Asherman Syndrome and Intrauterine Adhesions

Asherman syndrome is the formation of adhesions (synechiae) within the uterine cavity, typically following injury to the basal endometrium, that partially or completely obliterate the cavity. It is an acquired cause of uterine-factor infertility and is classically associated with reduced or absent menstruation, recurrent pregnancy loss, and difficulty conceiving, because functional endometrium needed for implantation is lost or scarred.

Definition

Asherman syndrome is the presence of intrauterine adhesions (synechiae) that partially or wholly obliterate the uterine cavity, usually following trauma to the basal endometrium, and is typically accompanied by menstrual abnormalities, infertility, or recurrent pregnancy loss.

Scope

This entry covers intrauterine adhesions and the syndrome named for Joseph Asherman — their causes, the mechanism by which they impair fertility, and their relationship to menstrual and reproductive symptoms. It is reference-educational and non-prescriptive.

Core questions

• What injuries to the endometrium lead to intrauterine adhesions?
• How do adhesions impair implantation and menstruation?
• How is the syndrome distinguished from other uterine-factor causes of infertility?

Key concepts

• Intrauterine adhesions (synechiae)
• Basal endometrial injury
• Postpartum and post-curettage trauma
• Hypomenorrhoea and amenorrhoea
• Cavity obliteration
• Recurrent pregnancy loss
• Endometrial regeneration

Mechanisms

The endometrium regenerates each cycle from its basal layer. When this basal layer is damaged — most often by curettage of a recently pregnant uterus, but also by intrauterine surgery, infection, or other trauma — fibrous adhesions can form that bridge the cavity walls and replace functional endometrium with scar. The resulting loss of responsive endometrium reduces or abolishes menstruation and impairs implantation; extensive adhesions can obliterate the cavity entirely. The comprehensive review by Yu et al. (2008) describes the spectrum of the syndrome, its grading, and the link between the degree of adhesion and reproductive impairment.

Clinical relevance

Asherman syndrome is an acquired uterine-factor cause of infertility and pregnancy loss and is considered in the evaluation of women with menstrual reduction after intrauterine procedures. This entry explains those associations for educational orientation; assessment and management are clinical matters and are not addressed prescriptively here.

Epidemiology

Intrauterine adhesions arise most commonly after curettage of a pregnant or recently pregnant uterus, so the burden relates to the frequency of such procedures; reported prevalence varies widely with the population studied and the diagnostic method. Severity ranges from filmy, focal adhesions to dense obliteration of the cavity, and reproductive outcomes worsen with increasing extent (Yu et al., 2008).

History

Heinrich Fritsch described intrauterine adhesions after curettage in 1894, but it was Joseph Asherman who characterised the syndrome systematically in the late 1940s, distinguishing cervical (atretic) and corporeal forms. The advent of hysteroscopy subsequently transformed both the diagnosis and the description of adhesions, as summarised in the centennial review by Yu and colleagues.

Key figures

• Joseph Asherman

Seminal works

• yu-2008

Frequently asked questions

What usually causes Asherman syndrome?

It most often follows trauma to the basal endometrium, classically curettage of a recently pregnant uterus, which can lead to fibrous adhesions that replace functional endometrium; intrauterine surgery and infection are additional causes.

How does it affect fertility and menstruation?

Loss or scarring of responsive endometrium reduces or abolishes menstruation and impairs implantation, so the syndrome is associated with infertility and recurrent pregnancy loss, with severity tracking the extent of adhesions.