quantity) and whether or not the person passing blood has a low blood pressure with elevated heart rate, as opposed to normal vital signs. The following tests are combined to determine the causes of the source of bleeding.

- Digital rectal exam (DRE) and fecal occult blood test (FOBT)

- Colonoscopy

- Anoscopy

- Esophagogastroduodenoscopy (EGD)

- Capsule endoscopy

- CT Scan

Melena is defined as dark, tarry stools, often black in color due to partial digestion of the RBCs.

Hematochezia is defined as bright red blood seen in the toilet either inside of, or surrounding the stool.

Hematochezia is typically presumed to come from the lower portion of the GI tract, and the initial steps of diagnosis include a DRE with FOBT, which if positive, will lead to a colonoscopy. If the person has a large amount of blood in their stool, an EGD test may be necessary. If no source of active bleeding is found on these examinations, a capsule endoscopy may be performed, in order to more closely examine the small bowel, which cannot be seen with the other types of studies. With melena, a DRE with FOBT is often also performed, however the suspicion for a source from the upper GI tract is higher, leading first to the use of EGD with the other tests being required if no source is identified. The anoscopy is another type of examination, which can be used along with a colonoscopy, which exams the rectum and distal portion of the descending colon.

With acutely ill patients, consider emergency surgery laparotomy if there is a high index of suspicion.

Plain radiography may demonstrate signs of duodenal obstruction with dilatation of the proximal duodenum and stomach but it is often non-specific. Upper gastrointestinal series is the modality of choice for the evaluation of malrotation as it will show an abnormal position of the duodeno-jejunal flexure (ligament of Treitz). In cases of malrotation complicated with volvulus, it demonstrates a corkscrew appearance of the distal duodenum and jejunum. In cases of obstructing Ladd bands, it will reveal a duodenal obstruction.

In equivocal cases, contrast enema, may be helpful by showing the caecum at an abnormal location.

It is usually discovered near birth, but in some cases is not discovered until adulthood. In adults, the "whirlpool sign" of the superior mesenteric artery can be useful in identifying malrotation.

A 2009 study which followed 189 patients found no excess mortality despite the increased risk of pancreatic cancer.

treatment of HP resemble that of chronic pancreatitis of other causes. Treatment focuses on enzyme and nutritional supplementation, pain management, pancreatic diabetes, and local organ complications, such as pseudocysts, bile duct or duodenal obstruction.(PMC1774562)

GAVE results in intestinal bleeding similar to duodenal ulcers and portal hypertension. The GI bleeding can result in anemia. It is often overlooked, but can be more common in elderly patients. It has been seen in a female patient of 26 years of age.

Watermelon stomach has a different etiology and has a differential diagnosis from portal hypertension. In fact, cirrhosis and portal hypertension may be missing in a patient with GAVE. The differential diagnosis is important because treatments are different.

Endoscopy, the looking down into the stomach with a fibre-optic scope, is not routinely needed if the case is typical and responds to treatment. It is recommended when people either do not respond well to treatment or have alarm symptoms, including dysphagia, anemia, blood in the stool (detected chemically), wheezing, weight loss, or voice changes. Some physicians advocate either once-in-a-lifetime or 5- to 10-yearly endoscopy for people with longstanding GERD, to evaluate the possible presence of dysplasia or Barrett's esophagus.

Biopsies performed during gastroscopy may show:

- Edema and basal hyperplasia (nonspecific inflammatory changes)

- Lymphocytic inflammation (nonspecific)

- Neutrophilic inflammation (usually due to reflux or "Helicobacter" gastritis)

- Eosinophilic inflammation (usually due to reflux): The presence of intraepithelial eosinophils may suggest a diagnosis of eosinophilic esophagitis (EE) if eosinophils are present in high enough numbers. Less than 20 eosinophils per high-power microscopic field in the distal esophagus, in the presence of other histologic features of GERD, is more consistent with GERD than EE.

- Goblet cell intestinal metaplasia or Barrett's esophagus

- Elongation of the papillae

- Thinning of the squamous cell layer

- Dysplasia

- Carcinoma

Reflux changes may not be erosive in nature, leading to "nonerosive reflux disease".

Resection is sometimes a part of a treatment plan, but duodenal cancer is difficult to remove surgically because of the area that it resides in—there are many blood vessels supplying the lower body. Chemotherapy is sometimes used to try to shrink the cancerous mass. Other times intestinal bypass surgery is tried to reroute the stomach to intestine connection around the blockage.

