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Understanding the most commonly billed diagnoses in primary care

Abdominal pain

Rogers, Julia DNP, RN, CNS, FNP-BC; Schallmo, Marianne DNP, APRN, ANP-BC

Author Information
doi: 10.1097/01.NPR.0000724512.95721.68
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This is the 8th article in a 12-part series on the most commonly billed diagnoses in primary care outpatient settings. The top 12 billed diagnoses were retrieved from compiling information obtained from the Centers for Medicare and Medicaid Services (CMS) and the CDC.1,2

Abdominal pain is common, affecting nearly every person at some point in their lifetime.3,4 It has a high disease burden, both in incidence and cost. There are approximately 6 million ED visits for abdominal pain in the US annually, and the incidence continues to rise.3 Abdominal pain is one of the most expensive gastrointestinal (GI) symptoms in the US, costing $10.2 billion annually in associated healthcare expenditures.3

An abdominal pain evaluation can be challenging for primary care practitioners. Abdominal pain symptoms may be vague or referred, often making the diagnosis elusive. Many different body system pathologies can cause abdominal pain, such as cardiopulmonary, genitourinary, reproductive, musculoskeletal, or GI disorders. Abdominal pain pathology can vary widely, including acute, chronic, or acute-on-chronic conditions. Certain acute conditions, such as an appendicitis, require prompt referral and treatment.

- Abdominal visceral structure with spinal innervation and pain region6-8
Abdominal structure Spinal segment innervation Pain region
Distal esophagus, stomach, duodenum, pancreas, liver, biliary tree T5-6 and T8-9 Between the xiphoid process and umbilicus
Small bowel, appendix, entire colon up to distal region T8-11 and L1 Periumbilicus
Distal colon and rectum T11-L1 Between the umbilicus and pubic symphysis

In the primary care setting, many cases of abdominal pain are benign and self-limiting and resolve with minimal intervention; however, approximately 10% of visits for abdominal pain involve an acute condition needing immediate care.4 In the adult population, the most common causes of abdominal pain in the primary care setting include gastroenteritis, irritable bowel syndrome, gastritis, and urologic sources.4 Chronic abdominal pain lasts 6 months or more, either intermittently or continuously.5 Chronic conditions can generally be managed in the outpatient setting.


The exact mediators and mechanism of how abdominal pain is experienced are not completely understood.6 Abdominal pain type, quality, intensity, and location depend on the activation of abdominal nociceptive receptors by mechanical and/or chemical stimuli. Pain is also characterized by chronicity, aggravating and alleviating factors, and associated symptoms. Factors such as patient perception and past pain experiences may also alter pain experience.

Abdominal pain is divided into three afferent relays: somatic, visceral, and referred.6-8 Patients may simultaneously experience one or more pain pathways. Somatic pain arises from cutaneous or deep structures, occurring in bones, joints, connective tissue, and muscles.7,8 Somatic abdominal pain arises from the parietal peritoneum.8 The quality of abdominal somatic pain tends to be asymmetric, well localized, and described as sharp. Because somatic innervation is unilateral, patients with somatic pain are often able to pinpoint the precise location. Somatic pain is intensified by sudden movement, deep inspiration, or application of pressure on the abdominal wall. An example of somatic pain is postoperative cholecystectomy pain.

Visceral pain occurs in hollow and solid organs and arises from infiltration, compression, traction, stretch, or distension.6-8 The capsule surrounding an organ is enriched with nerve endings. The visceral afferents innervate multiple abdominal visceral structures and bilaterally enter several spinal levels, thus causing diffuse pain findings.6,9 For example, the small intestine visceral nerve enters the spinal cord at levels T8 to L1.6 Patients with a distended appendix may locate their pain by moving their hand across the middle abdomen or periumbilical area (see Abdominal visceral structure with spinal innervation and pain region).9 Visceral pain quality tends to be described as vague, cramping, dull, and aching.

Referred pain is visceral pain felt along the same skin dermatome or shared afferent neuropathway as the organ, but at a site distant to the original visceral pain site.6-8 Since referred pain involves simultaneous somatic and visceral innervation, the patient may experience pain at multiple sites and different pain qualities. One pain site may have an aching quality but a distant site may have well-localized pain. An example of referred pain is when a patient with acute cholecystitis presents with dull, aching pain in the abdomen but a distant well-localized pain in the right scapula.

