Semen Analysis

Overview

Semen = spermatozoa + fluid. ~40% infertility = semen abnormalities → first infertility test. Defects: quantitative (absent/few sperm) or qualitative (morphology/function).

Indications: fertility/infertility, vasectomy confirmation, artificial insemination/ART suitability, medicolegal (rape cases — vaginal pool smear), donor selection.

Collection

Masturbation, 2-7 days abstinence, clean dry wide-mouth container. NO condom (spermicide impairs motility).

Physical exam

Liquefaction: semisolid at ejaculation → liquefies 15min → homogeneous/watery by 30min. Viscosity: normal drops freely; abnormal = thread >2cm (impairs motility). Appearance: opaque white-grey fresh → grey-opalescent after liquefaction. Red-brown = haemospermia (RBCs); yellow = jaundice/drugs. Volume: normal 1.4-1.7mL. Low = ductal obstruction/congenital vas deferens absence/collection difficulty. High = accessory gland inflammation. pH: alkaline 7.2-8 (measure after liquefaction, ~30min).

Microscopic exam

Sperm count: Neubauer chamber, Thoma pipette, 1:20 dilution. Normal 33-46 million/ejaculate.

Aspermia = no semen
Azoospermia = no sperm in ejaculate
Oligospermia = count below lower limit

Motility: normal 38-42% motile. WHO 2010 grading: PR (progressive), NP (non-progressive), IM (immotile) — replaced old a/b/c/d.

Vitality: dye exclusion/hypotonic swelling (intact membrane = alive). Normal 55-63% live. Key when motility <~40% — distinguishes dead vs merely immotile.

Morphology: Pap-stained smear. Normal sperm = head+neck+midpiece+principal piece. >30% normal = threshold. BOTH head AND tail must be normal to count as normal.

Head defects: size, shape, acrosomal, number (double-headed)
Neck/midpiece defects: bent neck, asymmetric insertion, irregular midpiece
Tail defects: short/bent/coiled/double

Aggregation vs agglutination: aggregation = nonspecific clumping (immotile-immotile, or motile-to-mucus/debris). Agglutination = MOTILE sperm sticking to EACH OTHER (head-head/tail-tail/mixed) — points to anti-sperm antibodies.

Other cells: epithelial cells + “round cells” (leukocytes, immature germ cells) noted separately — ↑round cells (esp. leukocytes) suggests infection.

Anti-sperm antibodies (ASA)

IgA/IgG class, in semen or sperm-free fluids (seminal plasma, serum, cervical mucus). Direct tests (on sperm): MAR test, immunobead (IB) test. Indirect tests: sperm-free fluids.

Clinical relevance

BOTH head+tail must be normal for morphologically-normal count — a perfect head with coiled tail still scores abnormal, explains why morphology % often lower than expected. Aggregation vs agglutination = real diagnostic fork, not semantics — aggregation has no immunologic implication; true motile-motile agglutination should prompt ASA testing. Volume direction (low vs high) points to different anatomic problems (ductal obstruction vs accessory gland inflammation) — useful first clue before targeted testing. Condom collection unsuitable (spermicide) — naive “convenient” sample can give falsely poor motility unrelated to actual fertility.

Overview

Semen consists of spermatozoa plus a fluid component. About 40% of infertility cases trace to semen abnormalities, so semen analysis is the first test in an infertility workup. Sperm defects are quantitative (absent or too few sperm) or qualitative (morphology/function abnormal).

Indications: fertility/infertility assessment; confirming vasectomy effectiveness; assessing suitability for artificial insemination or assisted reproduction (IVF, GIFT); medicolegal purposes (vaginal pool smears in alleged rape); donor selection.

Collection

By masturbation after 2–7 days of sexual abstinence, into a clean, dry, wide-mouthed container. Condom collection is unsuitable — spermicidal agents in most condoms impair sperm motility.