A 'Whipple' procedure is a type of surgery that is sometimes possible with this cancer. In this procedure, the duodenum, a portion of the Pancreas (the head), and the gall bladder are usually removed, the small intestine is brought up to the Pylorus (the valve at the bottom of the stomach) and the Liver and Pancreas digestive enzymes and bile are connected to the small intestine below the Pylorus.

The removal of part of the Pancreas often requires taking Pancreatic Enzyme supplements to aid digestion. These are available in the form of capsules by prescription.

It is not unusual for a patient having received a Whipple procedure to feel perfectly well, and to lead his/her normal life without difficulty.

It is important for the procedure to be performed by a surgeon with extensive experience having done and observed the procedure, as specific competence makes a big difference.

Some patients need to be fitted with tubes to either add nutrients (feeding tubes) or drainage tubes to remove excess processed food that can not pass the blockage.

Neonatal bowel obstruction is grouped into two general categories: high, or proximal, obstruction and low, or distal obstruction, both of which are suspected by failure to pass meconium at birth. High obstruction can be suspected based on the double bubble sign. Cases without distal gas are usually related to duodenal atresia, while high obstruction with distal gas need an upper gastrointestinal series because of the need to distinguish duodenal web, duodenal stenosis and annular pancreas from midgut volvulus, the latter being a surgical emergency. Confirmation is ultimately by surgical intervention.

A low obstruction is suspected on plain film, but needs follow up with a gastrografin enema, which itself can be therapeutic. The differential for low obstruction is ileal atresia, meconium ileus, meconium plug syndrome and Hirschsprung disease. In cases of meconium ileus or ileal atresia, the colon distal to the obstruction is hypoplastic, usually less than 1 cm in caliber, as development of normal colonic caliber "in utero" is due to the passage of meconium, which does not occur in either of these conditions. When diffusely small caliber is seen, it is referred to as microcolon. Radiographs in meconium ileus classically demonstrate a bubbly appearance in the right lower quadrant due to a combination of ingested air and meconium. If, on contrast enema, reflux into the dilated distal small bowel loops can be achieved, the study is both diagnostic and therapeutic, as the ionic contrast medium can dissolve the meconium to allow passage of enteric content into the unused colon.

If contrast cannot be refluxed into the distal small bowel, ileal atresia remains a diagnostic possibility. Jejunal and ileal atresia are caused by "in utero" vascular insults, leading to poor recanalization of distal small bowel segments, a condition in which surgical resection and reanastamosis are mandatory. Hirschsprung disease is due to an arrest in neural cell ganglia, leading to absent innervation of a segment distal bowel, and appears as a massively dilated segment of distal bowel on contrast enema. Surgical resection is necessary for this condition as well. Imperforate anus also requires surgical management, with the diagnosis made by inability to pass the rectal tube through the anal sphincter. Supportive intravenous hydration, gastric decompression, and ventilatory support may be needed due to poor neonatal nutrition resulting from dysfunctional bowel absorption.

A small bowel follow-through may suggest the diagnosis of Crohn's disease and is useful when the disease involves only the small intestine. Because colonoscopy and gastroscopy allow direct visualization of only the terminal ileum and beginning of the duodenum, they cannot be used to evaluate the remainder of the small intestine. As a result, a barium follow-through X-ray, wherein barium sulfate suspension is ingested and fluoroscopic images of the bowel are taken over time, is useful for looking for inflammation and narrowing of the small bowel. Barium enemas, in which barium is inserted into the rectum and fluoroscopy is used to image the bowel, are rarely used in the work-up of Crohn's disease due to the advent of colonoscopy. They remain useful for identifying anatomical abnormalities when strictures of the colon are too small for a colonoscope to pass through, or in the detection of colonic fistulae (in this case contrast should be performed with iodate substances).

CT and MRI scans are useful for evaluating the small bowel with enteroclysis protocols. They are also useful for looking for intra-abdominal complications of Crohn's disease, such as abscesses, small bowel obstructions, or fistulae. Magnetic resonance imaging (MRI) is another option for imaging the small bowel as well as looking for complications, though it is more expensive and less readily available. MRI techniques such as diffusion-weighted imaging and high-resolution imaging are more sensitive in detecting ulceration and inflammation compared to CT.