History, physical exam, and diagnosis

A key to effective abdominal pain management is to identify the underlying cause. The NP must determine if the etiology is acute or chronic. A thorough history and physical exam are critical in both developing and narrowing differential diagnoses, and the findings are important to differentiate between emergent and nonemergent pathology. Based on the history and physical exam findings, appropriate labs and imaging can be ordered. If the NP is unfamiliar with these practices, consequences to the patient may include needless and redundant office visits, advanced or repeated diagnostics, invasive procedures, or a missed urgent surgical intervention. These unintended consequences increase disease burden, cause undue patient stress, and delay treatment.

NPs should obtain and document a detailed history of present illness. The PQRSTU assessment is a mnemonic used to conduct a complete pain history (see PQRSTU pain assessment).10 There are several standardized pain intensity assessment tools, such as the Wong-Baker FACES Pain Rating Scale or the Numeric Rating Scale. It is important to use a pain intensity assessment tool appropriate for the patient's developmental level. Additionally, a complete review of systems must be obtained. Assessing associated symptoms during the review of systems can help guide the development of appropriate differential diagnoses (see Abdominal pain review of systems).11

Attaining an accurate medical history is just as critical. Patients with comorbid conditions such as type 2 diabetes mellitus (T2DM) can present with less pain due to neuropathic changes. Refer to article 4 in this series for more information on T2DM. NPs should inquire about the patients' surgical history—specifically previous abdominal surgeries. Finally, NPs should also review the social history, travel history, family history, recent sick contacts, and recent hospitalizations, and obtain a current list of medications. It is important to collect information about recent antibiotic use and about use of opioids and complementary medications.

- PQRSTU pain assessment10
Mnemonic Definition Example questions
P–provoke or palliative Aggravating and alleviating factors “What were you doing when the pain started? What makes the pain better or worse?”
Q–quality Characteristics of pain “What does your pain feel like?” (sharp, dull, tingling, burning, and the like)
R–region or radiation Location of pain “Point to the current location of your pain. Where did the pain start? Does the pain radiate or move?”
S–severity and symptoms
  1. Use a scale (numeric rating scale, visual analogue scale, or Wong-Baker FACES Pain Rating Scale) to quantify pain level

  2. Associated symptoms occurring with the pain

  1. “Rate your pain on a 0-10 scale with 0 meaning no pain and 10 meaning the worst pain imaginable, how bad is the pain at its worst?”

  2. “What other symptoms are you experiencing?” (nausea, vomiting, fever, and the like)

T–time frame Onset, duration, and frequency of pain “Is this your first episode of pain? When did the pain start, how long does it last, and does the intensity change with time?”
U–you Impact pain has on patient's daily routine “How is the pain affecting your life? Does it limit your function or activities?”

The physical exam should include a complete set of vital signs, assessing for tachycardia, hypotension, and/or fever, and a thorough abdominal exam. It is also imperative to assess the patient for altered mental status, scleral icterus, dry mucous membranes, adventitious lung sounds, jaundice, and decreased skin turgor. The abdominal exam proceeds in an orderly fashion starting with inspection, then auscultation, percussion, and finally palpation.10 It is important for the patient to be positioned properly and have an empty bladder. The NP should assess for tenderness, distension, rigidity, rebound tenderness, Murphy sign, and Carnett sign, and should document findings.10,12,13 Additional exams should be based upon initial findings. Since a normal aorta is less than 3 cm wide and abdominal aortic aneurysms are often asymptomatic, one key assessment finding upon palpation is locating a pulsatile abdominal mass suggesting an aortic aneurysm.14 If fecal impaction is suspected, then a rectal exam should be performed. Further assessment should also be considered in special populations. Males should be checked for hernias and testicular swelling, masses, or tenderness, and females may need a pelvic exam to assess for pelvic pathology.