Physical Examination

Liquefaction — freshly ejaculated semen is a semisolid coagulated mass; it liquefies within 15 minutes at room temperature, becoming fully homogeneous/watery by 30 minutes.
Viscosity — normal semen falls drop by drop from a wide-bore pipette; abnormal viscosity produces a thread >2 cm long. Increased viscosity impairs motility.
Appearance — opaque white-grey when fresh; homogeneous grey-opalescent after liquefaction. Red-brown colour (haemospermia) indicates RBCs; yellow suggests jaundice or certain drugs/vitamins.
Volume — normal 1.4–1.7 mL/ejaculate. Low volume: ejaculatory duct obstruction, congenital bilateral absence of the vas deferens, or collection difficulty. High volume: active exudation in inflammatory lesions of the accessory glands.
pH — alkaline, 7.2–8, measured after liquefaction (preferably at 30 minutes).

Microscopic Examination

Sperm count — Neubauer chamber with Thoma pipette, 1:20 dilution. Normal range 33–46 million/ejaculate.
- Aspermia — no semen at all.
- Azoospermia — no spermatozoa in the ejaculate.
- Oligospermia — sperm count below the lower reference limit.
Sperm motility — normal semen has 38–42% motile sperm (progressively + non-progressively motile). WHO (2010) grades motility as progressively motile (PR), non-progressively motile (NP), and immotile (IM), replacing the older a/b/c/d (I–IV) grading. Assessed on a wet mount under microscope.
Sperm vitality — distinguishes live from dead immotile sperm by intact-membrane assays (dye exclusion or hypotonic swelling); normal 55–63% live forms. Especially important when progressive motility is under ~40%, to establish whether immotile sperm are dead or merely non-motile.
Sperm morphology — Papanicolaou-stained smear. A normal spermatozoon has head, neck, midpiece, and principal piece; >30% normal morphology is the reference threshold, and a sperm counts as normal only if both head and tail are morphologically normal.
- Head defects — abnormal size (large/small), abnormal shape (pointed/tapered, round, pyriform, amorphous), acrosomal defects (vacuolated/abnormal acrosomal region), abnormal number (double-headed).
- Neck/midpiece defects — sharply bent neck, asymmetric midpiece insertion, thick/thin/irregular midpiece.
- Tail (principal piece) defects — short, bent, coiled, or double tail.
Sperm aggregation vs agglutination — aggregation is nonspecific clumping (immotile sperm to each other, or motile sperm sticking to mucus/debris/non-sperm cells); agglutination specifically means motile sperm sticking to each other (head-to-head, tail-to-tail, or mixed), and points toward anti-sperm antibodies.
Other cellular elements — epithelial cells (genitourinary tract) and “round cells” (leukocytes and immature germ cells) are noted separately from sperm counts, since elevated round cells (especially leukocytes) can itself signal infection.

Anti-Sperm Antibodies

Sperm agglutination may result from anti-sperm antibodies (ASAs, of IgA/IgG class) present in semen, or found in sperm-free fluids (seminal plasma, blood serum, cervical mucus). Direct tests (on the spermatozoa themselves) include the mixed antiglobulin reaction (MAR) test and the immunobead (IB) test; indirect tests detect ASAs in sperm-free fluids.

Clinical Relevance

The requirement that both head and tail be normal for a sperm to count as morphologically normal (not just one or the other) is a subtle but testable point — a sperm with a perfect head and a coiled tail is still scored abnormal, which is why morphology percentages are often lower than intuition suggests.
The aggregation-versus-agglutination distinction is a genuinely useful diagnostic fork rather than a semantic nicety: nonspecific aggregation (debris, mucus, dead sperm clumping) carries no particular immunologic implication, while true motile-sperm-to-motile-sperm agglutination is the specific finding that should prompt anti-sperm antibody testing.
Semen volume abnormalities point toward anatomically distinct problems depending on direction — low volume raises suspicion of ductal obstruction or congenital vas deferens absence, while high volume points toward accessory gland inflammation — making volume a useful first anatomic clue before more targeted testing.
Condom-based collection being unsuitable due to spermicide contamination is a small but practically important detail, since a naively collected “convenient” sample can produce a falsely poor motility result that has nothing to do with the patient’s actual fertility.

No Rendered Diagram for This Topic

Semen analysis is a reference panel of physical/microscopic parameters and their normal ranges, not a disease mechanism — no multi-step process to diagram.

Hand-Draw Suggestion

Sketch a labelled spermatozoon (head, neck, midpiece, principal piece) and mark where each morphology defect category (head/neck-midpiece/tail) applies — a quick anatomic anchor for the abnormal-forms classification in notes.md.

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