Mucus may also be found in stool.

A texture described as tarry stool is generally associated with dark black stool seen in partially digested blood. This is generally associated with melena.

With early intervention, morbidity and mortality of cases of intestinal obstruction is low. The outcome is in part dependent upon congenital comorbidities and delays in diagnosis and management.

A colonoscopy is the best test for making the diagnosis of Crohn's disease, as it allows direct visualization of the colon and the terminal ileum, identifying the pattern of disease involvement. On occasion, the colonoscope can travel past the terminal ileum, but it varies from person to person. During the procedure, the gastroenterologist can also perform a biopsy, taking small samples of tissue for laboratory analysis, which may help confirm a diagnosis. As 30% of Crohn's disease involves only the ileum, cannulation of the terminal ileum is required in making the diagnosis. Finding a patchy distribution of disease, with involvement of the colon or ileum, but not the rectum, is suggestive of Crohn's disease, as are other endoscopic stigmata.

The utility of capsule endoscopy for this, however, is still uncertain. A "cobblestone"-like appearance is seen in approximately 40% of cases of Crohn's disease upon colonoscopy, representing areas of ulceration separated by narrow areas of healthy tissue.

On x-rays, gas may be visible in the abdominal cavity. Gas is easily visualized on x-ray while the patient is in an upright position. The perforation can often be visualised using computed tomography. White blood cells are often elevated.

The role of "Helicobacter pylori" in functional dyspepsia is controversial, and no clear causal relationship has been established. This is true for both the symptom profile and pathophysiology of functional dyspepsia. Although some epidemiologic studies have suggested an association between "H. pylori" infection and functional dyspepsia, others have not. The discrepancy may stem in part from differences in methodology and lack of adequate consideration of confounding factors such as past history of peptic ulcer disease and socioeconomic status. Controlled trials disagree about whether or not "H. pylori" eradication is beneficial in functional dyspepsia, with roughly half of the trials showing improvement and the other half no improvement. In a recent multicenter U.S. trial that randomized 240 patients to treatment or placebo, and followed patients for 12 months, 28% of treated patients versus 23% of those receiving placebo reported relief of symptoms at the 12-month follow-up. Similarly, recent European trials have not shown significant differences in symptoms after "H. pylori" eradication as compared with controls. Systematic reviews of eradication have been conducted, with varying results. A systematic review in the Annals of Internal Medicine suggested no statistically significant effect, with an odds ratio (OR) for treatment success versus control of 1.29 (95% CI, 0.89–1.89; P = 0.18). Still, no effect was seen after adjusting for heterogeneity and for cure of "H. pylori". In contrast, a Cochrane review found a small but statistically significant effect in curing symptoms ("H. pylori" cure vs placebo, 36% vs 30%, respectively).

Choledocholithiasis (stones in common bile duct) is one of the complications of cholelithiasis (gallstones), so the initial step is to confirm the diagnosis of cholelithiasis. Patients with cholelithiasis typically present with pain in the right-upper quadrant of the abdomen with the associated symptoms of nausea and vomiting, especially after a fatty meal. The physician can confirm the diagnosis of cholelithiasis with an abdominal ultrasound that shows the ultrasonic shadows of the stones in the gallbladder.

The diagnosis of choledocholithiasis is suggested when the liver function blood test shows an elevation in bilirubin and serum transaminases. Other indicators include raised indicators of ampulla of vater (pancreatic duct obstruction) such as lipases and amylases. In prolonged cases the INR may change due to a decrease in vitamin K absorption. (It is the decreased bile flow which reduces fat breakdown and therefore absorption of fat soluble vitamins).

The diagnosis is confirmed with either an MRCP (magnetic resonance cholangiopancreatography), an ERCP, or an intraoperative cholangiogram. If the patient must have the gallbladder removed for gallstones, the surgeon may choose to proceed with the surgery, and obtain a cholangiogram during the surgery. If the cholangiogram shows a stone in the bile duct, the surgeon may attempt to treat the problem by flushing the stone into the intestine or retrieve the stone back through the cystic duct.

On a different pathway, the physician may choose to proceed with ERCP before surgery. The benefit of ERCP is that it can be utilized not just to diagnose, but also to treat the problem. During ERCP the endoscopist may surgically widen the opening into the bile duct and remove the stone through that opening. ERCP, however, is an invasive procedure and has its own potential complications. Thus, if the suspicion is low, the physician may choose to confirm the diagnosis with MRCP, a non-invasive imaging technique, before proceeding with ERCP or surgery.

