Health Information Management

ICD-10 anatomy refresher: Digestive system

JustCoding News: Outpatient, May 16, 2012

Want to receive articles like this one in your inbox? Subscribe to JustCoding News: Outpatient!

by Shelley C. Safian, PhD, CCS-P, CPC-H, CPC-I, AHIMA-approved ICD-10-CM/PCS trainer

The digestive system consists of two parts: the alimentary canal and the accessory organs. The alimentary canal is the direct path through the body from the mouth to the anus. This pathway includes:

  • Mouth
  • Pharynx
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Rectum
  • Anus

The digestive accessory organs play a role in the way the body processes food and water so that each tissue and organ system has the fuel to function. These organs secrete enzymes, alkalines, and other substances that are required for the digestive process and include:

  • Salivary glands
  • Liver
  • Gallbladder
  • Pancreas

In ICD-10-CM, codes for diseases of the digestive system fall under category K00-K95and are broken down into the following blocks:

  • K00-K14, diseases of oral cavity and salivary glands
  • K20-K31, diseases of esophagus, stomach, and duodenum
  • K35-K38, diseases of appendix
  • K40-K46, hernia
  • K50-K52, noninfective enteritis and colitis
  • K55-K64, other diseases of intestines
  • K65-K68, diseases of peritoneum and retroperitoneum
  • K70-K77, diseases of liver
  • K80-K87, disorders of gallbladder, biliary tract, and pancreas
  • K90-K95, other diseases of the digestive system

Start at the top—the mouth
Virtually all nourishment enters the body at the mouth, or oral cavity, which includes the:

  • Lips
  • Cheeks
  • Tongue
  • Lingual tonsils
  • Hard and soft palates
  • Uvula
  • Palatine tonsils
  • Pharyngeal tonsils
  • Teeth

Lips form the entranceway into the oral cavity and the alimentary canal. Their mobility and flexibility aids in the formation of sounds to enable speech.

Cheeks form an area as they meet the gingiva known as the buccal cavities. The inner lining of the cheek is made up of moist, stratified squamous epithelium cells.

The tongue does more than help you form the sounds of speech. It helps rotate food particles into position so the teeth, particularly the molars, can grind the food to enable swallowing safely. The tongue meets with the hyoid bone in the posterior of the mouth and has a surface of lymphatic tissue masses known as the lingual tonsils. When you touch the roof (hard palate) of your mouth with your tongue, you can see a membrane below that appears to connect your tongue with the sublingual gland along the bottom of your mouth. This is called the lingual frenulum.

On each side at the back of the tongue are collections of lymphatic tissue known as the palatine tonsils-so called because of their location at the back of the mouth where the soft palate begins to curve into the throat. The drop-shaped appendage hanging in the posterior of your throat, called the uvula, also helps modulate tones during speech.

The pharyngeal tonsils (adenoids) sit on the posterior wall of the pharynx and are also made of lymphatic tissue.

As the teeth and tongue break down food in preparation for the journey down the alimentary canal, three major salivary glands (the parotid, submandibular, and sublingual glands) secrete saliva to moisten and bind the food particles. This begins the chemical digestion of carbohydrates by dissolving foods so you can appreciate their flavor. It also makes swallowing food particles -easier. In addition, saliva helps clean the teeth and mouth after the particles leave the oral cavity.

One common condition coders see is gingivitis. ICD-10-CM includes codes for acute and chronic gingivitis. The codes further specify whether the gingivitis is plaque induced or non- plaque induced.

Move down the throat
The pharynx is an open cavity posterior to the nose and mouth leading down to the esophagus. This section of the human anatomy serves two important systems: the respiratory system when inhalation is in process and the digestive system when food and drink are ingested. The ¬pharynx is subdivided, for reference only, into three sections:

  • Nasopharynx
  • Oropharynx
  • Hypopharynx, also called the laryngopharynx

At the superior end of the larynx is the epiglottis, a flap that closes the path to the larynx and trachea, thereby directing food and liquid down the esophagus to the stomach.

The esophagus is a tubelike structure that connects the hypopharynx to the stomach. It lies parallel and posterior to the trachea. At the lower end of the esophagus, the upper esophageal sphincter restricts the entrance of air into the stomach.

A second esophageal sphincter is located at the juncture between the esophagus and the stomach (the lower esophageal sphincter). It is designed to prevent the contents of the stomach from splashing back up into the esophagus. When this sphincter does not function ¬properly, a person might experience chronic heartburn, nausea, and possibly a sore throat, potential symptoms of gastro-esophageal reflux disease (GERD).

If a patient does indeed suffer from GERD, coders have two choices in ICD-10-CM:

  • K21.0, gastro-esophageal reflux disease with esophagitis
  • K21.9, gastro-esophageal reflux disease without esophagitis

Now enter the stomach
The next organ along the alimentary canal is the stomach. As stated earlier, the stomach connects to the esophagus at the lower esophageal sphincter in the cardiac region of the stomach, also known as the cardia. To the left, the stomach curves upward creating the fundic region, or fundus. The fundus of the stomach is located superior to (above) the opening to the esophagus.

The lining of the stomach, a mucous membrane, contains gastric glands that secrete gastric juices. Similar to the function of saliva in the processing of food in the mouth, the gastric juices support the extraction of nutrients from the contents that entered from the esophagus.

