CCDS Exam Study Review Practice Questions
with Answers 2026–2027 Updated
Section 1: Principal Diagnosis & UHDDS Definitions (Questions 1–15)
1. A patient is admitted with chest pain, shortness of breath, and diaphoresis. Troponin is elevated,
and ECG shows ST-segment elevation. The physician documents "rule out MI" and "chest pain." What
is the appropriate principal diagnosis?
A) Chest pain
B) Shortness of breath
C) Acute myocardial infarction
D) Rule out MI
Answer: C – Acute myocardial infarction
Rationale: When a definitive diagnosis (acute MI) is established after study—even if initially documented
as "rule out"—the definitive diagnosis should be coded as principal. The clinical indicators (elevated
troponin, ST elevation) support the diagnosis. Uncertain diagnoses at admission are coded as if they
existed, but once confirmed, the confirmed diagnosis takes precedence.
2. A patient is admitted with weakness, anemia, and suspected GI bleed. Endoscopy reveals a bleeding
gastric ulcer. The patient receives PRBCs and the ulcer is cauterized. What is the principal diagnosis?
A) Weakness
B) Anemia
C) Suspected GI bleed
D) Bleeding gastric ulcer
Answer: D – Bleeding gastric ulcer
Rationale: The bleeding gastric ulcer is the definitive diagnosis established after study and is chiefly
responsible for the admission. Weakness and anemia are manifestations of the underlying condition. The
suspected GI bleed was confirmed as a bleeding gastric ulcer, so the specific diagnosis is coded.
3. According to UHDDS, the principal diagnosis is defined as:
A) The most severe condition documented
B) The condition that requires the most expensive treatment
C) The condition established after study to be chiefly responsible for occasioning the admission
, D) The first diagnosis listed in the discharge summary
Answer: C – The condition established after study to be chiefly responsible for occasioning the
admission
Rationale: This is the official UHDDS definition. The principal diagnosis is not necessarily the most severe
or the most costly, but rather the reason for admission as determined after evaluation.
4. A patient is admitted from a skilled nursing facility with fever, altered mental status, and
hypotension. Blood cultures are drawn, and the patient is started on broad-spectrum antibiotics. The
physician documents "possible sepsis." What is the most appropriate principal diagnosis?
A) Fever
B) Altered mental status
C) Possible sepsis
D) Sepsis
Answer: D – Sepsis
Rationale: Uncertain diagnoses (possible, probable, suspected, likely) documented at the time of
admission are coded as if they existed. The clinical picture (fever, hypotension, altered mental status,
antibiotics) supports coding of sepsis. A query may be sent to confirm the diagnosis, but for coding
purposes, the uncertain diagnosis is acceptable when no definitive diagnosis is established.
5. A patient is admitted for chemotherapy for lung cancer. The patient develops neutropenic fever on
day 2 and receives IV antibiotics. The discharge summary lists "lung cancer" and "neutropenic fever."
What is the principal diagnosis?
A) Lung cancer
B) Neutropenic fever
C) Chemotherapy
D) There is insufficient information to determine principal diagnosis
Answer: A – Lung cancer
Rationale: The patient was admitted for chemotherapy for lung cancer. The neutropenic fever developed
after admission (hospital-acquired). The principal diagnosis is the condition chiefly responsible for the
admission—lung cancer. Secondary diagnoses include the complication (neutropenic fever).
6. A patient is admitted with exacerbation of COPD and acute respiratory failure. Both conditions are
equally responsible for the admission. How should the principal diagnosis be sequenced?
A) Always sequence acute respiratory failure first
B) Always sequence COPD exacerbation first
C) Either may be sequenced first as they equally meet the definition
D) Query the physician for sequencing
,Answer: C – Either may be sequenced first as they equally meet the definition
*Rationale: When two or more conditions equally meet the definition of principal diagnosis and there
are no specific chapter sequencing rules, either may be sequenced first. Per ICD-10-CM guidelines, the
coder can choose based on the circumstances of the case.*
7. A patient is admitted with acute cholecystitis. During the admission, the patient develops acute
renal failure requiring dialysis. The discharge summary lists both conditions. What is the principal
diagnosis?
A) Acute cholecystitis
B) Acute renal failure
C) Both should be sequenced as principal
D) Query the physician for sequencing
Answer: A – Acute cholecystitis
Rationale: The principal diagnosis is the condition established after study to be chiefly responsible for the
admission. The acute renal failure developed after admission as a complication. Even if the renal failure
was more resource-intensive, the principal diagnosis remains the reason for admission.
8. A patient is admitted with community-acquired pneumonia and is found to have untreated
diabetes mellitus. The pneumonia resolves with antibiotics, and the diabetes is managed with oral
medications. What is the principal diagnosis?
