Abnormal uterine bleeding (formerly, dysfunctional uterine bleeding [DUB][1] ) is irregular uterine bleeding that occurs in the absence of recognizable pelvic pathology, general medical disease, or pregnancy. It reflects a disruption in the normal cyclic pattern of ovulatory hormonal stimulation to the endometrial lining. The bleeding is unpredictable in many ways. It may be excessively heavy or light and may be prolonged, frequent, or random.[16]
About 1-2% of women with improperly managed anovulatory bleeding eventually may develop endometrial cancer.
AUB should be suspected in patients with unpredictable or episodic heavy or light bleeding despite a normal pelvic examination. Typically, the usual moliminal symptoms that accompany ovulatory cycles will not precede bleeding episodes.
Pathologic causes of anovulatory bleeding
Because AUB is considered a diagnosis of exclusion, the presence or absence of signs and symptoms of other causes of anovulatory bleeding must be determined.
Patients who report irregular menses since menarche may have polycystic ovarian syndrome (PCOS). PCOS is characterized by anovulation or oligo-ovulation and hyperandrogenism. These patients often present with unpredictable cycles and/or infertility, hirsutism with or without hyperinsulinemia, and obesity.
Other signs of underlying pathology include the following:
See Clinical Presentation for more detail.
Laboratory studies
Studies used to exclude a pathologic source of anovulatory bleeding include the following:
Imaging studies
In obese patients with a suboptimal pelvic examination or in patients with suspected ovarian or uterine pathology, pelvic ultrasonographic evaluation may be helpful. Ultrasonography can be used to identify uterine fibroids, as well as endometrial conditions, including hyperplasia, carcinoma, and polyps.
Procedures
Rule out endometrial carcinoma in all patients at high risk for the condition, including those with the following characteristics:
Traditionally, carcinoma was ruled out by endometrial sampling via dilation and curettage (D&C). However, endometrial sampling in the office via aspiration, curetting, or hysteroscopy has become popular and is also relatively accurate.
Histology
Most endometrial biopsy specimens will show proliferative or dyssynchronous endometrium.
See Workup for more detail.
Pharmacologic treatment
Hysterectomy
Abdominal or vaginal hysterectomy may be necessary in patients who have failed or declined hormonal therapy, who have symptomatic anemia, and who are experiencing a disruption in their quality of life from persistent, unscheduled bleeding.
Endometrial ablation
Endometrial ablation is an alternative for patients who wish to avoid hysterectomy or who are not candidates for major surgery.
See Treatment and Medication for more detail.
Abnormal uterine bleeding (AUB) is irregular uterine bleeding that occurs in the absence of pathology or medical illness. It reflects a disruption in the normal cyclic pattern of ovulatory hormonal stimulation to the endometrial lining. The bleeding is unpredictable in many ways. It might be excessively heavy or light, prolonged, frequent, or random.
This condition usually is associated with anovulatory menstrual cycles but also can present in patients with oligo-ovulation. AUB occurs without recognizable pelvic pathology, general medical disease, or pregnancy. It is considered a diagnosis of exclusion.
AUB is a common diagnosis, making up 5-10% of cases in the outpatient clinic setting.
Patients with abnormal uterine bleeding (AUB) have lost cyclic endometrial stimulation that arises from the ovulatory cycle. As a result, these patients have constant, noncycling estrogen levels that stimulate endometrial growth. Proliferation without periodic shedding causes the endometrium to outgrow its blood supply. The tissue breaks down and sloughs from the uterus. Subsequent healing of the endometrium is irregular and dyssynchronous.
Chronic stimulation by low levels of estrogen will result in infrequent, light AUB. Chronic stimulation from higher levels of estrogen will lead to episodes of frequent, heavy bleeding.
