Dysmenorrhea

Dysmenorrhea is defined as difficult menstrual flow or painful menstruation. It is one of the most common gynecologic complaints in young women who present to clinicians. ^[5] Optimal management of this symptom depends on an understanding of the underlying cause. Dysmenorrhea can be divided into 2 broad categories: primary (spasmodic) and secondary (congestive). ^[6]

Primary dysmenorrhea is defined as menstrual pain that is not associated with macroscopic pelvic pathology (ie, occurs in the absence of pelvic disease). It typically occurs in the first few years after menarche ^[7] and affects as many as 50% of postpubertal females. ^[8] Secondary dysmenorrhea is defined as menstrual pain resulting from anatomic or macroscopic pelvic pathology, ^{[7, 9]} as is seen in women with endometriosis or chronic pelvic inflammatory disease. It is most often observed in women aged 30-45 years.

The following risk factors are associated with more severe episodes of dysmenorrhea ^[10] :

• Earlier age at menarche

• Long menstrual periods

• Heavy menstrual flow

• Smoking

• Positive family history

Some (not all) studies have found obesity and alcohol consumption to be associated with dysmenorrhea. ^{[11, 12, 13]}  There is mixed evidence on whether the duration of the menstrual cycle is associated with increased menstrual pain. ^[11]

Although dysmenorrhea is not life-threatening, it can be debilitating and psychologically taxing for many women. Some choose to self-medicate at home and never seek medical attention for their pain. Dysmenorrhea is responsible for significant absenteeism from work, and it is the most common reason for school absence among adolescents. ^[14]  A 2021 systematic review estimated that chronic pelvic pain, of which dysmenorrhea is a component, costs women up to $20,898 yearly in direct and indirect costs. ^[15]

The history is critical in establishing the diagnosis of dysmenorrhea and should include an assessment of the onset, duration, type, and severity of pain. A thorough menstrual history is also essential. A complete physical examination should be performed. For younger adolescents who have never been sexually active, a careful abdominal examination is appropriate. In older adolescents or those known to be sexually active, a pelvic examination is crucial. (See Presentation.)

No tests are specific to the diagnosis of primary dysmenorrhea. Studies that may be indicated to elucidate the cause of secondary dysmenorrhea include laboratory tests, abdominal or transvaginal ultrasonography, hysterosalpingography, hysteroscopy, or laparoscopy. (See Workup.)

Treatment of dysmenorrhea is aimed at providing symptomatic relief as well as inhibiting the underlying processes that cause symptoms. Grading dysmenorrhea according to the severity of pain and the degree of limitation of daily activity may help guide the treatment strategy. Medications used may include NSAIDs and opioid analgesics, as well as hormonal contraceptives. In addition to pain relief, mainstays of treatment include reassurance and education. Other therapies have been proposed, but most are not well studied. (See Treatment.)

Historical attitudes toward menstrual pain were often dismissive. Pain was often attributed to women’s emotional or psychological states or to misconceptions about sex and sexual behaviors. Although the etiology and pathophysiology of dysmenorrhea have not been fully elucidated, research has led to data supporting concrete physiologic explanations for dysmenorrhea, which discredit these prior dismissive theories. ^{[14, 16, 17]}

Primary dysmenorrhea

Current evidence suggests that the pathogenesis of primary dysmenorrhea is due to prostaglandin F2α (PGF2α), a potent myometrial stimulant and vasoconstrictor, in the secretory endometrium. ^[18] The response to prostaglandin inhibitors in patients with dysmenorrhea supports the assertion that dysmenorrhea is prostaglandin-mediated. Substantial evidence attributes dysmenorrhea to prolonged uterine contractions and decreased blood flow to the myometrium.

Elevated prostaglandin levels were found in the endometrial fluid of women with dysmenorrhea and correlated well with the degree of pain. ^[19] A 3-fold increase in endometrial prostaglandins occurs from the follicular phase to the luteal phase, with a further increase occurring during menstruation. ^[20] The increase in prostaglandins in the endometrium after the fall in progesterone in the late luteal phase results in increased myometrial tone and excessive uterine contraction. ^[9]

Leukotrienes have been postulated to heighten the sensitivity of pain fibers in the uterus. Substantial amounts of leukotrienes have been demonstrated in the endometria of women with primary dysmenorrhea that does not respond to treatment with prostaglandin antagonists. ^{[12, 21, 22, 23, 24]}

The posterior pituitary hormone vasopressin may be involved in myometrial hypersensitivity, reduced uterine blood flow, and pain in primary dysmenorrhea. ^{[25, 26, 14, 27]} Vasopressin’s role in the endometrium may be related to prostaglandin synthesis and release.

