A unicornuate uterus represents a uterine malformation where the uterus is formed from one only of the paired Müllerian ducts while the other Müllerian duct does not develop or only in a rudimentary fashion. The sometimes called "hemi-uterus" has a single horn linked to the ipsilateral fallopian tube that faces its ovary.

A bicornuate uterus or bicornate uterus (from the Latin "cornū", meaning "horn"), commonly referred to as a "heart-shaped" uterus, is a uterus composed of two "horns" separated by a septum. In humans, a bicornuate uterus is a type of uterine malformation, but in some other mammalian species, including rodents and pigs, it is normal.

A specific association of uterus didelphys (double uterus), unilateral hematocolpos (inadequate draining of menstrual blood) and ipsilateral renal agenesis (having only one kidney) has been described.

It is possible to diagnose a bicornuate uterus using gynecologic ultrasonography, specifically sonohysterography, and MRI. However, as there is no indication to do such procedures on asymptomatic women, the presence of a bicornuate uterus may not be detected until pregnancy or delivery.

In a C-section (usually done due to malpresentation), the irregular shape of the uterus will be apparent.

Other less reliable diagnostic imaging methods include hysterosalpingography and hysteroscopy; these procedures are typically done during the course of an infertility investigation.

Uterus didelphys (sometimes also "uterus didelphis") represents a uterine malformation where the uterus is present as a paired organ when the embryogenetic fusion of the Müllerian ducts fails to occur. As a result, there is a double uterus with two separate cervices, and rarely a double vagina as well. Each uterus has a single horn linked to the ipsilateral fallopian tube that faces its ovary.

In non human species ("e.g." nematodes), a didelphic genital tract may be normal rather than a malformation. Such species are described as didelphic, as opposed to monodelphic, with a single tract.

The following table distinguishes among some of the terms used for the position of the uterus:

A retroverted uterus should be distinguished from the following:

Additional terms include:

- "retrocessed uterus:" both the superior and inferior ends of the uterus are pushed posteriorly

- "severely anteflexed uterus:" the uterus is in the same position as "normal" and bends in the same direction (concave is anterior) but the bend is much more pronounced

- "vertical uterus:" the fundus (top of the uterus) is straight up.

In most cases, a retroverted uterus is genetic and is perfectly normal but there are other factors that can cause the uterus to be retroverted. Some cases are caused by pelvic surgery, pelvic adhesions, endometriosis, fibroids, pelvic inflammatory disease, or the labor of childbirth.

Women with the condition may be asymptomatic and unaware of having a uniconuate uterus; normal pregnancy may occur. In a review of the literature Reichman et al. analyzed the data on pregnancy outcome of 290 women with a unicornuate uterus. 175 women had conceived for a total of 468 pregnancies. They found that about 50% of patients delivered a live baby. The rates for ectopic pregnancy was 2.7%, for miscarriage 34%, and for preterm delivery 20%, while the intrauterine demise rate was 10%. Thus patients with a unicornuate uterus are at a higher risk for pregnancy loss and obstetrical complications.

It is often characterized by a decrease in flow and duration of bleeding (absence of menstrual bleeding, little menstrual bleeding, or infrequent menstrual bleeding) and become infertile. Menstrual anomalies are often but not always correlated with severity: adhesions restricted to only the cervix or lower uterus may block menstruation. Pain during menstruation and ovulation is sometimes experienced and can be attributed to blockages.

It has been reported that 88% of AS cases occur after a D&C is performed on a recently pregnant uterus, following a missed or incomplete miscarriage, birth, or during an elective termination (abortion) to remove retained products of conception.

The arcuate uterus is a form of a uterine anomaly or variation where the uterine cavity displays a concave contour towards the fundus. Normally the uterine cavity is straight or convex towards the fundus on anterior-posterior imaging, but in the arcuate uterus the myometrium of the fundus dips into the cavity and may form a small septation. The distinction between an arcuate uterus and a septate uterus is not standardized.

The American Fertility Society (now American Society of Reproductive Medicine) Classification distinguishes:

- Class I: Müllerian agenesis (absent uterus).

- Uterus is not present, vagina only rudimentary or absent. The condition is also called Mayer-Rokitansky-Kuster-Hauser syndrome. The patient with MRKH syndrome will have primary amenorrhea.

- Class II: Unicornuate uterus (a one-sided uterus).

- Only one side of the Müllerian duct forms. The uterus has a typical "banana shape" on imaging systems.

- Class III: Uterus didelphys, also uterus didelphis (double uterus).

- Both Müllerian ducts develop but fail to fuse, thus the patient has a "double uterus". This may be a condition with a double cervix and a vaginal partition (v.i.), or the lower Müllerian system fused into its unpaired condition. See Triplet-birth with Uterus didelphys for a case of a woman having spontaneous birth in both wombs with twins.