- Abdominal pain review of systems10
System Abnormal clinical manifestations
Constitutional Fever, chills, unintentional weight loss
Integumentary Pallor, jaundice, rashes
Cardiopulmonary Chest pain, shortness of breath, cough
GI Nausea, vomiting, diarrhea, constipation, hematochezia, melena, recent changes in stool color or consistency or bowel habit, pain in relation to meals or bowel movement, bloating, abdominal distension
Genitourinary Dysuria, urinary frequency, hematuria, dark amber urine
Psychological Unresolved interpersonal difficulties, depression, anxiety
Specific population Females should be screened for sexually transmitted diseases, pelvic inflammatory disease. Premenopausal woman should be asked about menstrual cycle history, contraceptive use, vaginal discharge and bleeding, dyspareunia, or dysmenorrhea.

- Abdominal pain imaging and preliminary diagnostic workup9,15
Imaging Labs
Individuals presenting with red flag symptoms or that require emergency workup should be referred to the nearest emergency department.
Nonemergent acute abdominal pain Abdominal ultrasound
  1. CBC with differential

  2. CMP

  3. Amylase, lipase

  4. ESR

  5. CRP

  6. Urinalysis or urine dipstick

  7. Pregnancy test (all women of child-bearing age)

Chronic abdominal pain
  1. Ultrasound, CT, or MRI may be indicated, unless previously completed and normal

  2. CBC with differential

  3. CMP

  4. Amylase, lipase

  5. Serum iron, total iron binding capacity, ferritin

  6. Anti-tissue transglutaminase

  7. ESR

  8. CRP

  9. Hepatitis screening panel

  10. Thyroid function panel

    • constipation/diarrhea

      Pregnancy test

    • all women of child-bearing age

Abbreviations: CBC, complete blood cell count; CMP, comprehensive metabolic panel; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate


The abdominal pain diagnostic workup is dependent on pain severity and patient history. Both emergent and nonemergent abdominal pain require lab and radiologic testing (see Abdominal pain imaging and preliminary diagnostic workup).11 Any patient with suspected urgent or emergent conditions, or those requiring surgical intervention, should be referred for immediate evaluation.5 Evaluation of nonemergent conditions is dependent on pain location and the differential diagnoses (see Abdominal pain location with etiology and differential diagnoses).11,15 Special considerations are taken into account regarding diagnostic testing for specific patient populations. Women of child-bearing age should have a pregnancy test, and adults over age 50 with new-onset, nonemergent abdominal pain should receive workup for cancer due to higher risk of colon cancer and other malignancies.11 Additional testing may also be required depending on initial lab and imaging results. However, it is important not to repeat negative computed tomography (CT) scans unless the presentation has changed, as the yield is low and this practice increases overall cost.15,16

- Abdominal pain location with etiology and differential diagnoses5,9
Pain location Etiology Differential diagnosis
Upper abdominal pain
• Right upper quadrant Hepatic and biliary
  1. Gallstones

  2. Acute cholecystitis

  3. Acute cholangitis

  4. Hepatitis

  5. Liver abscess

• Epigastric Pancreatic, gastric, or cardiac
  1. Acute myocardial infarction

  2. Pancreatitis

  3. Peptic ulcer disease

  4. Gastroesophageal reflux disease

  5. Gastritis

  6. Gastroparesis

  7. Dyspepsia

• Left upper quadrant Spleen
  1. Splenomegaly

  2. Splenic infarct

Lower abdominal pain Intestinal tract, kidney, bladder
  1. Acute appendicitis

  2. Diverticulitis

  3. Kidney stones

  4. Pyelonephritis

  5. Cystitis

  6. Acute urinary retention

  7. Infectious colitis

  8. Colon cancer

Female reproductive organs
  1. Pregnancy or pregnancy complication

  2. Ectopic pregnancy

  3. Pelvic inflammatory disease

  4. Ruptured ovarian cyst

  5. Endometriosis

  6. Leiomyomas

  7. Ovarian cancer

Male reproductive organs
  1. Testicular torsion

  2. Prostate cancer

Nonspecific abdominal pain Other
  1. Ileus or obstruction

  2. Mesenteric ischemia

  3. Inflammatory bowel disease

  4. Viral gastroenteritis

  5. Spontaneous bacterial peritonitis

  6. Malignancy (colorectal, gastric, or pancreatic)

  7. Celiac disease

  8. Ketoacidosis

  9. Adrenal insufficiency

  10. Foodborne illness

  11. Irritable bowel syndrome

  12. Constipation

  13. Diverticulosis

  14. Lactose intolerance

Uncommon causes Other
  1. Abdominal aortic aneurysm

  2. Chronic abdominal wall pain

  3. Herpes zoster

  4. Narcotic bowel syndrome

  5. Hypothyroidism

  6. Pulmonary etiology (pneumonia, pulmonary embolism)

  7. Sickle cell anemia

Note: This is not a complete list of all possible differential diagnoses for abdominal pain.

