Master Reference Guide — AGES Coding TECH
A comprehensive clinical and procedural coding reference for inpatient DRG accounts. Covering diagnosis sequencing, PCS root operations, clinical indicators, and DRG essentials.
Contents at a Glance
Neurological & Systemic Conditions
Cerebral oedema, encephalopathy, sepsis, CHF, MI types, AKI
PCS Root Operations & Procedures
PTCA, CABG, biopsy, debridement, vascular devices
DRG Structure & Coding Rules
POA indicators, CC/MCC, HAC, discharge disposition, elements
Obstetrics, Newborn & Clinical Queries
OB terms, newborn conditions, query process, quality metrics
Cerebral Oedema — Indicators
Cerebral oedema should be suspected and queried whenever the following conditions are documented:
Traumatic / Structural
- Traumatic head injury
- ICH — Intracerebral haemorrhage
- SDH — Subdural haemorrhage
Neurological Signs
- Seizures
- Memory loss
- Stroke / CVA
- Oedema on imaging
Cerebral Oedema — Treatment
Hyperbaric Oxygen Therapy
Delivers high-concentration O₂ to reduce cerebral swelling via pressure chambers.
Osmotherapy
Mannitol or hypertonic saline draws fluid out of oedematous brain tissue.
Hyperventilation
Reduces PaCO₂ causing cerebral vasoconstriction and lowering ICP acutely.
Ventriculostomy
Surgical insertion of a drain to monitor ICP and divert excess CSF.
AKI and Dehydration — Sequencing
Scenario: Patient admitted with nausea, vomiting, and lightheadedness × 1 week. Severe dehydration noted; AKI secondary to dehydration, treated with IV fluids.
Guidance: Sequence the reason for admission as PDx. If documentation is unclear, query the physician regarding the primary reason for hospitalisation. Both dehydration and AKI are valid PDx candidates depending on clinical context.
Rib Fracture + Pneumothorax — PDx
PDx: Pneumothorax
Per the tabular list instruction under rib fracture codes: "Code first any associated intrathoracic injury."
Pneumothorax is the intrathoracic injury and therefore sequences as the principal diagnosis. Rib fracture is assigned as a secondary diagnosis.
Rule
Tabular list instructions override default sequencing logic. Always check "Code First" and "Use Additional Code" notes in ICD-10-CM.
Hemiplegia from Past Medical History
A history notation alone is insufficient. Clinical validation via physical examination is mandatory before assigning a hemiplegia code.
Sepsis Sequencing Scenarios
Sepsis + Aspiration Pneumonia
PDx: Sepsis A41.9 → Pneumonia J18.9 → Aspiration pneumonia J69.0
Sepsis + COVID (present on admission)
Both POA: Sepsis as PDx, COVID U07.1 as secondary.
COVID admitted; sepsis develops during stay
COVID as PDx, sepsis as secondary with POA = N.
Sepsis + Catheter-Associated UTI (CAUTI)
CAUTI complication code as PDx; sepsis as secondary. (Post-operative complication guideline applies.)
Sepsis — Core Definitions
Bacteraemia
Presence of bacteria in the bloodstream — not the same as sepsis.
Sepsis
SIRS due to a localised infection. Treatment: antibiotics targeting the source organism.
Severe Sepsis
Sepsis with acute organ failure or acute organ dysfunction.
Common localised infection sources: Pneumonia, UTI, osteomyelitis, peritonitis, cellulitis, abscess, meningitis.
Sepsis — Special Scenarios
Sepsis secondary to COVID
A41.89 (Other specified sepsis) as PDx; COVID U07.1 as secondary.
Encephalopathy secondary to Sepsis
Classifies as severe sepsis; encephalopathy type = metabolic encephalopathy.
Sepsis + Aspiration Pneumonia
Sepsis A41.9, aspiration pneumonia J69.0, unspecified pneumonia J18.9.