In ovulatory cycles, progesterone production from the corpus luteum converts estrogen primed proliferative endometrium to secretory endometrium, which sloughs predictably in a cyclic fashion if pregnancy does not occur. Heavy but regular uterine bleeding implies ovulatory bleeding and should not be diagnosed as abnormal uterine bleeding (AUB). Subtle disturbances in endometrial tissue mechanisms, other forms of uterine pathology, or systemic causes might be implicated.
Anovulatory cycles are associated with a variety of bleeding manifestations. Estrogen withdrawal bleeding and estrogen breakthrough bleeding are the most common spontaneous patterns encountered in clinical practice. Iatrogenically induced anovulatory uterine bleeding might occur during treatment with oral contraceptives, progestin-only preparations, or postmenopausal steroid replacement therapy.
Anovulatory cycles have no corpus luteal formation. Progesterone is not produced. The endometrium continues to proliferate under the influence of unopposed estrogen.
Eventually, this out-of-phase endometrium is shed in an irregular manner that might be prolonged and heavy. This pattern is known as estrogen breakthrough bleeding and occurs in the absence of estrogen decline.
This frequently occurs in women approaching the end of reproductive life. In older women, the mean length of menstrual cycle is shortened significantly due to aberrant follicular recruitment, resulting in a shortened proliferative phase. Ovarian follicles in these women secrete less estradiol. Fluctuating estradiol levels might lead to insufficient endometrial proliferation with irregular menstrual shedding. This bleeding might be experienced as light, irregular spotting.
Eventually, the duration of the luteal phase shortens, and, finally, ovulation stops. Dyssynchronous endometrial histology with irregular menstrual shedding and eventual amenorrhea result.
Treatment with oral contraceptives, progestin-only preparations, or postmenopausal steroid replacement therapy might be associated with iatrogenically induced uterine bleeding.
Progesterone breakthrough bleeding occurs in the presence of an unfavorably high ratio of progestin to estrogen.
Intermittent bleeding of variable duration can occur with progestin-only oral contraceptives, depo-medroxyprogesterone, and depo-levonorgestrel.
rogesterone withdrawal bleeding can occur if the endometrium initially has been primed with endogenous or exogenous estrogen, exposed to progestin, and then withdrawn from progestin. Such a pattern is seen in cyclic hormonal replacement therapy.
The primary defect in the anovulatory bleeding of adolescents is failure to mount an ovulatory luteinizing hormone (LH) surge in response to rising estradiol levels. Failure occurs secondary to delayed maturation of the hypothalamic-pituitary axis. Because a corpus luteum is not formed, progesterone levels remain low.
The existing estrogen primed endometrium does not become secretory. Instead, the endometrium continues to proliferate under the influence of unopposed estrogen. Eventually, this out-of-phase endometrium is shed in an irregular manner that might be prolonged and heavy, such as that seen in estrogen breakthrough bleeding.
Anovulatory bleeding in menopausal transition is related to declining ovarian follicular function.
Estradiol levels will vary with the quality and state of follicular recruitment and growth. Bleeding might be light or heavy depending on the individual cycle response.
An international expert panel including obstetrician/gynecologists and hematologists has issued guidelines to assist physicians in better recognizing bleeding disorders, such as von Willebrand disease, as a cause of menorrhagia and postpartum hemorrhage and to provide disease-specific therapy for the bleeding disorder.[2, 17] Historically, a lack of awareness of underlying bleeding disorders has led to underdiagnosis in women with abnormal reproductive tract bleeding. The panel provided expert consensus recommendations on how to identify, confirm, and manage a bleeding disorder.
An underlying bleeding disorder should be considered when a patient has any of the following:
If a bleeding disorder is suspected, consultation with a hematologist is suggested.
Abnormal uterine bleeding is a common diagnosis, making up 5-10% of cases in the outpatient clinic setting.
