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Understanding the most commonly billed diagnoses in primary care

Urinary tract infections

Rogers, Julia DNP, RN, CNS, FNP-BC

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doi: 10.1097/01.NPR.0000718516.64801.27
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This is the next article in a 12-part series of 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 and the CDC.1,2

Urinary tract infections (UTIs) account for more than 8 million ambulatory visits per year in the US, making it among the most common infections encountered in primary care.3,4 UTI prevalence is higher in females, as women are responsible for 84% of the associated ambulatory visits.5 Up to 60% of women report having a lower UTI at some point in their lifetime.6 The cost associated with UTIs is $1.6 billion annually.4 Direct costs are related to prescription medications, diagnostic testing, outpatient office visits, and hospitalizations. Work absenteeism and loss of productivity are associated indirect costs.


UTIs are inflammation within the urinary epithelium caused by the same bacteria that inhabit the gut.7,8 UTIs can occur anywhere along the urinary tract, including the urethra, bladder, prostrate, ureter, or kidney. Acute cystitis involves an inflammation of the bladder. The most common cause of bladder inflammation is a lower UTI, and the most common route of infection is bacteria ascension from the urethra to the bladder. In a lower UTI, bacteria do not ascend beyond the bladder.8 In acute pyelonephritis, an upper UTI, bacteria replicate within the bladder, ascend, and invade the kidney through the ureter or spread to the body through the bloodstream.8,9

There are several natural protective factors within the genitourinary system to avert UTIs. Micturition, or urination, flushes most bacteria out of the urethra and is an important protective mechanism. In healthy individuals, the body has other natural defense mechanisms that maintain homeostasis. The body's maintenance of a low pH and high osmolality of urea produces a bactericidal effect along with the presence of uromodulin and secretions from the uroepithelium.7,10

Both males and females are protected by the periurethral mucus-secreting glands. These glands provide a layer of protection by trapping bacteria before it can ascend from the proximal urethra to the bladder. Men have added barriers, including the length of the male urethra and secretions from the prostate.7,10 The body's immune system is able to detect and destroy bacteria that are able to ascend to the urethra if the bacteria comes into contact with the bladder wall. The closure of the ureterovesical junction during bladder contraction prevents urine reflux, thereby preventing ascension of bacteria from the distal urethra to the ureters and kidneys, deterring an upper UTI. The patient's Lewis blood group influences the efficiency of the bladder's defenses. Individuals with certain Lewis blood groups are more prone to UTIs because they secrete fewer antigens capable of resisting bacterial adherence.7,10

The presence of UTI occurs when bacteria are able to circumvent or overwhelm the body's defense mechanisms. There are pathogens that have the virulence to rapidly reproduce, resist bactericidal effects of complement, and express toxins. One such pathogen is Escherichia coli, which is responsible for 86% of uncomplicated UTIs.4 Following colonization of the periurethral area, bacteria enter the urinary tract.7,8 Uropathogenic strains of E. coli have finger-like projections that bind to receptors on the uroepithelium and resist flushing during normal micturition and have flagella that propel them upstream. Certain bacterial species can enhance their virulence by acting together to form a biofilm that enhances colonization and can resist the innate host defense mechanisms and antimicrobial therapy.

Women are at higher risk for UTI than men due to an anatomically shorter urethra with relative proximity to the anus, increasing possibility of bacterial contamination. Women who are sexually active, pregnant, postmenopausal, use spermicides, or are being treated with antibiotics are at even greater risk.8,9,11 Postmenopausal women are at higher risk for UTI due to physiologic and hormonal changes including a thinning of vaginal tissue, trouble completely emptying the bladder, and lower estrogen levels.12 Estrogen may promote the growth of good bacteria that help keep infectious organisms in check.12 Other individuals at higher risk for UTIs include older adults, individuals with indwelling catheters, and patients with comorbid conditions (for example, type 2 diabetes mellitus, neurogenic bladder, or urinary tract obstruction).7

The inflammation in the bladder wall stimulates stretch receptors, initiating symptoms of bladder fullness with small volumes of urine and producing the urgency and frequency of urination associated with cystitis.7 There are sensory nerves located just beneath the urothelium that can invoke pain when stimulated from the inflammatory process associated with UTIs, thereby provoking suprapubic, flank or low back pain, and dysuria. Pain occurring at the start of urination may indicate urethral pathology, whereas pain occurring at the end of urination is usually of bladder origin.13

History, physical exam, and diagnosis

History. A patient's medical history is crucial in the diagnosis of UTI. The documentation of a thorough history of present illness includes symptom onset, quality, severity, duration, timing, context, and associated symptoms. The practitioner should document patient reports of urinary frequency, urgency, hesitancy, dysuria, hematuria, incontinence, nocturia, malodorous urine, and a history of UTIs. NPs should inquire about abdominal, suprapubic, and flank or low back pain. Women should be asked about vaginal discharge or irritation, most recent menstrual period, and the type of contraception used.13 NPs should also investigate modifying factors and utility. Additional information to collect includes medication, family, social, and procedural history. It is important to collect any medical history of vaginitis, prostatitis, sexually transmitted infections, bladder stones, reactive arthritis, and genitourinary dermatitis because these conditions may align with a complicated UTI or may provide clues of potential differential diagnoses.

The NP can establish initial differential diagnoses based on presenting symptoms. In the absence of vaginal secretions or pain, the positive predicative value of acute cystitis screening is 90% based solely on a subjective history of new onset of polyuria, dysuria, and urinary urgency.9,14 However, a patient with diabetes presenting with dysuria and systemic symptoms leads to a list of differential diagnoses, such as a complicated upper UTI, autonomic neuropathy, diabetic ketoacidosis, or urosepsis.4,9 The NP must be astute in taking the history of an older adult patient. This population can be quite ill with an upper or lower complicated UTI but only present with confusion or vague abdominal discomfort. Older adults are at a greater risk for morbidity and mortality due to UTI.7 Information collected during the history and physical exam can guide the NP in discerning a complicated from an uncomplicated UTI.

Physical exam. The physical exam should include vital signs and a complete abdominal assessment, including palpation for abdominal masses or tenderness, as well as evaluation for costovertebral angle pain and inspection for dermatologic conditions related to fungal infection or irritation and breakdown from incontinence.13 It is important for the NP to include a general exam and documentation on cardiac, pulmonary, gastrointestinal, genitourinary, and integumentary systems to rule out any other causative factors. The physical exam is typically normal for uncomplicated UTIs, although suprapubic tenderness is present in 10% to 20% of women.4,9 A patient with a complicated UTI may present with systemic symptoms such as fever, chills, mental status changes, tachycardia, hypotension, nausea, vomiting, pain, and incontinence. A complicated upper UTI may elicit pain with palpation or percussion to the upper abdomen, flank, or costovertebral angle. Female patients may complain of pain with a pelvic exam. The abdominal pain article in this series details other disease processes that provoke abdominal pain.

Diagnosis. UTIs are classified as upper (pyelonephritis) or lower (cystitis) and further categorized as uncomplicated, complicated, recurrent, relapsing, and catheter associated. Uncomplicated UTIs can be acute, sporadic, or a recurrence of an uncomplicated lower or upper UTI; patients present with mild symptoms of urinary frequency and dysuria. Uncomplicated UTIs are limited to nonpregnant women with no relevant anatomical or functional abnormalities within the urinary tract and no comorbidities.3,4,9 A complicated UTI often presents with systemic signs and symptoms and incorporates all UTIs not defined as uncomplicated. This includes all men, pregnant women, and patients with relevant anatomical or functional abnormalities of the urinary tract (for example, renal calculus), indwelling urinary catheters, renal diseases, or other concomitant immunocompromising diseases.3,7

Some patients have recurrent UTIs, defined as three or more uncomplicated or complicated UTIs within 12 months, or two or more occurrences within 6 months.13 There must be clear documentation of positive urine cultures for these occurrences, and they must be at least 2 weeks apart (unless a new pathogen is identified) and associated with symptoms.3,7,12 Occasionally, a patient might have a relapse, meaning there is a second UTI caused by the same pathogen within 2 weeks of completing appropriate antibiotic therapy; this is separate from a reinfection, which is a second UTI caused by the same or different pathogen more than 2 weeks after treatment completion.3,7 Catheter-associated UTI refers to a UTI occurring in those currently catheterized or who have had a catheter in place within the past 48 hours.3

Making a definitive diagnosis is further complicated by the approximate 10% of individuals with bacteriuria who are asymptomatic and another 30% of individuals who are symptomatic but test abacteriuric.7 Asymptomatic bacteriuria is the presence of 100,000 or more colony-forming units (CFU)/mL in a voided urine specimen from an individual without signs and symptoms attributable to UTI.3 Other patients may have symptoms that mimic a UTI, such as from overactive bladder or interstitial cystitis/bladder pain syndrome (IC/BPS), without an infection. Symptoms associated with IC/BPS include an unpleasant sensation related to the lower urinary tract lasting more than 6 weeks in the absence of infection or other unidentifiable causes.15

Diagnostics. The urine dipstick is a cost-effective alternative diagnostic test for UTI and provides much of the same information as the standard urinalysis. A midstream clean catch is the most accurate way to obtain a urine specimen.7,9 Positive nitrates and leukocyte esterase on the dipstick analysis are accurate indicators of a UTI.4 Screening for asymptomatic bacteriuria is only recommended for pregnant women and individuals who will be undergoing invasive urologic procedures.9,16 There is a high probability of uncomplicated UTI in women presenting with onset of classic UTI symptoms (including polyuria, dysuria, and urinary urgency); therefore, subjective symptomatology is its own valuable diagnostic test.9 Women reporting typical symptoms of uncomplicated lower UTI do not require any lab or diagnostic testing.9,13

Urinalysis and urine culture and sensitivity are required for patients with a complicated UTI, atypical symptoms, suspected pyelonephritis, or unresolved or recurrent symptoms within 2 to 4 weeks after completing treatment.4,17 A urine culture and sensitivity establishes a definitive diagnosis through identification of the uropathogen. A positive culture is characterized by bacteriuria of at least 105 CFU/mL.5 Patients with a complicated UTI or with atypical symptoms may require diagnostic imaging if there is no response to antibiotic treatment or there is a suspected obstruction. A computed tomography scan is useful in this case.

Treatment. Current treatment guidelines for adults recommend three options for first-line treatment of acute uncomplicated cystitis: nitrofurantoin, trimethoprim/sulfamethoxazole, or fosfomycin. Fosfomycin has minimal resistance but has inferior efficacy and is not widely available in the US.4,17 Second-line treatment options include fluoroquinolones and beta-lactam antibiotics. These are not considered first-line therapy because of antimicrobial resistance.17 It is essential to rule out a complicated UTI before treating a patient for an uncomplicated UTI. A misdiagnosed complicated UTI increases the risk of treatment failure.

Optimal therapy for acute uncomplicated pyelonephritis begins with a urine specimen for culture and sensitivity, which must be collected prior to antibiotic initiation.9,17 Therapy depends on severity and local resistance patterns. The guidelines currently recommend empiric therapy with a broader-spectrum agent (for example, fluoroquinolone) for patients with pyelonephritis not requiring hospitalization while awaiting culture and sensitivity results.17 The antibiotic choice is either ciprofloxacin or levofloxacin.17 Oral trimethoprim-sulfamethoxazole is an appropriate alternate. Oral beta-lactam agents should not be prescribed due to decreased efficacy in the treatment of pyelonephritis.17 Once the uropathogen is known, the NP should continue the current antibiotic regimen if the pathogen is susceptible or change to a microorganism-specific antibiotic based on susceptibility.17 It is important that NPs review their local bacterial resistance patterns and antibiograms.18 NPs should not perform a posttreatment test of cure urinalysis or urine culture in asymptomatic patients.12

While clinical symptoms may be relieved, bacteriuria may still be present.7,19 Asymptomatic bacteriuria is not treated with antibiotics to limit the development of antibiotic-resistant strains. Some postmenopausal women may benefit from a vaginal estrogen cream to decrease the risk of recurrent UTIs.5

Patients with recurrent or relapsing infections may require prolonged antibiotic treatment, especially if drug-resistant, thus warranting a referral to urology or an infectious-disease specialist. Other considerations for a referral include gross hematuria, incontinence, and complicated infections. Obstruction, urosepsis, and septic shock are medical emergencies that require referral to the ED. Noninfectious cystitis associated with radiation or chemotherapy treatment for pelvic and urogenital cancers is treated symptomatically and involves collaboration with radiology and oncology.7

It is vital for the NP to educate patients with a UTI about normal bladder function, self-care practices, and behavior modifications that can improve symptoms and prevent infections.15 Self-care practices for UTI prevention include urinating regularly and postcoital voiding, which can flush bacteria from the urinary tract before proliferation. Wiping genitalia from the front toward the back after micturition prevents bacteria near the rectum from getting close to the urethra. Douching should be avoided. Scrubbing and using overly harsh cleansing products on the genitalia should also be avoided because of the risk of damage to the skin, making an infection more likely. Behavioral modifications include adequate oral hydration, avoidance of common irritants such as coffee, citrus products, and spermicides, as well as engaging in safer sex practices.9,11,15

ICD-10-CM codes
Codes for disorders of genitourinary system start with N, and most diseases of the urinary system are built upon the base codes of N30-N39 and N10. Use appropriate disease coding as shown below.
N30.00 Acute cystitis without hematuria N30.01 Acute cystitis with hematuria
N30.10 Interstitial cystitis (chronic) without hematuria N30.11 Interstitial cystitis (chronic) with hematuria
N30.20 Other chronic cystitis without hematuria N30.21 Other chronic cystitis with hematuria
N30.30 Trigonitis without hematuria N30.31 Trigonitis with hematuria
N30.40 Irradiation cystitis without hematuria N30.41 Irradiation cystitis with hematuria
N30.80 Other cystitis without hematuria N30.81 Other cystitis with hematuria
N30.90 Cystitis, unspecified without hematuria N30.91 Cystitis, unspecified with hematuria
N39.0 Urinary tract infection, site not specified N10 Acute pyelonephritis
If pathogen related to acute pyelonephritis or cystitis is known from culture results, use both the specific B code below and the appropriate N10 or N30 code.
ICD-10-CM codes Specificity—Must use appropriate disease specificity coding as below
B95 Streptococcus, Staphylococcus, and Enterococcus as the cause of diseases classified elsewhere
  • B95.0 Streptococcus, group A

  • B95.1 Streptococcus, group B

  • B95.2 Enterococcus

  • B95.3 Streptococcus pneumoniae

  • B95.4 Other streptococcus

  • B95.5 Unspecified streptococcus

  • B95.61 Methicillin susceptible Staphylococcus aureus

  • B95.62 Methicillin resistant S. aureus

  • B95.7 Other staphylococcus

  • B95.8 Unspecified staphylococcus

B96 Other bacterial agents as the cause of diseases classified elsewhere
  • B96.0 Mycoplasma pneumoniae

  • B96.1 Klebsiella pneumoniae

  • B96.20 Unspecified Escherichia coli

  • B96.21 Shiga toxin-producing E. coli

  • B96.22 Other specified Shiga toxin-producing E. coli

  • B96.23 Unspecified Shiga toxin-producing E. coli

  • B96.29 Other E. coli

  • B96.3 Hemophilus influenzae

  • B96.4 Proteus (mirabilis) (morganii)

  • B96.5 Pseudomonas (aeruginosa) (mallei) (pseudomallei)

  • B96.6 Bacteroides fragilis

  • B96.7 Clostridium perfringens

  • B96.8 Other specified bacterial agents∗∗

  • B96.81 Helicobacter pylori

B97 Viral agents as the cause of diseases classified elsewhere
  • B97.0 Adenovirus

  • B97.10 Unspecified enterovirus

  • B97.11 Coxsackievirus

  • B97.12 Echovirus

  • B97.19 Other enterovirus

  • B97.2 Coronavirus∗∗

  • B97.3 Retrovirus∗∗

Codes with a greater degree of specificity should be considered first.
∗∗Further specification required for billing of these codes.

Billing. The International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) is a morbidity classification published by a joint effort between Centers for Medicare and Medicaid Services and the National Center for Health Statistics.20 The ICD-10-CM is the standard billing code system that is used to submit diagnosis codes for insurance reimbursement.

ICD-10-CM codes related to diseases of the genitourinary system start with the letter N. Most of the ICD-10-CM codes associated with diseases of the urinary system are listed under N10 and N30 to N39 (see ICD-10-CM codes). Cystitis-type UTIs start with N30.0 and are specified according to presence or absence of hematuria.20 The ICD-10-CM code for UTI, site not specified, is N39.0, whereas the code associated with acute pyelonephritis is N10.20 Codes N10 and N30 require a secondary B95-B97 billing code if the causative pathogen has been identified. B95 is used for Streptococcus, Staphylococcus, and Enterococcus; B96 is used to identify other bacterial agents; and B97 designates viral agents as the cause of diseases classified elsewhere.20 Each of the B codes are categorized even further to identify the specific infectious agent(s) if known at the time of billing. It is imperative for the NP to document supportive information within the patient's chart to provide justification for highly specified codes. The ICD-10-CM codes with the highest specificity will increase reimbursement.

Implications for practice

Important considerations for the NP when caring for a patient with a UTI include prescribing the correct antibiotic via the proper route for the shortest duration. As frontline providers, NPs can lead the way for outpatient clinics to follow treatment guidelines and use local antibiograms when treating UTIs.21

Hospital admissions attributable to UTIs have increased in recent years; however, patients are more likely to be treated in an outpatient rather than an inpatient setting.22,23 This article provides the clarity needed to help NPs differentiate upper and lower UTIs from asymptomatic bacteriuria, thereby reducing inappropriate antimicrobial prescriptions and improving antimicrobial stewardship.


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18. Waller TA, Pantin SAL, Yenior AL, Pujalte GGA. Urinary tract infection antibiotic resistance in the United States. Prim Care. 2018;45(3):455–466.
19. Dubbs SB, Sommerkamp SK. Evaluation and management of urinary tract infection in the emergency department. Emerg Med Clin North Am. 2019;37(4):707–723.
20. ICD-10-CM Official Guidelines for Coding and Reporting. 2019.
21. Guelman L, Hsieh CD, Pine K, Lough ME. Optimizing antibiotic management for acute simple cystitis in women: an evidence-based roadmap for the primary care ambulatory setting. Urol Nurs. 2019;39(6):283–292.
22. Tung A, Hepp Z, Bansal A, Devine EB. Characterizing health care utilization, direct costs, and comorbidities associated with interstitial cystitis: a retrospective claims analysis. J Manag Care Spec Pharm. 2017;23(4):474–482.
23. Foster K, Simmering JE, Polgreen PM, Polgreen LA. 1463. The rates of UTI outpatient and inpatient visits from 2001 to 2015 among an insured population. Open Forum Infect Dis. 2019;6(suppl 2):S534.

billing; clinical manifestations; pathophysiology; primary care; treatment; urinary tract infection; UTI

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