Differential Diagnosis in Gynaecology

There are a limited number of presenting complaints in gynaecology. Having a list of differential diagnoses in your head when a patient presents with intermenstrual bleeding or pelvic pain can help you take a focused history and perform a relevant examination to narrow down that list of differentials. This will make you appear practiced and knowledgeable in OSCE examinations, and help make it easier when seeing patients in real life. Some causes are responsible for many presenting complaints, and while the lists initially appear intimidating, as you learn about the core conditions in gynaecology, they will become easier to remember.



Amenorrhoea refers to a lack of menstrual periods. The causes of amenorrhoea is a big topic and covered in more detail later on.

Primary amenorrhoea is when the patient has never developed periods. This can be due to:

  • Abnormal functioning of the hypothalamus or pituitary gland (hypogonadotropic hypogonadism)
  • Abnormal functioning of the gonads (hypergonadotropic hypogonadism)
  • Imperforate hymen or other structural pathology

Secondary amenorrhoea is when the patient previously had periods that subsequently stopped. This can be due to:

  • Pregnancy (the most common cause)
  • Menopause
  • Physiological stress due to excessive exercise, low body weight, chronic disease or psychosocial factors
  • Polycystic ovarian syndrome
  • Medications, such as hormonal contraceptives
  • Premature ovarian insufficiency (menopause before 40 years)
  • Thyroid hormone abnormalities (hyper or hypothyroid)
  • Excessive prolactin, from a prolactinoma
  • Cushing’s syndrome


Irregular Menstruation

Abnormal uterine bleeding refers to irregularities in the menstrual cycle, affecting frequency, duration, regularity of the cycle length and the volume of menses. Irregular menstrual periods indicate anovulation (a lack of ovulation) or irregular ovulation. This occurs due to disruption of the normal hormonal levels in the menstrual cycle, or ovarian pathology. It can be due to:

  • Extremes of reproductive age (early periods or perimenopause)
  • Polycystic ovarian syndrome
  • Physiological stress (excessive exercise, low body weight, chronic disease and psychosocial factors)
  • Medications, particularly progesterone only contraception, antidepressants and antipsychotics
  • Hormonal imbalances, such as thyroid abnormalities, Cushing’s syndrome and high prolactin


Intermenstrual Bleeding

Intermenstrual bleeding (IMB) refers to any bleeding that occurs between menstrual periods. This is a red flag that should make you consider cervical and other cancers, although other causes are more common.

The key causes of intermenstrual bleeding are:

  • Hormonal contraception
  • Cervical ectropion, polyps or cancer
  • Sexually transmitted infection
  • Endometrial polyps or cancer
  • Vaginal pathology, including cancers
  • Pregnancy
  • Ovulation can cause spotting in some women
  • Medications, such as SSRIs and anticoagulants



Dysmenorrhoea describes painful periods. The causes are:

  • Primary dysmenorrhoea (no underlying pathology)
  • Endometriosis or adenomyosis
  • Fibroids
  • Pelvic inflammatory disease
  • Copper coil
  • Cervical or ovarian cancer



Menorrhagia refers to heavy menstrual bleeding. This can be caused by:

  • Dysfunctional uterine bleeding (no identifiable cause)
  • Extremes of reproductive age
  • Fibroids
  • Endometriosis and adenomyosis
  • Pelvic inflammatory disease (infection)
  • Contraceptives, particularly the copper coil
  • Anticoagulant medications
  • Bleeding disorders (e.g. Von Willebrand disease)
  • Endocrine disorders (diabetes and hypothyroidism)
  • Connective tissue disorders
  • Endometrial hyperplasia or cance
  • Polycystic ovarian syndrome


Postcoital Bleeding

Postcoital bleeding (PCB) refers to bleeding after sexual intercourse. This is a red flag that should make you consider cervical and other cancers, although other causes are more common. Often no cause is found. The key causes are:

  • Cervical cancer, ectropion or infection
  • Trauma
  • Atrophic vaginitis
  • Polyps
  • Endometrial cancer
  • Vaginal cancer


Pelvic Pain

Pelvic pain can be acute or chronic. The presentation of pelvic pain varies significantly. A detailed history and examination are usually able to identify the cause. There are a large number of possible causes, including:

  • Urinary tract infection
  • Dysmenorrhoea (painful periods)
  • Irritable bowel syndrome (IBS)
  • Ovarian cysts
  • Endometriosis
  • Pelvic inflammatory disease (infection)
  • Ectopic pregnancy
  • Appendicitis
  • Mittelschmerz (cyclical pain during ovulation)
  • Pelvic adhesions
  • Ovarian torsion
  • Inflammatory bowel disease (IBD)


Vaginal Discharge

Vaginal discharge is a normal physiological finding. Excessive, discoloured or foul-smelling discharge may indicate:

  • Bacterial vaginosis
  • Candidiasis (thrush)
  • Chlamydia
  • Gonorrhoea
  • Trichomonas vaginalis
  • Foreign body
  • Cervical ectropion
  • Polyps
  • Malignancy
  • Pregnancy
  • Ovulation (cyclical)
  • Hormonal contraception


Pruritus Vulvae

Pruritus vulvae refers to itching of the vulva and vagina. There are a large number of causes:

  • Irritants such as soaps, detergents and barrier contraception
  • Atrophic vaginitis
  • Infections such as candidiasis (thrush) and pubic lice
  • Skin conditions such as eczema
  • Vulval malignancy
  • Pregnancy-related vaginal discharge
  • Urinary or faecal incontinence
  • Stress


Last updated June 2020
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