Pharmacotherapy of unicornuate uterus is the use of medications in the treatment of unicornuate uterus (Pic. 1) and its associated conditions and complications. Although the condition itself is usually managed mainly surgically, medications are used in the management of obstetric complications of the condition.
Unicornuate uterus is a congenital uterine anomaly, where the uterus is has functional connection with only one Fallopian tube instead of two. Unicornuate uterus has therefore only one uterine horn and looks banana-shaped. On the other side, up to 65% of women with unicornuate uterus may have a smaller, rudimentary horn (an underdeveloped horn, the part of the uterus that connects it to the Fallopian tube). The rudimentary horn may be either solid or may have a small cavity with functioning endometrium (inner lining of the uterine cavity). The presence of a rudimentary uterine horn with cavity leads to well characteristic gynecological and obstetrical complications. Most rudimentary horns are asymptomatic; however, some contain functional endometrium, although not necessarily normal. Cyclic or chronic pelvic pain (usually the presenting symptom), hematometra (presence of blood in the uterine cavity), and endometriosis (presence of endometrial tissue outside of its normal location) are often associated in these cases.
Women with unicornuate uterus commonly have reduced fertility, and the condition may be discovered when the patient undergoes an infertility investigation. Patients are also in a significantly higher risk of adverse pregnancy outcomes, most notably spontaneous abortion (up to 62%), ectopic pregnancy, preterm labor and breech presentation at birth.
If a rudimentary horn is present, it may be surgically removed to prevent possible complications. Surgical intervention is required in case the rudimentary horn causes pelvic pain, pelvic mass (possibly endometriosis) or when ectopic pregnancy occurs. For these purposes, laparoscopic approach (Pic. 2) is advised.
Because of the morphological nature of the diagnosis, pharmacotherapy is limited and it is mostly used as supportive to the surgical solution. However, medications may be used to prevent or treat obstetric complications of the condition, such as premature labor. In the latter half of pregnancy, recent data suggest that progesterone (female sex hormone with dominant role in the second half of the menstrual cycle) may be important in maintaining uterine quiescence by limiting the production of stimulatory prostaglandins (a class of bioactive molecules with many functions in the body) and inhibiting the expression of contraction-associated protein genes within the myometrium (the muscular portion of the uterine wall). When premature uterine contractions and shortening of the cervix occurs, tocolytic therapy (medications reducing the tone of the myometrium and thus inhibiting contractions of the uterus) may be administered to prevent premature birth.
Numerous small studies and case reports show that with the employment of progesterone administration, and tocolytic therapy in situations of premature contractions and cervix shortening, better prognosis of unicornuate uterus pregnancies can be achieved. Nevertheless, the optimal management approach cannot be clearly stated. Further large observational and prospective studies are essential to investigate the treatments needed during pregnancies in this uterine anomaly.
Administration of progesterone for maintaining uterine quiescence and of tocolytic drugs carries the risk of certain side effects of these medications.
Progesterone is usually well-tolerated. However, its possible side effects include abdominal cramps, back pain, breast tenderness, constipation, nausea, dizziness, edema, vaginal bleeding, fatigue, depression, and irritability. Side effects affecting vigilance and cognitive functions, such as drowsiness, sedation, sleepiness, fatigue, sluggishness, reduced vigor, dizziness, lightheadedness, confusion, and cognitive, memory, and/or motor impairment may occur with at high doses of progesterone. Progesterone may be therefore taken before bed to avoid these side effects and/or to help with sleep.
Common side effects of tocolytic drugs such as terbutaline, hexoprenaline or magnesium sulfate include flushing, headache, lethargy, muscle weakness, tremor, nausea or vomiting.
Unicornuate uterus is among uterine anomalies with the worst reproductive outcome, with the live birth rate of only 29.2%, prematurity rate of 44% and an increased risk of ectopic pregnancy. The presence of a rudimentary horn poses additional risk of complications and symptoms negatively affecting the quality of life, such as pelvic pain, and may require surgical removal. The possibilities of pharmacotherapy are limited in patients with unicornuate uterus due to the nature of the condition, and although certain pharmacological interventions may be beneficial in the management of obstetric complications of the anomaly, no optimal management strategy is currently known.