Males are more commonly affected than females, with firstborn males affected about four times as often, and there is a genetic predisposition for the disease. It is commonly associated with people of Scandinavian ancestry, and has multifactorial inheritance patterns. Pyloric stenosis is more common in Caucasians than Hispanics, Blacks, or Asians. The incidence is 2.4 per 1000 live births in Caucasians, 1.8 in Hispanics, 0.7 in Blacks, and 0.6 in Asians. It is also less common amongst children of mixed race parents. Caucasian male babies with blood type B or O are more likely than other types to be affected.

Infants exposed to erythromycin are at increased risk for developing hypertrophic pyloric stenosis, especially when the drug is taken around two weeks of life and possibly in late pregnancy and through breastmilk in the first two weeks of life.

Delay in the diagnosis of SMA syndrome can result in fatal catabolysis (advanced malnutrition), dehydration, electrolyte abnormalities, hypokalemia, acute gastric rupture or intestinal perforation (from prolonged mesenteric ischemia), gastric distention, spontaneous upper gastrointestinal bleeding, hypovolemic shock, and aspiration pneumonia.

A 1-in-3 mortality rate for Superior Mesenteric Artery syndrome has been quoted by a small number of sources. However, after extensive research, original data establishing this mortality rate has not been found, indicating that the number is likely to be unreliable. While research establishing an official mortality rate may not exist, two recent studies of SMA syndrome patients, one published in 2006 looking at 22 cases and one in 2012 looking at 80 cases, show mortality rates of 0% and 6.3%, respectively. According to the doctors in one of these studies, the expected outcome for SMA syndrome treatment is generally considered to be excellent.

Pyloric stenosis seems to be multifactorial, with some genetic and some environmental components. It is four times more likely to occur in males, and is also more common in the first born. Rarely, infantile pyloric stenosis can occur as an autosomal dominant condition.

It is uncertain whether it is a congenital anatomic narrowing or a functional hypertrophy of the pyloric sphincter muscle.

SMA syndrome is extremely rare, evident in only 0.3% of upper-gastrointestinal-tract barium studies. However, unfamiliarity with this condition in the medical community coupled with its intermittent and nonspecific symptomatology probably results in its underdiagnosis.

As the syndrome involves a lack of essential fat, more than half of those diagnosed are underweight, sometimes to the point of sickliness and emaciation. Females are impacted more often than males, and while the syndrome can occur at any age, it is most frequently diagnosed in early adulthood. The most common co-morbid conditions include mental and behavioral disorders including eating disorders and depression, infectious diseases including tuberculosis and acute gastroenteritis, and nervous system diseases including muscular dystrophy, Parkinson's disease, and cerebral palsy.

The causes are divided into benign or malignant.

- Benign

- Peptic ulcer disease

- Infections, such as tuberculosis; and infiltrative diseases, such as amyloidosis.

- A rare cause of gastric outlet obstruction is blockage with a gallstone, also termed "Bouveret's syndrome".

- In children congenital pyloric stenosis / congenital hypertrophic pyloric stenosis may be a cause.

- A pancreatic pseudocyst can cause gastric compression.

- Pyloric mucosal diaphragm could be a rare cause.

- Malignant

- Tumours of the stomach, including adenocarcinoma (and its linitis plastica variant), lymphoma, and gastrointestinal stromal tumours

Incidence of hiatal hernias increases with age; approximately 60% of individuals aged 50 or older have a hiatal hernia. Of these, 9% are symptomatic, depending on the competence of the lower esophageal sphincter (LES). 95% of these are "sliding" hiatus hernias, in which the LES protrudes above the diaphragm along with the stomach, and only 5% are the "rolling" type (paraesophageal), in which the LES remains stationary, but the stomach protrudes above the diaphragm.

Hiatus hernia are most common in North America and Western Europe and rare in rural African communities. Some have proposed that insufficient dietary fiber and the use of a high sitting position for defecation may increase the risk.

In a peptic ulcer it is believed to be a result of edema and scarring of the ulcer, followed by healing and fibrosis, which leads to obstruction of the gastroduodenal junction (usually an ulcer in the first part of the duodenum).

Immediate treatment is the most important factor in a favorable prognosis. A delay in treatment greater than six hours or the presence of peritonitis, sepsis, hypotension, or disseminated intravascular coagulation are negative prognostic indicators.

