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Leiomyomas are the most frequently occurring tumours of the uterus, affecting 30–40% of women1. The peak incidence is during the third or fourth decade of life. Leiomyomas occur in 2–4% of pregnancies, and their incidence in pregnancy may be increasing as women delay childbearing2,3. In addition, routine use of ultrasound during pregnancy has increased the detection of leiomyomas3.

Leiomyomas in pregnancy may be associated with a variety of pregnancy complications, including miscarriage, preterm rupture of the membranes, preterm labour, placental abruption, painful degeneration, postpartum haemorrhage, fetal malpresentation, fetal growth restriction and the need for caesarean delivery, with or without hysterectomy2. Complications may be related to the size and location of the leiomyomas4. We describe the clinical course of a pregnant woman with a very large myomatous uterus resulting in complete obstruction of the inferior vena cava early in the second trimester of pregnancy. No previous report of complete obstruction of the inferior vena cava from a myoma during pregnancy was found during a Medline search of the English literature from 1966 to the present by using the keywords ‘leiomyoma’, ‘thrombosis’, ‘inferior vena cava’, ‘fibroid’, and ‘pregnancy’.

Case report

  1. Top of page
  2. Case report
  3. Discussion
  4. References

A 36 year old parous woman was seen at 17 weeks of gestation with an intrauterine pregnancy and an abdominal mass. She complained of increasing shortness of breath, abdominal pain, difficulty in walking, loss of appetite and weight loss since becoming pregnant. On clinical examination, there was a mass in her abdomen about 12 cm in diameter. Ultrasound examination revealed multiple myomas and a large, separate multicystic mass with solid areas in the left adnexa, extending from the left side of the pelvis to the xiphoid process, possibly of ovarian origin. We discussed pregnancy termination and the possibility of a complete hysterectomy with staging if an ovarian malignancy was discovered.

The woman was admitted for an exploratory laparotomy the following morning. On admission, her blood pressure was 118/60 mmHg, pulse 80 beats per minute, respirations 16 per minute and weight 65 kg. A midline incision was made from the pubic symphysis to the xiphoid process. A large, soft, degenerated cystic fundal leiomyoma filling the abdominal cavity was found. There were omental adhesions to the leiomyoma, with dilated parasitic vessels supplying the mass. The uterus was rotated to the left by approximately 180°, with the right side of the fundus adherent to the omentum in the left upper quadrant of the abdomen. The ovaries appeared normal, with large, dilated blood vessels. Multiple, smaller firm myomas were noted on the left side of the uterus. No definitive operative procedure was performed, and the abdomen was closed.

Post-operatively, the woman was given subcutaneous heparin injections, 5000 units twice daily, and she wore elastic stockings. On the second post-operative day, she experienced significant swelling of her left leg, the circumference of her left thigh measuring 10 cm more than her right thigh. Examination by Doppler ultrasound excluded deep vein thrombosis, but the blood flow from the legs was slow. Magnetic resonance venography was performed, which revealed no filling of the femoral veins or the inferior vena cava to the level of the renal veins. The inferior vena cava below the renal veins was markedly compressed by the mass, with collateral circulation present. Our initial diagnosis was thrombosis of the inferior vena cava. A Greenfield filter was inserted in the inferior vena cava above the renal veins, as the mass prevented placement below. Further examination of the magnetic resonance venogram, however, suggested that compression of the inferior vena cava was more likely. Her pregnancy continued.

The woman's appetite was poor and she had lost more weight. She was therefore treated by total parenteral nutrition, and her weight was constant at 64 kg for the rest of her pregnancy. From 24 weeks of gestation, she received intramuscular betamethasone weekly until 34 weeks of gestation. She was able to stay at home for the majority of the remainder of her pregnancy. Uteroplacental function was measured by serial fetal biometry and non-stress cardiotocography. Two weeks prior to delivery, the low molecular weight heparin was replaced by subcutaneous heparin injections twice daily, which was then discontinued two days prior to surgery.

Caesarean section was planned for 38 weeks of gestation to avoid potential problems associated with labour. On the morning of her operation, catheters were inserted into both femoral arteries in case arterial embolisation was required. General anaesthesia was induced, and the abdomen was opened by a midline incision. A posterior low vertical uterine incision was made between the uterosacral ligaments, in view of the rotation of the uterus. Her infant son was born without difficulty. He cried at birth. His weight was 2.78 kg. The uterus was left in the abdomen during repair on account of omental adhesions to the leiomyoma and concern over dislodging a possible thrombus in the inferior vena cava. The uterine incision was repaired in two layers with a polyglactin polymer suture. Myomectomy was not performed. Her estimated blood loss was 1500 mL. A prophylactic antibiotic was given after the umbilical cord was clamped.

The femoral catheters were removed 6 hours after the caesarean section. That same evening, she developed hypovolemic shock. Her haematocrit had decreased from 36.3 to 18.6 mg/dL. She received four units of packed red blood cells. On the second post-operative day, she had a fever of 38.4°C, possibly due to endometritis, which was treated with intravenous antibiotics. Low molecular weight heparin, which had been stopped for the caesarean section, was started again on the third post-operative day and continued for six weeks.

Computed tomography showed that the large fibroid compressed the descending colon. Magnetic resonance venography showed partial flow of blood in the right common iliac vein and the inferior vena cava, with the left common iliac vein completely blocked. She was discharged home on the ninth post-operative day. Her appetite returned postpartum and she gained back the weight she had lost. She subsequently had an uncomplicated myomectomy six months postpartum.

Discussion

  1. Top of page
  2. Case report
  3. Discussion
  4. References

The incidence of complications in pregnancy secondary to leiomyomas is 10–40%2. The most common complication is painful degeneration, which can usually be treated conservatively by analgesia. Retroplacental leiomyoma is associated with prelabour rupture of the membranes, intrauterine growth restriction and placental abruption2–4.

Compression of the inferior vena cava occurs in a majority of pregnant women, beginning in the mid-trimester. Uterine artery blood flow is decreased, but the uteroplacental circulation is well maintained5,6. There is no information about how much a very large leiomyoma might contribute to compression of the inferior vena cava.

Thrombosis of the inferior vena cava in pregnancy is rare and is usually associated with deep vein thrombosis or with thrombophilia6,7. Diagnosis may be difficult. Magnetic resonance imaging is the preferred diagnostic test, and if thrombosis of the inferior vena cava is confirmed, anticoagulation and the insertion of a filter are necessary.

There were many dilemmas in the treatment of this case. The initial radiologic suggestion of thrombosis of the inferior vena cava led to the insertion of the Greenfield filter above the renal veins. The revised diagnosis of extrinsic compression of the inferior vena cava by the large fibroid meant that the Greenfield filter was probably unnecessary, but once inserted, it was unjustified to remove it in pregnancy; besides, she was at high risk of secondary thrombosis in the tributaries of the vena cava. It was justified, therefore, to leave the Greenfield filter in place and to continue with anticoagulation. Low molecular weight heparin appears effective and safe in pregnancy8.

Due to possible complications in labour, such as uterine inertia, rupture of the uterus and postpartum haemorrhage, a caesarean section was performed. Myomectomy or hysterectomy at the time of caesarean section would have been too risky.

Another problem that had to be overcome was the woman's malnutrition due to compression of the intestine by the large fibroid. Intravenous nutrition was therefore necessary, and was successful in maintaining her weight.

The authors believe this is the first reported case of complete obstruction of the inferior vena cava due to a large uterine fibroid. This case illustrates the difficulties in the diagnosis and treatment of the condition.

References

  1. Top of page
  2. Case report
  3. Discussion
  4. References