Sepsis due to CAUTI (PDx?)
Complication of catheter infection as PDx: T83.511A, N39.0, Y84.6.
Coding Pairs — Single Code Rules
Hyponatraemia + SIADH
Code only SIADH. Hyponatraemia is the manifestation.
ARF + ARDS
Code only ARDS. ARDS is the more specific diagnosis.
Type 2 MI + Demand Ischaemia
Code only Type 2 MI.
Cocaine-Induced Chest Pain — PDx
Sequence cocaine poisoning as PDx. Chest pain is the manifestation and sequences as secondary. Per poisoning guidelines, the poisoning code always leads.
Cancer + Anemia — PDx
Cancer is always PDx. The combination code for anemia due to neoplasm is a manifestation code and cannot be used as PDx per official guidelines.
Non-Physician Documentation — Valid Sources
The following clinical data elements may be coded from non-physician documentation (nursing, therapy, dietitian notes) without a physician query:
BMI
Body Mass Index
GCS
Glasgow Coma Scale
NIHSS
NIH Stroke Scale
Pressure Ulcer Stage & Site
Duration of LOC
Loss of Consciousness
Laterality
PCS Root Operations — Excision vs. Resection
Excision
Removal of a portion of a body part.
- Partial nephrectomy
- Biopsy (excisional)
- Excision of skin lesion
- Breast lumpectomy
- Liver biopsy
Resection
Removal of all of a body part.
- Total lobectomy
- Total mastectomy
- Total nephrectomy
- Cholecystectomy
- Appendectomy
PCS Root Operations — Quick Reference
Fragmentation
Crushing/breaking of stones (lithotripsy)
Extirpation
Removal of solid material from a body part — atherectomy, thrombectomy, removal of sternal wire
Restriction
Partially closing an orifice or lumen — cervical cerclage, fundoplication, aneurysm clipping
Occlusion
Completely closing an orifice or lumen — ligation, sterilisation, embolisation
Destruction
Eradicating tissue without taking it out — control of nosebleed
Bypass
Rerouting body fluids — VP shunt, tracheostomy, CABG
Biopsy — Root Operation Selection
Qualifier for all biopsies: X — Diagnostic. Two codes required when biopsy (percutaneous excision) is followed by open partial mastectomy — one for each distinct procedure and approach.
HTN and DM from History — How to Code
Current Medication in Use
Even if a chronic condition such as hypertension or diabetes mellitus is well-controlled, code it as a current active condition if the patient is on continuous medication. The medication indicates ongoing management.
No Medication / Condition Resolved
If the patient is no longer on medication and the condition is documented as resolved, assign a personal history code (Z-category). Do not code as active.
PTCA — Percutaneous Transluminal Coronary Angioplasty
Root Operation: Dilation — Expanding an orifice or the lumen of a tubular body part.
Stent Type
Drug-eluting (Cypher, Endeavor, paclitaxel, sirolimus, taxol) vs. non-drug-eluting (bare metal, heparin-coated)
Number of Stents
1, 2, 3, or 4+ stents — determines DRG grouping
Arteries & Bifurcation
Number of coronary arteries involved; bifurcation involvement documented?
Atherectomy
Performed or not? Root operation: Extirpation
PTCA DRG Values
Drug-Eluting Stent
1–3 drug-eluting stents with MI
4+ Drug-Eluting
4 or more drug-eluting stents with MI
Non-Drug-Eluting
Non-drug-eluting (bare metal) stent
CABG — Coronary Artery Bypass Graft
Surgical treatment for CAD. Root operation: Bypass.
Number of bypass grafts performed
Bypass from / to
Aorta → coronary; coronary → coronary; LIMA / RIMA → coronary
Saphenous vein graft
If used, add additional excision code for harvesting of vein graft
Cardiopulmonary bypass
If performed, assign additional code. Off-pump CABG = without CPB
Myocardial Infarction — Types
Type 1
Spontaneous MI — primary coronary event (plaque rupture)
Type 2
Secondary to ischaemic imbalance — vasospasm, anaemia, hypotension; code only Type 2 MI when due to demand ischaemia
Type 3
Death with unavailable biomarkers
Type 4a / 4b / 4c
PCI-related MI / stent thrombosis / restenosis ≥50%
Type 5
CABG-related MI
Initial vs. Subsequent MI: First admission = Initial. Readmission within 4 weeks with new MI site = Subsequent.
CHF — Congestive Heart Failure
Systolic Failure
Left ventricle cannot contract normally. Insufficient force to push blood into circulation. EF <40%.
Diastolic Failure
Left ventricle cannot relax normally (stiffened muscle). Cannot fill adequately between beats. EF >50%.
Treatment
IV Lasix (furosemide) — brand-name diuretic to reduce fluid overload.
Cardiac Conditions — Key Definitions
Cardiomyopathy
Acquired or hereditary disease of the heart muscle impairing blood delivery; may lead to heart failure.
CAD — Coronary Artery Disease
Build-up of fats, cholesterol, and other substances in and on coronary artery walls.
Cardiac Tamponade
Compression of the heart due to fluid accumulation in the pericardium. Code underlying cause first, then I31.4. Treatment: pericardiocentesis (Drainage, pericardial cavity) or pericardial window (Drainage, pericardium).
Hypertensive Urgency vs. Emergency
Urgency: Very high BP, minimal/no symptoms, no organ damage. Emergency: Severe BP with progressive target organ damage.
Encephalopathy
Definition
Any disorder or disease of the brain, or malfunction of brain function.
Types
Metabolic, toxic, hepatic, alcoholic, chronic traumatic, ischaemic encephalopathy.
Treatment
Anti-seizure medications, antiviral medications, antibiotics.
Clinical Indicators
- AMS / ALOC
- Seizures
- Elevated ammonia levels
- Metabolic disorders: hyponatraemia, hypokalaemia, acidosis
- Infection sources: UTI, sepsis
- Alcohol use disorder
Debridement — Excisional vs. Non-Excisional
Excisional Debridement
Surgical removal using a sharp instrument (scalpel, blade) to cut away necrotic tissue, slough, or devitalised material.
Query for Debridement
- Type: excisional or non-excisional?
- Depth: skin, subcutaneous tissue, muscle fascia, bone, tendon, ligament
Non-Excisional Debridement
Non-operative removal using brushing, irrigating, scrubbing, or washing. Tools include:
- Versajet / ultra-high-pressure generator
- Ultrasound, whirlpool
- Mechanical scrubbing
- Wet-to-dry dressings
- Maggot therapy
Vascular Access Devices
Central Venous Catheter (CVC)
Placed into a large vein (internal jugular, subclavian, axillary, or femoral). Used for medication, IV fluids, CVP monitoring, and blood sampling.
PICC Line
Inserted peripherally (cephalic, basilic, or brachial vein) and advanced to the distal SVC or cavoatrial junction. Used for prolonged chemotherapy, extended antibiotics, or TPN (>1 year use).
Tunnelled vs. Non-Tunnelled
Tunnelled: Placed under skin for long-term use. Non-tunnelled: Temporary; inserted near neck, chest, or groin.
Cardiac Devices — AICD, Pacemaker, Impella
AICD
Automated Implantable Cardioverter Defibrillator. Lead inserts into right ventricle to monitor and correct arrhythmias. Inserted for cardiomyopathy, AV block, SSS, tachy-brady syndrome. Misfiring = mechanical complication.
Biventricular ICD
Battery-powered device maintaining normal heart pump function in both ventricles simultaneously.
Pacemaker
Implanted below collarbone to regulate dangerously slow heart rate electrical problems.
Impella
Catheter-based miniaturised VAD pumping blood from left ventricle into ascending aorta. Root operation: Performance.
Mechanical Ventilation vs. CPAP
Mechanical Ventilator
Moves air in and out of lungs, completely replacing diaphragm and respiratory muscle function.
Root Operation: Performance
Time: Start = intubation; Stop = extubation
- Less than 24 hours
- 24–96 hours
- Greater than 96 hours
CPAP
Provides one constant pressure. Cannot move air in and out — cannot ventilate alone.
Root Operation: Assistance
CPAP via tracheostomy: coded as mechanical ventilation.
Tracheostomy
Root Operation: Bypass
PCS Code Structure
Sections
Total 17 sections in ICD-10-PCS.
Root Operations
Total 31 root operations.
Approaches
Total 7 approaches: Open, Percutaneous, Percutaneous Endoscopic, Via Natural/Artificial Opening, Via Natural/Artificial Opening Endoscopic, Via Natural/Artificial Opening Percutaneous Endoscopic, External.
DRG — Inpatient Coding Elements
Admitting Diagnosis (ADx)
Symptom or condition stated by the patient at admission. Primarily sourced from ED and H&P documents.
Principal Diagnosis (PDx)
After study, the condition chiefly responsible for hospitalisation. Underlying condition is always PDx.
Secondary Diagnosis (SDx)
Coexisting conditions. May be present on admission or develop during the stay. Must meet criteria: diagnostic workup, therapeutic treatment, increasing care, clinical evaluation, or extended LOS.
Principal & Secondary Procedures
Principal procedure = surgical treatment directed at PDx. Secondary procedures coexist with the principal diagnosis.
DRG — Structure & Factors
DRG Types
- MS-DRG: Medical and Surgical DRG
- APR-DRG: All Patient Refined DRG
- S-DRG: Severity DRG
Severity Levels
- ** With MCC (Major Complications & Comorbidities)
- * With CC (Complications & Comorbidities)
- #/## Without CC and MCC
467 DRG groups across 25 MDCs.
Factors Affecting DRG
Principal Diagnosis
Additional factors: Secondary diagnosis (MCC/CC), principal procedure, additional procedures, discharge disposition, age, sex, birth weight.
CC / MCC Conditions
MCC Examples
- Acute respiratory failure
- Acute & chronic systolic CHF
- COVID-19
- Severe protein-calorie malnutrition
- Metabolic encephalopathy
- ESRD, Pneumonia, Sepsis
CC Examples
- Chronic atrial fibrillation
- Chronic systolic CHF
- CAD
- CKD Stage IV–V
- Hyponatraemia, UTI
- Acute renal failure
- Malnutrition, pleural effusion, atelectasis, ascites
POA Indicators
Y
Condition present on the day of admission.
N
Condition not present on admission; developed during hospital stay.
E
Status post / history conditions.
U
Undetermined by coder and physician.
W
Clinically undetermined.
Example: Patient admitted with Stage 3 pressure ulcer (POA = Y); develops Stage 4 during stay (POA = N). Code both stages.
Clinical Indicators — Quick Reference
Acute Respiratory Failure
- SpO₂ <80%, pH <7.3
- pCO₂ >50 mmHg, PaO₂ <60 mmHg
- RR >35/min, intubated
Sepsis
- Temp >101°F or <36°C
- Tachypnoea >20/min, tachycardia >90/min
- WBC >12,000 or <4,000; positive cultures
AKI
- ↑ Creatinine, ↑ BUN, ↑ potassium
- Oedema, proteinaemia
CHF
- SOB, chest pain, ankle oedema
- EF <40% (systolic) / >50% (diastolic)
- ↑ Troponin, ↑ BNP; CXR: pulmonary oedema
HAC — Hospital Acquired Conditions
Conditions that develop during the hospital stay and may result in payment denial. Selected examples:
Retained Foreign Object After Surgery
Stage III & IV Pressure Ulcers
Falls and Trauma
Fractures, dislocations, intracranial injuries, crushing, burns
Catheter-Associated UTI (CAUTI)
DVT / PE After Orthopaedic Procedures
Total knee and hip replacement
Surgical Site Infections
Post-CABG, bariatric surgery, orthopaedic procedures, CIED implantation
Obstetrics — Key Definitions
Preterm
Delivery <37 weeks
Term Delivery
37–40 weeks
Post-Term
40.1–42 weeks
Postpartum
After 6 weeks
Placental Abruption
Premature separation of the placenta from the uterine wall during pregnancy.
Placenta Praevia
Placenta partially or wholly blocks the cervical os, interfering with normal delivery.
OB Procedures — Coding Notes
Caesarean Section
Root Operation: Extraction
Cervical Cerclage
Root Operation: Restriction
Chorioamnionitis
Bacterial infection of the chorion, amnion, and amniotic fluid. Can cause maternal and foetal infections.
IUPC
Intrauterine pressure catheter — measures uterine contractions (frequency, duration, strength) to guide oxytocin dosing.
Bakri Balloon
Root Operation: Control (genitourinary tract). Code: 0W3R7ZZ — Control bleeding via natural or artificial opening.
Induction vs. Augmentation
Induction = starting labour before it begins. Augmentation = assisting labour already in progress. Methods: Pitocin, Cervidil, Cytotec, oxytocin.
Newborn Conditions
Neonate/Newborn age: 0–28 days
Common Conditions
- Jaundice, sleep apnoea, caput
- Mongolian spots, ARDS, ankyloglossia
- Transient tachypnoea of newborn
Size / Growth
- Preterm, SGA, LGA
- IDM (Infant of Diabetic Mother)
- Late preterm ≥37 weeks: query physician — "small for dates" or "light for dates"
Structural / Cardiac
- ASD, VSD, murmur, hydrocele
- GBS, ABO incompatibility
- Congenital dermal melanosis, sacral dimple
Poisoning vs. Adverse Effect vs. Underdosage
Poisoning
Drug used incorrectly: overdose, wrong dose, non-prescribed, improper route, given in error, drug + alcohol, illegal substances (cocaine, heroin, opioids)
Adverse Effect
Drug used correctly but causes an unintended harmful reaction.
Underdosage
Patient took less medication than prescribed.
Sequela
Any condition that develops after the acute phase of illness or injury. Example: post-COVID (U09.9) — also known as "late effect" of COVID-19.
DNR vs. Palliative Care
DNR: Patient refuses CPR; allows natural death.
Palliative Care: Specialised care focused on symptom relief and quality of life for serious illness.
Special Procedures — Root Operations
TIPS Procedure
Transjugular intrahepatic portosystemic shunt — stent connecting portal to hepatic veins. Root operation: Bypass
Lymphadenectomy
Partial removal of lymph nodes = Excision. Entire chain removal = Resection.
Abdominal Aortic Aneurysm Repair with Graft
Root operation: Restriction
Hartmann Procedure
Sigmoid colon resection with proximal colostomy; distal rectum oversewn. Root operation: Reposition, sometimes Excision or Resection.
Whipple Procedure
Pancreaticoduodenectomy — removes head of pancreas, duodenum, gallbladder, and portion of bile duct ± stomach. Pylorus-sparing variant preserves the stomach.
Kyphoplasty vs. Vertebroplasty
Vertebroplasty: Cement injection = Supplement. Kyphoplasty: Balloon cavity creation = Reposition + Supplement. Approach: Percutaneous.
Quality, Audits & Performance
Quality Target
Including all elements: SDx, PDx, CC, MCC, POA, discharge disposition, DRG
Charts / Day
Daily chart volume benchmark
Common Smart Auditor Findings
- Missing query opportunities
- Missing MCC and CC conditions
- DRG changes in respiratory cases
- Missing bedside procedures: ECHO, blood transfusion, vaccination, TPN, PICC, feeding tube insertion
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