In addition, a neuronal hypothesis has been advocated for the pathogenesis of primary dysmenorrhea. Type C pain neurons are stimulated by the anaerobic metabolites generated by an ischemic endometrium. Women with dysmenorrhea appear to have enhanced pain sensitivity compared to women without dysmenorrhea, even during phases of the menstrual cycle when they are not experiencing menstrual pain. ^[17] This enhanced pain sensitivity may increase the risk of affected women to other chronic conditions (eg, fibromyalgia) as well as negatively impact their quality of life. ^[17]

Primary dysmenorrhea has also been attributed to behavioral and psychological factors. Although these factors have not been convincingly demonstrated to be causative, they should be considered if medical treatment fails.

In primary dysmenorrhea, there is a highly complex interplay between hormones and mediators, basal body temperature, sleep patterns, and the central nervous system (CNS), the extent of which is not completely understood. ^[14]

A study by Liu et al found that patients with primary dysmenorrhea had significantly increased cortical thickness and decreased subcortical volumes. ^[28]

Air pollution may contribute to dysmenorrhea. Lin et al demonstrated that long-term exposure to air pollutants, such as nitrogen and carbon oxides and fine particulate matter, increased the risk of developing dysmenorrhea by up to 33.1-fold for women and girls with the highest exposure to pollutants, compared to those with the lowest exposure. ^[29]

Secondary dysmenorrhea

Elevated prostaglandins may also play a role in secondary dysmenorrhea, but by definition, concomitant pelvic pathology must be present. A number of factors may be involved in the pathogenesis of secondary dysmenorrhea, including the following:

• Endometriosis

• Pelvic inflammatory disease (PID)

• Ovarian cysts and tumors

• Cervical stenosis or occlusion

• Adenomyosis

• Fibroids

• Uterine polyps

• Intrauterine adhesions

• Congenital malformations (eg, bicornuate uterus or subseptate uterus)

• Intrauterine contraceptive device (IUCD), or intrauterine device (IUD)

• Transverse vaginal septum

• Pelvic congestion syndrome

• Allen-Masters syndrome

Almost any process that can affect the pelvic viscera can produce cyclic pelvic pain. ^[2]

Risk factors for primary dysmenorrhea include the following:

• Early age at menarche (< 12 years)

• Nulliparity

• Heavy or prolonged menstrual flow

• Smoking

• Positive family history

• Obesity

Risk factors for secondary dysmenorrhea include the following :

• Leiomyomata (fibroids)

• PID

• Tubo-ovarian abscess

• Ovarian torsion

• Endometriosis

In the following sections, the more common causes of secondary dysmenorrhea are briefly summarized.

Uterine leiomyoma

Uterine leiomyomata are benign tumors of the uterine musculature that are a common cause of dysmenorrhea because they enlarge when stimulated by estrogen. They are up to 9 times more common in black women than in white women. ^[30]

In addition to pain with menses, patients may present with menorrhagia, abdominal distention, or pressure. Pelvic examination may reveal a uterine mass or irregularity. Ultrasonography is often used for determining size and location of fibroids, though computed tomography (CT) is used if ultrasonographic information is limited. ^{[31, 32]} Unless patients are symptomatic from profound anemia, these patients can be safely discharged with appropriate gynecologic follow-up. Potential complications are anemia and infertility. ^[33]

Pelvic inflammatory disease

PID is an infection of the uterus and fallopian tubes, with or without ovarian or parametrial involvement. It is an ascending infection that develops during or immediately after menses; if chronic, it can lead to dysmenorrhea. The most common causative pathogens are Chlamydia trachomatis and Neisseria gonorrhoeae, though PID also can be caused by other organisms, such as Gardnerella vaginalis, anaerobes, and gram-negative rods. ^[31]

Previously, the diagnosis of PID, though primarily clinical, was based on the presence of 3 major criteria (abdominal pain, adnexal pain, and cervical motion tenderness), and 1 minor criterion (fever, vaginal discharge, leukocytosis, positive cervical cultures, gram-negative stain, intracellular diplococci, or white blood cells [WBCs] on vaginal smear). ^[31]

Data from the PEACH (Pelvic inflammatory disease Evaluation And Clinical Health) trial shows that the presence of adnexal tenderness has a sensitivity of 95.5% for histologic endometritis. The findings of this trial support empiric treatment of all women at risk for PID with adnexal tenderness and no other obvious cause.