Because most cases are associated with anovulatory menstrual cycles, adolescents[3] and perimenopausal women[4] are particularly vulnerable. About 20% of affected individuals are in the adolescent age group, and 50% of affected individuals are aged 40-50 years. In a study of 400 perimenopausal women, the most common type of bleeding pattern was menorrhagia (67.5%), and the most common pathology was simple endometrial hyperplasia without atypia (31%).[4]
Single episodes of anovulatory bleeding generally carry a good prognosis.
Patients who experience repetitive episodes might experience significant consequences. Frequent uterine bleeding will increase the risk for iron deficiency anemia. Flow can be copious enough to require hospitalization for fluid management, transfusion, or intravenous hormone therapy. Chronic unopposed estrogenic stimulation of the endometrial lining increases the risk of both endometrial hyperplasia and endometrial carcinoma. Timely and appropriate management will prevent most of these problems.
Many individuals with abnormal uterine bleeding are exposed to unnecessary surgical intervention, such as repeated uterine curettage, endometrial ablative therapy, or hysterectomy, before adequate workup and a trial of medical therapy can be completed.
The goals of therapy for abnormal uterine bleeding (AUB) are to control and prevent recurrent bleeding, correct or treat any pathology present, and induce ovulation in patients who desire pregnancy. Age, past history, and bleeding amount influence management.
After initial treatment and resolution of an episode of AUB, patients need to be educated that most often chronic therapy is mandatory to prevent further episodes.
Reassure patients that most bleeding stops with the appropriate hormonal therapy. Explain the physiologic reason for the anovulatory bleeding pattern. This is particularly true for the adolescent patient who establishes a predictable ovulatory type of menstrual pattern over time.
Perhaps the best measure of successful treatment is a good menstrual calendar. Encourage patients to keep a calendar to record daily bleeding patterns. This will serve to document severity of blood loss and impact on daily activities.
For patient education resources, see Women's Health Center and Pregnancy Center, as well as Vaginal Bleeding, Birth Control Overview, Birth Control Methods, and Pap Smear.
Suspect abnormal uterine bleeding (AUB) when a patient presents with unpredictable or episodic heavy or light bleeding despite a normal pelvic examination.
Note the following:
Patients who report irregular menses since menarche may have polycystic ovarian syndrome (PCOS).[5] PCOS is characterized by anovulation or oligo-ovulation and hyperandrogenism. These patients often present with unpredictable cycles and/or infertility, hirsutism with or without hyperinsulinemia, and obesity. A retrospective study by Maslyanskaya et al identified 125 female patients, 8-20 years of age, who were admitted for treatment of abnormal uterine bleeding and reported that PCOS accounted for 33% of admissions and was the most common underlying etiology. Other underlying causes were hypothalamic pituitary ovarian axis immaturity (31%); endometritis (13%); and bleeding disorders (10%).[6]
Patients with adrenal enzyme defects, hyperprolactinemia, thyroid disease, or other metabolic disorders also might present with anovulatory bleeding.
The physical examination can elicit several anatomic and organic causes of abnormal uterine bleeding (AUB).
A complete physical examination should begin with assessment of hemodynamic stability (vital signs) and proceed with evaluation of the following:
Laboratory studies for patients with abnormal uterine bleeding (AUB) include human chorionic gonadotropin (HCG), complete blood count (CBC), Pap smear, endometrial sampling, thyroid functions and prolactin, liver functions, coagulation studies/factors, and other hormone assays as indicated.[5]
The most common cause of abnormal uterine bleeding during the reproductive years is abnormal pregnancy. Rule out threatened abortion, incomplete abortion, and ectopic pregnancy.
Document blood loss. Charting the number of menstrual pads used per day, or keeping a menstrual calendar is helpful.
When in doubt, obtain a baseline CBC count for hemoglobin and hematocrit. Rule out anemia. Obtain a differential with platelet count if hematologic disease is suspected.
Pap smear should be up to date. Cervical cancer still is the most common gynecologic cancer affecting women of reproductive age in the world population.