- Red flags requiring urgent/emergent evaluation9
System Clinical manifestations
Constitutional Fever, unexplained weight loss, loss of appetite, pain awakening from sleep, immediate severe pain
Integumentary Jaundice, lower extremity edema
Cardiopulmonary Chest pain, tachycardia, tachypnea, hypotension
GI Hematemesis, hematochezia, severe vomiting, severe diarrhea, abdominal swelling, difficulty swallowing, rebound tenderness, abdominal rigidity, guarding, and right upper quadrant pain
Other Acute, accelerating chronic pain, or acute new symptoms in chronic abdominal pain


The suspected diagnosis drives the treatment plan. A stepwise approach to abdominal pain initially identifies patients presenting with emergent “red flags.” These patients will need immediate referral to the ED, gastroenterology, or another specialty for further evaluation (see Red flags requiring urgent/emergent evaluation).11 All nonemergent cases are generally treated in the outpatient setting. Chronic abdominal pain can be challenging to treat, as even with multiple office visits, the abdominal pain is often not successfully eliminated.

Abdominal pain involves a long list of differential diagnoses. Discussing treatment of all possible differentials is outside this article's scope; therefore, an overview of chronic abdominal pain management in the primary care setting is provided.4 Pharmacologic treatment and psychotherapy are equally important when managing chronic abdominal pain. After etiology has been determined and any correctable conditions addressed, pharmacologic therapy can be considered. Pharmacotherapy has been shown to help control visceral pain. Recent studies of gabapentin and pregabalin have shown beneficial results, most notably in inflammatory bowel disease.17 Other pain medications that may provide pain relief include nonsteroidal anti-inflammatory medications (NSAIDs) (including cyclooxygenase-2 [COX-2] inhibitors) and antispasmodics; however, long-term use of these medications can exacerbate some GI conditions or worsen bowel dysmotility, and they are contraindicated in some abdominal pain etiologies.17 For example, gastrointestinal lining injury can occur with NSAID and COX-2 inhibitor use and therefore these medications are contraindicated in gastroesophageal reflux and gastroduodenal ulcer disease.18 Controlling chronic visceral pain with opioids should be done with caution, as this may not only contribute to opioid-induced constipation, but also place the patient at risk for opioid dependency.19 Therefore, opioids are not the drug of choice in chronic abdominal pain.19

Chronic abdominal pain of any origin has been shown to have psychological effects that need to be addressed in order to improve patients' quality of life (QOL). Therefore, patients should be referred for psychotherapy such as cognitive behavioral therapy and screened for anxiety and depression related to the chronic abdominal pain. If a patient is diagnosed with associated anxiety or depression, pharmacologic options include selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and tricyclic antidepressants.17

Acute abdominal pain that does not require immediate intervention can be treated effectively in an outpatient family practice setting. Most acute gastroenteritis in a healthy immunocompetent patient is self-limiting and generally resolves without sequalae. Patients with vital sign abnormalities or comorbidities may be predisposed to complications such as dehydration or electrolyte abnormalities. Patients presenting with gastroenteritis need supportive care, including proper hydration, bland diet, electrolyte replacement, avoidance of caffeine, and disease course education.20 If a urinary tract infection is determined after urinalysis testing, then appropriate antibiotics should be initiated based on the culture and sensitivity results.8

- Abdominal and pelvic pain ICD-10-CM codes20-22
ICD-10-CM code Specificity
  1. Codes for abdominal pain are built on the base code:

  2. R10 Abdominal and pelvic pain

Some codes require fifth or sixth character to provide further specificity of location or character
R10.0 Acute abdomen
R10.1 Pain localized to upper abdomen
  • R10.10 Upper abdominal pain, unspecified