On the basis of data from the PEACH trial, the Centers for Disease and Control and Prevention (CDC) recommends that all women who are at risk for PID and who exhibit adnexal, uterine, or pelvic tenderness on bimanual examination in the absence of any other explanation for these findings be treated empirically for PID. ^[34]

In addition to appropriate analgesia, patients require appropriate antibiotic coverage. The most commonly used regimen consists of ceftriaxone 250 mg IM and doxycycline 100 mg daily for 14 days. ^[31] Patients should be hospitalized if outpatient therapy fails, if they have intractable nausea or vomiting, if they have a complicating tubo-ovarian abscess, or if they are immunocompromised. ^[31] Complications include tubo-ovarian abscess and Fitz-Hugh Curtis syndrome (perihepatitis) if pus from the fallopian tubes leaks into the peritoneum.

Tubo-ovarian abscess

Tubo-ovarian abscess is a loculated infection within the fallopian tubes or ovaries, usually occurring as a sequela of PID. It is often polymicrobial.

Most commonly, patients present with fever and gradually worsening pelvic pain and tenderness; nausea, vomiting, and vaginal bleeding or discharge may be present as well. Examination may elicit tenderness on cervical motion and in the adnexal area. A pelvic mass may be present, though it is often difficult to palpate. ^[31] Tubo-ovarian abscesses can be detected on pelvic ultrasonography or abdominal CT as a complex cystic structure in the pelvis, with or without loculations. ^[32]

Patients are often admitted for intravenous (IV) antibiotic therapy covering Neisseria gonorrhoeae, Chlamydia, anaerobes, and gram-negative organisms. If medical therapy fails or if peritoneal signs are found on examination, surgical drainage is indicated. ^[31] Infertility is almost always a complication of tubo-ovarian abscess. ^[31] The most feared complication, however, is rupture, which can lead to septic shock and death; this is a true surgical emergency. ^[33]

Ovarian torsion

Ovarian torsion involves twisting of the adnexal structures, which leads to ischemia and ultimately necrosis if the process is not reversed in time. In a nonpregnant woman, it is almost always caused by an abnormality in the ovary, such as a cyst or a tumor. Torsion can occur in pregnancy without a requisite adnexal abnormality, and in one large series, 20% of the patients found to have torsion were pregnant. ^[35]

Patients often present with severe, intermittent, colicky, unilateral pelvic or lower abdominal pain, frequently associated with nausea and vomiting. The diagnosis is often delayed because the presentation of ovarian torsion can resemble those of other disease entities, such as appendicitis or renal colic. ^{[31, 33]}

Because of these resemblances and the consequent potential for diagnostic uncertainty, CT is often performed before any other imaging modality. It is important to be familiar with the typical CT findings for torsion: ovarian enlargement exceeding 5 cm with a corkscrew appearance of the ipsilateral fallopian tube. ^[32] A sonogram will usually show a large ovarian mass or cyst, but ultrasonographic evidence of torsion is difficult to obtain, because the appearance changes depending on the length of time elapsed. ^[33]   Ultrasound findings concerning for torsion may include the whirlpool sign, ovarian stromal edema with peripherally displaced follicles, and the follicular ring sign. The absence of Doppler flow is only present in less than 50% of cases. 

If there is a high level of suspicion for ovarian torsion, a gynecologic consultation should be obtained early. Laparoscopy is not only diagnostic but also therapeutic and potentially fertility-saving. ^[33] These patients are all admitted.

Ovarian cyst rupture or hemorrhage

A hemorrhagic ovarian cyst comes from an ovarian follicle in the absence of ovulation; consequently, these cysts are exclusively found in menstruating females.