Perform a biopsy to rule out endometrial hyperplasia or cancer in high-risk women >35 years and in younger women at extreme risk for endometrial hyperplasia/carcinoma. Women with chronic eugonadal anovulation, obesity, hirsutism, diabetes, or chronic hypertension are at particular risk.
Most biopsies will confirm the absence of secretory endometrium.
Perform thyroid function tests and prolactin because hyperthyroidism, hypothyroidism, and hyperprolactinemia are associated with ovulatory dysfunction. Identify and treat these conditions.
Obtain liver function tests if alcoholism or hepatitis is suspected. Any condition affecting liver metabolism of estrogen can be associated with abnormal uterine bleeding.
Von Willebrand disease and factor XI deficiency initially might manifest during adolescence.
Primary or secondary thrombocytopenia can be factors in the mature patient.
Tailor the choice of laboratory tests to the presenting clinical situation. Generally speaking, when coagulopathies are present, heavy bleeding is regular (menorrhagia) and associated with ovulation.
For the patient with recurrent anovulatory bleeding, the mainstay of management is treatment of correctable disease.
Obtain a hormonal complete evaluation in women with signs of hyperandrogenism, such as those with polycystic ovarian syndrome, 21 hydroxylase deficiency, or ovarian or adrenal tumors, as dictated by their respective conditions.
Women in menopausal transition usually can be followed without an extensive hormonal evaluation.
Generally, patients with abnormal uterine bleeding can be managed appropriately without the use of expensive imaging studies.
In obese patients with suboptimal pelvic examination or in patients with suspected ovarian or uterine pathology, pelvic ultrasonographic evaluation might be helpful.
Ultrasonography can be used to examine the status of the endometrium. Endometrial hyperplasia, endometrial carcinoma, endometrial polyps, and uterine fibroids can be identified easily by this technology.
Rule out endometrial carcinoma in all patients at high risk for the condition, including patients with the following characteristics:
Traditionally, carcinoma was ruled out by endometrial sampling via dilation and curettage (D&C). More recently, endometrial sampling in the office via aspiration, curetting, or hysteroscopy has become popular and is also relatively accurate.
Real-time ultrasonographic measurement and evaluation of the endometrial stripe can be helpful in distinguishing individuals bleeding with thick endometrium from those with thin, denuded endometrium, endometrial polyps, uterine fibroids, or other uterine pathology.
Saline-infusion sonohysterography is also very useful in evaluating for intracavitary (submucosal) fibroids and endometrial polyps.
Most endometrial biopsy specimens will show proliferative or dyssynchronous endometrium.
In July 2013, The American College of Obstetricians and Gynecologists issued updated guidelines for the treatment of abnormal uterine bleeding caused by ovulatory dysfunction. They included the following recommendations[7] [8] :
Options for medical care of abnormal uterine bleeding (AUB) usually involve various protocols of estrogen or progesterone supplementation, yet there is no clear consensus on which exact regimen is most effective.[9] Medical therapy options are discussed below.
Oral contraceptive pills (OCPs) suppress endometrial development, reestablish predictable bleeding patterns, decrease menstrual flow, and lower the risk of iron deficiency anemia.
OCPs can be used effectively in a cyclic or continuous regimen to control abnormal bleeding.
Acute episodes of heavy bleeding suggest an environment of prolonged estrogenic exposure and buildup of the lining. Bleeding usually is controlled within the first 24 hours, as the overgrown endometrium becomes pseudodecidualized. Seek alternate diagnosis if flow fails to abate in 24 hours.
