2.5 Hemostasis Problem-Solving

Question 1

A 3-year-old male was admitted with scattered petechiae and epistaxis. The patient had normal growth and had no other medical problems except for chickenpox 3 weeks earlier. His family history was unremarkable.
Laboratory Results
Patient Reference Range
PT 11 sec 10–13 sec
APTT 32 sec 28–37 sec
PLT count 18 × 103/µL L 150–450 × 103/μL
These clinical manifestations and laboratory results are consistent with which condition?
A. TTP
B. DIC
C. ITP
D. HUS

Answer 1

C. ITP

Question 2

A 12-year-old white male has the following symptoms: visible bruising on arms and legs, bruising after sports activities, and excessive postoperative hemorrhage after tonsillectomy 3 months ago. His family history revealed that his mother suffers from heavy menstrual bleeding, and his maternal grandfather had recurrent nosebleeds and bruising.
Laboratory Results
Patient Reference Range
PLT count: 350 × 103/μL 200–450 × 103/μL
PT 11 sec 10–12 sec
APTT 70 sec 28–37 sec
TT 13 sec 10–15 sec
PLT AGGREGATION
Normal aggregation with collagen, EPI, ADP
Abnormal aggregation with ristocetin
CONFIRMATORY TESTS PATIENT REFERENCE RANGE
VWF:Rco 25% 45%–140%
VIII:C 20% 50%–150%
VWF:antigen 10% 45%–185%
These clinical manifestations and laboratory results are consistent with which diagnosis?
A. Factor VIII deficiency
B. von Willebrand disease
C. Glanzmann thrombasthenia
D. Bernard-Soulier syndrome

Answer 2

B. von Willebrand disease

Question 3

The following results are obtained from a patient who developed severe bleeding:
Prolonged PT and APTT
PLT count = 100 × 109/L
Fibrinogen = 40 mg/dL
Which of the following blood products should be recommended for transfusion?
A. Factor VIII concentrate
B. PLTs
C. FFP
D. Cryoprecipitate

Answer 3

D. Cryoprecipitate

Question 4

A 30-year-old woman develops signs and symptoms of thrombosis in her left lower leg after 5 days of heparin therapy. The patient had had open-heart surgery 3 days previously and has been on heparin ever since. Which of the following would be most helpful in making the diagnosis?
A. Fibrinogen assay
B. PT
C. PLT count
D. Increased heparin dose

Answer 4

C. PLT count

Question 5

The following laboratory results were obtained on a 25-year-old woman with menorrhagia after delivery of her second son. The patient has no previous bleeding history.
Normal PLT count; normal PT; prolonged APTT
Mixing of the patient’s plasma with normal plasma
corrected the prolonged APTT on immediate testing.
However, mixing followed by 2-hour incubation at 37°C
caused prolonged APTT.
What is the most probable cause of these laboratory results?
A. Lupus anticoagulant
B. Factor VIII deficiency
C. Factor IX deficiency
D. Factor VIII inhibitor

Answer 5

D. Factor VIII inhibitor

Question 6

A 62-year-old female presents with jaundice and the following laboratory data:
Peripheral blood smear = macrocytosis, target cells
PLT count = 355 × 109/L
PT = 25 sec (reference range = 10–14)
APTT = 65 sec (reference range = 28–36)
Transaminases = elevated (AST:ALT ratio greater than 1)
Total and direct bilirubin = elevated
These clinical presentations and laboratory results are consistent with:
A. Inherited factor VII deficiency
B. DIC
C. Cirrhosis of the liver
D. von Willebrand disease

Answer 6

C. Cirrhosis of the liver

Question 7

When performing a mixing study, the patient’s APTT is corrected to 12% of normal. What is the most appropriate interpretation of these findings?
A. The APTT is considered corrected
B. The APTT is considered uncorrected
C. The laboratory protocol should be followed for the interpretation of correction
D. A circulating anticoagulant can be ruled out

Answer 7

C. The laboratory protocol should be followed for the interpretation of correction

Question 8

A standard blue-top tube filled appropriately (with 4.5 mL blood) was submitted to the laboratory for preoperative PT and APTT testing. The results of both tests were elevated. The patient’s PT and APTT from the previous day were within normal limits, and he was not on heparin therapy. Which is the most appropriate first step to investigate the abnormal results?
A. Report the result as obtained
B. Perform a mixing study
C. Check the sample for a clot
D. Report APTT only

Answer 8

C. Check the sample for a clot

Question 9

A plasma sample submitted to the laboratory for PT testing has been stored for 25 hours at 4°C. PT is shortened. What is the most probable cause?
A. Factor VII deficiency
B. Activation of factor VII caused by exposure to cold temperature
C. Lupus inhibitor
D. Factor X inhibitor

