Abortion surgery may damage the endometrium, leading to thin endometrium, intrauterine adhesions (IUA), reduced menstrual flow, or even amenorrhea. In severe cases, it can result in decreased fertility. To better promote endometrial repair after abortion surgery, standardize clinical practice, strengthen awareness of endometrial protection, guide the selection of methods for promoting endometrial repair, and ultimately benefit patients, the following summary of common clinical issues is based on the guidelines.
Clinical Question 1
What are the clinical manifestations of endometrial injury after abortion surgery?
Clinical manifestations include absence of menstrual resumption, dysmenorrhea, reduced menstrual flow, or even amenorrhea after abortion surgery. In severe cases, long-term decreased fertility may occur, such as infertility, miscarriage, ectopic pregnancy, etc.
The cause is that abortion surgery may cause mechanical damage to the endometrial basal layer and trigger intrauterine inflammation or infection, which affects endometrial repair. Failure to effectively repair the injury can lead to thin endometrium or IUA.
Clinical Question 2
What pathophysiological mechanisms are involved in endometrial injury-repair after abortion surgery?
The injury-repair process involves multiple pathophysiological mechanisms, including the acute injury phase, inflammatory response phase, and tissue repair and regeneration phase. These processes are interconnected and jointly determine the quality and speed of endometrial repair.
- Acute injury phase: Direct stripping or cutting of the endometrium during surgery causes mechanical trauma. Meanwhile, local microvessels rupture with endometrial exfoliation, leading to bleeding. This phase may last for several days.
- Inflammatory response phase: After acute injury, the immune system responds rapidly at the injured site. White blood cells (mainly neutrophils and macrophages) enter the damaged area to clear necrotic tissue debris and release various inflammatory mediators to promote local inflammation and initiate the subsequent healing process. A temporary fibrin network is formed at the injured site to assist hemostasis and provide a scaffold for subsequent repair.
- Tissue repair and regeneration phase: As inflammation gradually subsides, fibroblasts become active and proliferate, producing collagen and other matrix components to facilitate tissue repair and regeneration. Estrogen and progesterone can stimulate the proliferation of endometrial epithelial cells, enhance vascular permeability, and improve blood supply. This phase is prone to adhesion formation and is a critical period for preventing IUA; appropriate supplementation of estrogen and progesterone can accelerate the repair process.
- Abnormal endometrial repair: If the scope and degree of endometrial injury are extensive and severe, excessive fibrosis (i.e., excessive formation of scar tissue) and a large number of adhesions may occur during the repair process. This can result in reduced menstrual flow or even amenorrhea, interfere with reproductive function, and increase the risk of infertility. Multiple abortion surgeries can exacerbate the above problems.
Clinical Question 3
How to diagnose and evaluate endometrial injury after abortion surgery?
Detailed medical history and menstrual history should be collected, and physical examinations should be performed and recorded. This includes the number of abortions, abortion surgery information, postoperative symptoms, time of postoperative menstrual resumption, menstrual cycle, menstrual flow, dysmenorrhea, etc.
Ultrasonography is non-invasive and reproducible. Two-dimensional transvaginal ultrasonography can measure endometrial thickness, morphology, and subendometrial blood perfusion, and identify intrauterine effusion, abnormal intrauterine lesions, and IUA, enabling multimodal assessment of endometrial receptivity. Three-dimensional transvaginal ultrasonography can provide three-dimensional imaging and measure endometrial volume, making it an important method for evaluating endometrial receptivity.
When ultrasonography suggests intrauterine abnormalities, hysteroscopy can be performed, and therapeutic procedures can be conducted simultaneously. If endometrial biopsy is performed, pathological changes can be clarified.
Magnetic resonance imaging (MRI) can assess the upper uterine cavity in cases of cervical adhesions layer by layer, but it is rarely used for the diagnosis of IUA due to its time-consuming and costly nature. Biomarkers in blood or intrauterine lavage fluid, such as growth factors and cytokines, require further exploration as evaluation methods.
Currently, there are no clear diagnostic and evaluation criteria for endometrial injury after abortion surgery. Clinical diagnosis should comprehensively consider clinical manifestations, combined with ultrasonography, and hysteroscopy if necessary.
Clinical Question 4
What is the goal of endometrial injury repair after abortion surgery?
The main goal is to promote the recovery of the anatomical structure of the uterine cavity and the organizational structure of the endometrium (ideally, the endometrial thickness on the ovulation day is ≥8mm), enabling the endometrium to provide a suitable implantation environment for fertilized eggs and protecting reproductive function.
Clinical Question 5
What are the high-risk factors for abnormal endometrial repair after abortion surgery?
Abortion surgery carries the risk of endometrial basal layer injury. Age (young age, advanced age), previous multiple abortion history, intrauterine surgery (procedure) history, endocrine abnormalities, and pathological abortion are high-risk factors affecting endometrial repair after abortion surgery.