A) Community-acquired pneumonia
B) Diabetes mellitus
C) Both are equally responsible
D) Query the physician
Answer: A – Community-acquired pneumonia
Rationale: The pneumonia is the acute condition that occasioned the admission. The diabetes is a chronic
condition that was managed but was not the reason for admission.
9. A patient is admitted for total knee replacement. On the day of surgery, the patient has a
myocardial infarction. The surgery is postponed. The discharge summary lists "MI" and "osteoarthritis
of the knee." What is the principal diagnosis?
A) Osteoarthritis of the knee
B) Myocardial infarction
C) Both should be sequenced
D) The condition that required the most resources
Answer: B – Myocardial infarction
Rationale: Even though the patient was admitted for surgery, the MI became the condition chiefly
, responsible for the patient's stay after study. The surgery was not performed, so the principal diagnosis is
the MI.
10. A patient is admitted for observation for possible appendicitis. After study, appendicitis is ruled
out, and the patient is discharged with a diagnosis of gastroenteritis. What is the principal diagnosis?
A) Possible appendicitis
B) Observation for possible appendicitis
C) Gastroenteritis
D) Abdominal pain
Answer: C – Gastroenteritis
Rationale: Once a definitive diagnosis (gastroenteritis) is established, it replaces the uncertain diagnosis.
The principal diagnosis is the condition established after study to be chiefly responsible for the admission.
11. A patient is admitted with acute pancreatitis due to gallstones. What is the principal diagnosis?
A) Acute pancreatitis
B) Gallstones
C) Both should be sequenced with pancreatitis principal
D) Both should be sequenced with gallstones principal
Answer: A – Acute pancreatitis
Rationale: The acute condition (pancreatitis) is the manifestation that occasioned the admission. The
underlying etiology (gallstones) is coded as a secondary diagnosis, unless there is an instruction to code
the underlying condition first.
12. A patient is admitted with acute blood loss anemia due to a bleeding duodenal ulcer. What is the
principal diagnosis?
A) Acute blood loss anemia
B) Bleeding duodenal ulcer
C) Both should be coded as combination code with ulcer principal
D) Query the physician for clarification
Answer: C – Combination code with ulcer principal
*Rationale: ICD-10-CM provides a combination code for bleeding duodenal ulcer (K26.0). The
combination code includes both the ulcer and the bleeding. The anemia is a manifestation and is coded
separately if the physician documents it as a separate condition.*
13. A patient is admitted with septic shock due to pneumonia. According to ICD-10-CM guidelines,
what is the correct sequencing?
A) Pneumonia, then septic shock
with Answers 2026–2027 Updated
Section 1: Principal Diagnosis & UHDDS Definitions (Questions 1–15)
1. A patient is admitted with chest pain, shortness of breath, and diaphoresis. Troponin is elevated,
and ECG shows ST-segment elevation. The physician documents "rule out MI" and "chest pain." What
is the appropriate principal diagnosis?
A) Chest pain
B) Shortness of breath
C) Acute myocardial infarction
D) Rule out MI
Answer: C – Acute myocardial infarction
Rationale: When a definitive diagnosis (acute MI) is established after study—even if initially documented
as "rule out"—the definitive diagnosis should be coded as principal. The clinical indicators (elevated
troponin, ST elevation) support the diagnosis. Uncertain diagnoses at admission are coded as if they
existed, but once confirmed, the confirmed diagnosis takes precedence.
2. A patient is admitted with weakness, anemia, and suspected GI bleed. Endoscopy reveals a bleeding
gastric ulcer. The patient receives PRBCs and the ulcer is cauterized. What is the principal diagnosis?
A) Weakness
B) Anemia
C) Suspected GI bleed
D) Bleeding gastric ulcer
Answer: D – Bleeding gastric ulcer
Rationale: The bleeding gastric ulcer is the definitive diagnosis established after study and is chiefly
responsible for the admission. Weakness and anemia are manifestations of the underlying condition. The
suspected GI bleed was confirmed as a bleeding gastric ulcer, so the specific diagnosis is coded.
3. According to UHDDS, the principal diagnosis is defined as:
A) The most severe condition documented
B) The condition that requires the most expensive treatment
C) The condition established after study to be chiefly responsible for occasioning the admission
, D) The first diagnosis listed in the discharge summary
Answer: C – The condition established after study to be chiefly responsible for occasioning the
admission
Rationale: This is the official UHDDS definition. The principal diagnosis is not necessarily the most severe
or the most costly, but rather the reason for admission as determined after evaluation.
4. A patient is admitted from a skilled nursing facility with fever, altered mental status, and
hypotension. Blood cultures are drawn, and the patient is started on broad-spectrum antibiotics. The
physician documents "possible sepsis." What is the most appropriate principal diagnosis?
