The Use of Point-Of-Care Ultrasound in Diagnosing Acute Abdominal Pain: An Overview

Introduction:

Point-of-care ultrasound (POCUS) is a type of test that is performed at the bedside to diagnose the abdomen. These POCUS machines are ultrasound machines that use sound waves, and these are affordable, movable, and can also be used by radiologists who are less trained. Abdominal pain is one of the common causes of getting admitted to an emergency department. Acute abdominal pain is an emergency that occurs suddenly and does not reduce within a few minutes.

What Is Point-Of-Care Ultrasound (POCUS)?

Point-of-care ultrasound is a type of ultrasound examination that makes decisions on the spot and is performed at the bedside by a physician as a part of a clinical examination. It can demonstrate blood flow and bowel movements. POCUS gives better diagnosis and, therefore, better patient care. The images that are produced are different due to the different densities. Black images demonstrate fluids such as urine or blood. Gray images demonstrate soft tissues such as the liver. White images without a shadow demonstrate fibrous tissues, and white images with a shadow demonstrate stones and bones.

What Are the Reasons for Acute Abdominal Pain?

The common reasons for acute abdominal pain that cause generalized abdominal tenderness include:

• Peritonitis (a condition in which a membrane that covers the abdominal cavity gets inflamed).

• Bowel obstruction.

• Pancreatitis (inflamed pancreas).

• Bowel ischemia (reduced blood flow to the intestines).

• Aortic aneurysm (bulged out aorta).

The common causes of acute abdominal pain that cause supra-pubic (below the abdomen) tenderness are:

Colonic Causes:

• Appendicitis (inflamed appendix).

• Colitis (inflamed colon).

• Diverticulitis (inflammation of the pouches that are formed from the walls of the bowels).

• Irritable bowel syndrome (a type of gastrointestinal disorder that affects the large intestine).

• Inflammatory bowel disease.

Gynecology Causes:

• Fibroids (benign tumors around the uterus).

• Ovarian mass.

• Ectopic pregnancy (the embryo attaches itself outside the womb, mostly in the fallopian tube).

• Torsion (twisted fallopian tube or ovary).

• Pelvic inflammatory disease (PID, infection of the reproductive system).

Renal Causes:

• Cystitis (inflamed bladder).

• Nephrolithiasis (kidney stones).

• Pyelonephritis (inflamed kidney).

The common causes of acute abdominal pain that cause epigastric (upper abdomen) pain are:

Biliary Causes:

• Cholelithiasis (gallstones).

• Cholangitis (inflamed bile ducts).

• Cholecystitis (inflamed gallbladder).

Gastric Causes:

• Esophagitis (inflamed esophagus).

• Peptic ulcer (an open sore that forms on the lining of the stomach).

• Gastritis (inflamed stomach lining).

Pancreatic Causes:

• Pancreatitis (inflamed pancreas).

• Mass in the pancreas.

Cardiac Causes:

• Pericarditis (inflamed outer layers of the heart).

• Myocardial infarction (heart attack).

Vascular Causes:

• Aortic dissection (tear in the aorta).

• Mesenteric ischemia (decreased blood flow to the small intestine).

The common causes of acute abdominal pain that causes pain in the right upper quadrant can be due to cardiac, biliary, colonic, and renal issues, other causes are:

Pulmonary Causes:

• Emboli (A clot in the lung arteries).

• Pneumonia (infection of the lung).

Hepatic Causes:

• Hepatitis (inflamed liver).

• Abscess (a localized collection of pus).

• Mass.

The common causes of acute abdominal pain in the left upper side can occur due to cardiac, pancreatic, gastric, vascular, renal, and pulmonary issues. Other causes are:

Splenic Causes:

• Infection.

• Abscess.

The common causes of acute abdominal pain that causes pain in the right lower and left lower quadrants, can be due to colonic, renal, and gynecological issues.

What Are the Uses of Point-Of-Care Ultrasound in Diagnosing Acute Abdominal Pain?

The uses include:

• POCUS can help in detecting intraperitoneal fluid (liquid in the abdominal cavity), which can occur due to ascites (accumulation of fluid due to liver diseases), traumatic bleeding, bile leak, ruptured ectopic pregnancy, and urinary leak. With the help of the POCUS machine, about 10 milliliters of intraperitoneal fluid can be detected. Areas, where fluids can accumulate, are the perihepatic space (around the liver), peri splenic space (around the spleen), and pelvis. It has 90 percent of sensitivity in the case of diagnosing intraperitoneal fluid.

• POCUS can help in diagnosing the cause of intestinal obstruction. About 15 percent of abdominal emergencies are due to intestinal obstruction. Loops of the small bowel can be scanned from above the abdomen to the pelvis. Graded compression can help in displacing bowel contents and gas. Therefore, POCUS can help in detecting blood flow, bowel movements, dilated bowel loops, and the thickness of the bowel wall of more than three millimeters. It has 95 percent of sensitivity in the case of diagnosing intestinal obstruction.

• POCUS can help in detecting free intraperitoneal air that occurs due to leakage of bowel gas through the bowel perforation, which needs emergency treatment. Intraperitoneal air is demonstrated as enhanced peritoneal stripe sign (alternating bright and dark lines), peritoneal stripe reverberations which occur due to forward and backward bouncing of soundwaves in the free intraperitoneal air, and ring-down artifacts (radiating parallel bands). Intraperitoneal air shows the shifting phenomenon, where the air can move when the patient moves. It has 86 percent of sensitivity in the case of diagnosing free intraperitoneal air.

• In the case of acute appendicitis, POCUS can be focused at the point of tenderness, and with the help of the graded compression technique, underlying structures can be seen by displacing the intraluminal gas by the bowel loops. POCUS helps in detecting inflamed appendix and can be visualized better in thin patients compared to obese patients. If the appendix does not undergo compression, it indicates inflammation. An appendix is demonstrated as a noncompressible structure with a diameter of more than six millimeters, distorted mucosa, positive intraperitoneal fluid, and positive fecalith (hard fecal matter). It has 100 percent of sensitivity in diagnosing appendicitis.

• POCUS helps in detecting gallstones. The POCUS probe is moved from the central abdomen to the right side. After localization of the gallbladder, in case of confirming gallstones, the patient is asked to move, which causes the gallstones to move. A gallstone is detected by posterior acoustic shadow (area of absent sound waves) along with an echogenic rim (bright rim), and the patient experiences pain when pressure is applied to the gallstone area. It has 88 percent of sensitivity in diagnosing gallstones.

Conclusion:

POCUS is an important diagnostic tool that all primary healthcare sectors should use. It has high sensitivity and helps in detecting acute abdominal emergencies such as appendicitis, bowel obstructions, ectopic pregnancies, perforated abdomen, and gallstones. The future of medicine should include training to use POCUS by all healthcare providers.