Teaching Case

A 28-year-old female patient presented to the emergency department with vaginal bleeding since that morning accompanied with mild abdominal pain cramping in nature. She has recently relocated from another state and is two months pregnant, has three living children and prior C-section(s). She had recently placed an intra-uterine device (IUD), and shortly after was found to be pregnant, prompting an ultrasound. She was told that she has two uteri with foetus in one uterus and IUD in the other. Due to the size of the foetus, the IUD was unable to be removed. Physical examination illustrated a non-tender abdomen with a closed cervical os with trace blood. Urine pregnancy test was positive and serum beta-hcg was measured at 151,586 miu/ml. Transabdominal and transvaginal ultrasound were performed.

Transabdominal and transvaginal ultrasound of the pelvis showed a uterus with two distinct cornua, likely related to a bicornuate uterus (Fig. 1). The right uterine horn contains a single gestation while the left uterine horn was found to have an IUD (Fig. 2). Foetal measurements corresponded to a gestational age of 11 weeks and 4 days. Foetal heart rate was 167 bpm (Fig. 3).

Here we report a rare case of a patient who has a bicornuate uterus, with an IUD in one horn of the uterus, and a viable pregnancy in another. There have been 5 similar cases reported [1-5]. In two of these cases, spontaneous abortion occurred at weeks 16 and 18. In the other three cases, pregnancy was terminated. Bicornuate uterus is an uncommon congenital uterine anomaly resulting from an incomplete fusion of the mullerian system. Partial fusion of the mullerian ducts at the proximal (upper) portion gives rise of complete or partial separation of the uterine horns, resulting in a uterus with two cavities, each containing a separate normal uterine lining [6].The prevalence of congenital uterine abnormalities is estimated around 4.3%. It is difficult to tell the prevalence of bicornuate uterus as many cases are not identified, however in one systematic review of the prevalence of congenital uterine anomalies revealed that bicornuate uterus is present in 0.4% in the unselected population [7]. Many patients with a bicornuate uterus are asymptomatic and have a normal physical exam, it is usually an incidental finding through imaging for other reasons. Spontaneous abortion, preterm labour, malpresentation, and increased incidence of caesarean section are all well-known complications of bicornuate uterine pregnancy. The pregnancy outcome is poor, with an abortion rate of 36%, preterm delivery rate of 23%, term delivery rate of 41%, and live birth rate of 55%. In a study outlining the clinical implications of uterine anomalies, it was found that the relative risk of first or second trimester miscarriage in a patient with a bicornuate uterus is 2.40. The same study also found that the relative risk of first-trimester spontaneous abortion in a patient with a bicornuate uterus is 2.32 [8]. The patient presented is multiparous and has three living children despite having the multiple risks associated with pregnancy in a bicornuate uterus. The patient has had three viable pregnancies, thus has less likelihood for suspicion of a congenital uterine abnormality. Congenital or acquired uterine anomalies, that distort the uterine cavity are among the several contraindications to IUD placement. Unlike other contraindications which could be easily ruled out by history, physical examination and basic labs, uterine anomalies are better detected with imaging. If an IUD is placed without screening for uterine abnormalities it can lead to complications such as uterine perforation, or like in this case, may not be an effective method of contraception for the patient. IUD insertion is normally done blindly, unless a difficulty is encountered, then an ultrasound can confirm the placement. Ultrasound is widely available, noninvasive, and a relatively inexpensive diagnostic tool used to evaluate uterine anatomy. Since bicornuate uterus is asymptomatic, undiagnosed patients, like our patient, may have an IUD placed in one horn of the uterus, but still have the other horn viable for conception. Due to the prevalence of congenital uterine anomalies, it may be considerable to perform an ultrasound during evaluation for IUD placement to prevent future occurrence of similar cases. A transvaginal ultrasound is the choice of imaging to make the diagnosis. A finding to suggest a bicornuate uterus is a caudally fused uterus comprising of two separate cavities. The angle between the two horns of the cavity is usually greater than 105. Other findings suggestive of a bicornuate uterus include a fundal depression depth of >1cm, and an intercornual distance of >4cm. Conclusion Although bicornuate uterus makes up for about 0.4% of the congenital uterine anomalies, most of these patients will not be diagnosed leaving for the possibility of IUD placement in patients for whom this would be an ineffective method of contraception. History and physical are often not enough to make the diagnosis, as in the presented patient. Screening for uterine abnormalities with an ultrasound could be a good way to ensure that there are no anatomical contraindications prior to IUD placement.

Written informed patient consent for publication has been obtained.