Digestive system

 
The digestive tract stretches some nine metres from the mouth to the anus and is divided into different sections. Each section processes food in a specific way to prepare it for the next section of the digestive tract, until the waste finally leaves the intestinal tract as faeces.

Functions of the digestive system:

• Mechanical and chemical breakdown of food into basic nutrients
• Absorption of nutrients into the blood
• Processing and elimination of waste
  
  

A number of organs work alongside the digestive tract, producing fluids and enzymes to aid indigestion:

• Salivary glands in the mouth
• Acid fluids in the stomach
• Liver and gallbladder
• Pancreas

The gastrointestinal tract comprises:

• Mouth
• Oesophagus
• Stomach
• Small intestine – jejunum & ileum
• Large intestine – colon
• Rectum
• Anus

The intestinal wall consists of several layers

The small intestine is approximately 5–7 m long in adults. It is divided into three main parts:

• Duodenum
• Jejunum
• Ileum

The jejunum and ileum are connected to the abdominal wall by the mesentery. The mesentery contains arteries, veins and lymph vessels that ensure the transport of oxygen and nutrients to and from the small intestine.

The large intestine is approximately 1–2 m long in adults. It is divided into six parts:

• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon, the S-shaped structure
• Rectum: final part of the digestive tract. Stool collects in the rectal ampulla. A filled ampulla initiates the urge to empty the bowels
• Anus, terminal opening of the digestive system

The urinary system

The overall function of the urinary system is to produce and drain urine, removing waste products and regulating the blood's fluid balance. The entire urinary system is located behind the digestive tract.

The urinary system consists of:

• Two kidneys
• Two ureters
• Bladder
• Urethra

The kidneys are two bean-shaped structures that continuously filter the blood, removing waste products and excess water, and balancing fluids and electrolytes. This filtering process results in the production of urine.

The ureters are ducts that carry urine from the kidneys to the bladder.

The bladder has a dual function. It is both a reservoir that stores urine and a pump that expels urine from the body. The muscle in the bladder wall pushes the urine out.

The urethra is a duct connecting the bladder to the outside of the body.

A preoperative marking to select the optimal location of the stoma site is important for patient quality of life. A favourable site can help reduce potential problems such as leakage, fitting issues, skin irritation, pain and psychological/emotional health.

When marking the stoma site, it’s important to consider the dynamics of the body as it changes according to factors such as different positions and scar formation. Creases and folds near the stoma should be avoided. In addition, the lifestyle and activity level of the patient will influence where the stoma should be located.

Before marking the site, consider these four factors:

1. Physical condition:
   Constitution, current weight and recent weight changes, manual dexterity and eyesight
2. Social activities:
   Occupation, physical positions at work, sports, hobbies, clothing preferences, cultural and religious aspects
3. Areas to avoid:
   Bony prominences, skin folds, scars from previous operations, the umbilicus, belt line and skin areas that have been irradiated and are highly sensitive (atrophic)
4. Visibility:
   The site should be placed in an area that the patient can see and reach. If not, the patient cannot perform stoma self-care, and will need help from other people when changing the appliance

Having a stoma alters body functions and body image. But if health care professionals - such as stoma care nurse and surgeon - work together to give end-users competent care, the chances of a good outcome for the patient are greatly increased.

The three types of stoma are:

- Colostomy
- Ileostomy
- Urostomy

Colostomy

In a colostomy operation, part of the colon is brought to the surface of the abdomen to form the stoma. A colostomy is usually created on the left-hand side of the abdomen. Stools in this part of the intestine are solid and, because a stoma has no muscle to control defecation, will need to be collected using a stoma pouch.

There are two different types of colostomy surgery: End colostomy and loop colostomy.

End colostomy
If parts of the large bowel (colon) or rectum have been removed, the remaining large bowel is brought to the surface of the abdomen to form a stoma. An end colostomy can be temporary or permanent. The temporary solution is relevant in situations where the diseased part of the bowel has been removed and the remaining part of the bowel needs to rest before the ends are joined together. The permanent solution is chosen in situations where it is too risky or not possible to re-join the two parts of the intestine.

Loop colostomy
In a loop colostomy, the bowel is lifted above skin level and held in place with a stoma rod. A cut is made on the exposed bowel loop, and the ends are then rolled down and sewn onto the skin. In this way, a loop stoma actually consists of two stomas (double-barrelled stoma) that are joined together. The loop colostomy is typically a temporary measure performed in acute situations. It can also be carried out to protect a surgical join in the bowel.

Ileostomy

In an ileostomy operation, a part of the small bowel called the ileum is brought to the surface of the abdomen to form the stoma. An ileostomy is typically made in cases where the end part of the small bowel is diseased, and is usually made on the right-hand side of your abdomen.

Stools in this part of the intestine are generally fluid and, because a stoma has no muscle to control defecation, will need to be collected in a pouch.

There are two different types of ileostomy surgery: