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CPT 85660: RBC Sickling Test with Reducing Solution

CPT code 85660 identifies a laboratory diagnostic procedure that tests patient blood for red blood cell sickling after the addition of a reducing solution. The test is clinically important for identifying sickle cell trait or disease and can inform follow-up hemoglobinopathy evaluation. Nationally, this code is part of the laboratory services mix used by hospitals, outpatient laboratories, and reference labs to support hematology and genetic evaluation pathways.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context for the test, typical sites of service, and which payer groups commonly process claims for this laboratory service. The publication outlines national benchmarking themes, coding and billing considerations relevant to laboratory administrators and billing teams, and any notable policy or reimbursement updates where available. Data not available in the input is indicated explicitly where applicable.

This summary serves clinicians, billing managers, and policy analysts seeking a focused reference on CPT code 85660, its clinical purpose, payer coverage landscape, and the operational settings in which the test is performed.

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Billing Code Overview

CPT code 85660 describes a laboratory procedure in which a specimen of the patient’s blood is tested for red blood cell sickling after exposure to a reducing solution. This test evaluates the propensity of red blood cells (RBCs) to assume the sickled shape under reducing conditions and is used in the diagnostic evaluation of hemoglobinopathies, particularly sickle cell trait or disease.

Service type: Laboratory diagnostic test
Typical site of service: Clinical laboratory or hospital laboratory setting

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CPT 85660: RBC Sickling Test with Reducing Solution

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Billing Code Overview

Service type: Laboratory diagnostic test
Typical site of service: Clinical laboratory or hospital laboratory setting

Clinical & Coding Specifications

Clinical Context

A typical scenario involves a hematology clinic or hospital laboratory performing a sickle cell screening or confirmatory test on a patient with a history of hemolytic anemia, recurrent painful vaso-occlusive episodes, or a newborn or child with suspected sickle cell disease. A phlebotomist collects a venous blood specimen, which is sent to the clinical laboratory. The laboratory technologist performs 85660 (sickling test) by adding a reducing solution to a red blood cell suspension and observing for sickling under a microscope. Results are reported to the ordering provider—commonly a hematologist, pediatrician, emergency physician, or primary care clinician—and used alongside hemoglobin electrophoresis or HPLC to confirm sickle cell trait or disease. Typical sites of service are hospital laboratories, outpatient hospital clinics, specialty hematology labs, and large reference laboratories. The procedure may be ordered during acute presentations (e.g., pain crisis, acute chest syndrome), routine screening of newborns or adolescents, preoperative clearance when sickle cell status is unknown, or follow-up of known hemoglobinopathy carriers.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the professional interpretation component if applicable (rare for this laboratory test).
`52`	Reduced services	Use when the test is partially performed or reduced in scope.
`53`	Discontinued procedure	Use when the test was started but discontinued due to patient condition or specimen issues.
`59`	Distinct procedural service	Use to indicate a distinct test when multiple unrelated lab procedures are billed same day.
`90`	Reference laboratory	Use when tests are performed by an outside reference laboratory.
`91`	Repeat clinical diagnostic laboratory test	Use when a repeat test is performed on the same day for clinical reasons.
`QW`	CLIA-waived test	Use when the performed test is CLIA-waived and billed accordingly.
`TC`	Technical component	Use when billing only the technical component of the laboratory test.
`90`	Reference laboratory	Use when the service was performed by an external reference lab (duplicate entry avoided in practice).
`25`	Significant, separately identifiable E/M service	Use when an evaluation and management service is performed the same day and is separate from ordering/testing.