- Class IV: Bicornuate uterus (uterus with two horns).

- Only the upper part of that part of the Müllerian system that forms the uterus fails to fuse, thus the caudal part of the uterus is normal, the cranial part is bifurcated. The uterus is "heart-shaped".

- Class V: Septated uterus (uterine septum or partition).

- The two Müllerian ducts have fused, but the partition between them is still present, splitting the system into two parts. With a complete septum the vagina, cervix and the uterus can be partitioned. Usually the septum affects only the cranial part of the uterus. A uterine septum is the most common uterine malformation and a cause for miscarriages. It is diagnosed by medical image techniques, i.e. ultrasound or an MRI. MRI is considered the preferred modality due to its multiplanar capabilities as well as its ability to evaluate the uterine contour, junctional zone, and other pelvic anatomy. A hysterosalpingogram is not considered as useful due to the inability of the technique to evaluate the exterior contour of the uterus and distinguish between a bicornuate and septate uterus.

A uterine septum can be corrected by hysteroscopic surgery.

- Class VI: DES uterus.

- The uterine cavity has a "T-shape" as a result of fetal exposure to diethylstilbestrol.

An additional variation is the arcuate uterus where there is a concave dimple in the uterine fundus within the cavity.

A rudimentary uterus is a uterine remnant not connected to cervix and vagina and may be found on the other side of an unicornuate uterus.

Patients with uterine abnormalities may have associated renal abnormalities including unilateral renal agenesis.

Various classification systems were developed to describe Asherman’s syndrome (citations to be added), some taking into account the amount of functioning residual endometrium, menstrual pattern, obstetric history and other factors which are thought to play a role in determining the prognoses. With the advent of techniques which allow visualization of the uterus, classification systems were developed to take into account the location and severity of adhesions inside the uterus. This is useful as mild cases with adhesions restricted to the cervix may present with amenorrhea and infertility, showing that symptoms alone do not necessarily reflect severity. Other patients may have no adhesions but amenorrhea and infertility due to a sclerotic atrophic endometrium. The latter form has the worst prognosis.

A uterine malformation is a type of female genital malformation resulting from an abnormal development of the Müllerian duct(s) during embryogenesis. Symptoms range from amenorrhea, infertility, recurrent pregnancy loss, and pain, to normal functioning depending on the nature of the defect.

A uterine septum is a form of a congenital malformation where the uterine cavity is partitioned by a longitudinal septum; the outside of the uterus has a normal typical shape. The wedge-like partition may involve only the superior part of the cavity resulting in an "incomplete septum" or a "subseptate uterus", or less frequently the total length of the cavity ("complete septum") and the cervix resulting in a double cervix. The septation may also continue caudally into the vagina resulting in a "double vagina".

An interstitial pregnancy is a uterine but ectopic pregnancy; the pregnancy is located outside the uterine cavity in that part of the fallopian tube that penetrates the muscular layer of the uterus. The term cornual pregnancy is sometimes used as a synonym, but remains ambiguous as it is also applied to indicate the presence of a pregnancy located within the cavity in one of the two upper "horns" of a bicornuate uterus. Interstitial pregnancies have a higher mortality than ectopics in general.

A heterotopic pregnancy is a rare complication of pregnancy in which both extra-uterine (ectopic pregnancy) and intrauterine pregnancy occur simultaneously. It may also be referred to as a combined ectopic pregnancy, multiple‑sited pregnancy, or coincident pregnancy.

Molar pregnancies usually present with painless vaginal bleeding in the fourth to fifth month of pregnancy. The uterus may be larger than expected, or the ovaries may be enlarged. There may also be more vomiting than would be expected (hyperemesis). Sometimes there is an increase in blood pressure along with protein in the urine. Blood tests will show very high levels of human chorionic gonadotropin (hCG).

Symptoms may include abdominal pain or vaginal bleeding during pregnancy. As this is nonspecific in areas where ultrasound is not available the diagnosis was often only discovered during surgery to investigate the abnormal symptoms. They are typically diagnosed later in the developing world than the developed. In about half of cases from a center in the developing world the diagnosis was initially missed.

It is a dangerous condition as there can be bleeding into the abdomen that results in low blood pressure and can be fatal. Other causes of death in people with an abdominal pregnancy include anemia, pulmonary embolus, coagulopathy, and infection.

Hematometra typically presents as cyclic, cramping pain in the midline of the pelvis or lower abdomen. Patients may also report urinary frequency and urinary retention. Premenopausal women with hematometra often experience abnormal vaginal bleeding, including dysmenorrhea (pain during menstruation) or amenorrhea (lack of menstruation), while postmenopausal women are more likely to be asymptomatic. Due to the accumulation of blood in the uterus, patients may develop low blood pressure or a vasovagal response. When palpated, the uterus will typically feel firm and enlarged.