Young women have immature reproductive organs and hypothalamic-pituitary-ovarian axis neuroendocrine mechanisms; women with advanced pregnancy have decreased estrogen levels in the body.
Previous multiple abortion history and intrauterine surgery (procedure) history, such as a history of placental adhesion stripping or curettage, endometrial polyp resection, submucosal uterine fibroid resection, or IUA lysis surgery, can lead to repeated endometrial damage, increasing the risk of thin endometrium and IUA.
Patients with endocrine abnormalities (such as polycystic ovary syndrome) have abnormal estrogen levels, which may affect endometrial repair.
In pathological abortion, the prolonged retention of gestational products and degenerated tissues in the uterine cavity and prolonged bleeding time can trigger a severe inflammatory response of the endometrium, aggravating endometrial damage and easily leading to thin endometrium and IUA.
Clinical Question 6
What preoperative preparations for abortion surgery help reduce intraoperative endometrial injury?
- Medical history inquiry and preoperative examination: Understand the patient's menstrual history and reproductive history; conduct gynecological examinations to assess cervical conditions and uterine position; perform vaginal discharge examinations to rule out genital tract inflammation, and blood inflammation index examinations if necessary. Identify high-risk groups for endometrial injury.
- Preoperative ultrasonography: Confirm the pregnancy location, assess the gestational age, and check for abnormalities. Select an appropriate abortion method to help reduce risks.
- Cervical preparation: Adequate cervical preparation can reduce complications. Preoperatively, medications and/or mechanical methods are used to increase the elasticity of cervical fibrous connective tissue, facilitating dilation and intrauterine manipulation and reducing injury.
- Prophylactic use of antibiotics: Prevent or control infection at the surgical site, create favorable conditions for endometrial regeneration after trauma, and promote endometrial repair. Abortion surgery is classified as a type Ⅱ incision (clean-contaminated surgery). Prophylactic antibiotics should target potential contaminating bacteria in the surgical path, avoiding unnecessary combination use. The effective coverage time of antibiotics should include the entire surgical process, and the medication duration should not exceed 24 hours.
Clinical Question 7
What intraoperative operations and measures for abortion surgery help reduce endometrial injury?
In vacuum aspiration, reasonable control of negative pressure, reduction in the number of uterine cavity entries and exits, and shortening of operation time help reduce damage to the endometrial basal layer.
Intraoperative ultrasonic monitoring can real-time observe intrauterine conditions, assist in locating gestational tissue, avoid blind manipulation, reduce missed aspiration and incomplete aspiration, and lower the risk of surgical injury to the endometrium.
Clinical Question 8
What postoperative interventions for abortion surgery help promote endometrial repair?
Currently, clinical practice mostly adopts medications, barrier materials, physical therapy, etc., to promote endometrial repair.
(I) Medications
- Estrogen alone: Estrogen can promote endometrial growth and regeneration.(1) Estradiol gel: Start on the first day after surgery, apply transdermally at a low dose [2.5g (i.e., 1 measuring scale), twice a day], with 1 month of continuous medication as one cycle; 1 cycle is recommended. A multicenter RCT showed that local application of estradiol gel after surgery can improve endometrial thickness and shorten the time to menstrual recovery. The transdermal estradiol gel formulation is absorbed through the skin without first-pass elimination, resulting in a lower risk of thrombosis.(2) Estradiol valerate tablets: Start on the first day after surgery, take orally (1mg, twice a day), and discontinue after 1 month of continuous use.
- Estrogen-progesterone sequential therapy: Timely use of estrogen-progesterone sequential artificial cycle therapy after surgery can promote endometrial repair and menstrual recovery.(1) Transdermal estrogen combined with progesterone: Start on the first day after surgery, apply transdermal estradiol gel 2.5g (1 measuring scale) twice a day for 28 consecutive days; add oral progesterone (dydrogesterone 10mg or progesterone 100mg) twice a day from day 15 to 28. If 2-3 cycles are needed, the next cycle can start on the 5th day of menstrual 来潮.(2) Oral estrogen combined with progesterone: Start on the first day after surgery, use low-dose estrogen, and add progesterone in the second half of the cycle; 1-3 cycles are recommended. Common preparations include: estradiol valerate tablets combined with dydrogesterone or progesterone tablets, estradiol tablets/estradiol dydrogesterone tablets composite packaging, estradiol valerate tablets/estradiol cyproterone acetate tablets composite packaging. Studies have shown that compared with not using hormonal drugs, sequential therapy with estradiol valerate combined with progesterone for 3 consecutive cycles has the effect of preventing IUA and promoting postoperative menstrual recovery.
