What are the common causes of intermenstrual spotting?

Why Does Spotting Between Periods Occur?

Intermenstrual spotting (bleeding between periods) occurs due to either hormonal contraceptive use—which is the most common benign cause—or underlying gynecological pathology that requires evaluation.

Common Causes of Intermenstrual Spotting

Hormonal Contraceptive-Related Causes

Hormonal contraceptives are the leading cause of intermenstrual spotting in women of reproductive age. This includes:

• Combined hormonal contraceptives (pills, patches, rings): Unscheduled spotting is common during the first 3-6 months of use, particularly with extended or continuous regimens 1
• Progestin-only methods:
  • DMPA injections: Unscheduled spotting or light bleeding is very common 1
  • Contraceptive implants: Unscheduled spotting occurs in approximately 34% of users 1
  • Progestin-only pills: Irregular bleeding patterns are expected 1
• Copper IUDs: Intermenstrual spotting is a recognized side effect 2

This bleeding is generally not harmful and often decreases with continued use 1.

Pathological Causes Requiring Evaluation

When spotting occurs without hormonal contraceptive use or persists despite counseling, consider these underlying conditions:

Structural Causes (PALM)

• Polyps: Endometrial polyps commonly cause intermenstrual bleeding 3, 4, 5
• Adenomyosis: Can produce irregular bleeding patterns 6, 3
• Leiomyomas (fibroids): Particularly submucous fibroids cause intermenstrual bleeding 6, 3, 4
• Malignancy/Hyperplasia: Endometrial cancer or hyperplasia, especially in perimenopausal/postmenopausal women 6, 7, 8

Non-Structural Causes (COEIN)

• Coagulopathy: Von Willebrand disease and other bleeding disorders 8
• Ovulatory dysfunction: Polycystic ovary syndrome, thyroid disease, hyperprolactinemia 7, 3, 4
• Endometrial disorders: Primary endometrial hemostatic defects 6, 4
• Iatrogenic: Medications (anticoagulants, phenytoin, digitalis) 8
• Infections: STDs, endometritis, cervicitis 1, 8

Other Causes

• Cervical pathology: Polyps, erosion, cervicitis 8
• Pregnancy complications: Ectopic pregnancy, threatened abortion, trophoblastic disease 8
• Trauma: Vaginal lacerations, foreign bodies 8

Clinical Approach Algorithm

Step 1: Determine Contraceptive Use

• If using hormonal contraceptives: Reassure that spotting is common and generally not harmful, especially in first 3-6 months 1
• If not using contraceptives or bleeding persists: Proceed to evaluation

Step 2: Rule Out Serious Causes

• Pregnancy test: Always exclude pregnancy complications first 8
• Age consideration: In perimenopausal/postmenopausal women, assume malignancy until proven otherwise 8
• Adolescents with heavy bleeding: Screen for coagulopathy 8

Step 3: Evaluate for Underlying Pathology

When clinically indicated, assess for 1:

• Drug interactions (especially enzyme-inducing medications)
• STD screening
• New uterine pathology (polyps, fibroids)
• Systemic disease (thyroid dysfunction, coagulopathy, liver disease)
• Inconsistent contraceptive use (if applicable)
• Cigarette smoking (affects contraceptive efficacy)

Step 4: Imaging and Diagnostic Testing

• Transvaginal ultrasound: First-line imaging for structural abnormalities 6, 3
• Saline infusion sonohysterography: More accurate for endometrial polyps and submucous fibroids 6, 5
• Hysteroscopy with biopsy: Gold standard for definitive diagnosis 5
• Endometrial sampling: Required for women with risk factors for endometrial cancer 6
• Laboratory tests: TSH, prolactin, coagulation studies as indicated 7, 8

Management Based on Cause

For Contraceptive-Related Spotting

If no pathology found and patient desires treatment 1:

• NSAIDs: 5-7 days during bleeding episodes (mefenamic acid 500mg three times daily or celecoxib 200mg daily)
• Hormonal treatment (if medically eligible): Low-dose combined oral contraceptives or estrogen for 10-20 days
• For extended/continuous CHC users: Consider 3-4 day hormone-free interval (not during first 21 days, not more than once monthly) 1

For Pathological Causes

Treat or refer based on specific diagnosis identified 1.

Critical Pitfalls to Avoid

1. Never assume spotting is benign without excluding pregnancy in reproductive-age women 8
2. Do not perform digital pelvic examination before excluding placenta previa in pregnant women with bleeding 9
3. Always consider malignancy in perimenopausal/postmenopausal women with new-onset intermenstrual bleeding 8
4. Screen adolescents with menorrhagia for coagulopathy—von Willebrand disease is more common than recognized 8
5. Avoid high-dose aspirin in women with baseline heavy bleeding as it increases blood loss 2
6. Counsel patients before contraceptive initiation about expected bleeding patterns to reduce discontinuation 1