SOP-H-006 — Bleeding Time and Clotting Time (Capillary and Slide Method) Procedure SOP

1.0 Purpose

This SOP sets the procedure for performing Bleeding Time (BT) and Whole-Blood Clotting Time (CT) at Tarangnan Community Hospital. It covers in vivo assessment of primary vascular-platelet hemostasis by the Ivy and Duke bleeding time methods, and in vitro screening of secondary intrinsic coagulation by non-heparinized capillary tube and glass slide clotting time techniques.

2.0 Scope

This procedure applies to all Registered Medical Technologists performing hemostasis screening at TCH outpatient phlebotomy stations and inpatient clinical wards. It covers patient pre-assessment, puncture standardization, timed blotting and fibrin observation, reference intervals, and clinical correlation for pre-operative clearance and bedside hemostatic evaluations.

3.0 Definitions

• Bleeding Time (BT): The measured time interval between the creation of a standardized superficial skin puncture or incision and the complete cessation of active capillary bleeding, reflecting primary hemostasis (platelet plug formation and microvascular constriction).
• Clotting Time (CT): The elapsed time required for unanticoagulated whole blood to form a macroscopic fibrin clot following contact with a glass surface, evaluating the intrinsic and common coagulation pathways.
• Ivy Method: Standardized bleeding time technique conducted on the volar forearm under a constant venous stasis pressure of 40 mmHg maintained by a sphygmomanometer cuff.
• Duke Method: Traditional bleeding time technique measuring hemorrhage cessation from a standardized puncture of the earlobe or finger pulp without venous stasis.
• Capillary Tube Method (Sabrazes / Dale-Laidlaw): Whole-blood clotting time technique where non-heparinized glass micro-capillary tubes are filled by skin puncture and broken at regular intervals to detect fibrin strand bridging.

4.0 Responsibility

4.1 Hospital Director

• Approves this SOP and authorizes procurement of single-use automated incision devices, non-heparinized capillary tubes, and calibrated timers.

4.2 Pathologist

• Reviews and authorizes reference intervals, clinical utility guidelines, and safety criteria for in vivo hemostasis testing.
• Interprets prolonged or discordant results in clinical consultation with attending surgeons and clinicians.

4.3 Chief Medical Technologist / Laboratory Quality Manager

• Oversees technical adherence to this SOP, verifies annual calibration of sphygmomanometers and timers, and monitors testing volume.
• Conducts technologist training and practical competency assessments in skin puncture and timed blotting techniques per Competency Assessment Policy.

4.4 Medical Technologists

• Verify patient eligibility, screen for aspirin and anticoagulant medications, explain procedures, and perform standardized punctures.
• Maintain accurate 30-second blotting and tube-breaking timing, detect cessation or fibrin strands, record numerical values, and immediately escalate prolonged times.

4.5 Laboratory Aides

• Restock alcohol prep pads, Whatman filter paper disks, butterfly bandages, and lancets at the testing station.
• Clean and decontaminate blood pressure cuffs and armboards following patient procedures.
• Shall never perform skin punctures, blot bleeding sites, break capillary tubes, or report hemostasis results.

5.0 Policy / Procedure

5.1 Clinical Indication and Patient Eligibility Screening

• Clinical Indications: Pre-operative screening for elective surgical procedures, assessment of suspected platelet function disorders, screening for severe intrinsic coagulation factor deficiencies (severe hemophilia), and bedside emergency bleeding assessment.
• Mandatory Pre-Test Medication Screening: - Interview the patient (or guardian) regarding medication history over the preceding 7 to 10 days. - Specifically inquire about aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs such as ibuprofen, naproxen, mefenamic acid), clopidogrel, dipyridamole, oral anticoagulants (warfarin, direct factor Xa inhibitors), and high-dose antihistamines. - If platelet-inhibiting drugs have been ingested within the preceding 7 days, notify the attending physician. The test shall be postponed until 7 days after drug cessation unless the physician specifically mandates immediate testing for emergency clinical reasons.
• Patient Positioning and Preparation: - Seat the patient comfortably with the arm extended supine on a firm armboard, or place the patient in a recumbent position. - Inspect the puncture site (volar forearm, earlobe, or finger) for scars, active dermatitis, hematomas, or prominent superficial veins. Avoid compromised skin areas.

