Fetal and neonatal alloimmune thrombocytopenia

What it is

From: Orphanet

A rare hematological disease characterized by maternal alloimmunisation against fetal platelet antigens that are inherited from the father and different from those present in the mother, and usually presents as a severe isolated thrombocytopenia in otherwise healthy newborns.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Neonatal alloimmune thrombocytopenia · Obligate (100%)

Low platelet count associated with maternal platelet-specific alloantibodies.

Abnormal bleeding · Frequent (79-30%)

An abnormal susceptibility to bleeding, often referred to as a bleeding diathesis. A bleeding diathesis may be related to vascular, platelet and coagulation defects.

Cephalohematoma · Frequent (79-30%)

Hemorrhage between the skull and periosteum of a newborn resulting from rupture of blood vessels that cross the periosteum.

Petechiae · Frequent (79-30%)

Petechiae are pinpoint-sized reddish/purple spots, resembling a rash, that appear just under the skin or a mucous membrane when capillaries have ruptured and some superficial bleeding into the skin has happened. This term refers to an abnormally increased susceptibility to developing petechiae.

Purpura · Frequent (79-30%)

Purpura (from Latin: purpura, meaning purple) is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin. This term refers to an abnormally increased susceptibility to developing purpura. Purpura are larger than petechiae.

Spontaneous hematomas · Frequent (79-30%)

Spontaneous development of hematomas (hematoma) or bruises without significant trauma.

Ecchymosis · Occasional (29-5%)

A purpuric lesion that is larger than 1 cm in diameter.

Gastrointestinal hemorrhage · Occasional (29-5%)

Hemorrhage affecting the gastrointestinal tract.

Hematuria · Occasional (29-5%)

The presence of blood in the urine. Hematuria may be gross hematuria (visible to the naked eye) or microscopic hematuria (detected by dipstick or microscopic examination of the urine).

Intracranial hemorrhage · Occasional (29-5%)

Hemorrhage occurring within the skull.

Melena · Occasional (29-5%)

The passage of blackish, tarry feces associated with gastrointestinal hemorrhage. Melena occurs if the blood remains in the colon long enough for it to be broken down by colonic bacteria. One degradation product, hematin, imbues the stool with a blackish color. Thus, melena generally occurs with bleeding from the upper gastrointestinal tract (e.g., stomach ulcers or duodenal ulcers), since the blood usually remains in the gut for a longer period of time than with lower gastrointestinal bleeding.

Abnormality of the nervous system · Very rare (<4-1%)

An abnormality of the nervous system.

Bilateral sensorineural hearing impairment · Very rare (<4-1%)

A form of sensorineural hearing impairment that affects both ears.

Blindness · Very rare (<4-1%)

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.

Other findings in the same source

From: Orphanet

Additional reported features include Cerebral palsy (Very rare (<4-1%)); Global developmental delay (Very rare (<4-1%)); Subarachnoid hemorrhage (Very rare (<4-1%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Antenatal; Neonatal

Inheritance in the source

From: Orphanet

Not applicable

Frequency and the population described

From: Orphanet

Point prevalence: 1-5 / 10 000; Worldwide; Value and class. Prevalence at birth: 6-9 / 10 000; Worldwide; Value and class.

Which doctor should you see?

The suggested department for discussing Fetal and neonatal alloimmune thrombocytopenia is Haematology, with a haematologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which blood-cell, marrow, bleeding or clotting finding matters most?
• Does the diagnosis need confirmation or a more precise subtype?
• Which symptoms or laboratory changes should trigger earlier review?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Fetal and neonatal alloimmune thrombocytopenia. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.