Uterine torsion and ischaemia of one horn of a bicornute uterus: a rare cause of failed second trimester termination of pregnancy

Authors


*Dr K. S. Ol´h, Department of Obstetrics and Gynaecology, Warwick Hospital, Lakin Road, Warwick CV34 6BN, UK.

Case report

A 30 year old woman with a known uterus didelphis bicollis (complete duplication with a midline vaginal septum) booked in her third pregnancy at 16 weeks of gestation. Her first pregnancy had resulted in an elective caesarean section for breech presentation at term, and the second had been a missed abortion at 12 weeks of gestation. The pregnancy had been in the right uterine horn on both occasions. An ultrasound scan had confirmed her dates to be correct, and that the right uterine horn was again the site of the pregnancy. The woman was booked for shared care and consultant review at 34 weeks of gestation.

At 21 weeks of gestation she came to the accident and emergency department with a history of lower abdominal pain and absent fetal movements. She described the pain to be acute in onset, severe and sharp. On examination she had a small volume pulse at 64 beats/minute, with a blood pressure of 110/80 mmHg. Her uterus corresponded to the size of a 28-week pregnancy and felt tense and distended. Examination of the right sided vaginal entrance and cervix confirmed an uneffaced cervix. An urgent ultrasound scan showed an absent fetal heart, with a huge mass within the uterus measuring 14.5 cm × 12 cm × 9 cm, probably a retroplacental clot resulting from placental abruption. Coagulation studies and crossmatching were performed before termination of pregnancy with gemeprost was commenced. However, 24 hours later there was no change in the cervix and her haemoglobin concentration had decreased to 8.4 gm/dL. A repeat ultrasound scan was arranged to check for the site of pregnancy, which was confirmed to be in the right uterine horn. A second course of gemeprost pessaries was started, on completion of which her labour was still not established. Her condition had deteriorated. Vaginal examination showed the right cervix to be uneffaced and undilated, whereas the left cervix was 1cm dilated.

After review it was decided to start an extra-amniotic prostaglandin infusion. Under aseptic conditions a Foley catheter was introduced into the right cervix and the prostaglandin infusion started. Forty hours later there was no change in the cervix and although she complained of continuous pain, there were no discernible contractions.

By the fifth day after admission all attempts at termination of her pregnancy had failed. On examination she had oedema of both legs, a generally distended abdomen and shortness of breath. There was no evidence of disseminated intravascular coagulopathy. A laparotomy was performed, when the right uterine horn was found to be distended to the size of a term pregnancy and was quite obviously ischaemic with a torsion (dextrorotation) at the level of the isthmus. The right ovary also appeared to be devoid of its blood supply. The left uterine horn looked normal, although the left adnexa was swollen with fibrinous adhesions. The right horn was opened with a cutting diathermy and the placenta, clot and fetus were evacuated. No bleeding occurred during the uterine incision. The contents of the uterus were foul-smelling. Resection of the right uterine horn and right salpingo-oophorectomy was performed. The woman made a full recovery and was discharged on the seventh post-operative day.

After a further year she was reviewed when she had failed to conceive. An ultrasonic hysterosalpingography showed a blocked left fallopian tube. After in vitro fertilisation she conceived with twins. Her pregnancy was uncomplicated initially, and serial ultrasound scans for growth were performed. At 30 weeks of gestation one twin showed an absence of growth from her previous scan at 28 weeks, and Doppler examination of the umbilical artery showed no end-diastolic flow. In view of these findings the woman was given steroids and transferred to a regional centre. An emergency caesarean section was performed. At operation there was a left unicornute uterus with normal left tube and ovary with filmy adhesions around the tube. The right uterine horn and adnexa were absent. Twin 1, a boy, weighed 1.44 kg, and Twin 2, a girl, weighed 830 gm. Both twins were transferred to the neonatal unit and made good progress.

Discussion

Uterine anomalies occur in 0.1%–0.5% of all women1,2. The most common of these are the symmetric or duplication anomalies, including didelphic, bicornute, and septate uteri. Bicornute and septate uteri occur more frequently than didelphic uteri.

Uterine torsion was first described by an Italian veterinary surgeon in the year 1662 and there have since been various theories put forward to explain its aetiology. Torsion is more common in the presence of uterine fibroids, presumably due to the asymmetrical weight distribution within the uterus. There is a consensus of opinion that the transmission of body movements plays an important part in activating torsion and has been implicated in previously reported cases3. Contractions of the abdominal muscles or the degree of filling of the bladder and distension of the intestines are thought to contribute to this mechanism. In malformed uteri the discrepancy in uterine vascularity and development of one-sided muscular and fibrous attachments causes the pregnant horn to develop a high degree of mobility.

As this condition is extremely rare a high degree of clinical suspicion is required. The correct diagnosis in this case was not made before her laparotomy. In fact, the reports of all cases published so far show that torsion of the pregnant uterus is very seldom recognised before it is demonstrated by operation. This is probably due partly to the infrequency of the complication, but chiefly to the lack of characteristic symptoms. In our case, the failure of the uterus to respond to oxytocics was due to ischaemia of the myometrium. Dilatation of the adjacent cervix was a result of the viability of that uterine horn and the absorption of prostaglandins into the systemic circulation. However, it is uncertain when the uterine torsion occurred. The condition is usually associated with pregnancy in the third trimester, and may have been precipitated by the rapid increase in size of the uterus following the placental abruption. Although uterine torsion may give rise to similar symptoms as a concealed placental abruption3 this case suggests that placental separation and fetal death were the antecedent events. In women who are known to have uterine anomalies who have acute severe abdominal pain in pregnancy, the possibility of uterine torsion should be considered.

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