Diagnosis is via a careful history and physical examination, often supplemented by radiographic imaging studies. Pyloric stenosis should be suspected in any young infant with severe vomiting. On physical exam, palpation of the abdomen may reveal a mass in the epigastrium. This mass, which consists of the enlarged pylorus, is referred to as the 'olive', and is sometimes evident after the infant is given formula to drink. Rarely, there are peristaltic waves that may be felt or seen (video on NEJM) due to the stomach trying to force its contents past the narrowed pyloric outlet.

Most cases of pyloric stenosis are diagnosed/confirmed with ultrasound, if available, showing the thickened pylorus and non-passage of gastric contents into the proximal duodenum. Muscle wall thickness 3 millimeters (mm) or greater and pyloric channel length of 15 mm or greater are considered abnormal in infants younger than 30 days.

Although somewhat less useful, an upper GI series (x-rays taken after the baby drinks a special contrast agent) can be diagnostic by showing the narrowed pyloric outlet filled with a thin stream of contrast material; a "string sign" or the "railroad track sign". For either type of study, there are specific measurement criteria used to identify the abnormal results. Plain x-rays of the abdomen sometimes shows a dilated stomach.

Although UGI endoscopy would demonstrate pyloric obstruction, physicians would find it difficult to differentiate accurately between hypertrophic pyloric stenosis and pylorospasm.

Blood tests will reveal low blood levels of potassium and chloride in association with an increased blood pH and high blood bicarbonate level due to loss of stomach acid (which contains hydrochloric acid) from persistent vomiting. There will be exchange of extracellular potassium with intracellular hydrogen ions in an attempt to correct the pH imbalance. These findings can be seen with severe vomiting from any cause.

Fetal and neonatal intestinal atresia are treated using laparotomy after birth. If the area affected is small, the surgeon may be able to remove the damaged portion and join the intestine back together. In instances where the narrowing is longer, or the area is damaged and cannot be used for period of time, a temporary stoma may be placed.

Treatment is surgical, potentially with a laparoscopic resection. In patients with bleeding, strangulation of bowel, bowel perforation or bowel obstruction, treatment involves surgical resection of both the Meckel's diverticulum itself along with the adjacent bowel segment, and this procedure is called a "small bowel resection". In patients without any of the aforementioned complications, treatment involves surgical resection of the Meckel's diverticulum only, and this procedure is called a simple diverticulectomy.

With regards to asymptomatic Meckel's diverticulum, some recommend that a search for Meckel's diverticulum should be conducted in every case of appendectomy/laparotomy done for acute abdomen, and if found, Meckel's diverticulectomy or resection should be performed to avoid secondary complications arising from it.

The cancerous mass tends to block food from getting to the small intestine. If food cannot get to the intestines, it will cause pain, acid reflux, and weight loss because the food cannot get to where it is supposed to be processed and absorbed by the body.

Patients with duodenal cancer may experience abdominal pain, weight loss, nausea, vomiting, and chronic GI bleeding.

A technetium-99m (99mTc) pertechnetate scan, also called Meckel scan, is the investigation of choice to diagnose Meckel's diverticula in children. This scan detects gastric mucosa; since approximately 50% of symptomatic Meckel's diverticula have ectopic gastric or pancreatic cells contained within them, this is displayed as a spot on the scan distant from the stomach itself. In children, this scan is highly accurate and noninvasive, with 95% specificity and 85% sensitivity; however, in adults the test is only 9% specific and 62% sensitive.

Patients with these misplaced gastric cells may experience peptic ulcers as a consequence. Therefore, other tests such as colonoscopy and screenings for bleeding disorders should be performed, and angiography can assist in determining the location and severity of bleeding. Colonoscopy might be helpful to rule out other sources of bleeding but it is not used as an identification tool. Angiography might identify brisk bleeding in patients with Meckel's diverticulum.

Ultrasonography could demonstrate omphaloenteric duct remnants or cysts. Computed tomography (CT scan) might be a useful tool to demonstrate a blind ended and inflamed structure in the mid-abdominal cavity, which is not an appendix.

In asymptomatic patients, Meckel's diverticulum is often diagnosed as an incidental finding during laparoscopy or laparotomy.