The appendix is a small attachment connected to the caecum, located at the lower right abdominal area where the large and small intestine meets.
It measures about 4 inches long. It is believed that the appendix has no functional value, but some researchers say it is a source of good bacteria that restores the intestinal microbial flora after a diarrhoea or gastrointestinal illness. 
Picture 1: Location of the appendix
Image source: digestive.niddk.nih.gov
Appendix Pain Location
Appendix pain is felt when the appendix becomes swollen. This condition is called appendicitis.
The pain starts in the upper abdomen, usually on the navel area . Afterwards, the pain shifts to the right lower abdominal area. A sharp pain can be felt when pressure is applied.
It also worsens during walking, coughing or doing any intense movements. The location of the pain, however, may vary in young children and pregnant women.
Along with the pain, other symptoms that are felt during appendicitis are nausea and vomiting, fever, diarrhea or constipation, abdominal swelling and loss of appetite .
Picture 2: Location of appendix pain
Image source: formulamedical.com
Picture 3: Normal appendix vs swollen appendix
Image source: biology-forums.com
Causes of Appendix Pain
The cause of appendix pain and inflammation is still unknown, but there are several theories regarding its cause, such as the following:
- Inflammation of the appendix may be caused by an obstruction, either by a stool, tumor, or any foreign body . Upon blockage, bacteria start to proliferate rapidly, inflaming the appendix and filling it with pus .
- Blockage can also be caused by some inflammatory bowel diseases, such as ulcerative colitis and Crohn’s disease. 
- Another source of obstruction is parasites, such as intestinal worms. 
- Appendicitis can also be caused by an infection. Any gastrointestinal infection, either bacterial or viral, may travel to the appendix, causing it to become inflamed. 
- A traumatic blow to the abdomen can also cause appendicitis. 
Diagnosis and Differential Diagnosis
Appendicitis is difficult to diagnose, because a large number of diseases also cause abdominal pain similar to appendicitis. Here are some of the diseases that also cause a similar abdominal pain:
- Gastrointestinal diseases, such as constipation, gastroenteritis, gastrointestinal obstruction, pancreatitis, intussusception, perforated peptic ulcer, strangulated hernia, diverticulitis, rectus sheath hematoma, mesenteric adenitis, acute cholecystits, Crohn’s disease and Meckel’s diverticulitis 
- Gynecological conditions, such as pelvic inflammatory disease, ectopic pregnancy, and rupture of a cyst in the ovary 
- Urological disorders, such as urinary tract infection, renal calculi and testicular torsion 
- Other conditions, such as pneumonia, porphyria, diabetic ketoacidosis, and side effects of immunomodulation therapies 
Different diagnostic tests are done to differentiate appendicitis from these diseases. Here are the diagnostic tests performed to identify appendicitis:
- Physical tests. This evaluates the pain felt by the patient. The doctor applies pressure on the abdominal area. When the doctor releases the pressure, the pain usually worsens, unlike in other conditions. The doctor will also observe if there is also rigidity and stiffness of the abdomen after application of the pressure.
- Imaging tests. such as an ultrasound scan or a magnetic resonance imaging scan. This helps in confirming if the condition is appendicitis or not. An abdominal x-ray is also recommended.
- Blood tests. High levels of white blood cells indicate an infection.
- Urinalysis. This determines if the cause of pain is the presence of kidney stones or urinary tract infection. If this is the case, red blood cells will be detected in the urine.
Pregnancy test. This will determine if the pain is caused by a gynecological condition or not. [1,3]
The results of the diagnostic tests are usually released several days after the examinations are done. Because of this, a surgery is often recommended even if appendicitis is still not confirmed to prevent the appendix from bursting.
When the appendix bursts, the infection spreads throughout the abdomen, which can cause a condition called peritonitis. This is much worse than appendicitis, so a surgery is immediately performed. 
Treatment and Surgery
When a surgery is still not performed, antibiotics are administered to combat infection in case the appendix suddenly bursts. It is also given before the start of a surgery.  The primary treatment for appendicitis is removing the appendix through a procedure called appendectomy.
Since the appendix has no proven function in the body, there are no health risks on removing the appendix. Appendectomy is an easy and simple operation that is usually successful. It also requires only a short time of recovery. Full recovery usually takes around 4-6 weeks. 
During appendectomy, general anesthesia is administered after the patient has taken antibiotics.
In an open surgery, a 4-inch cut is made on the abdomen, where the appendix is directly removed. A laparoscopic surgery can also be performed, where the appendix is removed through three holes in the abdomen. The latter is the more preferred procedure, as it has a shorter recovery time. 
Open surgery, on the other hand, is recommended when the appendix has already burst. It is also used in people who have tumors in the digestive tract and for pregnant women during their first trimester . The incision or the holes are then stitched after the procedure.
Picture 4: Location of incisions in open and laparoscopic appendectomy
Image source: walgreens.com
Although appendectomy only takes a short time for recovery, complications may occur. The attention of the doctor must be called during the following circumstances :
- Uncontrolled vomiting
- Severe abdominal pain
- Presence of blood in the urine or vomit
- Pain and erythema in the incision site
- Pus in the incision site
When the appendix has already burst, the abscess is drained or irrigated first. It is done by installing a tube through the skin to reach the abscess. This is done to control and avoid the spread of infection. When the infection is already in control, the surgeon then proceeds with appendectomy after several weeks .