SOP-CM-003 — Routine Fecalysis (Macroscopic Inspection and Direct Fecal Smear — Saline and Lugol's Iodine Wet Mount) SOP

1.0 Purpose

This SOP sets out the procedure for routine fecalysis at Tarangnan Community Hospital: macroscopic examination of stool and standardized microscopic examination using a dual direct fecal smear (DFS) with 0.85% physiological saline and 1% Lugol's iodine. The method detects intestinal helminths, protozoa, cellular exudates, and endemic parasites (notably Schistosoma japonicum in Eastern Visayas).

2.0 Scope

This procedure applies to all human fecal specimens submitted to the Clinical Microscopy Section of Tarangnan Community Hospital for routine parasitological examination. It covers gross visual examination, slide preparation, zigzag battlement microscopic scanning, species identification, cellular quantification, and clinical reporting.

3.0 Definitions

• Direct Fecal Smear (DFS): An analytical wet mount examination in which a small aliquot of fresh feces is emulsified in liquid reagents and examined microscopically without concentration.
• Physiological Saline (0.85% NaCl): An isotonic solution used to examine live, motile protozoan trophozoites (Entamoeba histolytica, Giardia lamblia), helminth eggs, larvae, and cellular exudates.
• Lugol's Iodine (1%): A chemical stain containing potassium iodide and iodine that kills and immobilizes vegetative trophozoites while staining internal protozoan cyst structures (glycogen masses, nuclear chromatin, and karyosomes) yellow-brown.
• Battlement Scan: A continuous serpentine track covering the entire area beneath a coverslip from edge to edge to ensure complete field coverage.
• Charcot-Leyden Crystals: Slender, diamond-shaped, pointed crystals formed from the breakdown products of eosinophils, signifying intestinal hypersensitivity, allergy, or invasive helminthic infection.
• Endemic Parasite Vigilance: Heightened diagnostic scrutiny for Schistosoma japonicum eggs due to documented endemicity in Samar and the Eastern Visayas region.

4.0 Responsibility

4.1 Hospital Director

• Grants final approval for this analytical SOP.
• Ensures the hospital procures optical microscopes, calibrated eyepieces, reference parasitology atlases, and staining reagents.

4.2 Pathologist

• Provides clinical and technical oversight of stool parasitology examinations.
• Confirms atypical protozoan cysts, trophozoites with erythrophagocytosis, heavy mixed parasitic infestations, and Schistosoma japonicum eggs.

4.3 Chief Medical Technologist / Laboratory Quality Manager

• Maintains this SOP, conducts annual competency assessments in parasitology, and oversees slide review archives.
• Verifies monthly quality control of 0.85% physiological saline and 1% Lugol's iodine reagents (checking for bacterial contamination or iodine precipitation).
• Investigates discordant fecalysis findings or specimen rejection trends per LAB-QM-010.

4.4 Medical Technologists

• Check stool specimen collection time, container integrity, and the clinical requisition on receipt.
• Perform macroscopic examination (color, consistency, gross blood, mucus, and adult parasites).
• Prepare dual saline and Lugol's iodine direct fecal smears with proper suspension density.
• Perform battlement microscopic scans under 10× LPF and high-power verification under 40× HPF.
• Quantify cellular elements (RBCs, pus cells), identify parasitic stages, record findings, and authorize reports.

4.5 Laboratory Aides

• Receive sealed stool specimen containers and place them in the designated biohazard processing tray.
• Clean and disinfect bench surfaces, staining racks, and microscope stages with 0.5% sodium hypochlorite solution after every shift.
• Prepare disposal containers and autoclave biohazard waste bags containing used stool containers and wooden applicators.
• Do not prepare smears, operate microscopes, identify parasites, or encode results.

5.0 Policy / Procedure

5.1 Macroscopic / Physical Examination

` Direct Fecal Smear Examination Architecture | +---> Phase 1: Macroscopic / Gross Examination | Color (Brown, Black/Tarry, Clay/Acholic, Red, Green) | Consistency (Formed, Soft, Semi-formed, Mushy, Watery, Mucoid) | Inspect for Gross Blood, Mucus, Pus, and Adult Worms/Proglottids | +---> Phase 2: Dual Slide Preparation (Saline & Lugol's Iodine) | Left Drop: 1 drop 0.85% Saline + ~2 mg stool (emulsify smoothly) | Right Drop: 1 drop 1% Lugol's Iodine + ~2 mg stool (emulsify smoothly) | Apply 22 x 22 mm coverslips at 45° angle (newsprint legible through smear) | +---> Phase 3: Systematic Microscopic Examination 10x LPF Battlement Scan: entire coverslip for Helminth Ova & Larvae 40x HPF Confirmation: Protozoan Cysts/Trophozoites, RBCs, Pus Cells * Samar Endemic Vigilance: Schistosoma japonicum ova detection `

