What are the normal parameters of the menstrual cycle and the recommended evaluation and treatment for abnormal uterine bleeding?

Normal Menstrual Cycle and Management of Abnormal Uterine Bleeding

Normal menstrual periods last 3-6 days with blood loss up to 80ml, and menorrhagia is defined as periods lasting more than 7 days and/or blood loss exceeding 80ml 1.

Normal Menstrual Cycle Parameters

A normal menstrual cycle involves:

• Duration: 3-6 days of bleeding
• Blood loss: Up to 80ml total
• Cycle regularity: Predictable intervals in ovulatory cycles

Abnormal uterine bleeding (AUB) affects 11-13% of the general population, increasing to 24% in women aged 36-40 years 1.

Classification System: PALM-COEIN

Use the PALM-COEIN classification to systematically identify the cause of AUB 2. This divides causes into:

Structural Causes (PALM):

• Polyp
• Adenomyosis
• Leiomyoma (submucosal or other)
• Malignancy and hyperplasia

Nonstructural Causes (COEIN):

• Coagulopathy (most commonly von Willebrand disease)
• Ovulatory dysfunction
• Endometrial
• Iatrogenic
• Not yet classified

Evaluation Algorithm

Initial Assessment

Order these tests immediately: pregnancy test (β-hCG), complete blood count with platelets, TSH, and prolactin levels 2. The pregnancy test is non-negotiable regardless of patient history.

Perform speculum examination and Pap smear early to rule out cervical pathology 1.

Age-Specific Endometrial Biopsy Indications

For women >45 years: endometrial biopsy is mandatory 3.

For women ≤45 years: perform endometrial biopsy if:

• Age ≥35 years with recurrent anovulation
• Any age with risk factors for endometrial cancer (obesity, PCOS, diabetes, unopposed estrogen exposure)
• Excessive bleeding unresponsive to medical therapy 4

Endometrial biopsy is preferred over dilation and curettage because it is less invasive, safer, and lower cost 2.

Imaging Strategy

Transvaginal ultrasound is the first-line imaging modality for evaluating AUB 1, 5. Do not order MRI as first-line 1.

If initial ultrasound is inconclusive, proceed to saline infusion sonohysterography, which has 96-100% sensitivity and 94-100% negative predictive value for detecting intracavitary pathology 2, 5.

Reserve hysteroscopy for second-line evaluation when medical treatment fails or when focal lesions need direct visualization and biopsy 2, 5.

Treatment Algorithm

For Ovulatory AUB (Menorrhagia with Regular Cycles)

First-line treatment is the levonorgestrel-releasing intrauterine system (LNG-IUD), which has the highest efficacy among medical treatments 1, 6.

If LNG-IUD is contraindicated or refused, use this hierarchy:

1. Tranexamic acid (FDA-approved for ovulatory bleeding, though expensive) 4, 6
2. Combined oral contraceptives 1, 6
3. Oral progestins for 21 days per month 1, 4
4. NSAIDs (can be combined with hormonal methods) 1, 6

Add iron supplementation for all patients with iron-deficiency anemia 1.

For Anovulatory AUB (Irregular, Heavy Bleeding)

Treat with combined oral contraceptives or progestins to regulate cycles 2. These work by providing the missing progesterone effect and preventing prolonged unopposed estrogen stimulation.

Investigate and treat underlying causes:

• PCOS, diabetes (check hemoglobin A1c)
• Thyroid dysfunction (already checked TSH)
• Hyperprolactinemia (already checked prolactin)
• Medication effects (antipsychotics, antiepileptics) 4

For Acute Heavy Bleeding Requiring Urgent Intervention

Assess hemodynamic stability first 3, 7. If unstable, this is a medical emergency requiring IV access and potential transfusion.

For acute bleeding with hemodynamic stability, use:

• Multidose combined oral contraceptive regimen (3 times daily until bleeding stops, then taper)
• Parenteral estrogen if oral route unavailable
• Multidose progestin-only regimen
• Tranexamic acid 6, 7

Surgical Management

Reserve surgery for: medical treatment failure, contraindications to medical therapy, intolerance, or significant structural lesions 2.

Surgical options in order of invasiveness:

1. Polypectomy or fibroidectomy for discrete lesions
2. Second-generation endometrial ablation (thermal balloon, microwave, radiofrequency) - preferred over first-generation techniques 1
3. Uterine artery embolization for fibroids
4. Hysterectomy (vaginal or laparoscopic route preferred over abdominal) 1

Do not perform first-line hysterectomy for functional bleeding 1. This is a critical pitfall - always attempt medical management or conservative surgical options first unless malignancy is present.

Special Populations

Patients with Coagulopathy

All hormonal methods and tranexamic acid are effective for women with inherited bleeding disorders 6. Screen for von Willebrand disease in adolescents with heavy menstrual bleeding from menarche.

Patients on Anticoagulation

Use progestin-only methods or GnRH agonists rather than combined hormonal contraceptives to avoid additional thrombotic considerations 6.

Critical Pitfalls to Avoid

Do not miss endometrial cancer - the age and risk factor criteria for endometrial biopsy exist because chronic anovulation creates prolonged unopposed estrogen, increasing malignancy risk 4.

Do not use transvaginal ultrasound in virgins - use transabdominal imaging instead, though it is less sensitive 2.

Do not delay referral for hyperplasia with atypia or adenocarcinoma - these require immediate gynecologic oncology consultation 4.

Do not forget that endometrial biopsy can miss focal lesions - if clinical suspicion remains high despite negative biopsy, proceed to hysteroscopy 2.