Patients often present with the acute onset of pelvic or abdominal pain, along with nausea and vomiting. Examination may reveal an adnexal mass, but almost all patients with ruptured ovarian cysts have some level of adnexal tenderness. Signs of peritoneal irritation may be apparent as well. Although CT and ultrasonography can be used to visualize hemoperitoneum and the cyst, ^[32] laparoscopy is required for the definitive diagnosis. ^[31]

Endometriosis

Endometriosis is the presence of endometriumlike tissue found outside of the uterus, most commonly in the ovaries. Women often present with dyspareunia and pelvic and back pain. Although endometriosis is a diagnosis of exclusion, patients may give a history of dysmenorrhea that was cyclic with menses. ^[31] It is important to note, however, that endometriosis can exist concomitantly with other disease processes causing dysmenorrhea; this makes the diagnosis even more difficult. ^[36]

The history may also include chronic pelvic pain unresponsive to antibiotics or analgesics. In addition, a good obstetric history may elicit frequent miscarriages or difficulty conceiving. ^{[31, 36]} The classic examination finding is a fixed uterus with “ash” spots (purple-blue discolorations) on the cervix, although this finding is not always present, ^[31]  and the examination may be unremarkable. 

In the future, CT may hold some promise as a diagnostic tool, ^[32] but at present, endometriosis can be definitively diagnosed only via laparoscopy or laparotomy. Some argue that definitive diagnosis may not even be necessary. ^[36] Often, endometriosis, if found, is assumed to be the cause of discomfort when it may not be. Even if endometriosis is the cause of dysmenorrhea, surgery may not be necessary if pain is controlled with hormonal therapy or analgesia. ^[36]  

Adenomyosis

Adenomyosis is defined as an invasion of myometrium by uterine adrenal glands. It is a rare disease and can resemble uterine leiomyomas and endometrial carcinoma in its presentation; accordingly, diagnosis is difficult.

Definitive diagnosis is typically accomplished by means of transvaginal ultrasonography or magnetic resonance imaging (MRI). When the latter is used, the key finding is a thickened junctional zone (JZ line)—that is, the border between myometrium and endometrium. One paper showed that adenomyosis should be in the differential diagnosis when a patient is treated for presumptive endometriosis and has chronic persistent pain. ^[37]

Intrauterine contraceptive device

IUCDs (IUDs) may cause bladder or uterine perforation. The sooner a patient has a uterine perforation after IUCD placement, the more likely it is that she will present with peritoneal signs. ^[31] Patients with bladder perforation may have recurrent cystitis that is unresponsive to antibiotics. The IUCD must be removed immediately to prevent further damage to the uterine or bladder walls. Abdominal radiographs may reveal the location of an IUCD if the string is not seen in the vaginal vault. A gynecologist should be consulted early. ^[31]

Premenstrual dysphoric disorder

Besides dysmenorrhea, patients with premenstrual dysphoric disorder (formerly premenstrual syndrome) may have bloating, body aches, migraine headaches, breast tenderness, and emotional complaints. The effects of these symptoms are occasionally debilitating. Aside from possible vaginal brownish discharge or bleeding, pelvic examination findings are normal. It is the emergency physician’s responsibility to ensure adequate analgesia and appropriate follow-up with a gynecologist.

United States statistics

Dysmenorrhea may affect more than 50% of menstruating women, and its reported prevalence has been highly variable (eg, 45-95% ^[17] ). A survey of 113 patients in a family practice setting showed a prevalence of 29-44%, ^[38] but figures as high as 90% in women aged 18-45 years have been reported. ^[5] The use of oral contraceptives (OCs) and nonsteroidal anti-inflammatory drugs (NSAIDs), both of which are effective in ameliorating symptoms of primary dysmenorrhea, may hinder accurate assessment of prevalence.

Primary dysmenorrhea peaks in late adolescence and the early 20s. ^[39] The incidence falls with increasing age and with increasing parity. In many studies, ^{[11, 40, 41]} though not all, ^[5] the reported prevalence and severity of dysmenorrhea in parous women are substantially lower. An epidemiologic study found no significant differences in prevalence and severity of dysmenorrhea between nulligravid women and those in whom pregnancy had been terminated by either spontaneous or induced abortion. ^[11]

In an epidemiologic study of an adolescent population (age range, 12-17 years), Klein and Litt reported that dysmenorrhea had a prevalence of 59.7%. ^[42] Of patients reporting pain, 12% described it as severe, 37% as moderate, and 49% as mild. Dysmenorrhea caused 14% of patients to miss school frequently. 