5.2 Equipment, Reagents, and Materials

• For Bleeding Time (Ivy Method): - Sphygmomanometer with calibrated aneroid or digital manometer and appropriate adult/pediatric cuff. - Sterile, single-use automated incision device (e.g., Surgicutt or standardized automated lancet producing a 1.0 mm deep by 5.0 mm long incision) or standard sterile 2.0 mm blood lancet. - Whatman No. 1 circular filter paper disks (11 cm diameter) or equivalent absorbent filter paper strips. - Calibrated digital stopwatch / timer. - 70% isopropyl alcohol pads and sterile gauze pads. - Butterfly closure strips (steri-strips) and adhesive bandages.
• For Bleeding Time (Duke Method): - Sterile, single-use lancet (2.0 mm depth). - Whatman No. 1 circular filter paper. - Digital stopwatch, 70% alcohol pads, sterile gauze.
• For Clotting Time (Capillary Tube Method): - Non-heparinized (blue-banded or plain) glass capillary tubes (length 75 mm, internal diameter 1.1–1.2 mm). - Sterile disposable blood lancet (2.0–2.4 mm puncture depth). - Metal file / scoring blade (if capillary tubes are not pre-scored), sterile gauze, and timer.
• For Clotting Time (Slide Method): - Clean, dry, lint-free glass microscope slides. - Sterile disposable lancet, sterile needle/wooden applicator stick, timer, and gauze.

5.3 Bleeding Time — Standardized Ivy Method Procedure

• Wrap the sphygmomanometer cuff smoothly around the patient's upper arm above the antecubital fossa.
• Select an area on the muscular volar surface of the forearm approximately 5 cm distal to the antecubital crease, avoiding superficial veins, tendons, scars, and visible hair.
• Cleanse the site with a 70% isopropyl alcohol pad using concentric outward circles and allow to air-dry completely for 30 seconds.
• Inflate the cuff to exactly 40 mmHg and maintain this pressure constant throughout the entire procedure.
• Within 30 to 60 seconds of cuff inflation, firmly place the sterile automated incision device onto the prepared volar skin parallel to the long axis of the arm (or perpendicular per device specifications). Do not press deeply into the flesh.
• Trigger the device blade to make the standardized incision, and start the stopwatch simultaneously (T0). Remove the device immediately and discard it into the sharps container.
• After 30 seconds, bring the edge of a clean Whatman filter paper disk within 1 mm of the bleeding puncture without touching the incision wound itself.
• Allow the exiting drop of blood to absorb onto the filter paper by capillary action without scraping, rubbing, or pressing the paper against the wound. Touching the wound disrupts the developing platelet plug and invalidates the test.
• Repeat the blotting procedure every 30 seconds, rotating the filter paper disk so that each successive drop forms a distinct blood spot along the perimeter.
• As primary hemostasis develops, the absorbed blood spots become progressively smaller.
• Stop the stopwatch at the exact moment blood no longer stains the filter paper.
• Immediately deflate and remove the blood pressure cuff.
• Record the bleeding time to the nearest 30 seconds.
• Clean the surrounding skin with alcohol-free antiseptic gauze, draw the edges of the incision together, apply a sterile butterfly closure strip across the wound, and cover with an adhesive bandage. Instruct the patient to keep the strip intact for 24 hours to prevent scarring.
• If bleeding continues beyond 15 minutes, stop the timed blotting, apply firm direct gauze pressure with a pressure dressing, notify the physician, and report the result as: "> 15 minutes (Test terminated due to prolonged bleeding)".

5.4 Bleeding Time — Duke Method Procedure

• Cleanse the lower fleshy lobe of the patient's ear (or the palmar surface of the 3rd or 4th finger) thoroughly with 70% isopropyl alcohol and allow to air-dry.
• Make a quick, firm, standardized puncture approximately 2.0 mm deep into the dependent margin of the earlobe using a sterile disposable lancet.
• Start the stopwatch simultaneously as the puncture is made (T0).
• Wipe away the first small drop of blood with dry sterile gauze (initiates timing from fresh capillary flow).
• At 30-second intervals, bring the edge of the filter paper into gentle contact with the forming blood drop without touching the skin surface.
• Continue blotting every 30 seconds until bleeding completely ceases.
• Stop the timer and record the Duke Bleeding Time in minutes and seconds. Apply firm pressure with sterile gauze until hemostasis is complete.

