The pylorus (from the lower Latin pylorus, coming from the Greek pulôros, meaning gatekeeper) constitutes the last part of the stomach, making the link with the small intestine.

Location. The pylorus is located in the pyloric region, constituting the terminal part of the stomach. The pylorus is prolonged by the duodenum, the initial part of the small intestine (1).

Structure. Funnel-shaped, the pyloric region is made up of several parts:

• The pyloric antrum is the broad upper part that lies between the body of the stomach and the pyloric duct
• The pyloric duct is a narrowing that lies between the pyloric antrum and the pylorus
• The pylorus is located after the pyloric canal and communicates with the duodenum. It contains the pyloric sphincter muscle whose function is to control gastric evacuation.

Wall. The stomach wall, including that of the pyloric region and the pylorus, is made up of different envelopes (2) (3):

• The mucous membrane is the inner layer that has different glands that secrete mucus, stomach acid, and gastric juices like digestive enzymes.
• The submucosa is the middle layer where various blood vessels and nerves circulate.
• The muscularis is the outer layer which is made up of three muscle layers.
• The serous membrane, or peritoneum, is an envelope lining the outer surface.

Vascularization and innervation. The vascularization of the stomach, including that of the pylorus and its region, is carried out by three nerve branches originating from the celiac trunk. They originate from both pneumogastric nerves and the great sympathetic nerve (4).

The many contractions of the stomach, including those in the pyloric region, allow the chyme to be brought to the pylorus. The chyme constitutes the liquid comprising the food pre-digested by the gastric juices. Passing from the pyloric region to the duodenum, the chyme crosses the pylorus by releasing the sphincter, which is kept closed the rest of the time (3).

Gastritis. This pathology corresponds to an inflammation of the internal lining of the stomach. This inflammation can be caused in particular by taking certain medications or by bacterial infection. The development of bacteria can lead to a peptic ulcer (5).

Peptic ulcer. This pathology corresponds to the formation of a deep wound in the wall of the stomach or that of the duodenum. It manifests itself by sharp pains in the stomach. Peptic ulcer disease is often caused by bacterial growth but can also occur with certain medications (5).

Pylorus stenosis. This pathology can develop in newborns. It is due to the increase in the volume of the sphincter at the level of the pylorus. This congenital malformation causes severe vomiting.

Stomach cancer. Cancerous tumors can develop in the stomach (6).

Medical treatment. Depending on the pathology diagnosed, certain treatments may be prescribed such as antibiotics.

Surgical treatment. Depending on the pathology diagnosed and its evolution, a surgical intervention may be implemented. In the case of pyloric stenosis, pyloroplasty may be performed to enlarge the pylorus.

Chemotherapy, radiotherapy or targeted therapy. Depending on the type and stage of the tumor, these treatments may be used to destroy cancer cells.

Physical examination. First, a clinical examination is performed to assess the symptoms.

Medical imaging exams. Depending on the suspected or proven pathology, additional examinations may be performed such as an ultrasound or an upper digestive endoscopy.

Biological examination. Blood tests can be done.

biopsy. A sample of gastric cells may be taken to complete or confirm a diagnosis.

Pierre Fredet, French surgeon, was one of the first to perform, in 1907, a successful pyloroplasty in a newborn with pyloric stenosis (7).