Management of Abnormal Uterine Bleeding in Pregnancy
Abnormal uterine bleeding (AUB) in a pregnant patient is not managed using standard AUB protocols—pregnancy must first be confirmed or excluded, as bleeding in pregnancy represents a distinct clinical entity requiring pregnancy-specific evaluation and management rather than the PALM-COEIN framework used for non-pregnant patients.
Critical First Step: Pregnancy Status Determination
- Mandatory pregnancy testing (β-hCG) must be performed immediately in all reproductive-age women presenting with uterine bleeding before any AUB evaluation or treatment is initiated 1, 2, 3, 4.
- This is the single most important step, as the presence of pregnancy completely changes the diagnostic and therapeutic approach 2, 3.
Understanding the Distinction
The provided evidence addresses AUB management exclusively in non-pregnant patients. The PALM-COEIN classification system (Polyp, Adenomyosis, Leiomyoma, Malignancy/hyperplasia, Coagulopathy, Ovulatory dysfunction, Endometrial, Iatrogenic, Not classified) is specifically designed for categorizing bleeding causes in non-pregnant women 2, 3, 5.
If Pregnancy is Confirmed: Different Management Pathway
When pregnancy is confirmed, bleeding requires evaluation for:
- Threatened abortion, inevitable abortion, or ectopic pregnancy (first trimester)
- Placental complications including placenta previa, placental abruption, or vasa previa (second/third trimester)
- Gestational trophoblastic disease
- Cervical causes unrelated to pregnancy
The only pregnancy-related guidance in the provided evidence addresses antiphospholipid syndrome (APS) in pregnancy, where combined low-dose aspirin and prophylactic-dose heparin (usually LMWH) is strongly recommended for patients meeting criteria for obstetric APS to improve pregnancy outcomes 6.
If Pregnancy is Excluded: Standard AUB Management
Once pregnancy is definitively ruled out, proceed with standard AUB evaluation:
Diagnostic Workup
- Complete blood count with platelets to assess for anemia and thrombocytopenia 3.
- Thyroid-stimulating hormone and prolactin levels to exclude thyroid dysfunction and hyperprolactinemia 1, 3.
- Combined transabdominal and transvaginal ultrasound with Doppler as first-line imaging 2, 3.
Medical Management (Non-Pregnant)
- Levonorgestrel-releasing intrauterine device (LNG-IUD) is the most effective first-line treatment, reducing menstrual blood loss by 71-95% 2, 3, 4.
- Combined hormonal contraceptives for ovulatory dysfunction bleeding 2, 3.
- Tranexamic acid for heavy menstrual bleeding, though contraindicated in cardiovascular disease due to thrombosis risk 2, 3.
Critical Pitfall to Avoid
Never initiate standard AUB medical treatments (hormonal contraceptives, tranexamic acid, NSAIDs, or LNG-IUD) without first excluding pregnancy, as these interventions are inappropriate and potentially harmful in pregnancy 1, 2, 3. The question asks about "AUB in a pregnant patient," which is a clinical contradiction—if the patient is pregnant, the bleeding is not classified or managed as AUB but rather as pregnancy-related bleeding requiring obstetric evaluation.