Taxonomy Code	Specialty	Notes
207RH0000X	Hematology	Hematologists commonly order and interpret sickling tests in diagnosis and management of hemoglobinopathies.
207K00000X	Pediatrics	Pediatricians order newborn and childhood screening tests and follow-up for suspected sickle cell disease.
207L00000X	Emergency Medicine	Emergency physicians may order sickling tests during acute presentations such as pain crises.
2080P0207X	Clinical Laboratory	Pathologists and clinical laboratory directors oversee performance and reporting of this test.
207Q00000X	Internal Medicine	Primary care physicians and internists order screening in adults and coordinate confirmatory testing.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D57.0`	Sickle-cell anemia with crisis	Positive or confirmatory sickling testing may be performed during vaso-occlusive crises to assess sickling status.
`D57.1`	Sickle-cell disease without crisis	Used for baseline evaluation and monitoring of patients with known sickle-cell disease.
`D57.2`	Sickle-cell/Hb-C disease	Sickling tests help screen for hemoglobin S–related disorders prior to confirmatory testing.
`D57.8`	Other sickle-cell disorders	Supports diagnosis when variants or atypical presentations are suspected.
`D57.3`	Sickle-cell trait	Screening tests identify carriers; positive sickling tests often prompt confirmatory electrophoresis.
`R71.8`	Other abnormality of blood chemistry	May be listed when laboratory abnormalities prompt hemoglobinopathy testing.
`Z13.79`	Encounter for screening for other diseases and disorders	Used when routine or targeted screening for hemoglobinopathies is performed.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`85025`	Complete blood count (CBC) with automated differential	Ordered alongside `85660` to assess anemia, reticulocyte count, and white blood cell indices that support hemoglobinopathy evaluation.
`83020`	Hemoglobin electrophoresis, qualitative; single determination	Commonly performed after a positive sickling test to identify hemoglobin S and other variants for diagnostic confirmation.
`83021`	Hemoglobin electrophoresis, quantitative; each fraction	Used for quantification of hemoglobin variants following sickling screening.
`82784`	Hemoglobin; sickling test (alternative lab methods)	Performed as complementary or alternative laboratory method to evaluate abnormal hemoglobins.
`36415`	Collection of venous blood by venipuncture	The specimen collection procedure that precedes `85660` in workflow.

Related Codes

CPT-85002-BLEEDING-TIME-TEST-LABORATORY

CPT 85002: Bleeding Time Test, Laboratory

CPT-85004-AUTOMATED-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

CPT 85004: Automated Differential White Blood Cell Count

CPT-85007-MANUAL-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

CPT 85007: Manual Differential White Blood Cell Count

CPT-85008-BLOOD-SMEAR-MORPHOLOGIC-REVIEW-NO-DIFFERENTIAL

CPT 85008: Blood Smear Morphologic Review Without Differential

CPT-85009-MANUAL-WBC-COUNT-BUFFY-COAT

CPT 85009: Manual White Blood Cell Count Using Buffy Coat

CPT-85013-MICROHEMATOCRIT-TEST-LABORATORY-DIAGNOSTIC

CPT 85013: Microhematocrit Test, Laboratory Diagnostic

CPT-85014-HEMATOCRIT-VOLUME-PERCENT-RED-BLOOD-CELLS

CPT 85014: Hematocrit (Volume Percent of Red Blood Cells)

CPT-85018-HEMOGLOBIN-ASSAY-WHOLE-BLOOD

CPT 85018: Hemoglobin Measurement in Whole Blood

CPT-85025-COMPLETE-BLOOD-COUNT-CBC

CPT 85025: Complete Blood Count (CBC)

CPT-85027-COMPLETE-BLOOD-COUNT-HGB-HCT

CPT 85027: Complete Blood Count with Hemoglobin and Hematocrit

Showing 1–10 of 99

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when billing only the professional interpretation component if applicable (rare for this laboratory test).
`52`	Reduced services	Use when the test is partially performed or reduced in scope.
`53`	Discontinued procedure	Use when the test was started but discontinued due to patient condition or specimen issues.
`59`	Distinct procedural service	Use to indicate a distinct test when multiple unrelated lab procedures are billed same day.
`90`	Reference laboratory	Use when tests are performed by an outside reference laboratory.
`91`	Repeat clinical diagnostic laboratory test	Use when a repeat test is performed on the same day for clinical reasons.
`QW`	CLIA-waived test	Use when the performed test is CLIA-waived and billed accordingly.
`TC`	Technical component	Use when billing only the technical component of the laboratory test.
`90`	Reference laboratory	Use when the service was performed by an external reference lab (duplicate entry avoided in practice).
`25`	Significant, separately identifiable E/M service	Use when an evaluation and management service is performed the same day and is separate from ordering/testing.

Taxonomy Code	Specialty	Notes
207RH0000X	Hematology	Hematologists commonly order and interpret sickling tests in diagnosis and management of hemoglobinopathies.
207K00000X	Pediatrics	Pediatricians order newborn and childhood screening tests and follow-up for suspected sickle cell disease.
207L00000X	Emergency Medicine	Emergency physicians may order sickling tests during acute presentations such as pain crises.
2080P0207X	Clinical Laboratory	Pathologists and clinical laboratory directors oversee performance and reporting of this test.
207Q00000X	Internal Medicine	Primary care physicians and internists order screening in adults and coordinate confirmatory testing.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D57.0`	Sickle-cell anemia with crisis	Positive or confirmatory sickling testing may be performed during vaso-occlusive crises to assess sickling status.
`D57.1`	Sickle-cell disease without crisis	Used for baseline evaluation and monitoring of patients with known sickle-cell disease.
`D57.2`	Sickle-cell/Hb-C disease	Sickling tests help screen for hemoglobin S–related disorders prior to confirmatory testing.
`D57.8`	Other sickle-cell disorders	Supports diagnosis when variants or atypical presentations are suspected.
`D57.3`	Sickle-cell trait	Screening tests identify carriers; positive sickling tests often prompt confirmatory electrophoresis.
`R71.8`	Other abnormality of blood chemistry	May be listed when laboratory abnormalities prompt hemoglobinopathy testing.
`Z13.79`	Encounter for screening for other diseases and disorders	Used when routine or targeted screening for hemoglobinopathies is performed.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`85025`	Complete blood count (CBC) with automated differential	Ordered alongside `85660` to assess anemia, reticulocyte count, and white blood cell indices that support hemoglobinopathy evaluation.
`83020`	Hemoglobin electrophoresis, qualitative; single determination	Commonly performed after a positive sickling test to identify hemoglobin S and other variants for diagnostic confirmation.
`83021`	Hemoglobin electrophoresis, quantitative; each fraction	Used for quantification of hemoglobin variants following sickling screening.
`82784`	Hemoglobin; sickling test (alternative lab methods)	Performed as complementary or alternative laboratory method to evaluate abnormal hemoglobins.
`36415`	Collection of venous blood by venipuncture	The specimen collection procedure that precedes `85660` in workflow.

Related Codes

CPT-85002-BLEEDING-TIME-TEST-LABORATORY

CPT 85002: Bleeding Time Test, Laboratory

CPT-85004-AUTOMATED-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

CPT 85004: Automated Differential White Blood Cell Count

CPT-85007-MANUAL-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

CPT 85007: Manual Differential White Blood Cell Count

CPT-85008-BLOOD-SMEAR-MORPHOLOGIC-REVIEW-NO-DIFFERENTIAL

CPT 85008: Blood Smear Morphologic Review Without Differential

CPT-85009-MANUAL-WBC-COUNT-BUFFY-COAT

CPT 85009: Manual White Blood Cell Count Using Buffy Coat

CPT-85013-MICROHEMATOCRIT-TEST-LABORATORY-DIAGNOSTIC

CPT 85013: Microhematocrit Test, Laboratory Diagnostic

CPT-85014-HEMATOCRIT-VOLUME-PERCENT-RED-BLOOD-CELLS

CPT 85014: Hematocrit (Volume Percent of Red Blood Cells)

CPT-85018-HEMOGLOBIN-ASSAY-WHOLE-BLOOD

CPT 85018: Hemoglobin Measurement in Whole Blood

CPT-85025-COMPLETE-BLOOD-COUNT-CBC

CPT 85025: Complete Blood Count (CBC)

CPT-85027-COMPLETE-BLOOD-COUNT-HGB-HCT

CPT 85027: Complete Blood Count with Hemoglobin and Hematocrit

Showing 1–10 of 99

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.