International statistics

The prevalence of dysmenorrhea worldwide is similar to that in the United States. Reported prevalences have ranged from 15.8% to 91.5%, with higher rates reported in adolescent populations. ^{[43, 44, 45, 11, 46, 40, 47, 48, 49, 50]}

A study of 408 young Italian women found that the prevalence of dysmenorrhea was 84.1% when only menstrual pain was considered, 55.2% when menstrual pain was associated with a need for medication, 31.9% when menstrual pain was associated with absenteeism, and 25.3% when menstrual pain was associated with both a need for medication and absenteeism. ^[51]

In a longitudinal population study of 9,067 Australian women, researchers found that those who began smoking by age 13 had the greatest risk of developing chronic dysmenorrhea. Overall, approximately 60% of the women reported experiencing dysmenorrhea symptoms at some time during the study period. ^{[52, 53]}

The prevalence of period pain was higher among current smokers (29%) than nonsmokers (23%). Compared with never-smokers, ex-smokers had a 33% increased risk of chronic symptoms (odds ratio, 1.33; 95% confidence interval, 1.05 - 1.68), while current smokers had a 41% increased risk (odds ratio, 1.41; 95% CI, 1.17 - 1.70). After adjustment for socioeconomic status, lifestyle, and reproductive factors, women who began smoking before or by age 13 had a 59% increased risk (odds ratio, 1.59; 95% CI, 1.18 – 2.15), those who began at ages 14-15 had a 50% increased risk (1.50; 95% CI 1.18 to 1.90), and those who began at age 16 or older had a 26% increased risk (1.26; 95% CI 1.03 to 1.55). ^{[52, 53]}

In a cross-sectional study of 311 female Iranian undergraduate students (aged 18-27 y), the prevalence of primary dysmenorrhea was 89.1%. ^[54] Factors that were significantly associated with higher dysmenorrhea pain intensity included younger age as well as familial factors (eg, low maternal formal education, family history of dysmenorrhea), social factors (living at home), and menstruation factors (eg, higher menstrual bleeding severity and shorter menstrual intervals). ^[54]

In a cross-sectional study of 647 Ethiopian university students, the prevalence of dysmenorrhea was reported at 51.5%. Associated risk factors included chocolate consumption (95% CI adjusted odds ratio [AOR], 1.28-8.93), irregular menses (95% CI AOR, 1.55-3.54), and family history of dysmenorrhea (95% CI AOR, 2.25-4.81). ^[49]

In a cross-sectional study of 892 Irish university students, the prevalence of dysmenorrhea was reported at 91.5%. ^[50]

Assessing the prevalence of dysmenorrhea worldwide is complicated by differing definitions of dysmenorrhea in study surveys, as well as cultural and societal differences in characterizing pain.

Age- and race-related demographics

The most common causes of dysmenorrhea differ by age. The prevalence of this condition is estimated to be 25% among adult women and as high as 90% among adolescents.

No data suggest that race affects the incidence of dysmenorrhea.

With the use of NSAIDs, the prognosis for primary dysmenorrhea is excellent. The prognosis for secondary dysmenorrhea varies, depending on the underlying disease process. If a diagnosis of secondary dysmenorrhea is missed, the underlying pathology may lead to increased morbidity, including difficulty conceiving. ^[36]

Although dysmenorrhea itself is not life-threatening, it can have a profound negative impact on a woman’s day-to-day life. Besides missing work or school, she may be unable to participate in sports or other activities and thus experience additional emotional distress. Some 10% of dysmenorrheal women have severe pain that can be incapacitating. Dysmenorrhea is a public health problem associated with substantial economic loss related to work absences (an estimated 600 million work hours and 2 billion dollars in the United States). ^[55]

A cross sectional study that included 897 adolescent girls reported that those in the dysmenorrhea group had significantly higher depression, aggression, insomnia, daytime sleepiness and sleep apnea scores compared to the control and the premenstrual syndrome groups. ^[56]