The type of OCP and underlying patient factors may be important determinants of potential risk for complications associated with OCPs. Studies have shown an increased risk of nonfatal venous thromboembolic events (blood clots) associated with contraceptives that contain drospirenone as compared with those that contain levonorgestrel.[10]
Levonorgestrel-releasing intrauterine system is considered a first-line treatment for adolescents with heavy menstrual bleeding.[8, 3]
A study by Jain et al indicated that in women with AUB, the NuvaRing, which releases a daily dose of 15 μg ethinyl estradiol and 120 μg etonogestrel, can control heavy menstrual bleeding as effectively as a combined oral contraceptive pill containing 30 μg ethinyl estradiol and 150 μg levonorgestrel. The study included 60 women, who used either the NuvaRing or the combined oral contraceptive pill for 3 consecutive months. Both forms of contraception significantly reduced blood loss in each menstrual cycle, with no significant difference between them on the pictorial blood loss assessment chart.[11]
Estrogen alone, in high doses, is indicated in certain clinical situations.
Prolonged uterine bleeding suggests the epithelial lining of the cavity has become denuded over time. In this setting, a progestin is unlikely to control bleeding. Estrogen alone will induce return to normal endometrial growth rapidly.
Hemorrhagic uterine bleeding requires high-dose estrogen therapy. If bleeding is not controlled within 12-24 hours, a D&C is indicated.
Beginning progestin therapy shortly after initiating estrogen therapy to prevent a subsequent bleeding episode from treatment with prolonged unopposed estrogen is wise.
Chronic management of AUB requires episodic or continuous exposure to a progestin. In patients without contraindications, this is best accomplished with an oral contraceptive given the many additional benefits, including decreased dysmenorrhea, decreased blood loss, ovarian cancer prophylaxis, and decreased androgens.
In patients with a pill contraindication, cyclic progestin for 12 days per month using medroxyprogesterone acetate (10 mg/d) or norethindrone acetate (2.5-5 mg/d) provides predictable uterine withdrawal bleeding, but not contraception. Cyclic natural progesterone (200 mg/d) may be used in women susceptible to pregnancy, but may cause more drowsiness and does not decrease blood loss as much as a progestin.
In some women, including those who are unable to tolerate systemic progestins/progesterone or those who have contraindications to estrogen-containing agents, a progestin-secreting IUD may be considered that controls the endometrium via a local release of levonorgestrel, avoiding elevated systemic levels.[12]
On rare occasions, a young patient with anovulatory bleeding also might have a bleeding disorder. Desmopressin, a synthetic analog of arginine vasopressin, has been used as a last resort to treat abnormal uterine bleeding in patients with documented coagulation disorders. Treatment is followed by a rapid increase in von Willebrand factor and factor VIII, which lasts about 6 hours.
Most cases of abnormal uterine bleeding (AUB) can be treated medically. Surgical measures are reserved for situations when medical therapy has failed or is contraindicated.
D&C is an appropriate diagnostic step in a patient who fails to respond to hormonal management. The addition of hysteroscopy will aid in the treatment of endometrial polyps or the performance of directed uterine biopsies. As a rule, apply D&C rarely for therapeutic use in AUB because it has not been shown to be very efficacious.
Abdominal or vaginal hysterectomy might be necessary in patients who have failed or declined hormonal therapy, have symptomatic anemia, and who experience a disruption in their quality of life from persistent, unscheduled bleeding.
Endometrial ablation is an alternative for those who wish to avoid hysterectomy or who are not candidates for major surgery.[13] Ablation techniques are varied and can employ laser, rollerball, resectoscope, or thermal destructive modalities. Most of these procedures are associated with high patient satisfaction rates.
Pretreat the patient with an agent, such as leuprolide acetate, medroxyprogesterone acetate, or danazol, to thin the endometrium.
The ablation procedure is more conservative than hysterectomy and has a shorter recovery time. Some patients may have persistent bleeding and require repeat procedures or move on to hysterectomy. Rebleeding following ablation has raised concern about the possibility of an occult endometrial cancer developing within a pocket of active endometrium. Few reported cases exist, but further studies are needed to quantify this risk.
Endometrial ablation is not a form of contraception. Some studies report up to a 5% pregnancy rate in postablation procedures.