An abdominal pregnancy can be regarded as a form of an ectopic pregnancy where the embryo or fetus is growing and developing outside the womb in the abdomen, but not in the Fallopian tube, ovary or broad ligament.

While rare, abdominal pregnancies have a higher chance of maternal mortality, perinatal mortality and morbidity compared to normal and ectopic pregnancies; on occasion, however, a healthy viable infant can be delivered.

Because tubal, ovarian and broad ligament pregnancies are as difficult to diagnose and treat as abdominal pregnancies, their exclusion from the most common definition of abdominal pregnancy has been debated.

Others—in the minority—are of the view that abdominal pregnancy should be defined by a placenta implanted into the peritoneum.

Adenomyosis can vary widely in the type and severity of symptoms that it causes, ranging from being entirely asymptomatic 33% of the time to being a severe and debilitating condition in some cases. Women with adenomyosis typically first report symptoms when they are between 40 and 50, but symptoms can occur in younger women.

Symptoms and the estimated percent affected may include:

- Chronic pelvic pain (77%)

- Heavy menstrual bleeding (40-60%), which is more common with in women with deeper adenomyosis. Blood loss may be significant enough to cause anemia, with associated symptoms of fatigue, dizziness, and moodiness.

- Abnormal uterine bleeding

- Painful cramping menstruation (15-30%)

- Painful vaginal intercourse (7%)

- A 'bearing' down feeling

- Pressure on bladder

- Dragging sensation down thighs and legs

Clinical signs of adenomyosis may include:

- Uterine enlargement (30%), which in turn can lead to symptoms of pelvic fullness.

- Tender uterus

- Infertility or sub-fertility (11-12%) - In addition, adenomyosis is associated with an increased incidence of preterm labour and premature rupture of membranes.

Women with adenomyosis are also more likely to have other uterine conditions, including:

- Uterine fibroids (50%)

- Endometriosis (11%)

- Endometrial polyp (7%)

Fallopian tube obstruction is a major cause of female infertility. Blocked fallopian tubes are unable to let the ovum and the sperm converge, thus making fertilization impossible. Fallopian Tubes are also known as oviducts, uterine tubes, and salpinges (singular salpinx).

Symptoms of a rupture may be initially quite subtle. An old cesarean scar may undergo dehiscence; but with further labor the woman may experience abdominal pain and vaginal bleeding, though these signs are difficult to distinguish from normal labor. Often a deterioration of the fetal heart rate is a leading sign, but the cardinal sign of uterine rupture is loss of fetal station on manual vaginal exam. Intra-abdominal bleeding can lead to hypovolemic shock and death. Although the associated maternal mortality is now less than one percent, the fetal mortality rate is between two and six percent when rupture occurs in the hospital.

In pregnancy uterine rupture may cause a viable abdominal pregnancy. This is what accounts for most abdominal pregnancy births.

- Abdominal pain and tenderness. The pain may not be severe; it may occur suddenly at the peak of a contraction. The woman may describe a feeling that something "gave way" or "ripped."

- Chest pain, pain between the scapulae, or pain on inspiration—Pain occurs because of the irritation of blood below the woman's diaphragm

- Hypovolemic shock caused by haemorrhage— Falling blood pressure, tachycardia, tachypnea, pallor, cool and clammy skin, and anxiety. The fall in blood pressure is often a late sign of haemorrhage

- Signs associated with fetal oxygenation, such as late deceleration, reduced variability, tachycardia, and bradycardia

- Absent fetal heart sounds with a large disruption of the placenta; absent fetal heart activity by ultrasound examination

- Cessation of uterine contractions

- Palpation of the fetus outside the uterus (usually occurs only with a large, complete rupture). The fetus is likely to be dead at this point.

- Signs of an abdominal pregnancy

- Post-term pregnancy

Bleeding before the expected time of menarche could be a sign of precocious puberty. Other possible causes include the presence of a foreign body in the vagina, molestation, vaginal infection (vaginitis), and rarely, a tumor.

A pelvic examination may reveal a double vagina or double cervix that should be further investigated and may lead to the discovery of a uterine septum. In most patients, however, the pelvic examination is normal. Investigations are usually prompted on the basis of reproductive problems.

Helpful techniques to investigate a septum are transvaginal ultrasonography and sonohysterography, MRI, and hysteroscopy. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to delineate the condition. Prior to modern imaging hysterosalpingography was used to help diagnose the uterine septum, however, a bicornuate uterus may deliver a similar image.

An important category of septate uterus is the hybrid type a variant that may be misdiagnosed as bicornuate uterus when seen by laparoscopy Professor El Saman From Egypt was the first to describe this anomaly and warned gynecologist about this common misdiagnosis, whenever there is a uterine fundus depression on laparoscopy gynecologists should compare the depth of this depression with the depth of the dividing internal interface. Hybrid septate uterus benefit from hysteroscopic metroplasty under laparoscopic control.