Fibroids, Red Degeneration

Gynecology & Obstetrics

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Take home messages:
1. Red degeneration in pregnancy is believed to occur when a fibroid outstrips its blood supply, leading to progressive degeneration and necrosis.
2. These patients often present with an acute abdomen, with non-specific symptoms.
3. Ultrasound allows rapid and easy detection of fibroids. However, ultrasound is not sensitive for determining the presence of red degeneration.
4. As red degeneration is self-limiting, the management is usually conservative.

Uterine fibroids are the most common tumor of the female genital tract, with a reported incidence of between 0.1% to 3.9% during pregnancy. Less than half of these fibroids are detectable clinically - mainly if they are large.

Most pregnant patients with fibroids are completely asymptomatic. However, many others experience complications ranging from pain to bleeding to miscarriage.

When fibroids cause pain during pregnancy, the commonest cause is red degeneration. Less often, torsion of a pedunculated fibroid or impaction of a fibroid may also result in pain. Overall, it is estimated that red degeneration affects between 5% to 10% of pregnant patients with fibroids, with the highest incidence between 12 to 20 weeks of amenorrhea.

These patients typically present with acute lower abdominal pain, with may be severe and is often associated with nausea, vomiting and even fever. Examination may show a tender palpable mass in the uterus. In severe cases, there may be signs of localized peritonism.

Ultrasound scanning is the primary modality of diagnosis, and typically shows a fibroid corresponding to the area of tenderness over the uterus. Most often, the degenerating fibroid has a mixed echogenic appearance. Note however, that these sonographic findings of dengeneration are insensitive - their absence does not exclude this diagnosis.

As fibroids may cause other complications such as fetal growth restriction and malpresentations, ultrasonography is also important for evaluation in this regard.

Where sonography is inconclusive, abdominal MRI may be considered. In red degeneration, the typical finding is an uterine fibroid with increased T1 signal intensity.

Red degeneration is a self-limiting condition and is almost always managed conservatively. The pain should be managed symptomatically, with either NSAIDs or opioids. Where opioids are ineffective, a 24 to 48 hour course of indomethacin has been shown to be efficacious.

Note that NSAIDs are best avoided during the third trimester, as there is an increased risk of premature closure of the ductus arteriosus and oligohydramnios.

Myomectomy during pregnancy is best avoided, as there is a significantly increased risk of intraoperative bleeding. In addition, myomectomy should not be carried out at the time of cesarean section either, as there is a high morbidity due to hemorrhage.

Obstetrics & Gynecology Clinics of North America : Approach to the Acute Abdomen in Pregnancy (2007)
Obstetrical and Gynecological Survey : Fibroids in Pregnancy - Common but Poorly Understood (2006)
Best Practice & Research Clinical Obstetrics and Gynaecology : Acute complications of fibroids (2009)
American Journal of Roentgenology : MRI of Adnexal Masses in Pregnancy (2008)

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