Abdominal pain

Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem. Most frequently the cause is benign and/or self-limited, but more serious causes may require urgent intervention.

Introduction

Abdominal pain is traditionally described by its chronicity (acute or chronic), its progression over time, its nature (sharp, dull, colicky), its distribution (by various methods, such as abdominal quadrant (left upper quadrant, left lower quadrant, right upper quadrant, right lower quadrant) or other methods that divide the abdomen into nine sections), and by characterization of the factors that make it worse, or alleviate it.

Due to the many organ systems in the abdomen, abdominal pain is a concern of general practitioners/family physicians, surgeons, internists, emergency medicine doctors, pediatricians, gastroenterologists, urologists and gynecologists. Occasionally, patients with rare causes can see a number of specialists before being diagnosed adequately (e.g., chronic functional abdominal pain)

Types and mechanisms

1. The pain associated with the abdomen of inflammation of the parietal peritoneum (the part of the peritoneum lining the abdominal wall) is steady and aching, and worsened by changes in the tension of peritoneum caused by pressure or positional change. It is often accompanied by tension of the abdominal muscles contracting to relieve such tension.
2. The pain associated with obstruction of a hollow viscus (as opposed to peritoneal and solid organ pain) is often intermittent or "colicky", coinciding with the peristaltic waves of the organ. Such cramps are exactly what is experienced with early acute appendicitis and gastroenteritis and are somewhat relieved by writhing and massage.
3. The pain associated with abdominal vascular disturbances (thrombosis or embolism) can be sudden or gradual in onset, and can be severe or mild. Pain associated with the rupture of an abdominal aortic aneurysm may radiate to the back, flank, or genitals.
4. Pain that is felt in the abdomen may be "referred" from elsewhere (e.g., a disease process in the chest may cause pain in the abdomen), and abdominal processes can cause radiated pain elsewhere (e.g., gall bladder pain—in cholecystitis or cholelithiasis—is often referred to the shoulder).

Causes

The following is an incomplete list of possible causes of abdominal pain.

• Gastrointestinal
  • Inflammatory: gastroenteritis, appendicitis, gastritis, esophagitis, diverticulitis, Crohn's disease, ulcerative colitis, microscopic colitis
  • Obstruction: hernia, intussusception, volvulus, post-surgical adhesions, tumours, superior mesenteric artery syndrome, severe constipat ion
  • Vascular: embolism, thrombosis, hemorrhage, sickle cell disease, abdominal angina, blood vessel compression (such as celiac artery compression syndrome)
  • digestive: peptic ulcer, lactose intolerance, celiac sprue, Jasohnstritis
• Bile system
  • Inflammatory: cholecystitis, cholangitis
  • Obstruction: cholelithiasis, tumours
• Liver
  • Inflammatory: hepatitis, liver abscess
• Pancreatic
  • Inflammatory: pancreatitis
• Renal and urological
  • Inflammation: pyelonephritis, bladder infection
  • Obstruction: kidney stones, urolithiasis, Urinary retention, tumours
  • Vascular: left renal vein entrapment
• Gynecological or obstetric
  • Inflammatory: pelvic inflammatory disease
  • Mechanical: ovarian torsion
  • Endocrinological: menstruation, Mittelschmerz
  • Tumors: endometriosis, fibroids, ovarian cyst, ovarian cancer
  • Pregnancy: ruptured ectopic pregnancy, threatened abortion
• Abdominal wall
  • muscle strain or trauma
  • muscular infection
  • neurogenic pain: herpes zoster, radiculitis in Lyme disease, abdominal cutaneous nerve entrapment syndrome (ACNES), tabes dorsalis

• Referred pain
• from the thorax: pneumonia, pulmonary embolism, ischemic heart disease, pericarditis
• from the spine: radiculitis
• from the genitals: testicular torsion

• Metabolic disturbance

• uremia, diabetic ketoacidosis, porphyria, C1-esterase inhibitor deficiency, adrenal insufficiency,lead poisoning, black widow spider bite, narcotic withdrawal

• Blood vessels
  • aortic dissection, abdominal aortic aneurysm
• Immune system
  • sarcoidosis
  • vasculitis
  • familial Mediterranean fever
• Idiopathic
  • irritable bowel syndrome (affecting up to 20% of the population, IBS is the most common cause of recurrent, intermittent abdominal pain)

Acute Abdomen

Acute abdomen can be defined as severe, persistent abdominal pain of sudden onset that is likely to require surgical intervention to treat its cause. The pain may frequently be associated with nausea and vomiting, abdominal distention, fever and signs of shock.

Selected causes of acute abdomen

• Traumatic : blunt or perforating trauma to the stomach, bowel, spleen, liver, or kidney
• Inflammatory :
  • Infections such as appendicitis, cholecystitis, pancreatitis, pyelonephritis, pelvic inflammatory disease, hepatitis, mesenteric adenitis, or a subdiaphragmatic abscess
  • Perforation of a peptic ulcer, a diverticulum, or the caecum
  • Complications of inflammatory bowel disease such as Crohn's disease or ulcerative colitis
• Mechanical :
  • Small bowel obstruction secondary to adhesions caused by previous surgeries, intussusception, hernias, benign or malignant neoplasms
  • Large bowel obstruction caused by colorectal cancer, inflammatory bowel disease, volvulus, fecal impaction or hernia
• Vascular : occlusive intestinal ischemia, usually caused by thromboembolism of the superior mesenteric artery

Recurrent Abdominal Pain in Children and Adolescents

Recurrent abdominal pain (RAP) occurs in 5–15% of children 6–19 years old. In a community-based study of middle and high school students, 13–17% had weekly abdominal pain. Using criteria for irritable bowel syndrome (IBS), 14% of high school students and 6% of middle school students fit the criteria for adult IBS. As with other difficult to diagnose chronic medical problems, patients with RAP account for a very large number of office visits and medical resources in proportion to their actual numbers. Most patients with RAP benefit from reassurance and techniques to manage anxiety and stress, which are frequently associated with episodes.

Medical Assessment

When a physician assesses a patient to determine the etiology and subsequent treatment for abdominal pain the patients history of the presenting complaint and physical examination should derive a diagnosis in over 90% of cases.

It is important also for a physician to remember that abdominal pain can be caused by problems outside the abdomen, especially heart attacks and pneumonias which can occasionally present as abdominal pain.

Investigations that would aid diagnosis include

• Blood tests including full blood count, electrolytes, urea, creatinine, liver function tests, pregnancy test and lipase.
• 
  
Urinalysis
• Imaging including erect chest X-ray and plain films of the abdomen
• An electrocardiograph to rule out a heart attack which can occasionally present as abdominal pain

If diagnosis remains unclear after history, examination and basic investigations as above then more advanced investigations may reveal a diagnosis. These as such would include

• Computed Tomography of the abdomen/pelvis
• Abdominal or pelvic ultrasound
• Endoscopy and colonoscopy (not used for diagnosing acute pain)