What is semen contact allergy?
Semen contact allergy is a rare but notable form of allergic contact urticaria that occurs during or after contact with seminal fluid.
It is also known as human seminal plasma allergy, seminal plasma hypersensitivity, or seminal fluid hypersensitivity.
Who gets semen contact allergy?
The true prevalence of semen contact allergy in the general population is unclear. Less than 100 well-documented cases exist in the medical literature worldwide, however, the condition is likely underreported due to its sensitive nature. A survey of 1073 symptomatic women in the United States suggested a probable prevalence of around 8%.
- Semen contact allergy is exclusively seen in women.
- Over 40% of affected women present with symptoms after their first sexual intercourse.
- Greater than 60% are diagnosed between 20 and 30 years of age, but there are reports of women becoming symptomatic for the first time after menopause.
- There is a significant association with a personal or family history of atopy, particularly in those with systemic reactions.
What causes semen contact allergy?
The cause of semen contact allergy is unclear. Various authors of case studies have hypothesised that disruption of the normal female genital-tract immunomodulation may occur through:
- Reproductive or hormonal changes (eg, pregnancy, menopause)
- Genital tract procedures (eg, tubal ligation, hysterectomy, insertion of an intrauterine device, or prostatectomy or reversal of vasectomy in a partner)
- Genetic predisposition (eg, familial 'allergic seminal vulvovaginitis' as reported in a case series of a mother and three daughters with localised reactions to semen since the first contact).
A systemic reaction to semen is typically due to type I (immediate) hypersensitivity with subsequent development of IgE antibodies against proteins in human seminal fluid. Multiple allergens may be involved. Prostate-specific antigen, a 33–34 kD glycoprotein, is believed to play an integral role. It has been postulated that a highly cross-reactive protein in dog dander might be responsible for sensitisation, explaining how women may present after their first sexual intercourse.
In contrast to a systemic response, a localised reaction does not appear to involve IgE. While there have been occasional reports of type III (immune-complex) reaction and a fixed cutaneous eruption, the underlying immune mechanism of most localised semen contact allergy is unknown.
What are the clinical features of semen contact allergy?
Allergy to seminal fluid may present as a localised reaction or a systemic response. Symptoms are fully prevented by the use of condoms.
A review of semen contact allergy case studies reported that:
- 31% of women experienced only localised vulvovaginal symptoms
- 28% experienced only systemic symptoms
- 39% suffered from both localised and systemic symptoms
- 1% developed a fixed cutaneous eruption.
Additional case studies describe repeated exacerbations of asthma after intercourse and a systemic reaction after topical contact with seminal fluid.
The localised reactions to semen contact allergy include:
- Immediate onset after seminal fluid contact
- Severe vulvovaginal burning sensation, itching, or tingling
- Redness, swelling, and less commonly, blistering around the vulva and vaginal opening.
The systemic reactions to semen contact allergy include:
- Onset within 30 minutes up to several hours after exposure
- Generalised itching, urticaria, and swelling of the tongue, lips, and throat (angioedema), which may or may not be preceded by initial localised symptoms
- Respiratory symptoms, such as shortness of breath, wheezing, chest tightness, coughing, runny nose, and sneezing
- Gastrointestinal symptoms such as nausea, vomiting, and diarrhoea
- Life-threatening anaphylactic reactions — however, no fatalities have been reported to date.
Symptom resolution typically occurs within 24 hours, although localised vulvovaginal pain, urticaria, and malaise may persist for several days to weeks. Increasing intensity of reaction with subsequent exposures is a common feature.
After the initial onset, symptoms usually arise with all subsequent contact irrespective of the partner. However, the occurrence may be restricted to a specific partner.
What are the complications of semen contact allergy?
Complications of semen contact allergy include the emotional impact on the individual and their relationships, resulting in anxiety and sexual dysfunction, and concerns about conception and pregnancy.
- Semen contact allergy is not associated with primary infertility
- Specific management as discussed below can allow for natural conception
- Artificial insemination with washed spermatozoa is generally very well-tolerated, although there have been cases of persisting allergy.
How is semen contact allergy diagnosed?
Diagnosis is often based on clinical history alone. The following investigations are undertaken to rule out other causes of symptoms.
- Vaginal examination.
- Vaginal swabs for microscopy and culture to rule out bacterial and yeast infections and nucleic acid amplification tests (NAATs) for chlamydia and gonorrhoea to rule out sexually transmitted infections.
- For systemic reactors, blood tests may include blood count and microscopy with differential, renal, liver and thyroid function, complement proteins (C3 and C4) and antinuclear antibody (ANA) to exclude other causes of angioedema and urticaria.
Investigations to confirm semen contact allergy may include a skin prick test using seminal fluid proteins obtained from the patient’s sexual partner.
- Fresh ejaculate is liquefied at room temperature for 30 minutes, then centrifuged at 5000 g to separate spermatozoa from seminal fluid.
- The patient’s partner should be concurrently prick tested as a control.
- Note that a false negative can occur with the use of antihistamines or due to a dilutional effect from other irrelevant proteins.
Serum-specific IgE antibodies to whole seminal fluid or fractionated seminal plasma proteins are found in all women with systemic reactions but are not consistently detected in those with localised reactions.
Positive contact urticaria test
What is the differential diagnosis for semen contact allergy?
Other conditions that should be considered in a patient with symptoms suggestive of semen contact allergy may include:
- Physical factors (eg, small introitus)
- Irritant contact dermatitis to various substances such as sexual lubricant, spermicide, local anaesthetic used within a condom, soap, scented toilet tissue, or feminine hygiene products
- Allergic contact dermatitis to another allergen such as a rubber accelerant in a condom
- Contact urticaria to another allergen such as latex
- Chronic inducible urticaria
- Seminal plasma fluid transfer of a food allergen (eg, peanut), drug allergen (eg, penicillin) or a drug metabolite (eg, a chemotherapeutic agent)
- Exercise-induced bronchoconstriction or post-coital asthma triggered by sexual activity.
What is the treatment for semen contact allergy?
General management of semen contact allergy may include:
- Education and counselling
- Avoidance of the allergen (eg, abstinence, use of a barrier contraceptive such as a condom)
- Prophylactic oral antihistamine taken 30–60 minutes prior to intercourse may reduce the severity of a non-anaphylactic reaction
- An adrenaline autoinjector for all patients with a history of a systemic reaction.
Specific management of semen contact allergy may include:
- Desensitisation via intravaginal graded challenge using dilutions of whole seminal fluid
- Subcutaneous desensitisation to the relevant fractionated seminal plasma proteins obtained from the patient’s sexual partner.
What is the outcome for semen contact allergy?
Subcutaneous desensitisation using relevant seminal plasma proteins eliminates symptoms in > 95% of women over time. Women must be exposed to semen at least two to three times weekly to maintain tolerance.
Those with localised reactions tend to have more variable treatment outcomes. Neither form of semen contact allergy has been associated with infertility. Despite this, the condition may place an inordinate strain on any relationship.