  • R10.11 Right upper quadrant pain

  • R10.12 Left upper quadrant pain

  • R10.13 Epigastric pain

R10.2 Pelvic and perineal pain
R10.3 Pain localized to other parts of lower abdomen
  • R10.30 Lower abdominal pain, unspecified

  • R10.31 Right lower quadrant pain

  • R10.32 Left lower quadrant pain

  • R10.33 Periumbilical pain

R10.8 Other abdominal pain
  • R10.81 Abdominal tenderness

    • R10.811 Right upper quadrant abdominal tenderness

    • R10.812 Left upper quadrant abdominal tenderness

    • R10.813 Right lower quadrant tenderness

    • R10.814 Left lower quadrant abdominal tenderness

    • R10.815 Periumbilic abdominal tenderness

    • R10.816 Epigastric abdominal tenderness

    • R10.817 Generalized abdominal tenderness

    • R10.819 Abdominal tenderness, unspecified site

  • R10.82 Rebound abdominal tenderness

    • R10.821 Right upper quadrant rebound abdominal tenderness

    • R10.822 Left upper quadrant rebound abdominal tenderness

    • R10.823 Right lower quadrant rebound abdominal tenderness

    • R10.824 Left lower quadrant rebound abdominal tenderness

    • R10.825 Periumbilic rebound abdominal tenderness

    • R10.826 Epigastric rebound abdominal tenderness

    • R10.827 Generalized rebound abdominal tenderness

    • R10.829 Rebound abdominal tenderness, unspecified site

  • R10.83 Colic

  • R10.84 Generalized abdominal pain

R10.9 Unspecified abdominal pain


The International Classification of Disease, 10th Revision, Clinical Modification (ICD-10-CM) is a morbidity classification published by a joint effort between the CMS and the National Center for Health Statistics.21 The ICD-10-CM is the standard billing code system that is used to submit diagnosis codes for insurance reimbursement (see Abdominal and pelvic pain ICD-10-CM codes).22

R10 is the general base code of abdominal and pelvic pain. The R10 code should not be used alone, as there are over 30 codes with greater specificity. The R10 billing codes include pain location, such as upper abdominal pain (R10.1) or lower abdominal pain (R10.3), and/or characteristics such as acute abdomen (R10.0), pain (R10.1, R10.2, R10.3, and R10.8), tenderness (R10.81), rebound tenderness (R10.82), colic (R10.83), or generalized pain (R10.84). Many codes require additional characters to provide further specificity by location.23

The most detailed ICD-10-CM code should be submitted. Only submitting the code R10.9 (unspecified abdominal pain), if the assessment supports greater detail, indicates poor quality documentation, and may prompt a chart audit.22 The R10 code group is only used for signs and symptoms and when a definitive diagnosis is unknown. If a diagnosis is determined, the known diagnosis supersedes the R10 code. For example, if a patient who presents with abdominal pain is determined to have gastroesophageal reflux, the ICD-10-CM code for gastroesophageal reflux without esophagitis (K21.9), or with esophagitis (K21.0), should be submitted as appropriate.

Implications for practice

NPs assess, diagnose, treat, counsel, and educate their patients on a myriad of illnesses.24 Patients with abdominal pain can present with specific warning signs, or with a multitude of nonspecific symptoms, which encompasses a vast list of differential diagnoses. Determining the exact cause often requires multiple office visits and diagnostic testing. This can lead to frustration, decreased QOL, and increased cost to the patient. NPs are in a perfect position to provide high-quality care and offer much-needed reassurance to this patient population. It is, therefore, obligatory to have a thorough understanding of abdominal pain pathophysiology. The NP must use a systematic, comprehensive, and stepwise approach in abdominal pain assessment and management.25

The NP facilitates a holistic approach to the care of patients. Given the prevalence of patients seen in primary care presenting with abdominal pain, NPs are well suited in their expertise to manage this condition. Furthermore, NPs judiciously maintain cost-effectiveness and appropriately collaborate with other healthcare team members to tailor the care management for these patients.


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abdominal pain; appendicitis; billing; clinical manifestations; gastritis; inflammatory bowel disease; pathophysiology; primary care; treatment

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