Historically, GDV has held a guarded prognosis. Although "early studies showed mortality rates between 33% and 68% for dogs with GDV," studies from 2007 to 2012 "reported mortality rates between 10% and 26.8%". Mortality rates approach 10% to 40% even with treatment. A study determined that with prompt treatment and good preoperative stabilization of the patient, mortality is significantly lessened to 10% overall (in a referral setting). Negative prognostic indicators following surgical intervention include postoperative cardiac arrhythmia, splenectomy, or splenectomy with partial gastric resection. Interestingly, a longer time from presentation to surgery was associated with a lower mortality, presumably because these dogs had received more complete preoperative fluid resuscitation and were thus better cardiovascularly stabilized prior to the procedure.

Anemia associated with Cameron lesions usually responds to oral iron medication, which may be needed for years. Gastric acid suppression may promote lesion healing and a proton-pump inhibitor such as omeprazole is often prescribed. Surgical hernia repair is sometimes needed for indications such as refractory anemia requiring repeated blood transfusions, or anemia combined with other hernia symptoms.

Gastric volvulus of unknown cause comprises two thirds of cases and is presumably due to abnormal laxity of the gastrosplenic, gastroduodenal, gastrophrenic, and gastrohepatic ligaments. Type 1 gastric volvulus is more common in adults but has been reported in children.

Type 2 gastric volvulus is found in one third of patients and is usually associated with congenital or acquired abnormalities that result in abnormal mobility of the stomach.

The prevalence of Klippel–Feil syndrome is unknown due to the fact that there was no study done to determine the true prevalence.

Although the actual occurrence for the KFS syndrome is unknown, it is estimated to occur 1 in 40,000 to 42,000 newborns worldwide. In addition, females seem to be affected slightly more often than males.

As a general rule, GDV is of greatest risk to deep-chested dogs. The five breeds at greatest risk are Great Danes, Weimaraners, St. Bernards, Gordon Setters, and Irish Setters. In fact, the lifetime risk for a Great Dane to develop GDV has been estimated to be close to 37 percent. Standard Poodles are also at risk for this health problem, as are Irish Wolfhound, Doberman Pinschers, Rottweilers, German Shorthaired Pointer, German Shepherds, Rhodesian Ridgebacks. Basset Hounds and Dachshunds have the greatest risk for dogs less than .

The reported incidence of constriction ring syndrome varies from 1/1200 and 1/15000 live births. The prevalence is equally in male and female.

Fetomaternal factors like prematurity, maternal illnes, low birth weight and maternal drug exposure are predisposing factors for the constriction ring syndrome.

No positive relationship between CRS and genetic inheritance has been reported.

Based on their surgical observations, Windsor and Collis in 1967 proposed that blood loss was due to local trauma to the stomach where it rides to and fro in the hiatus on respiration. Boutelier et al. noted on gastroscopy ulcers and erosions at the level of the neck of the hernia in individuals with acute and chronic bleeding, but no detailed description was given. Cameron and Higgins in 1986 described linear gastric erosions, later called "Cameron lesions", in people with x-rays showing one-third or more of the stomach above the diaphragm. (figure 1). Over 6 years, Cameron and Higgins studied 109 persons with large hiatal hernias, 55 with anemia and 54 without anemia, at esophagogastroduodenoscopy. Cameron lesions, often multiple, were found at or near the level where the herniated stomach was constricted by the diaphragm. The lesions were typically white, superficial, linear, and oriented along the crests of inflamed appearing mucosal folds (figure 2). Small amounts of blood were often seen on the lesions (Fig 3). Mucosal folds at the diaphragm level were often seen rubbing against each other on respiration (Fig 4). It was proposed that the lesions were caused by mechanical trauma at the level of constriction by the diaphragm Cameron lesions were found in 42% of persons with anemia compared to 24% in those without anemia, a statistically significant difference, p<0.05. Spots of fresh or clotted blood were seen on the lesions in 25% of persons with anemia compared to 7% without anemia, also a significant difference, p<0.05. In the 109 persons in this study, 15 had reflux esophagitis, 11 had peptic ulcers, and 7 had Barrett's esophagus, but none of these findings correlated with anemia. Thus, in people with large hernias, Cameron lesions with evidence of slow bleeding were associated with iron deficiency anemia.

Acute bleeding from Cameron lesions, vomiting blood, or passing black bowel movements, is rare; in one report Cameron lesions were found in 3.8% of people presenting with anemia, but in only 0.2% of those with acute bleeding. Small hernias with 2–5 cm of stomach above the diaphragm are commoner than large hernias but Cameron lesions are usually found with large hernias.