A) Fever
B) Altered mental status
C) Possible sepsis
D) Sepsis
Answer: D – Sepsis
Rationale: Uncertain diagnoses (possible, probable, suspected, likely) documented at the time of
admission are coded as if they existed. The clinical picture (fever, hypotension, altered mental status,
antibiotics) supports coding of sepsis. A query may be sent to confirm the diagnosis, but for coding
purposes, the uncertain diagnosis is acceptable when no definitive diagnosis is established.
5. A patient is admitted for chemotherapy for lung cancer. The patient develops neutropenic fever on
day 2 and receives IV antibiotics. The discharge summary lists "lung cancer" and "neutropenic fever."
What is the principal diagnosis?
A) Lung cancer
B) Neutropenic fever
C) Chemotherapy
D) There is insufficient information to determine principal diagnosis
Answer: A – Lung cancer
Rationale: The patient was admitted for chemotherapy for lung cancer. The neutropenic fever developed
after admission (hospital-acquired). The principal diagnosis is the condition chiefly responsible for the
admission—lung cancer. Secondary diagnoses include the complication (neutropenic fever).
6. A patient is admitted with exacerbation of COPD and acute respiratory failure. Both conditions are
equally responsible for the admission. How should the principal diagnosis be sequenced?
A) Always sequence acute respiratory failure first
B) Always sequence COPD exacerbation first
C) Either may be sequenced first as they equally meet the definition
D) Query the physician for sequencing
,Answer: C – Either may be sequenced first as they equally meet the definition
*Rationale: When two or more conditions equally meet the definition of principal diagnosis and there
are no specific chapter sequencing rules, either may be sequenced first. Per ICD-10-CM guidelines, the
coder can choose based on the circumstances of the case.*
7. A patient is admitted with acute cholecystitis. During the admission, the patient develops acute
renal failure requiring dialysis. The discharge summary lists both conditions. What is the principal
diagnosis?
A) Acute cholecystitis
B) Acute renal failure
C) Both should be sequenced as principal
D) Query the physician for sequencing
Answer: A – Acute cholecystitis
Rationale: The principal diagnosis is the condition established after study to be chiefly responsible for the
admission. The acute renal failure developed after admission as a complication. Even if the renal failure
was more resource-intensive, the principal diagnosis remains the reason for admission.
8. A patient is admitted with community-acquired pneumonia and is found to have untreated
diabetes mellitus. The pneumonia resolves with antibiotics, and the diabetes is managed with oral
medications. What is the principal diagnosis?
A) Community-acquired pneumonia
B) Diabetes mellitus
C) Both are equally responsible
D) Query the physician
Answer: A – Community-acquired pneumonia
Rationale: The pneumonia is the acute condition that occasioned the admission. The diabetes is a chronic
condition that was managed but was not the reason for admission.
9. A patient is admitted for total knee replacement. On the day of surgery, the patient has a
myocardial infarction. The surgery is postponed. The discharge summary lists "MI" and "osteoarthritis
of the knee." What is the principal diagnosis?
A) Osteoarthritis of the knee
B) Myocardial infarction
C) Both should be sequenced
D) The condition that required the most resources
Answer: B – Myocardial infarction
Rationale: Even though the patient was admitted for surgery, the MI became the condition chiefly
, responsible for the patient's stay after study. The surgery was not performed, so the principal diagnosis is
the MI.
10. A patient is admitted for observation for possible appendicitis. After study, appendicitis is ruled
out, and the patient is discharged with a diagnosis of gastroenteritis. What is the principal diagnosis?
A) Possible appendicitis
B) Observation for possible appendicitis
C) Gastroenteritis
D) Abdominal pain
Answer: C – Gastroenteritis
Rationale: Once a definitive diagnosis (gastroenteritis) is established, it replaces the uncertain diagnosis.
The principal diagnosis is the condition established after study to be chiefly responsible for the admission.
11. A patient is admitted with acute pancreatitis due to gallstones. What is the principal diagnosis?
A) Acute pancreatitis
B) Gallstones
C) Both should be sequenced with pancreatitis principal
D) Both should be sequenced with gallstones principal
Answer: A – Acute pancreatitis
Rationale: The acute condition (pancreatitis) is the manifestation that occasioned the admission. The
underlying etiology (gallstones) is coded as a secondary diagnosis, unless there is an instruction to code
the underlying condition first.
12. A patient is admitted with acute blood loss anemia due to a bleeding duodenal ulcer. What is the
principal diagnosis?
A) Acute blood loss anemia
B) Bleeding duodenal ulcer
C) Both should be coded as combination code with ulcer principal
D) Query the physician for clarification
Answer: C – Combination code with ulcer principal
*Rationale: ICD-10-CM provides a combination code for bleeding duodenal ulcer (K26.0). The
combination code includes both the ulcer and the bleeding. The anemia is a manifestation and is coded
separately if the physician documents it as a separate condition.*
13. A patient is admitted with septic shock due to pneumonia. According to ICD-10-CM guidelines,
what is the correct sequencing?
A) Pneumonia, then septic shock