Answer 9

B. Activation of factor VII caused by exposure to cold temperature

Question 10

APTT is not increased in a patient receiving heparin. Which of the following factors may be associated with the lack of response to heparin therapy in this patient?
A. Protein C deficiency
B. AT deficiency
C. Protein S deficiency
D. Factor VIII deficiency

Answer 10

B. AT deficiency

Question 11

A 50-year-old patient was admitted to the emergency department with a complaint of pain in the right leg. The leg was red, swollen, and warm to the touch. DVT was suspected, and the patient was started on heparin therapy. Which of the following is (are) the proper protocol(s) to evaluate patients receiving heparin therapy?
A. Baseline APTT and PLT count; APTT testing every 4 to 6 hours after the initial heparin bolus
B. Repeat APTT 5 days after heparin therapy to adjust the therapeutic dose
C. Monitor the PLT count daily and every other day after heparin therapy is completed
D. Monitor PT daily to adjust the therapeutic dose

Answer 11

A. Baseline APTT and PLT count; APTT testing every 4 to 6 hours after the initial heparin bolus

Question 12

A 46-year-old female was admitted to the emergency department with complaints of headache, dizziness, lethargy, nausea, vomiting, and weakness. The patient had undergone a gastrectomy procedure 4 months earlier for removal of adenocarcinoma of the stomach and had been placed on mitomycin therapy. Diagnostic procedures indicated recurrence of the carcinoma.
Admission Complete Blood Count (CBC) Results
Patient Reference Range
WBCs 17.1 × 109/L 4.8–10.8 × 109/L
RBCs 2.29 × 1012/L 3.80–5.50 × 1012/L
Hgb 8.1 g/dL 12.0–15.2 g/dL
Hct 23% 37%–46%
MCV 95.7 fL 79–101 fL
MCH 35.4 pg 27–33 pg
MCHC 35.0 % 31%–34 %
RDW 18.5 11.5–14.5
PLTs 48.0 × 109/L 140–450 × 109/L
MPV 11.2 7.4–9.4
DIFERENTIAL COUNTS (%)
Segmented neutrophils 79 30%–70%
Band neutrophils 3 0%–10%
Lymphocytes 11 20%–50%
Monocytes 6 2%–12%
Basophils 1 0%–2%
NRBCs (/100 WBCs) 3 0
Manual platelet count 18 × 109/L 140–450 × 109/L
Marked anisocytosis None
Marked RBC fragmentation None
PT, APTT, and TT Normal
ADDITIONAL LABORATORY DATA
Urinalysis PATIENT REFERENCE RANGE
pH 5.0 5–7
Protein 30.0 mg/dL 0–15 mg/dL
RBCs 60–100/μ.
Casts 10/high-power field (hpf) granular/hyaline Not detectable
Plasma PATIENT REFERENCE RANGE
Creatinine 3.1 mg/dL 0.7–1.3 mg/dL
BUN 39 mg/dL 8–22 mg/dL
Haptoglobin 5.0 mg/dL 50–150 mg/dL
These clinical manifestations and laboratory results are consistent with:
A. ITP
B. von Willebrand disease
C. TTP
D. DIC

Answer 12

C. TTP

Question 13

A 1-year-old infant was admitted with recurrent epistaxis for the past 5 days. Past medical history revealed easy bruising and a severe nosebleed that had occurred when he was 3 months of age, necessitating transfusion therapy. The mother had a severe nosebleed 8 years ago. The father was reported to bleed easily after lacerations. The patient was transfused with 2 units of packed RBCs on admission.
Admission Laboratory Results
Patient Reference Range
Hgb 4.5 g/dL 13–15 g/dL
Platelet count 249 × 109/L 150–450 × 109/L
PT 11.2 sec 11–13 sec
APTT 34 sec 28–37 sec
ADDITIONAL LABORATORY TESTS
Factor VIII assay 70% 50%–150%
PLT aggregation: Abnormal to ADP, EPI, and thrombin; normal to ristocetin
These clinical manifestations and laboratory results are consistent with which condition?
A. von Willebrand disease
B. Bernard-Soulier syndrome
C. Glanzmann thrombasthenia
D. Factor VIII deficiency

Answer 13

C. Glanzmann thrombasthenia

Question 14

A 30-year-old female was referred to the hospital for evaluation for multiple spontaneous abortions and current complaint of pain and swelling in her right leg. Her family history is unremarkable.
Laboratory Tests Patient Reference Range
PT 14.5 sec 11–13 sec
APTT 63.0 sec 28–37 sec
TT 12.0 sec 10–15 sec
Mixing Study APTT
Preincubation and after 2-hour incubation at 37°C 57.0 sec
Platelet neutralization procedure
Patient plasma + freeze-thawed platelets APTT = 35 sec
Patient plasma + saline APTT = 59 sec
Anticardiolipin antibodies done by ELISA Negative
These clinical manifestations and laboratory results are consistent with:
A. Factor VIII inhibitor
B. Factor VIII deficiency
C. Anticardiolipin antibodies
D. Lupus anticoagulant

