All discharges are categorized into five hospitalization types (i.e., service lines) in the following hierarchical order: maternal/neonatal, mental health/substance abuse, injury, surgical, and medical. The criteria for identifying the hospitalization types varies across data years.

Beginning in Data Year 2019

Beginning in data year 2019, the five hospitalization types are defined as follows:

Maternal and neonatal discharges are defined using the following Major Diagnostic Categories (MDC):

• MDC 14 Pregnancy, Childbirth and Puerperium
• MDC 15 Newborn and Other Neonates (Perinatal Period)

Mental health/substance use discharges^* are defined using the following MDCs:

• MDC 19 Mental Diseases and Disorders
• MDC 20 Alcohol/Drug Use or Induced Mental Disorders

Injury discharges^* are identified using the following screen:

• Clinical Classification Software Refined (CCSR) categories for the principal ICD-10-CM diagnosis:
  • INJ001 - INJ027
  • INJ032

Surgical discharges are identified by a surgical DRG, the same definition used prior to data year 2019. The DRG grouper first assigns the discharge to a Major Diagnostic Category (MDC) based on the principal diagnosis. For each MDC there is a list of procedure codes that qualify as operating room procedures. If the discharge involves an operating room procedure, it is assigned to one of the surgical DRGs within the MDC category.

All other discharges that are not assigned to a surgical DRG are identified as a medical discharge. If the DRG indicated the information on the record was ungroupable (i.e., not identifiable as medical or surgical), then the discharge was assumed to be medical. This rarely occurred (less than 0.1 percent of total discharges).

^* It should be noted that discharges with a principal diagnosis of injury or poisoning by intentional self-harm are classified under the service line of medical and not the service lines of mental health/substance use or injury.

Prior to Data Year 2019

Prior to data year 2019, the five hospitalization types were identified using the following definitions:

Maternal and neonatal discharges are defined using the following Clinical Classification Software (CCS) categories for the principal ICD-10-CM diagnosis (beta version):

• Maternal:
  • 176: Contraceptive and procreative management
  • 177: Spontaneous abortion
  • 178: Induced abortion
  • 179: Postabortion complications
  • 180: Ectopic pregnancy
  • 181: Other complications of pregnancy
  • 182: Hemorrhage during pregnancy; abruptio placenta; placenta previa
  • 183: Hypertension complicating pregnancy; childbirth and the puerperium
  • 184: Early or threatened labor
  • 185: Prolonged pregnancy
  • 186: Diabetes or abnormal glucose tolerance complicating pregnancy; childbirth; or the puerperium
  • 187: Malposition; malpresentation
  • 188: Fetopelvic disproportion; obstruction
  • 189: Previous C-section
  • 190: Fetal distress and abnormal forces of labor
  • 191: Polyhydramnios and other problems of amniotic cavity
  • 192: Umbilical cord complication
  • 193: OB-related trauma to perineum and vulva
  • 194: Forceps delivery
  • 195: Other complications of birth; puerperium affecting management of mother
  • 196: Normal pregnancy and/or deliver
• Neonatal:
  • 218: Liveborn
  • 219: Short gestation; low birth weight; and fetal growth retardation
  • 220: Intrauterine hypoxia and birth asphyxia
  • 221: Respiratory distress syndrome
  • 222: Hemolytic jaundice and perinatal jaundice
  • 223: Birth trauma
  • 224: Other perinatal conditions

Mental health/substance abuse discharges are defined using the following CCS categories for principal ICD-10-CM diagnosis:

• 650: Adjustment disorders
• 651: Anxiety disorders
• 652: Attention-deficit, conduct, and disruptive behavior disorders
• 653: Delirium, dementia, and amnestic and other cognitive disorders
• 654: Developmental disorders
• 655: Disorders usually diagnoses in infancy, childhood, or adolescence
• 656: Impulse control disorders, NEC
• 657: Mood disorders
• 658: Personality disorders
• 659: Schizophrenia and other psychotic disorders
• 660: Alcohol-related disorders
• 661: Substance-related disorders
• 662: Suicide and intentional self-inflicted injury
• 663: Screening and history of mental health and substance abuse codes
• 670: Miscellaneous disorders

Injury discharges are identified using the principal ICD-10-CM diagnosis using a translated version of the ICD-9-CM scheme recommended by Safe States Alliance, previously known as the State and Territorial Injury Prevention Directors Association (STIPDA).

• First three digits of S00-T34: Fractures; dislocations; sprains and strains; intracranial injury; internal injury of thorax, abdomen, and pelvis; open wound of the head, neck, trunk, upper limb, and lower limb; injury to blood vessels; late effects of injury, poisoning, toxic effects, and other external causes, Superficial injury; contusion; crushing injury; effects of foreign body entering through orifice; burns; injury to nerves and spinal cord; traumatic complications and unspecified injuries, initial or subsequent encounter or sequela; excluding those of complications of surgical and medical care.
• First three digits of T36-T50: Poisoning of drugs, medicaments and biological substances, initial or subsequent encounter or sequela; excluding adverse effects and underdosing of drugs, medicaments and biological substances (codes with the 6th character of 5 or 6; or with the 5th–6th characters of 5X or 6X).
• First three digits of T51-T75: Toxic effects of substances chiefly nonmedicinal as to source; other and unspecified effects of external causes, initial or subsequent encounter or sequela.
• First three digits of T76: Adult and child abuse, neglect and other maltreatment, suspected, initial or subsequent encounter or sequela.
• First three digits of T79: Certain early complications of trauma, initial or subsequent encounter or sequela.

The above definition of injury includes ICD-10-CM diagnosis codes that are also included under two CCS diagnosis categories used for the definition of the mental health/substance use hospitalization type:

• CCS = 661 (Substance-related disorders): ICD-10-CM diagnoses with the first three digits of T40 (excluding codes with the 6th character of 5 or 6; or with the 5th–6th characters of 5X or 6X) indicating poisoning by opium, heroin, cocaine, cannabis, and other psychodysleptics.
• CCS = 662 (Suicide and intentional self-inflicted injury): ICD-10-CM diagnoses with the first three digits of T36-T65 or T71 indicating self-harm by poisoning or asphyxiation.

Because of the hierarchical ordering used to assign discharges to hospitalization type, discharges with these principal ICD-10-CM diagnosis codes are assigned to the mental health/substance use hospitalization type and not the injury hospitalization type.

Surgical discharges are identified by a surgical DRG. The DRG grouper first assigns the discharge to a Major Diagnostic Category (MDC) based on the principal diagnosis. For each MDC there is a list of procedure codes that qualify as operating room procedures. If the discharge involves an operating room procedure, it is assigned to one of the surgical DRGs within the MDC category; otherwise it is assigned to a medical DRG.

Medical discharges are identified by a medical DRG. The DRG grouper first assigns the discharge to an MDC based on the principal diagnosis. For each MDC there is a list of procedure codes that qualify as operating room procedures. If the discharge involves an operating room procedure, it is assigned to one of the surgical DRGs within the MDC category; otherwise it is assigned to a medical DRG. If the DRG indicated the information on the record was ungroupable (i.e., not identifiable as medical or surgical), then the discharge was assumed to be medical. This rarely occurred (less than 0.1 percent of total discharges).

For data prior to the fourth quarter of 2015, the service line indicator is stored in the data element SERVICELINE to indicate the use of the ICD-9-CM coding system.