Anemia in patients with large hernias was corrected by surgical repair in the majority of instances, but Cameron lesions were found in only about half of these individuals. One explanation is that endoscopists unfamiliar with their appearance can miss the lesions However, in the original description of Cameron lesions they were found in less than half the patients despite careful search, and no other causes of gastrointestinal bleeding. were seen. It is probable that these superficial lesions can heal and recur, with the bleeding stopping temporarily

The heterogeneity of the Klippel–Feil syndrome has made it difficult to outline the diagnosis as well as the prognosis classes for this disease. Because of this, it has complicated the exact explanation of the genetic cause of the syndrome.

The prognosis for most individuals with KFS is good if the disorder is treated early on and appropriately. Activities that can injure the neck should be avoided, as it may contribute to further damage. Other diseases associated with the syndrome can be fatal if not treated, or if found too late to be treatable.

Stenosis of the pulmonary artery is a condition where the pulmonary artery is subject to an abnormal constriction (or stenosis). Peripheral pulmonary artery stenosis may occur as an isolated event or in association with Alagille syndrome, Berardinelli-Seip congenital lipodystrophy type 1, Costello syndrome, Keutel syndrome, nasodigitoacoustic syndrome (Keipert syndrome), Noonan syndrome or Williams syndrome.

It should not be confused with a pulmonary valve stenosis, which is in the heart, but can have similar hemodynamic effects. Both stenosis of the pulmonary artery and pulmonary valve stenosis are causes of pulmonic stenosis.

In some cases it is treated with surgery.

The following are risk factors that can result in a hiatus hernia.

- Increased pressure within the abdomen caused by:

- Heavy lifting or bending over

- Frequent or hard coughing

- Hard sneezing

- Violent vomiting

- Straining

- Stress

Amniotic band syndrome is considered an accidental event and it does not appear to be genetic or hereditary, so the likelihood of it occurring in another pregnancy is remote. The cause of amnion tearing is unknown and as such there are no known preventative measures.

The exact incidence of ischemic colitis is difficult to estimate, as many patients with mild ischemia may not seek medical attention. Ischemic colitis is responsible for about 1 in 2000 hospital admissions, and is seen on about 1 in 100 endoscopies. Men and women are affected equally; ischemic colitis is a disease of the elderly, with more than 90% of cases occurring in people over the age of 60.

The prognosis depends on the location and severity of the constricting bands. Every case is different and multiple bands may be entangled around the fetus.

Bands which wrap around fingers and toes can result in syndactyly or amputations of the digits. In other instances, bands can wrap around limbs causing restriction of movement resulting in clubbed feet. In more severe cases, the bands can constrict the limb causing decreased blood supply and amputation. Amniotic bands can also sometimes attach to the face or neck causing deformities such as cleft lip and palate. If the bands become wrapped around the head or umbilical cord it can be life-threatening for the fetus.

The number of cases of miscarriage that can be attributed to ABS is unknown, although it has been reported that it may be the cause of 178 in 10,000 miscarriages.

Most patients with ischemic colitis recover fully, although the prognosis depends on the severity of the ischemia. Patients with pre-existing peripheral vascular disease or ischemia of the ascending (right) colon may be at increased risk for complications or death.

Non-gangrenous ischemic colitis, which comprises the vast majority of cases, is associated with a mortality rate of approximately 6%. However, the minority of patients who develop gangrene as a result of colonic ischemia have a mortality rate of 50-75% with surgical treatment; the mortality rate is almost 100% without surgical intervention.

Constriction ring syndrome (CRS) is a congenital disorder with unknown cause. Because of the unknown cause there are many different, and sometimes wrong names. It is a malformation due to intrauterine bands or rings that give deep grooves in, most commonly, distal extremities like fingers and toes. In rare cases the constriction ring can form around other parts of the fetus and cause amputation or even intrauterine death (see Types and Classification). The anatomy proximal to the site of constriction (or amputation) is developmentally normal.

CRS can be associated with other malformations with club foot being most common.

(see also Types and Classification).

The precise configuration of the bands, lymphedema, and character of the amputations are not predictable and vary with each individual patient. Also more than one extremity is usually affected, and it is rare for only one ring to present as an isolated malformation with no other manifestation of this syndrome.

Singleton Merten Syndrome is an autosomal dominate genetic disorder with variable expression with an onset of symptoms during childhood.

Worldwide, it has been documented in 110 persons, 85 of them Finnish. It is a recessive genetic disease. Many people with Mulibrey nanism have parents who are closely related, consanguine. Signs and symptoms are variable, siblings who suffer this disease sometimes do not share the same symptoms.