Before microscopic slide preparation, the examining Medical Technologist shall perform visual inspection of the raw stool specimen:

• Color Assessment: - Brown: Normal adult stool color resulting from stercobilin (urobilin). - Black / Tarry (Melena): Indicates upper gastrointestinal bleeding, or ingestion of bismuth compounds, oral iron therapy, or activated charcoal. - Clay / Acholic / Grayish-White: Indicates biliary tract obstruction, cholestasis, or lack of bile pigment secretion. - Red (Hematochezia): Indicates lower gastrointestinal bleeding, hemorrhoids, active dysentery, or recent beet ingestion. - Green: Indicates rapid intestinal transit (unaltered biliverdin), severe diarrhea, or high intake of green vegetables.
• Consistency Assessment: - Formed: Normal solid cylindrical stool. - Soft / Semi-Formed: Loose but retains some shape, typical in mild gastrointestinal disturbance. - Mushy: Pasty, unformed consistency. - Watery / Diarrheal: Completely liquid with minimal particulate matter, indicative of acute secretory or osmotic diarrhea (must be examined within 30 minutes for motile trophozoites). - Mucoid: Dominated by thick gelatinous strands of mucus, suggestive of inflammatory colitis or dysentery.
• Gross Inclusions and Adult Parasite Inspection: - Carefully inspect the container for streaks of visible blood, pus, or excess mucus. Preferentially sample these areas for microscopic evaluation. - Screen macroscopic stool surfaces for expelled adult helminths: - Ascaris lumbricoides: Large, smooth, cylindrical cream-colored roundworms (15 to 35 cm in length). - Enterobius vermicularis: Small, white, thread-like pinworms (8 to 13 mm in length), frequently found crawling on stool surface. - Taenia species: Ribbon-like, segmented ivory-white proglottids (flat tapeworm segments, 1 to 2 cm). - If adult worms or proglottids are present, rinse gently in saline, examine under a dissecting lens or microscope, and refer to the Pathologist for taxonomic confirmation.

5.2 Reagents and Equipment

• 0.85% Physiological Saline (NaCl): 0.85 g reagent-grade sodium chloride dissolved in 100 mL distilled water. Clear, colorless, free of precipitate or fungal contamination; store in a clean dropper bottle at room temperature (18 to 25 °C).
• 1% Lugol's Iodine Solution: Working solution prepared by diluting 5% stock Lugol's iodine 1:5 with distilled water, or commercially prepared 1% Lugol's iodine. Clear, brownish-tea color; store protected from direct sunlight in an amber dropper bottle at room temperature. Discard and replace every 6 months or whenever fading occurs.
• Clean wooden applicator sticks.
• Clean, grease-free glass microscope slides (25 × 75 mm).
• Clean glass coverslips (22 × 22 mm, No. 1 or 1.5 thickness).
• Binocular brightfield microscope equipped with 10× low-power and 40× high-power objectives, condenser, and calibrated mechanical stage.
• Disinfectant solution (0.5% sodium hypochlorite) and biohazard disposal containers.

5.3 Microscopic Examination Protocol (Dual Saline & Lugol's Iodine)

5.3.1 Slide Preparation Sequence

• Take a clean, dry glass microscope slide and label the frosted end with two patient identifiers (Patient Name and Accession Number).
• Place one drop of 0.85% physiological saline on the left half of the slide.
• Place one drop of 1% Lugol's iodine on the right half of the slide.
• Using a clean wooden applicator stick, select approximately 2 mg of feces (an amount roughly equivalent to the tip of a match head). Preferentially sample multiple sites, targeting abnormal areas containing flecks of mucus, blood, or watery exudate. If the stool is formed, sample from both surface and core.
• Emulsify the 2 mg stool sample smoothly and thoroughly into the saline drop on the left half of the slide, creating a uniform, homogeneous suspension without large chunks or air bubbles.
• Pick up an equal 2 mg portion of stool using the applicator stick and emulsify thoroughly into the Lugol's iodine drop on the right half of the slide.
• Verify suspension density: the suspension should be moderately translucent. Newsprint held directly behind the slide should be barely legible through the fecal film. If the suspension is too thick, microscopic illumination is blocked and parasites are obscured; if too thin, diagnostic sensitivity is reduced.
• Holding a clean 22 × 22 mm coverslip by its edges, place one edge at a 45° angle at the perimeter of the saline suspension, then lower it gently onto the droplet. Repeat with a second coverslip over the iodine suspension.
• Verify that liquid spreads smoothly beneath both coverslips without trapping large air bubbles, flowing over the tops, or bridging the gap between the saline and iodine sides. Remove excess fluid using filter paper touching the edge if necessary.