Answer 14

D. Lupus anticoagulant

Question 15

A 60-year-old patient was admitted to a hospital for a liver biopsy. The biopsy was scheduled for 11:00 a.m. The coagulation results obtained at the time of admission revealed prolonged PT with an INR of 4.5. What is the physician’s most appropriate course of action?
A. Proceed with biopsy because prolonged PT is expected in liver disease
B. Postpone the procedure for a couple of days
C. Cancel the procedure and start the patient on vitamin K therapy
D. Put patient on vitamin K therapy and proceed with the procedure immediately

Answer 15

C. Cancel the procedure and start the patient on vitamin K therapy

Question 16

A fresh blood sample was sent to the laboratory at 8:00 a.m. for the PT test. At 4:00 p.m., the doctor requested for the APTT test to be done on the same sample. What should the technologist do?
A. Rerun the APTT on the 8:00 a.m. sample and report the result
B. Request a new sample for APTT
C. Run the APTT in duplicate and report the average
D. Mix patient plasma with normal plasma and run the APTT

Answer 16

B. Request a new sample for APTT

Question 17

An APTT test is performed on a patient and the result is 50 sec (reference range 27–37 sec). The instrument flags the result because of failure of the delta check. The patient had had an APTT of 35 sec the previous day. The technologist calls the nursing unit to check whether the patient is on heparin therapy. The patient is not receiving heparin. What is the next appropriate step?
A. Check the patient’s family history for inherited factor VIII deficiency
B. Check to see if the patient has received any other anticoagulant medications
C. Perform mixing studies
D. Perform a factor VIII assay

Answer 17

B. Check to see if the patient has received any other anticoagulant medications

Question 18

A patient was put on heparin therapy postoperatively for prevention of thrombosis. The patient had the following laboratory results on admission: Platelet count = 350 × 109/L; PT = 12 sec (reference: 10–13 sec); APTT = 35 sec (reference: 28–37). After 6 days of heparin therapy, the patient complained of pain and swelling in her left leg. Her platelet count dropped to 85 × 109/L, and her APTT result was 36 sec. The physician suspected HIT and ordered the PLT aggregation test to be performed immediately. The heparin- induced PLT aggregation test result was negative. Heparin therapy was continued. Several days later, the patient developed a massive clot in her left leg that necessitated amputation. Which of the following should have been recognized or initiated?
A. The patient should have been placed on LMWH
B. The heparin dose should have been increased
C. The negative PLT aggregation does not rule out HIT
D. The patient should have been placed on warfarin therapy

Answer 18

C. The negative PLT aggregation does not rule out HIT

Question 19

A 50-year-old female was admitted to a hospital for hip replacement surgery. Preoperative tests were performed, and the results showed the following:
Hgb = 13.5 g/dL; Hct = 42%; PT = 12 sec; APTT = 36 sec.
The patient was bleeding during surgery, and postoperative test results revealed the following:
Hgb = 5.0 g/dL; Hct = 16%; PT = 8 sec; APTT = 25 sec.
What steps should be taken before releasing these results?
A. No follow-up steps are needed; report the results as obtained
B. Report Hgb and Hct results, adjust the anticoagulant volume, and redraw a new sample for PT and APTT
C. Call the nurse and ask if the patient is receiving heparin
D. Because the patient is severely anemic, multiply the PT and APTT results by two and report the results

Answer 19

B. Report Hgb and Hct results, adjust the anticoagulant volume, and redraw a new sample for PT and APTT

Question 20

A 45-year-old woman visited her doctor complaining of easy bruising and menorrhagia occurring for the past few weeks. The patient had no history of excessive bleeding during child birth several years earlier or during a tonsillectomy in childhood. Her family history was unremarkable.
Laboratory Tests Patient Reference Range
PT 45 sec 11–13 sec
APTT 125 sec 28–37 sec
TT 14 sec 10–15 sec
Mixing studies (patient plasma + normal plasma): PT = 40 sec; APTT = 90 sec
Platelet count and morphology: normal
Liver function tests: normal
These clinical manifestations and laboratory results are consistent with:
A. Factor VIII inhibitor
B. Factor V inhibitor
C. Factor VIII deficiency
D. Lupus anticoagulant

Answer 20

B. Factor V inhibitor