A study by Vitagliano et al comparing thermal balloon ablation with transcervical endometrial resection in the treatment of AUB indicated that postoperative pain is greater following the thermal ablation procedure. In the study, 47 women with AUB underwent one of the two procedures, with pelvic pain evaluated one and four hours postoperatively and the need for analgesics assessed. Patients treated with thermal balloon ablation were found to have more pain at both evaluations, and the need for analgesic rescue dose was greater in this group. At 30-day postoperative evaluation, pain seemed to still be greater in these patients. However, complications such as heavy blood loss, uterine perforation, and thermal injuries did not occur in any of the study’s patients.[14]
In a study that compared the efficacy and safety of the Novasure impedance control system and microwave endometrial ablation (MEA) in 66 women with AUB, women in the former treatment group had significantly higher rates of amenorrhea 1 year following treatment (75.8%) compared with those in the MEA treatment group (24.2%).[15]
Estrogens, progestins, androgens, nonsteroidal anti-inflammatory drugs (NSAIDs), ergot derivatives, antifibrinolytics, and gonadotropin-releasing hormone (GnRH) agonists have been used to treat abnormal uterine bleeding (AUB). More recently, desmopressin has been used to control bleeding when associated with diagnosed bleeding disorders that do not respond entirely to traditional management.
Ergot derivatives are not recommended for treatment of AUB because they have been shown to be effective rarely in clinical studies and have many side effects.
At the onset of menses, secretory endometrium contains a high concentration of plasminogen activator. A reduction in menstrual blood loss has been demonstrated in some ovulatory patients taking ε -aminocaproic acid (EACA) or aminomethylcyclohexane-carboxylic acid (AMCHA) tranexamic acid, both potent antifibrinolytics. However, this therapeutic effect was no greater than that seen with oral contraceptive therapy. Antifibrinolytics are associated with significant side effects, such as severe nausea, diarrhea, headache, and allergic manifestations, and cannot be used in patients with renal failure. Because of the high side-effect profile and expense, these agents rarely are used today for this indication.
Clinical Context: Women in perimenopause generally are estrogen deficient and might experience bouts of estrogen withdrawal bleeding. Many of these patients will recover regular menses and develop an improved sense of well-being with the initiation of hormonal replacement therapy, including estrogen and a progestin.
Very effective in controlling acute, profuse bleeding. Exerts a vasospastic action on capillary bleeding by affecting the level of fibrinogen, factor IV, and factor X in blood, as well as platelet aggregation and capillary permeability. Estrogen also induces formation of progesterone receptors, making subsequent treatment with progestins more effective.
Most AUB is secondary to anovulation. In these patients, endometrium continues to proliferate with asynchronous development. As blood supply is outgrown, irregular shedding occurs. Bleeding might be controlled acutely with high-dose estrogen for a short period of time. Several hours are required to induce mitotic activity, so most regimens require 48 h of therapy before continued bleeding is ruled a treatment failure.
Estrogen therapy only controls bleeding acutely and does not treat underlying cause. Appropriate long-term therapy can be administered once the acute episode has passed.
Clinical Context: Short-acting synthetic progestin. Drug of choice for patients with anovulatory AUB. After acute bleeding episode is controlled, can be used alone in patients with adequate amounts of endogenous estrogen to cause endometrial growth. Progestin therapy in adolescents produces regular cyclic withdrawal bleeding until positive feedback system matures.
Stops endometrial cell proliferation, allowing organized sloughing of cells after withdrawal. Typically does not stop acute bleeding episode but produces a normal bleeding episode following withdrawal.
Occasional anovulatory bleeding that is not profuse or prolonged can be treated with progestins. Progestins inhibit estrogen receptor replenishment and activate 17-hydroxysteroid dehydrogenase in endometrial cells, converting estradiol to the less active estrone. Medroxyprogesterone acetate (Provera) is the most commonly used progestin in this country, but other types, including norethindrone acetate (Aygestin) and norethindrone (Micronor), are equally efficacious. In some patients in which systemic progestins are intolerable due to side effects, a progestin secreting IUD (Mirena) may be considered.