5.3.2 Zigzag Battlement Scanning (10× LPF)

• Place the prepared slide onto the microscope stage, securing it with stage clips.
• Begin examination on the saline mount (left half) under the 10× Low-Power Objective (LPF).
• Lower the condenser slightly and adjust the iris diaphragm to produce good contrast against transparent ova and cysts.
• Position the objective at the upper-left corner of the coverslip.
• Perform a battlement scan: move the stage horizontally across the top edge to the upper-right corner; step down by one full field width; move horizontally back to the left edge; step down one field; and continue this serpentine track until the entire area beneath the 22 × 22 mm coverslip has been examined.
• The 10× LPF scan detects: - Helminth Ova and Larvae: Large, refractile structures easily visualized at low power. - Protozoan Cysts and Trophozoites: Visible as small refractile circular or oval bodies requiring high-power identification. - Cellular Clumps: Pus cell accumulations, mucus strands, and Charcot-Leyden crystals.
• Repeat the identical 10× battlement scan on the Lugol's iodine mount (right half) to screen for stained cysts.

5.3.3 High-Power Objective (40× HPF) Confirmation and Identification

Whenever a suspicious ovum, larva, cyst, or trophozoite is encountered, switch to the 40× High-Power Objective (HPF) and adjust the fine focus knob continuously to evaluate morphological details:

• Helminth Ova Identification: - Ascaris lumbricoides (Fertilized): Golden-brown, oval, 45 to 75 µm × 35 to 50 µm; thick shell covered by an uneven, mammillated albuminous coat; contains an unsegmented ovum surrounded by a clear crescentic space at each pole. - Ascaris lumbricoides (Unfertilized): Elongated, larger (88 to 94 µm × 44 µm); thinner shell with irregular, prominent mammillations; filled with amorphous, highly refractile granules. - Ascaris lumbricoides (Decorticated): Lacks the outer mammillated coat, displaying a smooth, thick, colorless shell. - Trichuris trichiura (Whipworm): Yellow-brown, barrel-shaped (50 to 54 µm × 22 µm); thick shell with two prominent, transparent bipolar mucoid plugs. - Hookworm (Necator americanus / Ancylostoma duodenale): Colorless, oval (55 to 75 µm × 36 to 40 µm); very thin, transparent shell; typically contains an embryo in the 4-cell or 8-cell cleavage stage separated from the shell by a clear space. - Enterobius vermicularis (Pinworm): Asymmetrical, elongated oval flattened on one side (50 to 60 µm × 20 to 30 µm); smooth, colorless shell containing a folded, developed larva. - Strongyloides stercoralis (Rhabditiform Larva): Actively motile larva (200 to 300 µm × 15 µm) with a short buccal cavity (mouth) and a prominent, notched genital primordium located midway along the body; eggs are rarely seen in stool as they hatch in the intestinal mucosa. - Schistosoma japonicum Ova (Samar / Eastern Visayas Endemic): Round to broadly oval (70 to 100 µm × 50 to 65 µm); thin, transparent pale-yellow shell; possesses a small, inconspicuous lateral spine or knob (often obscured by adhering debris); contains a fully developed, ciliated miracidium. High clinical priority: Any egg resembling S. japonicum shall be verified immediately by the Pathologist.
• Protozoan Trophozoite and Cyst Differentiation: - Entamoeba histolytica vs. Entamoeba dispar: - Trophozoite (Saline): 15 to 20 µm; progressive, directional motility using rapid, finger-like pseudopodia. In fresh dysenteric stool, the presence of ingested red blood cells within the cytoplasm (erythrophagocytosis) is pathognomonic for invasive E. histolytica. - Cyst (Iodine): Spherical, 10 to 20 µm; mature cysts possess 1 to 4 spherical nuclei with a small, central pinpoint karyosome and even, fine peripheral chromatin beads; young cysts contain smooth, rounded, cigar-shaped chromatoid bodies. - Entamoeba coli: - Trophozoite (Saline): 20 to 30 µm; sluggish, non-progressive motility with blunt, granular pseudopodia. - Cyst (Iodine): Spherical, 10 to 35 µm; mature cysts possess 1 to 8 nuclei with an eccentric, large karyosome and coarse, irregular peripheral chromatin; chromatoid bodies (if present) are splintered with jagged, needle-like ends. - Giardia lamblia (Giardia duodenalis): - Trophozoite (Saline): Pear-shaped, 10 to 20 µm × 5 to 15 µm; flattened with a concave ventral sucking disc; characteristic tumbling or "falling-leaf" motility; two anterior nuclei producing a bilateral "face" appearance. - Cyst (Iodine): Oval, 8 to 14 µm × 7 to 10 µm; thick cyst wall; contains 2 to 4 nuclei clustered at one pole, distinct longitudinal curved axonemes (fibrils), and median bodies. - Blastocystis hominis: - Vacuolar form: Spherical, variable size (5 to 15 µm); characterized by a large, central, fluid-filled vacuole occupying up to 90% of the cell volume, surrounded by a thin peripheral rim of cytoplasm containing multiple tiny nuclei.
• Non-Parasitic Cellular Elements and Artifacts (40× HPF): - Leukocytes / Pus Cells: Spherical, granular cells (10 to 14 µm) with lobed nuclei; counted and reported as range per HPF (e.g., 0–2, 2–5, 10–20 / HPF). Presence of > 5 pus cells / HPF indicates invasive bacterial enteritis (e.g., Shigella, Salmonella, Campylobacter) or inflammatory bowel disease. - Erythrocytes (RBCs): Non-nucleated biconcave discs (~7 µm); reported as range per HPF (e.g., 0–2, 5–10 / HPF). Indicates lower gastrointestinal ulceration, active amebic colitis, or severe hemorrhoidal bleeding. - Charcot-Leyden Crystals: Slender, sharply pointed, diamond-shaped or hexagonal crystals; reported as Few, Moderate, or Many / HPF. - Yeast Cells: Oval, refractile bodies (3 to 6 µm) exhibiting budding and pseudohyphae; distinguish from protozoan cysts by irregular size, oval shape, and lack of internal nuclei on iodine stain. - Fecal Artifacts: Vegetable cells and spiral vessels (thick, dark cell walls), starch granules (round/angular, stain intense dark blue-black with iodine), muscle fibers (striated rectangular blocks), pollen grains, and air bubbles.