Mucous cells coat the internal wall of the stomach to prevent the gastric juices from digesting the stomach itself. When this coating is flawed, a person might develop a gastric (peptic) ulcer, where the acids in the stomach actually eat a hole in the lining and wall of the stomach.

To code for an ulcer in ICD-10-CM, coders need to know what type of ulcer it is:

  • Gastric
  • Duodenal
  • Peptic (site unspecified)
  • Gastrojejunal

Physicians will also need to document whether the ulcer is acute or chronic, and with or without hemorrhage, perforation, or both.

For a patient with an acute duodenal ulcer with both hemorrhage and perforation, coders would report K26.2.

As the stomach curves downward, the inside of the curve on the cardiac side is referred to as the lesser curvature. The outside curve, coming down from the fundus, is referred to as the greater curvature. The lower portion of the stomach narrows as it nears the duodenum and connects to the small intestine. The pyloric sphincter is located here to control the emptying of the stomach contents forward into the lower half of the digestive system.

Welcome to the lower GI
The gallbladder is an oblong-shaped pouch lying atop of the duodenum. This sac stores bile, a yellow-green liquid that is used by the body to assist in digestion. When required, the gallbladder contracts to release bile into the duodenum via the common bile duct.

Tucked right below the diaphragm and above the gallbladder, on the right side of the superior aspect of the abdominal cavity, sits the liver, a triangular-shaped organ. The liver is subdivided in two sections by a ligament. The left lobe of the liver is equal to about one-third of the total size with the right lobe making up the remaining two-thirds.

The liver helps metabolize proteins, carbohydrates, and lipids. In addition, it stores glycogen, iron, and vitamins A, D, and B12; removes damaged red blood cells, foreign matters, and toxins by filtering the blood; and secretes bile into the common bile duct by way of the common hepatic duct.

The inferior aspect of the pyloric sphincter is the duodenum, the first segment of the small intestine. The duodenum curves around like the letter "c,” with the pancreas tucked in the center. The hepatopancreatic sphincter, also called the sphincter of Oddi, is the connection point between the duodenum, the pancreatic duct, and the common bile duct that comes from the gallbladder and the liver.

The pancreas provides pancreatic juice, via the pancreatic duct into the duodenum, to assist with proper digestion. The pancreatic islets (the islets of Langerhans) are responsible for secreting hormones, including glucagon and insulin.

As the duodenum trails into that last portion (at the bottom of the "c”) it curves around and becomes the jejunum (the segment of the small intestine that twists and turns throughout the abdomen). The mesentery membrane connects to the jejunum like a spiderweb filled with blood vessels, nerves, and lymphatic vessels to provide nourishment to the intestine. The greater omentum, a double-fold of the peritoneum, looks like a protective curtain on the anterior side of the abdominal cavity from the greater curvature of the stomach down to the anterior of the jejunum.

The ileum is the last segment of the small intestine. It connects to the cecum, the bridge to the large intestine, via the ileocecal sphincter. This sphincter controls the passage of material from the small intestine to the large intestine. At this point, one will find the vermiform appendix, a rounded tubular appendage, protruding from the end of the cecum.

And finally into the colon
The colon is also known as the large intestine and the two terms are used almost interchangeably. Actually, the large intestine consists of the cecum, the colon, the rectum, and the anal canal. The colon represents the majority of the large intestine, but the two are technically not the same..

Starting at the cecum, the colon frames the abdomen and is referred to in four segments. The ascending colon stretches upward from the cecum to just below the liver in the superior aspect of the abdomen. At this point, this tubular structure makes a left turn, known as the hepatic flexure, and stretches directly across the abdomen to the left side. This is named the transverse colon because it traverses the abdomen. Here on the left side, the colon turns downward at a curve known as the splenic flexure. This downward segment, known as the descending colon, continues down until it slightly curves, just above the pelvis, and becomes the sigmoid colon.

The large intestine turns downward again into the rectum, which leads directly into the anal canal. At the distal end of the anal canal, the internal and external anal sphincters form the anus, the opening to the outside—the end … literally.

Shelley C. Safian, PhD, MAOM/HSM, CCS-P, CPC-H, CHA, of Safian Communications Services in Orlando, Fla., answered this question. She is a senior assistant professor who teaches medical billing and insurance coding at Herzing University Online in Milwaukee, Wis. Email her at

Want to receive articles like this one in your inbox? Subscribe to JustCoding News: Outpatient!

    Briefings on APCs
  • Briefings on APCs

    Worried about the complexities of the new rules under OPPS and APCs? Briefings on APCs helps you understand the new rules...

  • HIM Briefings

    Guiding Health Information Management professionals through the continuously changing field of medical records and toward a...

  • Briefings on Coding Compliance Strategies

    Submitting improper Medicare documentation can lead to denial of fees, payback, fines, and increased diligence from payers...

  • Briefings on HIPAA

    How can you minimize the impact of HIPAA? Subscribe to Briefings on HIPAA, your health information management resource for...

  • APCs Insider

    This HTML-based e-mail newsletter provides weekly tips and advice on the new ambulatory payment classifications regulations...

Most Popular