- Combined oral contraceptives (COC): COC is often used for contraception after abortion to prevent unintended pregnancy and repeated abortion. Immediate application of COC after abortion can reduce intrauterine bleeding; long-term use can inhibit endometrial hyperplasia, and fertility can be quickly restored after discontinuation. The effect of COC on endometrial repair requires further research.
- Traditional Chinese medicine (TCM) preparations: TCM believes that abortion surgery can damage the Chong and Ren meridians, cause blood stasis in the uterine vessels, consume kidney qi, and affect the transformation of essence and blood.
For TCM conditioning after abortion surgery, comprehensive syndrome differentiation should be considered based on individual differences, the time and method of termination of pregnancy, and the amount of bleeding during abortion surgery. Generally, nourish blood on the basis of removing blood stasis to balance qi, blood, yin, and yang. Commonly used Chinese patent medicines include Motherwort Granules, Shenghua Granules, and Paridis Rhizoma.
(II) Barrier Materials
Barrier materials physically isolate the surface of damaged tissue to avoid abnormal adhesion with surrounding tissues during the critical healing period, thereby preventing postoperative IUA. Existing barrier materials, such as intrauterine devices (IUDs) and intrauterine balloon stents, are mostly inert materials that only provide physical isolation and lack evidence of promoting endometrial repair.
Sodium hyaluronate is a natural high-molecular-weight glycosaminoglycan that can promote mucosal regeneration and repair, with good biocompatibility and safe degradation and absorption. However, it has low viscosity, high fluidity, rapid degradation, and a short retention time in the uterine cavity.
Self-crosslinking sodium hyaluronate gel improves the balance between viscosity and fluidity, can effectively cover and isolate damaged tissue, stably remain in the uterine cavity, and continuously provide a suitable environment for the regeneration and repair of damaged endometrium. It can both prevent IUA and promote endometrial repair after abortion surgery. It does not contain bio-toxic substances, nor does it cause cytotoxicity or sensitization reactions, and will not trigger local inflammatory responses.
Multiple RCTs have shown that the use of self-crosslinking sodium hyaluronate gel can reduce the formation of IUA after abortion surgery, reduce the severity of IUA, improve the pregnancy rate of in vitro fertilization (IVF) in patients with moderate to severe IUA, increase postoperative endometrial thickness, and improve reduced postoperative menstrual flow.
(III) Physical Therapy
Low-intensity focused ultrasound (LIFU) can promote local uterine blood circulation, enhance cell activity, and stimulate the formation of new blood vessels through mechanical effects, thermal effects, and cavitation effects, thereby promoting endometrial repair.
Pelvic floor neuromuscular electrical stimulation (NMES) may help patients after abortion surgery reduce pain, shorten bleeding time, and contribute to the recovery of the menstrual cycle by improving local blood circulation. Combined with estrogen, it can increase endometrial thickness. An RCT showed that NMES can enhance the efficacy of intrauterine injection of sodium hyaluronate in increasing endometrial thickness and reducing IUA.
Acupuncture can increase the expression of pinopodes, increase the thickness of thin endometrium, improve morphology-related indicators such as endometrial type A rate, and reduce microcirculation indicators such as subendometrial blood flow pulsatility index and resistance index.
Physical therapy may help promote endometrial repair after abortion surgery by promoting local blood circulation and enhancing cell activity, but its specific efficacy requires further verification through more clinical studies.
(IV) Emerging Technologies
Platelet-rich plasma (PRP), stem cell therapy, and aspirin have all been used in related mechanism studies on promoting endometrial regeneration and repair, and may serve as auxiliary means to improve the effect of endometrial repair after abortion surgery in the future.
Clinical Question 9
How to set the follow-up strategy after abortion surgery?
- Postoperative observation: Immediately after surgery, observe the patient's vaginal bleeding and general condition. For patients not monitored by intraoperative ultrasonography, immediate postoperative ultrasonography helps reduce the incidence of residual gestational products. Initiate measures to promote endometrial repair.
- Regular re-examination and monitoring: The first re-examination can be performed 2 weeks to 1 month after surgery, and the follow-up frequency can be adjusted according to specific conditions. During follow-up, it is necessary to collect medical history (whether there is abnormal bleeding, pain, or other symptoms, menstrual recovery, etc.), perform necessary physical and gynecological examinations, blood tests (blood routine, serum hCG, etc.), and gynecological ultrasonography (including examinations for intrauterine residue and endometrial thickness), as well as other necessary medical examinations. Clinically, the results of the above follow-up should be comprehensively used to evaluate the status of endometrial repair, detect abnormalities in a timely manner, and intervene.
- Contraceptive guidance and education: Emphasize the importance of effective contraception during each follow-up, and provide patients with appropriate contraceptive options to prevent repeated abortion. For women who do not plan to have children in the short term, long-acting and effective contraceptive methods are recommended.