5.5 Clotting Time — Capillary Tube Method Procedure

• Cleanse the palmar surface of the 3rd or 4th fingertip (or the lateral plantar surface of the heel in infants) with 70% alcohol and allow to air-dry completely.
• Perform a firm, deep skin puncture (2.0–2.4 mm depth) using a sterile lancet. A free, generous flow of blood is essential; do not squeeze or milk the site vigorously, as excess tissue thromboplastin invalidates the test.
• Wipe away the first drop of blood with dry sterile gauze.
• Start the stopwatch simultaneously (T0) as fresh blood emerges.
• Immediately bring the tip of a plain, non-heparinized glass capillary tube into contact with the second large drop of blood, holding the tube horizontally or slightly tilted downward so blood fills the tube rapidly by capillary action. Fill at least two to three capillary tubes to two-thirds capacity.
• Seal the ends or hold the filled tubes horizontally at room temperature (18–25 °C).
• At 1 minute from puncture, and every 30 seconds thereafter, carefully break off approximately 1 cm of the capillary tube from one end.
• Slowly separate the broken ends by 5 mm and inspect the gap for the formation of a delicate, elastic fibrin thread bridging the broken ends.
• Continue breaking segments every 30 seconds.
• The endpoint is reached at the exact moment a visible, continuous fibrin strand spans across the separated tube ends and resists gentle stretching.
• Stop the timer and record the elapsed Clotting Time in minutes and seconds.

5.6 Clotting Time — Glass Slide Method Procedure

• Perform hand hygiene and don gloves. Cleanse the patient's puncture site with 70% alcohol and allow to air-dry.
• Perform a deep, standardized puncture using a sterile lancet and start the stopwatch simultaneously (T0).
• Wipe away the first drop of blood.
• Allow two to three large, non-spreading drops of blood to fall onto separate sections of a clean, room-temperature glass microscope slide.
• Every 30 seconds, gently pass the tip of a clean wooden applicator stick or sterile needle through the edge of the first blood drop, drawing the stick upward.
• Repeat the maneuver on successive drops every 30 seconds.
• Observe carefully for the first formation of macroscopic fibrin threads adhering to and trailing the tip of the stick.
• Stop the timer when firm, elastic fibrin threads span across the drop and adhere to the stick.
• Record the elapsed time as Clotting Time (Slide Method) in minutes and seconds.
• Apply sterile gauze pressure to the puncture site until bleeding stops. Dispose of used glass slides and lancets directly into the puncture-resistant sharps container.

5.7 Quality Assurance and Technical Precaution Rules

• Avoid vigorous tissue squeezing ("milking"), which introduces excess interstitial tissue factor, falsely shortening the clotting time.
• Ensure puncturing instruments are sterile, sharp, single-use, and of verified penetration depth. Dull lancets tear tissue and prolong bleeding.
• Keep Whatman filter paper completely dry before blotting. Damp paper dissolves clots or accelerates capillary flow.
• Ensure the patient's forearm is kept warm; shivering or cold-induced vasoconstriction falsely shortens the bleeding time.
• Calibrate stopwatches annually against an authorized national standard time signal and log in the equipment binder.

5.8 Reporting and Reference Intervals

• Diagnostic reports shall state the specific testing method used (Ivy BT, Duke BT, Capillary Tube CT, or Slide CT), the measured time in minutes and seconds, and the corresponding TCH reference interval.

• Clinical Interpretation of Abnormal Results: - Prolonged Bleeding Time (> 8 minutes Ivy / > 5 minutes Duke): Suggests quantitative thrombocytopenia (< 50 × 10³/µL), qualitative platelet dysfunction (thrombasthenia, Bernard-Soulier syndrome), von Willebrand disease, severe vascular purpura, or recent anti-platelet therapy (aspirin, NSAIDs). - Prolonged Clotting Time (> 8 minutes Capillary / > 10 minutes Slide): Suggests severe deficiency of intrinsic coagulation factors (Factor VIII / Hemophilia A, Factor IX / Hemophilia B, Factor XI), severe hypofibrinogenemia, presence of circulating heparin, or marked liver failure. Clotting time is relatively insensitive and will only become abnormal when factor levels drop below 1% to 5% of normal; it is not a substitute for formal PT/APTT testing.
• Any Bleeding Time > 15 minutes or Clotting Time > 15 minutes shall be classified as a critical result and notified immediately to the attending physician per SOP-H-001.

6.0 Records

7.0 References

• DOH Clinical Laboratory QMS Tool, Section 3 — Service Delivery
• DOH Administrative Order No. 2021-0037, Annex B1 — Technical Standards for Clinical Laboratories
• ISO 15189:2022, Clause 7.3 Examination processes
• Ivy bleeding time method — standard textbook procedure (no CLSI bleeding time standard is in force; CLSI H02-A5 covers the erythrocyte sedimentation rate test, see SOP-H-004)
• Lee and White whole-blood clotting time method — standard textbook procedure

Companion policies:

• Hematology Section Workflow Quality Control and Result Validation Sop — Hematology Section workflow, quality control, and result validation SOP
• Laboratory Reporting Policy — Result review, validation, and diagnostic report release
• Laboratory Retention Schedule Policy — Retention schedules for worksheets and patient reports