Synthetic progestins have an antimitotic effect, allowing the endometrium to become atrophic if administered continuously. These drugs are very effective in cases of endometrial hyperplasia. In patients with chronic eugonadal anovulation who do not desire pregnancy, treatment with a progestin for 10-12 d/mo will allow for controlled, predictable menses and will protect the patient against the development of endometrial hyperplasia.
Some perimenopausal patients will not respond well to progestin therapy because of an inherent estrogen deficiency. Also, patients with thin, denuded endometrium occurring after several days of chronic bleeding might require induction of new endometrial proliferation by estrogen therapy first.
Avoid synthetic progestins in early pregnancy. They induce an endometrial response that is different from normal preimplantation secretory endometrium. Also, several reports suggest an association between intrauterine exposure to synthetic progestins in the first trimester of pregnancy and genital abnormalities in male and female fetuses. The risk of hypospadias, 5-8 per 1000 male births, might be doubled with early in-utero exposure to these drugs. Some synthetic progestins might cause virilization of female external genitalia in utero.
Patients at risk for conception can be treated safely with natural progesterone preparations. These preparations induce a normal secretory endometrium appropriate for implantation and subsequent growth of a developing conceptus.
Clinical Context: Reduces secretion of LH and FSH from pituitary by decreasing amount of GnRH.
Contraceptive pills containing estrogen and progestin have been advocated for nonsmoking patients with AUB who desire contraception. Therapy also used to treat acute hemorrhagic uterine bleeding but is not as effective as regimens previously mentioned. Apparently takes longer to induce endometrial proliferation when progestin is present. In long-term management of AUB, combination oral contraceptives are very effective.
Clinical Context: Isoxazole derivative of 12 alpha-ethinyl testosterone.
Certain androgenic preparations have been used historically to treat mild to moderate bleeding, particularly in ovulatory patients with abnormal uterine bleeding. These regimens offer no real advantage over other regimens and might cause irreversible signs of masculinization in the patient. They seldom are used for this indication today.
Use of androgens might stimulate erythropoiesis and clotting efficiency. Androgens alter endometrial tissue so that it becomes inactive and atrophic.
Clinical Context: Used for relief of mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing activity of cyclo-oxygenase, which is responsible for prostaglandin synthesis.
Blocks formation of prostacyclin, an antagonist of thromboxane, which is a substance that accelerates platelet aggregation and initiates coagulation. Prostacyclin is produced in increased amounts in menorrhagic endometrium. Because NSAIDs inhibit blood prostacyclin formation, they might effectively decrease uterine blood flow. NSAIDs have been shown to treat menorrhagia in ovulatory cycles but generally are not effective for the management of AUB.
Clinical Context: Suppresses ovarian steroidogenesis by decreasing LH and FSH levels.
Work by reducing concentration of GnRH receptors in the pituitary via receptor down regulation and induction of postreceptor effects, which suppress gonadotropin release. After an initial gonadotropin release associated with rising estradiol levels, gonadotropin levels fall to castrate levels, with resultant hypogonadism. This form of medical castration is very effective in inducing amenorrhea, thus breaking ongoing cycle of abnormal bleeding in many anovulatory patients. Because prolonged therapy with this form of medical castration is associated with osteoporosis and other postmenopausal side effects, its use is often limited in duration and add back therapy with a form of low-dose hormonal replacement is given. Because of the expense of these drugs, they usually are not used as a first line approach but can be used to achieve short-term relief from a bleeding problem, particularly in patients with renal failure or blood dyscrasia.
Clinical Context: Has been used to treat abnormal uterine bleeding in patients with coagulation defects. Transiently elevates factor VIII and von Willebrand factor.