5.4 Quality Control Protocol

• Reagent Quality Control: - Physiological Saline (0.85%): Check daily for clarity and microbial contamination. If turbidity, cloudiness, or fungal mycelia develop, discard immediately and prepare fresh saline. - Lugol's Iodine (1%): Inspect weekly. The solution must maintain a rich brownish-tea color. If the reagent fades to pale yellow, iodine has volatilized and staining capacity is lost; discard and replace.
• Microscope Maintenance: Optical lenses, condenser, and stage shall be cleaned using lens paper before and after each working shift. Clean oil-immersion lenses with lens cleaner if immersion oil was used.
• Reference Collection: The section shall maintain laminated parasitology bench charts and photomicrographic atlases at the workstation for immediate morphological comparison.
• Confirmatory Pathologist Review: Medical Technologists shall hold and refer slides exhibiting any of the following to the Pathologist: - Any suspected Schistosoma japonicum ovum. - Trophozoites displaying erythrophagocytosis (Entamoeba histolytica). - Unidentified helminth ova, larvae, or atypical proglottids. - Heavy cellular exudates with packed pus cells (> 50 / HPF) and sheets of red blood cells.

5.5 Result Reporting Format and Standardization

Diagnostic reports are compiled on the standard TCH Fecalysis Result Form:

• Macroscopic Examination: - Color: Brown, Black, Clay, Red, Green - Consistency: Formed, Soft, Semi-formed, Mushy, Watery, Mucoid - Gross Blood: Present / Absent - Mucus: Present / Absent - Adult Helminths: Species identified, or None seen
• Microscopic Examination: - Parasites (Ova / Larvae / Cysts / Trophozoites): - If no parasites are observed after scanning the entire coverslip area: Report as "No Ova or Parasite seen" (NOPS). - If parasites are identified: Report the exact scientific species name, life-cycle stage (ovum, rhabditiform larva, cyst, or trophozoite), and semi-quantitative density: - Few (1 to 2 per coverslip preparation) - Moderate (3 to 9 per coverslip preparation) - Many (10 or more per coverslip preparation) - Example: "Ascaris lumbricoides ova: Moderate; Trichuris trichiura ova: Few." - Cellular Elements: - Red Blood Cells (RBCs): Report range per HPF (e.g., 0–2, 2–5, 10–20 / HPF). - Pus Cells (WBCs): Report range per HPF (e.g., 0–2, 5–10, 20–30 / HPF). - Other Findings: - Yeast cells, Fat globules, or Charcot-Leyden crystals (reported as Few, Moderate, or Many / HPF).

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, Section 7.3 — Examination processes
• WHO Laboratory Quality Management System Handbook, Chapter 5 — Process Control
• CLSI M28-A2, Procedures for the Recovery and Identification of Parasites from the Intestinal Tract; Approved Guideline
• World Health Organization: Basic Laboratory Methods in Medical Parasitology (Geneva)

Companion policies:

• Scope of Service and Laboratory User Information Policy — Laboratory test menu and parasitology diagnostic scope
• LAB-QM-PRE-001 — Specimen collection, acceptance criteria, and rejection management
• Laboratory Reporting Policy — Result review, validation, and diagnostic report release