2025 Strategies for resolving uterine fluid during pregnancy in surrogate mothers

I. Causes and pathologic mechanisms of uterine fluid during pregnancy in surrogate mothers

Fluid in the uterine cavity during pregnancy of surrogate mothers is a common clinical phenomenon in early pregnancy, the essence of which is the rupture of blood vessels at the edge of the placenta, resulting in blood accumulation between the chorionic villus and the meconium, forming a local hematoma. The following are the key causes:

Increased vascular fragility: Assisted reproductive technologies (e.g., IVF) may result in endometrial microvascular injury due to hormonal fluctuations or embryo transfer manipulation.
Immunologic and coagulation abnormalities: Antiphospholipid antibody syndrome, prothrombotic states, or prolonged anticoagulant therapy (e.g., low molecular heparin) may exacerbate the risk of bleeding.
Anatomic structural abnormalities: uterine malformations (e.g., longitudinal uterine septum) or a history of previous surgical procedures for uterine adhesions may interfere with normal placental attachment.
Infection and inflammation: pelvic infections (e.g., chronic endometritis) may trigger local microenvironmental imbalance, leading to increased vascular permeability.

II. Assessment of the impact of uterine fluid on pregnancy outcome in surrogate mothers during pregnancy

1. Quantitative relationship between hematoma volume and pregnancy risk

Volume threshold: if hematoma volume accounts for ≥25% of the volume of the gestational sac, the risk of spontaneous abortion is significantly elevated (OR=3.2, 95% CI 1.5-6.8).
Positional correlation: hematomas close to the placental margin or endocervical os were associated with a 2.4-fold higher rate of preterm labor than other positions .

2. Duration of hematoma and clinical regression

Absorption rate: Approximately 70% of early pregnancy hematomas are spontaneously absorbed by 12 weeks of gestation7.
Risk of persistence: If the hematoma persists into the second trimester, the risk of placental abruption is increased by 18% and requires close monitoring.

3. Early warning significance of associated symptoms

Vaginal bleeding: the rate of preterm labor is 26.6% in those with combined bleeding, which is significantly higher than in those without symptoms (7.0%).
Increased abdominal pain: may indicate hematoma enlargement or contraction initiation, requiring urgent intervention.

III. Clinical management strategies of uterine fluid in surrogate mothers

1. Prospective treatment: core principle of observation and monitoring

Applicable conditions: hematoma volume <2 cm, no active bleeding, normal embryonic development.
Monitoring program:
Ultrasound frequency: once a week to assess changes in hematoma volume and fetal heartbeat7.
Laboratory tests: regular testing of β-hCG, progesterone and coagulation function (e.g. D-dimer).

2. Medication: balancing hemostasis and fetal preservation

(1) Progesterone support

Progesterone: intramuscular or vaginal administration (200-400 mg/day) stabilizes endometrial tolerance57.
Deferiprone: 10 mg/dose orally twice daily for luteal insufficiency.

(2) Adjustment of anticoagulation therapy

Low molecular heparin tapering: if hematoma continues to enlarge, it is recommended that the dose be halved or suspended in favor of sodium sulfadiazepoxide (lower risk of bleeding).
Discontinuation of aspirin: stop immediately if bleeding > menstrual flow or hematoma size increases significantly.

(3) Immunomodulation and anti-inflammation

Intravenous immunoglobulin (IVIG): for antiphospholipid antibody-positive patients, with a dose of 0.4 g/kg/day × 5 days, which reduces the level of inflammatory factors.

3. Surgical treatment: strictly limited indications

Clearance: only for refractory cases with co-infection (e.g., pus in the uterine cavity) or residual pregnancy material >2.5 cm in diameter47.
Cervical cerclage: can be performed at 14-16 weeks of gestation if the hematoma is combined with cervical insufficiency.

IV. Daily management suggestions for surrogate mothers

1. Scientific balance between activity and rest

Necessity of bed rest: absolute bed rest (head-down-hip-up position) is needed during acute bleeding to reduce pelvic pressure.
Gradual resumption of activities: after bleeding stops, low-intensity activities (e.g. short-distance walking) can be performed, avoiding sedentary activities or lifting heavy objects.

2. Nutritional and metabolic support

Key nutrients:
Vitamin C and bioflavonoids: enhance blood vessel elasticity, recommend citrus fruits and dark green vegetables.
Omega-3 fatty acids: inhibit the inflammatory response, supplement with 1-2 g of fish oil daily8.
Dietary contraindications: Avoid spicy foods, alcohol, and high-sugar beverages to prevent vasodilation and exacerbation of bleeding.

3. Psychological intervention and stress management

Cognitive Behavioral Therapy (CBT): Reduce cortisol levels and improve uterine blood flow by reframing negative thinking.
Positive thinking meditation: practiced for 10-15 minutes daily, it reduces the frequency of anxiety-related contractions.

V. International Frontier Advances and Future Directions

1. Clinical application of molecular markers

Integrin αVβ: serum levels <5 ng/mL suggest low endothelial tolerance and require intensive progesterone therapy.
MicroRNA-21: as a predictive marker for hematoma resorption, elevated expression indicates a favorable prognosis.

2. Emerging explorations in targeted therapies

Antiangiogenic drugs: local infusion of bevacizumab can reduce vascular leakage, but fetal safety needs to be weighed.
Stem cell therapy: mesenchymal stem cell transplantation promotes endothelial repair and is currently in clinical trials.

VI.Conclusion: individualized strategy to improve pregnancy success rate

Management of uterine fluid during pregnancy in surrogate mothers requires comprehensive consideration of hematoma characteristics, embryonic status, and underlying maternal disease. With precise expectant treatment, medication adjustment and lifestyle optimization, most patients can achieve good pregnancy outcomes. In the future, with breakthroughs in molecular diagnosis and targeted therapy, surrogate mothers will have access to more efficient and safe fertility preservation options.