Pregnancy in a rudimentary horn of the uterus is a very rare type of

ectopic pregnancy Ectopic pregnancy is a complication of pregnancy in which the embryo attaches outside the uterus. Signs and symptoms classically include abdominal pain and vaginal bleeding, but fewer than 50 percent of affected women have both of these sympto ...

. This type of pregnancy can be life-threatening, as the rudimentary horn is not meant to sustain a pregnancy and is at risk of rupturing.

Unicornuate uterus A unicornuate uterus represents a uterine malformation where the uterus is formed from only one of the paired Müllerian ducts while the other Müllerian duct does not develop or only in a rudimentary fashion. The sometimes called hemi-uterus ha ...

with rudimentary horn is a type of congenital uterine anomaly that arises when one of the

Müllerian duct The paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo in the reproductive system of humans and other mammals that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive uroge ...

s fails to develop fully, resulting in a small rudimentary horn on one side of the uterus. Different terms have been used in the literature to describe the rudimentary horn, such as uterus bicornis with accessory horn, uterus bicornis unicollis with rudimentary horn, uterus bicornis unicollis with atretic horn, hernia uterus inguinale, and Robert's uterus.

Complications

This condition is considered a medical emergency, as rupture of the rudimentary horn can occur in the late first or second trimester of pregnancy (between 10 and 15 weeks of gestation), leading to massive bleeding and threatening the patient's life. Pregnancy in a rudimentary horn is typically associated with several complications, including

intrauterine growth restriction Intrauterine growth restriction (IUGR), or fetal growth restriction, is the poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's ...

, low amniotic fluid levels,

preterm birth Preterm birth, also known as premature birth, is the Childbirth, birth of a baby at fewer than 37 weeks Gestational age (obstetrics), gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 ...

, fetal death, and occasionally, full-term gestation. While there have been cases of successful live births, the prognosis for pregnancy in the rudimentary horn is generally poor.

Epidemiology

It is reported that 1 out of every 200 to 600 fertile women have a congenital uterine anomaly, while the occurrence of unicornuate uterus with rudimentary horn is even less common, with a frequency of 1 in 100,000. Although pregnancy in the rudimentary horn is extremely rare, it can lead to an ectopic gestation with an incidence of 1 in 100,000 to 1 in 140,000 pregnancies.

Diagnosis

Diagnosing rudimentary horn pregnancy requires specific tests, such as

hysteroscopy Hysteroscopy is the inspection of the uterine cavity by endoscopy with access through the cervix. It allows for the diagnosis of intrauterine pathology and serves as a method for surgical intervention (operative hysteroscopy). Hysteroscope A hyst ...

hysterosalpingography Hysterosalpingography (HSG), also known as uterosalpingography, is a radiology, radiologic procedure to investigate the shape of the uterine cavity and the shape and patency of the fallopian tubes. It is a special x-ray procedure using Contrast ...

, and

laparoscopy Laparoscopy () is an operation performed in the abdomen or pelvis using small incisions (usually 0.5–1.5 cm) with the aid of a camera. The laparoscope aids diagnosis or therapeutic interventions with a few small cuts in the abdomen.Medli ...

, and close monitoring is essential if a person with a suspected rudimentary horn becomes pregnant to avoid the risk of rupture and its complications. Recent progress in diagnostic imaging techniques, including

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

and ultrasound, have enabled the detection of these pregnancies before they lead to rupture.

Obstetric ultrasonography Obstetric ultrasonography, or prenatal ultrasound, is the use of medical ultrasonography in pregnancy, in which sound waves are used to create real-time visual images of the developing embryo or fetus in the uterus (womb). The procedure is a stand ...

, particularly the transvaginal method, is used for attempting prenatal diagnosis. Many patients experience

acute abdominal pain An acute abdomen refers to a sudden, severe abdominal pain. It is in many cases a medical emergency, requiring urgent and specific diagnosis. Several causes need immediate surgical treatment. Differential diagnosis Common causes of an acute ab ...

, and it can be challenging to differentiate rudimentary horn pregnancy from other acute abdominal or gestational problems through ultrasound, leading to a high rate of misdiagnosis. Additionally, during advanced stages of gestation, rudimentary horn pregnancy can closely resemble

abdominal pregnancy An abdominal pregnancy is a rare type of ectopic pregnancy where the embryo or fetus is growing and developing outside the uterus, in the abdomen, and not in a fallopian tube (usual location), an ovary, or the broad ligament. Because tubal, ov ...

Management

The standard approach for managing a rudimentary horn, regardless of the trimester, is to remove it along with the corresponding

tube Tube or tubes may refer to: * ''Tube'' (2003 film), a 2003 Korean film * "Tubes" (Peter Dale), performer on the Soccer AM television show * Tube (band), a Japanese rock band * Tube & Berger, the alias of dance/electronica producers Arndt Rör ...

using either laparoscopy or

laparotomy A laparotomy is a surgical procedure involving a surgical incision through the abdominal wall to gain access into the abdominal cavity. It is also known as a celiotomy. Origins and history The first successful laparotomy was performed without ...

. This is advised because the functional endometrial horn has a higher risk of ectopic pregnancy, infertility, and

dysmenorrhoea Dysmenorrhea, also known as period pain, painful periods or menstrual cramps, is pain during menstruation. Its usual onset occurs around the time that menstruation begins. Symptoms typically last less than three days. The pain is usually in the ...

References

{{Pregnancy Ectopic pregnancy